430-435 CHP now.....What can I do to get 500-510 CHP?

[Vette73]

Right now I'm 382 hp to the rear at 7,000 RPM...

Headers, exhaust , Chip,ported plenum , air horn and I/Hs ..
What can I do to bring this 91 to the 500-510 CHP?

I'm located in NY....Sent Pete an email this morning asking for his advice
since he did my porting..I know port matching the heads will give me more power, yet I don't do that type of work....

Any idea of the cost this might be to accomplish 500-510 horsepower at the crank ? I know Marc has a 510 package but my car is already modded with what I described above...

I was thinking of going to Vette Drs and picking there brain...
I heard stories that were good and bad about the place...

As far as labor, would it be easier to do head work by taking the entire motor out to get to the heads or,just breaking down the motor while its in the car?

[George Maz]

http://www.zr1.net/forum/showthread.php?t=26300
Hib has a 93-95 chip for sale. I'm not sure if it would work for a 91 without head porting. I'm surprised a California owner hasn't already purchased it considering the adjustment made to help pass emissions.
Otherwise, take a ride to Stafford VA and Dyno-tune at the new shop. You can always have Marc burn a chip with the modification info you send him.

[G8nightman]

Get a light weight fly wheel it should help you on your hp quest.

[We Gone]

I have Marc's 510 with stock FW and cats right at 495HP, I would say get your heads done.

[Hib Halverson]

To get 500 SAE at the flywheel w. stock manifolds and cats you need:

Ported heads
Ported housings
Fully or partually ported plenum
Cams reset
Bigger injectors
Low restruction air filter assembly
Exhaust manifolds deburred internally with port entries blended.
Stock cats with cat entries deburred and blended.
Low restriction exhaust system w. 2.75" or 3.0" pipe
Aluminum flywheel
93-94.5 octane fuel
Proper calibration

With the above set-up, my engine made 416 SAE at the wheels on a DynoJet and, using the .82 correction for C4 manuals, 507 SAE at the flywheel. The exact power output depends on the dyno and a host of other issues unrelated to the engine itself. Many other engines with similar packages of mods have made 495-505-hp SAE at the flywheel.

If headers are legal in your state, given proper cal and exhaust system, their addition will get you to 510-520 SAE at the flywheel.

[FU]

The Vette Dr's really don't work on LT5's now.

[Vette73]

The Vette Dr's really don't work on LT5's now.

Nobody does.....Maybe I will drive it out to Petes garage and take Amtrak home...Lol.......Its free for me....

[Paul Workman]

Nobody does.....Maybe I will drive it out to Petes garage and take Amtrak home...Lol.......Its free for me....

Marc's Web site lays out the steps to get to 510 @ the crank.

Either Pete or Marc can get you there, and as Hib suggested, it is comprehensive; yeah the motor has to come out.

Once the porting is done, the cam phasing has to be optimized and the calibration none during a live dyno session. (In that regard every motor is unique enough that to get the most from it the tuning can't be "cookie-cutter" i.e., someone burning you a chip.

Worth it? Oh...Yeah! You get a power delivery across a wider rpm range like what you might expect from a lot more cubic inches! It transforms the LT5. You get the performance without sacrificing reliability or driveability.

[FU]

Being that the heads are off for porting install a bigger intake valve and larger intake cams. If you want to go fast.

[XfireZ51]

My motor has gone thru an "evolutionary" upgrade, with Phase 1 being ported top end and port matched heads + headers/tune(my own). That put it at
398+rwhp.

Phase 2 was fully ported (GVD) heads + Pete's intake cams + my tune
430something rwhp. Very nice combo. Smooth power delivery

Phase 3 added Pete's exhaust cams + top end port touch up + SW Xpipe w
DynoMax muffs. Again, my tuning both on part throttle driveability and WOT.
This combo did more for torque which just feels great. As much as I liked Phase 2, I would not go back. Idle is a bit rougher, but all is forgotten once in motion.
454rwhp/402rwtq.

[Vette73]

My motor has gone thru an "evolutionary" upgrade, with Phase 1 being ported top end and port matched heads + headers/tune(my own). That put it at
398+rwhp.

