secondarries

[janozr1]

Hi to all ,
Im going to eliminate secondarries with Haibeck prom - got vacum
hadecke with this nassesary sistem....everything will go out :mad:
Will cruise control - tempomat , afer that still working?
Thanks fo repy.
Jano

[Blue Flame Restorations]

I doubt that you'll ever regret "ripping out" the secondaries.

I'm sure someone will answer your question shortly.

[Paul Workman]

Hi to all ,
Im going to eliminate secondarries with Haibeck prom - got vacum
hadecke with this nassesary sistem....everything will go out :mad:
Will cruise control - tempomat , afer that still working?
Thanks fo repy.
Jano

Yes, cruise control and themperature controls, etc will still work. And, I think you will like the way it runs without them too!

Everything in PINK comes out. As you can see, the vacuum port on the right side of the plenum supplies vacuum for the cruise and everything else.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/plenumvacuumcircuitsLT5LargeLarge.jpg


Unless you have a "kit", you'll need some gaskets and some freeze plugs. I would assume Marc is going to round those up as a package and send it along with the prom, yes? If NO, then be sure to ask him for them, or PM me and we'll get it handled.

Jerry...are you reading this? You know the gaskets he'll need, and also the freeze plugs (Dorman 555s, as I recall?).

P.

[scottfab]

Hi to all ,
Im going to eliminate secondarries with Haibeck prom - got vacum
hadecke with this nassesary sistem....everything will go out :mad:
Will cruise control - tempomat , afer that still working?
Thanks fo repy.
Jano

Good luck with your LT4.9 conversion. :)

[Dynomite]

Hi to all ,
Im going to eliminate secondarries with Haibeck prom - got vacum
hadecke with this nassesary sistem....everything will go out :mad:
Will cruise control - tempomat , afer that still working?
Thanks fo repy.
Jano

As Paul says....Cruize Control is still functional as long as you do not eliminate the Cruize Control Vacuum on Passenger Side of Plenum. I think the passenger side Vacuum is Cruize Control and HVAC Vacuum ONLY which I think is what Paul is saying :handshak:


As you can see, the vacuum port on the right side of the plenum supplies vacuum for the cruise and everything HVAC else.
P.

see # 3 of LT5 Eliminated Systems (http://forums.corvetteforum.com/c4-zr-1-discussion/2942569-tech-info-lt5-eliminated-systems.html)
See Vacuum Systems (Secondary and Cruize) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581460752)

[Blue Flame Restorations]

Woops..... Another KLUDGE! :bootyshak

[Fully Vetted]

Good luck with your LT4.9 conversion. :)

Let's see. That means our hp per litre actually goes up!

[scottfab]

Woops..... Another KLUDGE! :bootyshak

It's not a kludge if it's well documented and supportable. Just a LT4.9 :sign12:

[Paul Workman]

It's not a kludge if it's well documented and supportable. Just a LT4.9 :sign12:

Well, I guess this delete secondaries thread is officially complete now! :)

P.

PS That should be LT5.1 = an improvement in performance and reliability.:dancing

[GOLDCYLON]

Documented failure

http://www.zr1.net/forum/showthread.php?t=15601&highlight=compelling+story


Pull em just saying :cheers:

[Blue Flame Restorations]

Documented failure

http://www.zr1.net/forum/showthread.php?t=15601&highlight=compelling+story


Pull em just saying :cheers:

I say just "rip 'em!!!".;)

[scottfab]

Well, I guess this delete secondaries thread is officially complete now! :)

P.

PS That should be LT5.1 = an improvement in performance and reliability.:dancing

I suppose that could be true. Does anyone have dyno results from a "secondaries only" change? In any event it's not an LT5 anymore.:mad:

As far as secondary hardware coming loose and falling out? Not a common failure I think.
I know I've heard of a tire pressure waring sensor letting loose and got smashed up in the tire but I chose not to take mine out. I just fixe them when they fail. I varied (mod) the sensor to not fail again in the same way it did.

[janozr1]

Ok Z owners , looks like that is my decision correct ...I would call it LT6 - need to get new engine badge :cool:
Just tell me where is located and how is looking sensor who stay there on
my 94
Of course , for help with parts that I will need to finish my engine will
touch Mr Jerry .... he allways resolve my wishes here oversea.....:salute:
regards ,Jano

[Blue Flame Restorations]

I suppose that could be true. Does anyone have dyno results from a "secondaries only" change? In any event it's not an LT5 anymore.:mad:

As far as secondary hardware coming loose and falling out? Not a common failure I think.
I know I've heard of a tire pressure waring sensor letting loose and got smashed up in the tire but I chose not to take mine out. I just fixe them when they fail. I varied (mod) the sensor to not fail again in the same way it did.

So why does "ripping/yanking out" the secondaries make it anything but an LT5?

[GOLDCYLON]

So why does "ripping/yanking out" the secondaries make it anything but an LT5?


I dont hear or see the logic either

[Blue Flame Restorations]

I dont hear or see the logic either


None to hear or see....:icon_scra

[scottfab]

So why does "ripping/yanking out" the secondaries make it anything but an LT5?

Is it then a LT4.9 or LT6? ummm, I don't think it's to be taken literally.
Just saying
Is a narrow body 88 with an LT5 in it a ZR-1?
Is a 63 with an LT5 in it a ZR-1 ?
Is a ZR-1 with a LS9 in it a ZR-1?
Is Fastlane's highly modified LT5/ZR-1 with ford parts still a ZR-1 ?
Don't really know if there is an answer.
Who really cares except NCRS ?

[Blue Flame Restorations]

Ummm.....yeah....just sayin'......

[GOLDCYLON]

None to hear or see....:icon_scra


I hear nothing posted here in this thread and I see nothing posted here in this thread to make the logical and supportable argument that removing the secondaries no longer qualifies a LT5 engine platform to still be anything less than a LT5 engine platform.

http://crayfisher.files.wordpress.com/2011/10/schultz.jpg

Even after a proven and documented failure with pictures no less. Using the earlier presented logic my 380 bottom end also no longer qualifies as an LT5 as too the 415 and 441 stroker motors????What about the top end port and enhanced intake cams?? Same argument I guess

The LT5 is still a LT5 no matter how you improve it, modify it..... reguardless.

Now the argument is about dropping the LT5 in a different car and Calling it a ZR-1. Which again is illogical and an apples to organges argument.