Phase 2 was fully ported (GVD) heads + Pete's intake cams + my tune
430something rwhp. Very nice combo. Smooth power delivery

Phase 3 added Pete's exhaust cams + top end port touch up + SW Xpipe w
DynoMax muffs. Again, my tuning both on part throttle driveability and WOT.
This combo did more for torque which just feels great. As much as I liked Phase 2, I would not go back. Idle is a bit rougher, but all is forgotten once in motion.
454rwhp/402rwtq.

Sounds very good....

Right now I am basically happy with the performance of the car but seeing there is much you can do to the LT-5 I'm all ears..

Pete did my plenum and I/Hs and air horn...Picked up nice power...From what I hear if you do the heads and some cam work on the LT-5 much like your phase two, you can get a nice boost in horsepower ....

With that said,the cost ? That's what I have to find out before undertaking anything...I really don't want to get to the point on the Z where I'm spending a lot of money on mods and the value is basically going to stay the same...

I see a lot of modded C5 ZO6s on the corvette forum and that has peaked an interest.....The thing about my Z is that it's clean as hell and runs tops- knock wood......Only thing since owning it that went were, the starter,antenna, and now one of my rear speakers....The rear shocks are leaking and I have a good used set from one of the members that I will install soon..

[XfireZ51]

Well I would suggest that many of us put money into our cars for the enjoyment of it, not expecting any kind of return from the investment. The car is just a absolute blast to drive w 500hp+. Frankly, I think u r looking at diminishing returns when considering C5s which are pretty much a dime a dozen.
If u r going to be at BG, u r welcome to take a ride in my car and then tell me if you think the mods aren't worth it.

[We Gone]

Sorry but if your looking to get a return on your mods $ Personally I don't think it will happen in my lifetime. Including the buy in price for a 9k mile ZR-1 back in 02 I have over $45K in my now 60k mile car, but have loved every mile of it that money can't buy. Cars are for enjoyment not investment.

[G8nightman]

I agree MODS are moneys lost but always a plus for the next guy.

[1990 quasar blue]

You and I are in a similar boat. Similar mods and I'm at 390rwhp sae corrected. I go back and forth myself, as I know the next 35 hp don't come cheap. (Count on five grand easy.)Part of me thinks that I should do it, and part of me figures it's a 26 yo car that traps over 118 and can pull 30mpg if the circumstances are right. That usually makes me want to leave it alone and in a couple of years add something else that'll curl someone's hair. Right now a c5 z06 with a blower can be had for 25k. How long before a C6Z with heads and cam is at a similar price?That's less than I paid for my Z bone stock. They both will also make 500+ at the wheels. Now I'd never sell my Z for either but, I may save my pennies for another couple of years and give it a brother. Just a thought from someone in a similar circumstance. YMMV.

[Vette73]

You and I are in a similar boat. Similar mods and I'm at 390rwhp sae corrected. I go back and forth myself, as I know the next 35 hp don't come cheap. (Count on five grand easy.)Part of me thinks that I should do it, and part of me figures it's a 26 yo car that traps over 118 and can pull 30mpg if the circumstances are right. That usually makes me want to leave it alone and in a couple of years add something else that'll curl someone's hair. Right now a c5 z06 with a blower can be had for 25k. How long before a C6Z with heads and cam is at a similar price?That's less than I paid for my Z bone stock. They both will also make 500+ at the wheels. Now I'd never sell my Z for either but, I may save my pennies for another couple of years and give it a brother. Just a thought from someone in a similar circumstance. YMMV.

Yeah I hear Ya....The Z in my opinion is a very unique car and has a really good cockpit feel.....I sat in a new C7 and yeah it was a beautiful auto.The feel in the drivers seat just wasn't the same.....I'm not saying for this reason I would turn one down, but with the Zs sloping doors and cockpit feel, it's unique....

Just like you I go back and forth with adding the additional power....To port the heads with a tune is like 5,500 turn key...

[secondchance]

I agree MODS are moneys lost but always a plus for the next guy.

As for me, there won't be the next guy.

[cuisinartvette]

Headwork larger stroke etc youll dig it
Portmatching the heads not worth it $$

[ghlkal]

I go back and forth myself, as I know the next 35 hp don't come cheap. (Count on five grand easy.)

I was in the same position. While I really _wanted_ the 500HP crank, it was just too expensive. For many it's worth it to get into the heads and get that extra 35-40HP, but it wasn't worth the big bucks to me. I'm happy to merely have the 460 HP :)

[Paul Workman]

I was in the same position. While I really _wanted_ the 500HP crank, it was just too expensive. For many it's worth it to get into the heads and get that extra 35-40HP, but it wasn't worth the big bucks to me. I'm happy to merely have the 460 HP :)

You make an excellent point! As Miarc's web sit shows, you can get to "whatever" hp level you want a bit at a time as budget allows.

Maybe the best "bang for the buck" is porting the top-end: the plenum, the IH's, and port matching the heads (and a tune afterward, of course) and headers. You'll get 90+% of the performance increase one would expect after also doing the heads, for a fraction of the $$$. AND...ALL of it can be done w/o removing the motor. The next step in the evolution is porting the heads (at least). Because to do so is a "quantum leap" $$$$ wise, this point is characterized as "PHASE-I".

At this level the performance is transformed. My trap went from 113 mph to 118 mph without loosing a bit of dirveability or reliability in the process. And, honestly, if it were not for a burnt valve (probably due to the bad injector) I may have stayed at that level. But, since the motor had to come out to fix the valve, etc., I opted to finish my porting.

And, that said, although I picked up ~ 35 hp at the wheels for the effort (and $$), it wasn't the 'kick in the butt' I got from "PHASE-I"

Speed cost $$. So, get your wallet out for the next step.

The next "PHASE" (call it PHASE - II) i.e., porting the heads, involves removing the motor, the porting itself, re-phasing the cams, reinstalling the motor and then a live dyno tune...at a minimum.

At that point you'd be at your "510" goal. However, for far less than the incremental cost to port the heads, NOW would be the ideal time to install cams too! Cams more or less double the wheel hp you would expect from porting the heads alone. And, if the TB has not been opened to 63mm by now, doing so completes what all but the most intrepid modders would call PHASE II. Rear wheel (Dynojet) HP at this point will be around 450 SAE (where it matters). But, for bragging rights - dividing 450 by .82 to .85 will give you a nice chp number look at and show your friends.

As far as costs go, obviously the more of the work you can do yourself, the less out of pocket expense will be - not to mention the experience gained in the process!

In my mind, the next two phases (NA) are bore (sleeves, to be exact), and maybe off-set grinding the crank. The last phase is adding closed deck sleeves and a crank, tho the closed deck option could be done any time the motor is out for whatever reason, $$$ provided, of course.:p

Those boys that have done "the whole 9 yards" (427 or 441s) can attest to the raw snap of the neck one gets from going all the way. But, it ain't for those with thin wallets, fer sher!!

[Billy Mild]

We need a blower. :)

[Vette73]

We need a blower. :)

Yep we do......Everybody else has one....I saw a guy with a V6 Mustang have one....

[Billy Mild]

I have looked everywhere but have not found one yet. Also I don't know where we could put one unless we modded an intake and put it in the V of the engine. Delete the plenum and putting an E force supercharger in there. That would be awesome.

[Vette73]

They don't make one...From what I hear the compression is too high on the LT-5...Yet, than again with so much technology out there you would think someone would come up with one...

I mean every car you see out there is practically boosted.....Just basically bolt it on, modify your cooling system , a belt here and there and away Ya go...!!!

[Top Toy]

You can get close to your target without head work or headers if you Siamese your plenum and injector housings. I made 411 RWHP thru stock heads and manifolds. No loss of low end torque or drivability.

[Vette73]

You can get close to your target without head work or headers if you Siamese your plenum and injector housings. I made 411 RWHP thru stock heads and manifolds. No loss of low end torque or drivability.

My car does have headers, one of the first things I did when I got it.....

My plenum, inj housings and air horn are ported by Pete....

What, if anything is Siamese porting?

How does it differ from what I have done already...

[XfireZ51]

You can get close to your target without head work or headers if you Siamese your plenum and injector housings. I made 411 RWHP thru stock heads and manifolds. No loss of low end torque or drivability.

Dennis,

Do you think the siamesed ports even up the air flow between the two runners, or that it allows greater cfm?