Scott you truely are confused as your smiley suggests.... GC

:cheers:

[scottfab]

.... snip....
Scott you truely are confused as your smiley suggests.... GC

:cheers:

I think there is a big "tell" here for several of those that "rip" secondaries out. The "tell" is the sensitivity. If one really believed that ripping stuff off the car (be it secondaries or Bose or ????) instead of simply fixing it there would not be this sensitivity and prodding for an argument repeatedly. There would be righteous indignation and non, if any, defensive reaction. Those that have had the secondaries ripped and reallllly believe it's right would "relax" and in the knowledge it "right for them". I'm done. Have your last shot. "confused"? That's pathetic.

[Blue Flame Restorations]

Scott, it "was" you, who sensitive, went on a rant about how cars that had the secondaries removed were "kludges" (your word) and were undocumented messes. Then, you got personal and your posts were so damning that the mods on CF deleted them. That was truly pathetic in itself.

Just because someone mods THEIR own car rather than doing what you think is correct doesn't mean that they are wrong or making their car anything but an LT5 ZR-1.

Many, including myself, choose to rip them out. Not because they failed.

Yeah, relax........:cry:

[Paul Workman]

I think there is a big "tell" here for several of those that "rip" secondaries out. The "tell" is the sensitivity. If one really believed that ripping stuff off the car (be it secondaries or Bose or ????) instead of simply fixing it there would not be this sensitivity and prodding for an argument repeatedly. There would be righteous indignation and non, if any, defensive reaction. Those that have had the secondaries ripped and reallllly believe it's right would "relax" and in the knowledge it "right for them". I'm done. Have your last shot. "confused"? That's pathetic.

http://i185.photobucket.com/albums/x220/6PPC_bucket/AwJeez2.jpg

SENSITIVITY?? The ONLY one that seems to have an issue with deleting secondaries...IS YOU, Scott. But, the rest of us that have pulled them for various reasons aren't wringing our hands for having done it, or berating anyone who is a purist (as your "tell" indicates) for keeping it an NCRS car. In fact, I'll wager those sans secondaries are all pretty happy to say "good ridance!" So, it appears to me that if there is any "sensitivity" by us, it is being berated again for doing what may well be considered an improvement by those that have done it.

Externally she looks stock. Nobody would ever know from the outside that anything was amiss...

http://i185.photobucket.com/albums/x220/6PPC_bucket/Vettes/10-17-10012.jpg

Only after the top end is pulled would it become obvious just why keeping the secondaries is moot...

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Headporting1.jpg

500+ FBI package, sans secondaries... [I]WHAT IS NOT TO LIKE?

Have a look at this video of this LT5 assembled.

http://www.youtube.com/watch?v=y1YFa8ruh8A

Personally, I researched opting out of the secondaries for over a year; make it two years before doing it. It is a well thought out procedure, works like a charm as result - with multiple upsides, plenty of people that have done it and like the results, no downsides I'm aware of, and it is a well documented, clean disinstallation with no rough edges: no "kludge".

And one of the final tuning points for me was seeing the next generation LT5 that didn't go into production. Guess what? NO SECONDARY RUNNERS! So, enough already with dem "negative waves" K? We got it. You don't like it. But, we're not lesser men because we improved upon the design of the LT5 to our needs/liking.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1007.jpg

[Dynomite]

Am I missing something :sign10:

http://i287.photobucket.com/albums/ll142/dynomite007/D%20Engine%20LT5/56166ae0-ebac-4d2f-a0ee-bfc040371a6b.jpg
http://i287.photobucket.com/albums/ll142/dynomite007/D%20Engine%20LT5/58321d12-26c5-46ef-addf-e8d79e06317e.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/D%20Engine%20LT5/5b237cbb-96a3-4636-8b08-ca33751969b0.jpg

[Pete]

Yeah,secondaries. LOL



Am I missing something :sign10:

http://i287.photobucket.com/albums/ll142/dynomite007/D%20Engine%20LT5/56166ae0-ebac-4d2f-a0ee-bfc040371a6b.jpg
http://i287.photobucket.com/albums/ll142/dynomite007/D%20Engine%20LT5/58321d12-26c5-46ef-addf-e8d79e06317e.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/D%20Engine%20LT5/5b237cbb-96a3-4636-8b08-ca33751969b0.jpg

[Fully Vetted]

Holy crap! This turned fugly fast.

Scott, and this is an honest question, what is the difference between removing the secondaries and removing unwanted metal aka porting. In each instance we are removing something that was put there by the manufacturer to, in our opinion, either improve performance OR improve reliability. My secondaries were removed by the PO so I'm trying to put myself in the shoes of someone that is considering this procedure.

[Pete]

As everybody knows my secondaries have been out for about 10 years.

My understanding as to why chevy put secondaries was emissions and gas guzler tax.
I can also see the point where our Z's are known/famous for the power key.

I really never had anybody in my Z that asked me to run her with the power key off.
Another point i would like to make is the C6 ZO6 with the exhaust flappers most replace them,does that make it a lesser ZO6? i call it a mod.
It would not stop me from buying it,unless i was looking for a NCRS car.

If someone was looking for a collector low mileage stock Z there are plenty of those and for those that are looking for a clean fast Z plenty of those and they don't have to worry about vacuum leaks.

Either or way people decide to go it's there choice.
I will add it will not effect drivability,w/chip reprogram.
Just my thoughts.

Pete

[Dynomite]

As everybody knows my secondaries have been out for about 10 years.

My understanding as to why chevy put secondaries was emissions and gas guzler tax.
I can also see the point where our Z's are known/famous for the power key.

I really never had anybody in my Z that asked me to run her with the power key off.
Another point i would like to make is the C6 ZO6 with the exhaust flappers most replace them,does that make it a lesser ZO6? i call it a mod.
It would not stop me from buying it,unless i was looking for a NCRS car.

If someone was looking for a collector low mileage stock Z there are plenty of those and for those that are looking for a clean fast Z plenty of those and they don't have to worry about vacuum leaks.

Either or way people decide to go it's there choice.
I will add it will not effect drivability,w/chip reprogram.
Just my thoughts.

Pete

Excellent Description of the issues regarding Secondaries and Elimination of Secondaries :thumbsup:

Here is yet another description of Secondary Elimination issues including some facts regarding effects on Horsepower :cheers:

Another Professional Opinion on Removing The Secondaries (http://forums.corvetteforum.com/c4-zr-1-discussion/2942569-tech-info-lt5-eliminated-systems.html#post1579114178)

[Hib Halverson]

As everybody knows my secondaries have been out for about 10 years.

My understanding as to why chevy put secondaries was emissions and gas guzler tax.(snip)

Exhaust emissions and beating guzzler had nothing to do with the existence of the port throttles. In fact, guzzler was never and issue with the LT5.

The secondary port throttles exist soley to improve low speed torque and throttle response.

Another point i would like to make is the C6 ZO6 with the exhaust flappers most replace them. (snip)

Actually, most C6ers with cars having NPP do not "...replace them". Admittely, some folks do swap an aftermarket exhaust for the stock dual-mode system, but more C6 people retain the NPP system but add an device ("Mile2Wild", "Exhaust Commander" and similar products) which allows them to manually control the exhaust bypasses.

[Blue Flame Restorations]

Exhaust emissions and beating guzzler had nothing to do with the existence of the port throttles. In fact, guzzler was never and issue with the LT5.

The secondary port throttles exist soley to improve low speed torque and throttle response.


Actually, most C6ers with cars having NPP do not "...replace them". Admittely, some folks do swap an aftermarket exhaust for the stock dual-mode system, but more C6 people retain the NPP system but add an device ("Mile2Wild", "Exhaust Commander" and similar products) which allows them to manually control the exhaust bypasses.


Any data to support "most"?

[Pete]

Exhaust emissions and beating guzzler had nothing to do with the existence of the port throttles. In fact, guzzler was never and issue with the LT5.

The secondary port throttles exist soley to improve low speed torque and throttle response.


Actually, most C6ers with cars having NPP do not "...replace them". Admittely, some folks do swap an aftermarket exhaust for the stock dual-mode system, but more C6 people retain the NPP system but add an device ("Mile2Wild", "Exhaust Commander" and similar products) which allows them to manually control the exhaust bypasses.


If it was for low speed torque then they didn't do a very good job.
My Z stock was peaking 330RWTQ @ 5200 now i make that at 2500 and peak is right at 400 @ 5200.
If you look at Z's with ported top end and no secondaries they make anywhere from 300-330tq @ 2500-3000rpm and close to 400 peak.
If you tune the car right you will loose nothing at low speed,my Z with huge cams for a 350 can cruise at 1300 rpm and get 24 MPG highway.
A lot more has been done with todays technology in the tuning department for our Z's.

If you ask most will post there before and after dyno sheets.

If it wasn't for guzler tax then it must have been for emissions,back in the old days when we had that thing they call emissions (rollers) i forgot my secondaries on it failed next day with no changes just kept secondaries off it passed.(same location)

On the C6 ZO6 mufflers there are half dozen for sale as we speak on top of the half dozen i have bought the most recent (2 weeks ago) the gentleman replaced them with B&B's,there's a few ZO6 guys that replace them,you might not be one of them.
Most car shows and dragstrips i go to i see most have replaced them.

Pete

[Corbusa]

Ok I'm no mechanic as far as the LT5 goes , and I wish I knew more . I personally do like the secondaries being switched because ( I think its cool ) , yet I also like as much power without hastles of vaccume leaks . At this point in time I'd probably keep them in place, port all I can to get some extra ponies, and find some sort of space shuttle,futuristic alien tech vaccume line materials and put them on the engine , hoping to settle the issues of vaccume leaks.
So I guess keeping it simple , If I can get close to 500 ponies with them in and not have a constant headeches with vaccume issues I'll leave'm in , If not I'll have Pete yank'em out when Its time. Then use the extra key switch for some NOS.

[FU]

And I thought that Pete took out the secondaries for weight saving's.....

[Hog]

If it was for low speed torque then they didn't do a very good job.
My Z stock was peaking 330RWTQ @ 5200 now i make that at 2500 and peak is right at 400 @ 5200.
If you look at Z's with ported top end and no secondaries they make anywhere from 300-330tq @ 2500-3000rpm and close to 400 peak.
If you tune the car right you will loose nothing at low speed,my Z with huge cams for a 350 can cruise at 1300 rpm and get 24 MPG highway.
A lot more has been done with todays technology in the tuning department for our Z's.

If you ask most will post there before and after dyno sheets.

If it wasn't for guzler tax then it must have been for emissions,back in the old days when we had that thing they call emissions (rollers) i forgot my secondaries on it failed next day with no changes just kept secondaries off it passed.(same location)

On the C6 ZO6 mufflers there are half dozen for sale as we speak on top of the half dozen i have bought the most recent (2 weeks ago) the gentleman replaced them with B&B's,there's a few ZO6 guys that replace them,you might not be one of them.
Most car shows and dragstrips i go to i see most have replaced them.

Pete
Obviously Hib was talking about a stock application. Even Mark H admits torque loss under 1500rpm.

The secondaries are simply there to change the geometry of the intake manifold. Single small runner for low rpm torque, and 2 small runners for more upper rpm torque.power.

GM also used the variable geometry intake manifold on the 1992-95 CPI 4.3 V6. I'm sure there are other GM examples.

But of course ECM tuning will bring back some lost low rpm torque and throttle response.

In order to retain off idle low rpm throttle response, the single runner is used, this allows the engine to lumber around al low rpms, which allows for improved fuel economy and better emissions. Having low intake airspeed by having too much runner area (ie both runers open) at off idle rpms, in 4th gear(skip shift) will result in excessive throttle use and economy/emissions to worsen.

We are talking about 80's technology here, the LT5 ECM was very cutting edge with its injector control, but the calibration of the LT5 leaves much to be desired.
using todays ECM tuning and modern tuning techniques this can be overcome, but this ability wasnt available to the masses in the early 90's.
GM had to make bug power while meeting stringent emissions contraints. The engine must function in a variety of temps, humidities and altitudes and even in different countries with varying octanes and fuel qualities. All of these factors coupled with the technology at the time, all contributed to GM needing the primary/secondary runner/injector setup.
When the LT5 was being thought of, the wheezy TPI engine was top dog, it had great low/mid rpm torque, but was very wheezy in stock form, and only moderatley better on the 305.
GM had a choice, have a high revving engine, that had bad off idle/low rpm manners, would have poor emmisions and wouldnt satisfy the MAJORITY of drivers need for low rpm torque, or build an engine that did great at low rpm, but didnt have the power numbers that a flagship performance car needs.
The comprimise (if you can call it that) was the LT5 with its variable geometry intake. Decent off idle torque, with excellent high winding power numbers. Its like having the best of both worlds, being accomplished with what was available in 1980's engineering.