[Top Toy]

Siamesing removes the partition between the primary and secondary runners. Answering Dom's questions, it both Increases air flow and balances flow between the two sides, although increasing air flow is the major benefit. Also eliminates the dead space in the secondary runner when your secondaries are not open if you haven't already eliminated your secondaries (also highly recommended). Vapors in the dead space coke in the runner and on the back side of the intake valve and make a real power robbing mess after a while.

Contrary to conventional wisdom, siamesing did not result in any loss of low end torque or drivability. Then adding headers (still stock heads) really woke it up! Didn't get to dyno it in that state, but conservatively estimate it at over 430 RWHP. 120 in the 1/4 on stock tires.

Now it's at Marc's finally getting the heads done and new cams. Stay tuned...

[XfireZ51]

Thanks Dennis. That's one thing I have not done on my intake. What would u suppose siamesing would add incrementally to a motor producing ~450rwhp?
Also, are you siamesing top and bottom of the injector housing, or just where it mates to the plenum?

[Vette73]

So basically when I sent out my plenum and I/Hs I should have been aware of Siamese porting? I'm guessing this should have been done when I originally had my porting done?

Or, is this modification have to be done in stages, and to get the most out of it, should the secondaries be relieved?

Juuuuuust a little confused....

[XfireZ51]

So basically when I sent out my plenum and I/Hs I should have been aware of Siamese porting? I'm guessing this should have been done when I originally had my porting done?

Or, is this modification have to be done in stages, and to get the most out of it, should the secondaries be relieved?

Juuuuuust a little confused....

There's no "silver bullet" to this. You could make the case that u should have had the heads ported and cams installed too. I think most of us have "upgraded" power on a step by step basis. I know I have. It helps if u r the kind that likes to constantly tweak things.

[Vette73]

There's no "silver bullet" to this. You could make the case that u should have had the heads ported and cams installed too. I think most of us have "upgraded" power on a step by step basis. I know I have. It helps if u r the kind that likes to constantly tweak things.

Good point ....As far as pulling the heads for porting I know I could not have done that....If I go that route I would have someone do all the work...

[Paul Workman]

Point of fact, Pete's motor does not have siamesed plenum or IH and is making north of 474 rwhp, back maybe 5 years ago. (Has bigger cams now). But, on the other hand, the GEN-II LT5 has siamesed runners, a single injector per cylinder, and made close to 550 hp at the FW. (I guess one could conclude that removing the secondary port throttles appears to have some advantage, being it is supported by the latter design. I know I'd never return to the SPTs - even if I could.)

There is some serious engineering that goes into intake dimensions architecture, and being that such parts for the LT5 are not so abundant as to experiment with, for ME I'd rather do the math and/or follow the successes of others that be on the "bleeding edge" of a hot rodder.

[Top Toy]

Dom - considering the porting and other mods you've already completed, my best guess is you'd pick up another 10-15 RWHP with siamesing. My plenum and injector housings are completely siamesed all the way down to the heads.

Vette 73 - as Dom pointed out, many of us have made a sport out of continually tweaking our cars to get more out of them and benefit from each other's experiences. Siamesing may be the last thing many people do but it was the first thing I did to my otherwise stock engine and I could not have been happier with the results.

[LGAFF]

alot of factors in individual results; cam timing, etc. My 90 made 441 rwhp @ 7100 373 ftlbs @5300 with siamesed runners and ported heads, but the torque seemed alittle low and they were large ports. Given, the car was never professionally tuned....cams are smaller, now I have ported 93 runners on the car ported to 36MM+, would be curious to see the difference; last year ran 12.1@121MPH with an 800RPM launch and a tach that was way off...

http://i134.photobucket.com/albums/q115/lgaff/188-1.jpg


My large plenum test resulted in a 20hp loss.



large plenum:
http://www.zr1.net/forum/showthread.php?t=24504&highlight=siamese

[tpepmeie]

But, on the other hand, the GEN-II LT5 has siamesed runners, a single injector per cylinder, and made close to 550 hp at the FW.

One has to be very careful drawing a comparison to the Gen-III engine, which indeed did feature a single intake runner per cylinder. That manifold and intake port were designed from the outset as a single hole--it is not as wide side-to-side as two separate holes with a divider in between.