IMO the LT5 engineering challenge was akin to the STS-Space Shuttle program. GM knew they wanted a 400hp engine, but it had to fit in the Vette from underneath. Whereas, NASA wanted easy access to space, but were given parameters by the Gov. that the Shuttle had to fit. Like being more inexpensive(make it reuseable to be cheaper), in order for the Shuttle to get Airforce money, the shuttle needed wings to get cross range capability.
Lotus and NASA knew what had to be done, but were forced by outside influence to design a certain way.

Just imagine what the LT5 would have been if the car it was going into wasnt designed yet? There possibly could have been more room to fit in, therefore sprockets could have been larger, therefore increasing high rpm durability etc etc. Some big clues are found on the OBD2 version of the GEN 2 LT5. There was almost 10 years of tech. advancement between the 1st and 2nd GEN LT5 as well.
GM was able to satisfy power/torque needs, emissions(now OBD2) all without a variable geometry intake. IIRC they were using VVT in the GEN 2 OBD2 version of the LT5.

Sorry for the book, but I think that in a round about way, all of the reasons mentioned by EVRYONE previous are all correct reasons for the variable geometry intake manifold( dual runners/dual injectors per cylinder) that the LT5 uses.
Bottom line everyone is correct in some way because all the reasons mentioned are interrelated.

peace
Hog

[Pete]

Obviously Hib was talking about a stock application. Even Mark H admits torque loss under 1500rpm.

The secondaries are simply there to change the geometry of the intake manifold. Single small runner for low rpm torque, and 2 small runners for more upper rpm torque.power.

GM also used the variable geometry intake manifold on the 1992-95 CPI 4.3 V6. I'm sure there are other GM examples.

But of course ECM tuning will bring back some lost low rpm torque and throttle response.

In order to retain off idle low rpm throttle response, the single runner is used, this allows the engine to lumber around al low rpms, which allows for improved fuel economy and better emissions. Having low intake airspeed by having too much runner area (ie both runers open) at off idle rpms, in 4th gear(skip shift) will result in excessive throttle use and economy/emissions to worsen.

We are talking about 80's technology here, the LT5 ECM was very cutting edge with its injector control, but the calibration of the LT5 leaves much to be desired.
using todays ECM tuning and modern tuning techniques this can be overcome, but this ability wasnt available to the masses in the early 90's.
GM had to make bug power while meeting stringent emissions contraints. The engine must function in a variety of temps, humidities and altitudes and even in different countries with varying octanes and fuel qualities. All of these factors coupled with the technology at the time, all contributed to GM needing the primary/secondary runner/injector setup.
When the LT5 was being thought of, the wheezy TPI engine was top dog, it had great low/mid rpm torque, but was very wheezy in stock form, and only moderatley better on the 305.
GM had a choice, have a high revving engine, that had bad off idle/low rpm manners, would have poor emmisions and wouldnt satisfy the MAJORITY of drivers need for low rpm torque, or build an engine that did great at low rpm, but didnt have the power numbers that a flagship performance car needs.
The comprimise (if you can call it that) was the LT5 with its variable geometry intake. Decent off idle torque, with excellent high winding power numbers. Its like having the best of both worlds, being accomplished with what was available in 1980's engineering.

IMO the LT5 engineering challenge was akin to the STS-Space Shuttle program. GM knew they wanted a 400hp engine, but it had to fit in the Vette from underneath. Whereas, NASA wanted easy access to space, but were given parameters by the Gov. that the Shuttle had to fit. Like being more inexpensive(make it reuseable to be cheaper), in order for the Shuttle to get Airforce money, the shuttle needed wings to get cross range capability.
Lotus and NASA knew what had to be done, but were forced by outside influence to design a certain way.

Just imagine what the LT5 would have been if the car it was going into wasnt designed yet? There possibly could have been more room to fit in, therefore sprockets could have been larger, therefore increasing high rpm durability etc etc. Some big clues are found on the OBD2 version of the GEN 2 LT5. There was almost 10 years of tech. advancement between the 1st and 2nd GEN LT5 as well.
GM was able to satisfy power/torque needs, emissions(now OBD2) all without a variable geometry intake. IIRC they were using VVT in the GEN 2 OBD2 version of the LT5.

Sorry for the book, but I think that in a round about way, all of the reasons mentioned by EVRYONE previous are all correct reasons for the variable geometry intake manifold( dual runners/dual injectors per cylinder) that the LT5 uses.
Bottom line everyone is correct in some way because all the reasons mentioned are interrelated.

peace
Hog

Hog we are saying the same thing,about old technology what they had to do with what they had at the time.

We are also agreeing about technology has gotten better,performance has been vastly improved from 20-30 years ago and tuning devices have been improved.

I might have to disagree on this i don't think there is a loss below 1500 rpm if so what are we talking about? Again tuning comes into play.

If you as much as graze my gas pedal heck if you sneeze on it jumps to 1500 i will put my throttle response over any stock Z's thottle response.

I do have to say that i do idle at 900 with the big Stage III intake cams .242 .450 with .224 .420 exhaust in a 350ci motor.

When i drive my Z to Bowling Green(highway) i basicly leave her in 6th anything at or above 45mph she's good anything lower i'm at idle speed.

Pete

[RHanselman]

Just one data point from the guys working on the ECM at MegaSquirt. They found that keeping the secondaries closed at the lower RPM's helped them increase low-end torque by 40-50 at the wheels on my stock Ruby. They spent lot's of time maximizing the torque curve playing with the secondaries. He said they keep them closed a little longer than the stock tune. They also turn on the secondary injectors when the primaries get to a 80% duty cycle and then start ramping up the secondary injectors. He said that when the secondaries do finally open the graph on the dyno took a turn to the vertical... Ben from MS said several times during his phone report that they are very impressed with the LT5...

I'm sure the'll have more on the specifics during their presentation at BG...

Cheers,
RH

[Pete]

Just one data point from the guys working on the ECM at MegaSquirt. They found that keeping the secondaries closed at the lower RPM's helped them increase low-end torque by 40-50 at the wheels on my stock Ruby. They spent lot's of time maximizing the torque curve playing with the secondaries. He said they keep them closed a little longer than the stock tune. They also turn on the secondary injectors when the primaries get to a 80% duty cycle and then start ramping up the secondary injectors. He said that when the secondaries do finally open the graph on the dyno took a turn to the vertical... They (MS) are impressed with the LT5...

I'm sure the'll have more on the specifics during their presentation at BG...

Cheers,
RH

Again tuning comes in play you can't just yank the socendaries and think all is good.

So my understanding is if you were to port the top end on that Z it won't be driveable since we'll loose so much more low end.

Ron, my heads are 270cc intake runner plenum/IH's ported to 38mm,63mmTB,no secondaries huge cams my Z should be needing a push at every stop light like a Formula 1 car but i make more torque at 3000 rpm then most stock Z's make peak,so if i'm making 300 RWTQ @ 2500, 250 RWTQ @ 2000 and for arguement sake lets say a stocker makes 50 less at those RPM's so my dyno sheet should read like a turbo car dyno graph at 12-1500rpm i make 100-150 torque but as soon as i get to 2000-2500 it would double and shoot up to 300+ torque so it would be a straight vertical line.

Brotha,i'm not smelling what anyone steped in.:neutral:

Again i will put my throttle response over a stocker anytime.

Pete

[RHanselman]

Again tuning comes in play you can't just yank the socendaries and think all is good.

So my understanding is if you were to port the top end on that Z it won't be driveable since we'll loose so much low end,it would be like a Formula 1 car it would need a push to get it going.

Brotha,i'm not smelling what they steped in.:neutral:

Again i will put my throttle response over a stocker anytime.

Pete

Just reporting what they found but I know it's apples and oranges... My car is stock... No port work... I know you have perfected your combination w/tuning... You may be able to do the same or better with the stock car with your techniques but we won't know until we compare the two side by side.

[Pete]

Almost forgot or just remembered.:)

Ok, here's the pudding on the secondaries.
Secondaries will open anytime you go WOT no matter what RPM your at.
From idle to 7000 rpm you go WOT secondaries are open.

I don't see too many guys complaining of how there stock Z's don't pull from a stop when they go WOT.

I don't know how they tested the low speed loss cause if they went WOT secondaries are open or did they just keep them closed etc.

Ron i didn't mean that comment towards you or the shop "not smelling what anyone steped in"
I meant it as to either i'm missing something or something is wrong and i could not put my finger on it,getting older and forgetful.:-D

Pete

[Paul Workman]

My stock 90 LT5 WOT (w/ secondaries) torque vs. WOT after porting both runners and SPTs removed.

As Pete said before, I too can't see where torque was lost on the low end - at least not above 2000 rpm...

http://i185.photobucket.com/albums/x220/6PPC_bucket/Dyno%20graphs/Dynographs_zps723fdad7.jpg

YMMV...

P.

[RHanselman]

Almost forgot or just remembered.:)

Ok, here's the pudding on the secondaries.
Secondaries will open anytime you go WOT no matter what RPM your at.
From idle to 7000 rpm you go WOT secondaries are open.

I don't see too many guys complaining of how there stock Z's don't pull from a stop when they go WOT.

I don't know how they tested the low speed loss cause if they went WOT secondaries are open or did they just keep them closed etc.

Ron i didn't mean that comment towards you or the shop "not smelling what anyone steped in"
I meant it as to either i'm missing something or something is wrong and i could not put my finger on it,getting older and forgetful.:-D

Pete

Ya Pete I know you're not directing at me... Just realize these guy's throughout the book (or never had it) on how the secondaries work. Their techniques for opening are nothing like GM programmed (from what they tell me). This is what's been taking them the longest. I'll share their technique as soon as I understand it or maybe we can ask some pointed questions at BG.

[RHanselman]

My stock 90 LT5 WOT (w/ secondaries) torque vs. WOT after porting both runners and SPTs removed.

As Pete said before, I too can't see where torque was lost on the low end - at least not above 2000 rpm...

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Dynographs_zps723fdad7.jpg

(Excel graph of data taken from separate dynos, SAE corrected.)

YMMV...

P.

Paul,

What we need is a comparison of the stock car with the GM ECM with and without the secondaries and then with the MS. If their tail is true then you'll see more TQ with the new ECM and the secondaries.

Cheers,
RH

[Paul Workman]

Paul,

What we need is a comparison of the stock car with the GM ECM with and without the secondaries and then with the MS. If their tail is true then you'll see more TQ with the new ECM and the secondaries.

Cheers,
RH

Yep. Looking fwd to it. Hope took see the presentation @ BG!

[Pete]

Thanks for posting the graph Paul.

If you notice it has 25 more torque across the whole graph w/no secondaries.
You guys are saying from 1000 rpm it would spike up and at 2000rpm it smooths out.
So the graph would look like this.

[RHanselman]

Thanks for posting the graph Paul.

If you notice it has 25 more torque across the whole graph w/no secondaries.
You guys are saying from 1000 rpm it would spike up and at 2000rpm it smooths out.
So the graph would look like this.

Nope, I'm not saying anything. Just passing along a data-point that the MS guys experienced during tuning my stock car. I'd like to find out if it's true.

Pete, I think you meant: "if you notice it has 25 more torque across the whole graph w/no secondaries AND PORTING"... By the graph it's unclear as to what mod caused the increase in TQ. Port could have made it all or they could have a ratio.

Paul, go out and put your secondaries back in real quick like and get us some numbers! In jest of course...

Cheers,
R

[Pete]

Ron,sometimes my brain is faster then my one finger typing.

I'm just speaking in general,not directly to you, just throwing out the way a stock LT5 chip programing works.

Paul don't worry you don't have to put your secondaries back in to find out.

From the old thinking bigger ports slow down velocity then Pauls ZR-1 and every other top end ported lt5 should loose more TQ/power.

Like i said in my previous post a pure stock Z secondaries are open anytime you go WOT no matter the RPM.

Stock LS3 has 260cc intake runner with no secondaries drives just fine,some CnC them to 275cc, stock LT5 head is a whole lot less from what i can remember 210-215 it shouldn't have any drivability issues we also have better valve angle.
Like i said i'm putting this stuff out from memory it's been a while since i did the R&D on the LT5 stuff (10 years).

The LT5 was ahead of it's time heck most LS stuff today came from LT5 development.
Pete

[Hib Halverson]

It is true that the port throttles are open anytime the engine is is at WOT, however, anything below 90% TPS (ie: "almost WOT") that's not the case. Below 90% TPS, SPT opening strategy varies according to TPS and RPM.

Stock or near stock 350s need port throttles to have good driveability and good torque at high part throttle in the lower RPM ranges.

Highly modified 350s may not need them and drag race-only 350s don't need them. Also, any engine modified by someone who doesn't give a s@@t about performance/drivability other than at WOT/high-rpm doesn't need them.

368s which are otherwise stock or near stock may not need them.

Bigger than 368s...rip 'em out.

If you're takin' 'em out, and you're actuators are good, send them to me.

[Paul Workman]

(snip) ...any engine modified by someone who doesn't give a s@@t about performance/drivability other than at WOT/high-rpm doesn't need them.

Hib... with all due respect... you're dead wrong about this. You're basing your statement on what "someone" has said or written, methinks, but certainly NOT on actual experience or testing! Theory goes just so far, and then truth is where you find it.

It's all in the tuning. May I suggest you put whatever tech references you're referring to aside and acutally drive one, so modified. I think you'd have some :confused: about what "some" have said or predicted about performance/drivability up to that point.

Incidently, the second generation LT5 under development did NOT have dual runners. Instead the runners resemble the siamesed Lingenfelter runners; i.e., one BIG oval port. Evolving from dual runners to a single runners, while maintaining the 4-valve head suggests (to me and others) some performance gain could be had without giving up performance and drivability. This is something perhaps suggested by the Lingenfelter mod success, but for certain has been demonstrated over and over again by those that have removed the secondaries (essentially reverting to a single port) in favor of drivability and performance. If they had it to do over, would Lotus have gone with the dual set of runners, etc? I wonder...

[LancePearson]

Most of us don't spend a whole lot of time at 750 to 1500 rpm so pulling them out is pretty much a non issue and if combined with porting and relieving and bigger exhausts with tubes seems to me the engine will breath better and be easily up there where the Lotus dyno tests were at a minimum if not well over that. If and when I open my plenum I may just go ahead and pull the secondaries to simplify the engine's mechanics entirely.

[XfireZ51]

Hib,

I wonder how much of the "stock motor needs secondaries" conventional wisdom is a result of removal but not addressing the tuning properly. Anecdotally, the problem should be exacerbated by top end porting of an otherwise stock motor.
More air by increasing volume should negatively affect flow velocity on the low end. And that should demonstrate itself as a loss of low end torque.
Perhaps the addition of freer flowing exhaust (re: headers) which tend to accompany other mods, may mitigate the effect of greater volume. How much of the "loss of low end" is SOTP instead of data driven? My own personal experience has been that porting the top end, and having secondaries come on just after idle has increased torque throughout the rpm range and I could post dyno sheets showing that. Most tuners will tune for WOT, but the process of tuning for part throttle is much more time consuming and involved than WOT.
Which is why it's not done. Having looked at calibrations from other tuners, I can tell you that the stock calibration is hardly modified if at all. And in fact, it needs to be modified quite a bit.
So my point is that we can't be sure how much of the low end loss is due to improper tune rather than strictly a result of removing secondaries. Maybe we'll never know.

[Hog]

Hog we are saying the same thing,about old technology what they had to do with what they had at the time.

We are also agreeing about technology has gotten better,performance has been vastly improved from 20-30 years ago and tuning devices have been improved.

I might have to disagree on this i don't think there is a loss below 1500 rpm if so what are we talking about? Again tuning comes into play.

If you as much as graze my gas pedal heck if you sneeze on it jumps to 1500 i will put my throttle response over any stock Z's thottle response.

I do have to say that i do idle at 900 with the big Stage III intake cams .242 .450 with .224 .420 exhaust in a 350ci motor.

When i drive my Z to Bowling Green(highway) i basicly leave her in 6th anything at or above 45mph she's good anything lower i'm at idle speed.

Pete
Cool Pete, sounds great. I was just following Mark Haibeck's lead about the under 1500rpm torque loss. I'm not sure, but maybe he was talking about removing the secondaries and then tuning for the new injector operations and not tuning to recover that under 1500rpm torque loss(if there is a loss at all)

You comments anout your highly modified/cammed 350 LT5 is very encouraging. It sounds like you car is very very driveable. I wouldn't enjoy a car that required excessive pedalling in order to pull away from stoplights.

I agree 100% with the ECM tuning. Having the proper calibration for any combo is paramount.

Sounds like removing secondaries along with "good" ECM calibration will not negatively affect drivability in the slightest, with only benefits being realized due to the improved calibration when compared to the stock late 80's early 90's calibrations.

I know that in the mid 90's OBD2 calibrations there are marked gains to be had from fueling alone, then add in the gains realized from Torque Management recalibration, makes for some very thrilling improvements in acceleration.
In the middle/late 2000's, acceleration gains from fueling/timing are much smaller, with a majority of gains coming from recalibrating PCM/ECM/TCM torque managemnt functions. In other words, in modern platforms there is less power to be found from tuning, as OEM calibrations are getting very precise. Conversely there is a lot to be found from 80's early 90's platforms.

I wish there was a way to pull the secondaries, but still allow the Power Key to function. Like could we pull secondaries, allow both injectors to run all the time, but when needed, only use 1 single injector when reduced power is requested with the key? My feeling is no, because that would result in excessivley lean mixtures with both intake runners providing air even with just the single injector functioning.
Is there any way to enable say a 4500rpm rev limit using the Power Key?

peace
Hog

[Hib Halverson]

(snip)
The LT5 was ahead of it's time heck most LS stuff today came from LT5 development.
Pete

Sheesh, Pete.
Where did you get the information that has you making that statement?
Or...maybe it's something in the water where you live?

[Pete]

Sheesh, Pete.
Where did you get the information that has you making that statement?
Or...maybe it's something in the water where you live?

Hib no matter what i say you just disagree.

Here's a couple of things that come to mind.
When was the last time GM build a production aluminum SBC that worked with no issues.

When did a production SBC have a front mount oil pump.
Among other little things.

Yeah i know it's a coincidence.

So go ahead and disagree nothing new.
Pete

[XfireZ51]

The LT5 was responsible for the GM Powertrain guys getting off their asses and developing the LSx series of motors. Minimizing pumping losses due to crankcase pressure was another area where the LT5 provided direction for the LSx. Accessories packaging was another.

[Paul Workman]

The LT5 was responsible for the GM Powertrain guys getting off their asses and developing the LSx series of motors. (snip)

That, if I recall, may have been a direct quote from Dave McLellan, said to a group of us standing around BSn at a BG gathering function...:wink:

[Blue Flame Restorations]

Pete, you're the credible one here. Anything to the contrary is just "talking to hear their head rattle".

[grahambehan]

At the time of the project ending announcement Roy Midgely made a presentation to the LT5 team at Lotus which included a page and a half of A4 bullet points on the technology transfer from the LT5 programme to what would become the LS engine family, guess I need to dig that out.

Meanwhile, fuel to the secondary debate:)

[Paul Workman]

At the time of the project ending announcement Roy Midgely made a presentation to the LT5 team at Lotus which included a page and a half of A4 bullet points on the technology transfer from the LT5 programme to what would become the LS engine family, guess I need to dig that out.

Meanwhile, fuel to the secondary debate:)

Thanks, Graham! Thanks for the graph (and hope to see the bullet points soon), and most especially, thanks for the LT5!!:cheers:

P.

[grahambehan]

Thanks, Graham! Thanks for the graph (and hope to see the bullet points soon), and most especially, thanks for the LT5!!:cheers:

P.

No problem Paul, I was just lucky enough to be part of the team, family really, that made the LT5 what it is.

Graham.

[XfireZ51]

Graham,

First of all, welcome! Super to have your one of a kind perspective.
Looking at the curves, was anyone ever able to explain that sag in the torque curve between 4-5Krpm that seems so characteristic of the LT-5.
I know Marc H. can show you graphs of variously modded LT-5 but that sag shows up on each one of them. Just curious.
BTW, how about a thread on the 2nd Gen LT-5 build?

Cheers.

[tf95ZR1]

Meanwhile, fuel to the secondary debate:)

OK, I'll be the dope. What are we looking at on these dyno curves?
I see pt open vrs closed and 2 sets of pulls, but..........

[Tyler Townsley]

Graham,

First of all, welcome! Super to have your one of a kind perspective.
Looking at the curves, was anyone ever able to explain that sag in the torque curve between 4-5Krpm that seems so characteristic of the LT-5.
I know Marc H. can show you graphs of variously modded LT-5 but that sag shows up on each one of them. Just curious.
BTW, how about a thread on the 2nd Gen LT-5 build?

Cheers.

Talked to Geoff today and he confirmed what I always thought. The dip you see is a combination of the 1 injector going into saturation and the 'turning on' of the 2 injector mode. I would be interested in seeing a run with the 2 injector graph right behind a all in graph on the same motor. Apparently the crossover point causes the motor to run a little lean in that part of the calibration.

Tyler

[grahambehan]

Tyler,
OK we have already confirmed that the LT5 goes into 16 injector at WOT, so lets think about that? There are many phenomina that influence the characteristics of an engine, ie the fundamental shape of the curve, P/T switching is not one of them, in this instance

Graham.

[Tyler Townsley]

Tyler,
OK we have already confirmed that the LT5 goes into 16 injector at WOT, so lets think about that? There are many phenomina that influence the characteristics of an engine, ie the fundamental shape of the curve, P/T switching is not one of them, in this instance

Graham.

OK Todd has a calibration mod that can be used in a stock motor that can be used to test that. It pulls the secondary throttle blades open and goes 16 injectors on startup. It changes nothing else in the calibration, run that back to back vs a stock calibration and see what happens.
In the stock configuration going WOT does not enable an instant 16 injector secondary's open mode there are a series of check points that have to be met before going to the next calibration configuration and into the final PE table.

If not that then its cam design? Ie the lower rpm profiles are such that its engineered for a leaner mixture and it gets more aggressive as the rpms elevate with a transition point where the motor is slightly under fueled.

Its got to be in the fueling, calibration or cams.

Tyler

[grahambehan]

OK Todd has a calibration mod that can be used in a stock motor that can be used to test that. It pulls the secondary throttle blades open and goes 16 injectors on startup. It changes nothing else in the calibration, run that back to back vs a stock calibration and see what happens.
In the stock configuration going WOT does not enable an instant 16 injector secondary's open mode there are a series of check points that have to be met before going to the next calibration configuration and into the final PE table.

If not that then its cam design? Ie the lower rpm profiles are such that its engineered for a leaner mixture and it gets more aggressive as the rpms elevate with a transition point where the motor is slightly under fueled.

Its got to be in the fueling, calibration or cams.

Tyler

Tyler,
You guys are "Really" too funny! If you press the right pedal at 1000 rpm the PT are open, so if, as the original question was about, there is nothing to do with PT opening what it is about is tuning resonances, whatever that means, google it.

Take Care

Graham.

[XfireZ51]

Tyler,
You guys are "Really" too funny! If you press the right pedal at 1000 rpm the PT are open, so if, as the original question was about, there is nothing to do with PT opening what it is about is tuning resonances, whatever that means, google it.

Take Care

Graham.

Graham,

Yes since the dyno graphs are at WOT, both injectors are obviously operational. By your response I take it is the fingerprint of the induction system harmonics.

[grahambehan]

Graham,

Yes since the dyno graphs are at WOT, both injectors are obviously operational.

No, if your talking about the dyno graphs I posted, the curves are PT open and PT closed, just trying to dispell the myth as potificated by an earlier post.

Graham.

[XfireZ51]

No, if your talking about the dyno graphs I posted, the curves are PT open and PT closed, just trying to dispell the myth as potificated by an earlier post.

Graham.

I was alluding to my own dyno graphs or ones that Marc H has in his shop. The graphs you posted reminded me of that.

[grahambehan]

Graham,

Yes since the dyno graphs are at WOT, both injectors are obviously operational. By your response I take it is the fingerprint of the induction system harmonics.

Sorry, obviously didn't read the question enough, my bad. There are many things that influence the characteristics of the engine. Fundamentaly we design the engine from the combustion chamber out. The variables include, zip tube length, plenum volume, runner length, runner gemetry, port length, port geometry,port volume, combustion chamber, exhaust geometry, valve timing, exhaust runner length, cam profile, timing etc. If we look at the modifications the aftermarket has done to the LT5 the fundamental characteristics of the engine have not really changed that much, so the shape torque curve, or it's relationship to BMEP, versus engine rpm will not change that much either. Now , obviously the peaks occur at different rpm, but the rest is what it is, without major geometry and architecture changes.

Graham

[tf95ZR1]

Nevermind............

:confused:

[grahambehan]

Ok, I guess I get to try and figure the graph out myself. It looks
like the primaries add a lot at the low end, but then fall. That's
when the secondaries kick in to haul a**. But deleting the
secondaries shouldn't affect the primaries at low RPM if the A/F is
adjusted, right? Are you saying it "bogs" at low RPM?

No, I'm not quite sure what takes figuring out. The primary port is a swirl generator and port throttles closed at low rpm = more torque. C0mbination of port geometry and cam profile. At higher rpm both open = more torque * 5252 = more power.

Graham.

[tf95ZR1]

re thinking

[XfireZ51]

tf,

The fact is elimination of secondaries usually accompanies other mods like top end port etc. So I think Graham's graph shows that there is an appreciable increase in low end torque w just primaries activated up through 4k when you eliminate other changes. Beyond that, not sure we have enough data. Perhaps gb does.

[tf95ZR1]

Thanks xf.
But we aren't really "eliminating" the secondaries, just adding them to the primaries throughout the RPM range. So the total possible airflow (volume) at low RPM increases, but I guess Mr. Behan's point is that the airflow dynamics and characteristics change in an unfavorable manner. There must be a solution.........

[Blue Flame Restorations]

eliminating the mechanical operation

[XfireZ51]

eliminating the mechanical operation

Thx Brett.:handshak:

[tf95ZR1]

eliminating the mechanical operation

Didn't somebody try electronic activation with servos? Scott F?

[Pete]

1: That can be fixed in the tune.

2: From the torque #'s this a 368ci ?

I've seen a lot of tuners programs none had any low rpm tuning.





http://zr1.net/forum/attachment.php?attachmentid=2354&d=1365253936 (http://zr1.net/forum/attachment.php?attachmentid=2354&d=1365253936)

[Pete]

Didn't somebody try electronic activation with servos? Scott F?

Ted the argument is if one takes secondaries completely out of the car it won't drive nice in traffic and then it's only a race car.

Pete

[Dynomite]

Ted the argument is if one takes secondaries completely out of the car it won't drive nice in traffic and then it's only a race car.

Pete

My 91' ZR-1 is both.....it drives nice in traffic and is a race car (with Pete's cams and Marc's chip) and porting (plenum, IH, Heads) and Jerry's gaskets and SW off road headers/exhaust and 87 octane or 91 octane fuel and power key always on and no secondaries and Ron Davis Radiator with Marc's 180 deg thermostat engine runs cool ALL the time with TB coolant blocked off and and and.....:p

Defective Stant Thermostats by Marc Haibeck (http://www.zr1specialist.com/HAT%20Web/facts%20and%20failures/thermostat.htm)

And and and.....cruise control works fine in answere to the question that started this thread :D

Hi to all ,
Im going to eliminate secondarries with Haibeck prom - got vacuum
headache with this necessary system....everything will go out :mad:
Will cruise control - after that still be working?
Thanks fo reply.
Jano

[RHanselman]

2: From the torque #'s this a 368ci ?

Pete,

I was able to get 450 rwtq from my stock block 350. Just a little top-end porting (excluding heads) with the secondaries remaining. Wasn't really that hard :)

http://i1132.photobucket.com/albums/m578/rhanselman/img001.jpg

[PhillipsLT5]

mine are eliminated, no problems, extra 10hp

[Pete]

Pete,

I was able to get 450 rwtq from my stock block 350. Just a little top-end porting (excluding heads) with the secondaries remaining. Wasn't really that hard :)

http://i1132.photobucket.com/albums/m578/rhanselman/img001.jpg


Nice
Ron,i almost fell off my chair when i saw this.:p
How much boost?
If i had to guess i'd say around 5lbs.
Pete

[XfireZ51]

I thought the same thing. That can't be NA!

[Paul Workman]

mine are eliminated, no problems, extra 10hp

10hp....Ain't too shabby, depending on whatcha pay for the chip calibration.;)

[RHanselman]

Nice
Ron,i almost fell off my chair when i saw this.:p
How much boost?
If i had to guess i'd say around 5lbs.
Pete

4-5 psi... Don't you love the area under that torque curve!

I'm going to do a single project when the stock car returns.

Raptor LT1/4 Single Turbo system on the LT5
Stock LT5 w/Jerry's Head Gaskets
The new ECM
Meth (for safety not power)
Fuel System upgrade (pump and inj)
6-8 psi
Goal is 525 - 550 squared...

[janozr1]

i get it .................Marc thanks , anybody see mr.Jeery ?


URL=http://imageshack.us/photo/my-images/543/img0256ak.jpg/]http://imageshack.us/a/img543/105/img0256ak.th.jpg[/URL]

[RHanselman]

Jerry is on vacation. I believe his last text was from a black sand beach in Tahiti...

Cheers,

[Hog]

At the time of the project ending announcement Roy Midgely made a presentation to the LT5 team at Lotus which included a page and a half of A4 bullet points on the technology transfer from the LT5 programme to what would become the LS engine family, guess I need to dig that out.

Meanwhile, fuel to the secondary debate:)
Thanks for posting that dyno graph Graham I have never seen a Secondary open vs. Secondary Closed dynograph overlayed before.

As expected extra airflow adds power and torque, and also raises the rpm at which peak power and torque occurs.

Looks like having the plenum throttles open costs about 30 lb/ft of torque at 2500rpm, I assume that if we exrapolated that graph to lower rpm, we would see even more torque loss with the Plenum throttles closed..

Both PT open and PT Closed both make the same 290 horsepower at 3900rpm.

Thanks again Graham.

peace
Hog

[Hog]

1: That can be fixed in the tune.

2: From the torque #'s this a 368ci ?

I've seen a lot of tuners programs none had any low rpm tuning.





http://zr1.net/forum/attachment.php?attachmentid=2354&d=1365253936 (http://zr1.net/forum/attachment.php?attachmentid=2354&d=1365253936)
I have looked for quite a while for this dyno readout that shows a pull with the Port throttles closed and another with the Port Throttles Open. Appears to be making more low rpm torque and less power with the Port Throttles closed, and less low rpm torque but more upper rpm power with the Port Throttles Open.
Thanks again for posting Graham.
I couldn't find it as I wasn't spelling secondaries the same as the title of this thread in the search box.

Graham, did you ever find that page with the bullets that illustrated what engineering from the LT5 program was used in the eventual GEN 3 LS1 engine program?