When one makes our design injector housings "Siamese", you are dramatically changing the cross-section area of the manifold runner. And it doesn't necessarily flow more than a properly ported 2-hole design. I have airflow data showing a ported 2-hole design approx. 36mm each outflowing a maxed out fully siamesed housing.

I am a believer in keeping the correct port velocity through the whole intake tract. Not everyone subscribes to that--a lot of "bigger is better" out there. That's ok, different courses for different horses, or however that saying goes.

[LGAFF]

Wanna flow test a bigass plenum?

[Johnny5]

You make an excellent point! As Miarc's web sit shows, you can get to "whatever" hp level you want a bit at a time as budget allows.

Maybe the best "bang for the buck" is porting the top-end: the plenum, the IH's, and port matching the heads (and a tune afterward, of course) and headers. You'll get 90+% of the performance increase one would expect after also doing the heads, for a fraction of the $$$. AND...ALL of it can be done w/o removing the motor. The next step in the evolution is porting the heads (at least). Because to do so is a "quantum leap" $$$$ wise, this point is characterized as "PHASE-I".

At this level the performance is transformed. My trap went from 113 mph to 118 mph without loosing a bit of dirveability or reliability in the process. And, honestly, if it were not for a burnt valve (probably due to the bad injector) I may have stayed at that level. But, since the motor had to come out to fix the valve, etc., I opted to finish my porting.

And, that said, although I picked up ~ 35 hp at the wheels for the effort (and $$), it wasn't the 'kick in the butt' I got from "PHASE-I"

Speed cost $$. So, get your wallet out for the next step.

The next "PHASE" (call it PHASE - II) i.e., porting the heads, involves removing the motor, the porting itself, re-phasing the cams, reinstalling the motor and then a live dyno tune...at a minimum.

At that point you'd be at your "510" goal. However, for far less than the incremental cost to port the heads, NOW would be the ideal time to install cams too! Cams more or less double the wheel hp you would expect from porting the heads alone. And, if the TB has not been opened to 63mm by now, doing so completes what all but the most intrepid modders would call PHASE II. Rear wheel (Dynojet) HP at this point will be around 450 SAE (where it matters). But, for bragging rights - dividing 450 by .82 to .85 will give you a nice chp number look at and show your friends.

As far as costs go, obviously the more of the work you can do yourself, the less out of pocket expense will be - not to mention the experience gained in the process!

In my mind, the next two phases (NA) are bore (sleeves, to be exact), and maybe off-set grinding the crank. The last phase is adding closed deck sleeves and a crank, tho the closed deck option could be done any time the motor is out for whatever reason, $$$ provided, of course.:p

Those boys that have done "the whole 9 yards" (427 or 441s) can attest to the raw snap of the neck one gets from going all the way. But, it ain't for those with thin wallets, fer sher!!


Ok, I don't really follow. My understanding is that porting the heads is porting the heads, its only called port matching if you ported the plenum and IHs. Aren't you just making the air holes larger on the heads? Why are some people saying you can port with motor in and do a full porting with the heads out??

[Vette73]

Ok, I don't really follow. My understanding is that porting the heads is porting the heads, its only called port matching if you ported the plenum and IHs. Aren't you just making the air holes larger on the heads? Why are some people saying you can port with motor in and do a full porting with the heads out??

What's up Johnny?

Yeah I hear Ya......With my backyard mechanic skills I'm a little confused also about portong with motor in and porting with motor out...

From what I inderstand is to port the more " important " part of the head, the motor has to come out....With that I say, with the motor in and doing whatever porting you can, how much horsepower and breathability will I pick up? 20-25 RWHP?

Hey, maybe that's good enough without having to pull the motor, am I right?

I think I see Evolutions point about pulling the motor because you have access to the cams at that point.......

End result is- how much are you willing to spend to get more useable power? That's the question....

Or, you can just pick up a C5 Z06 with a head and cam package, and if your lucky enough a supercharger and be done with it...Lol..

Peace ...

[We Gone]

My understanding of why pull the motor to do the heads is in a nut shell, Its a lot easier to remove the heads and everything that has to come off. Upon reinstall parts it makes timing the cams much easier. The plus is you can do a better job cleaning the engine and engine bay.

[32valvesftw]

In the big scheme of things you may actually save time by pulling the engine, as your access for porting would be much better and it will be easier to deal with the grinding dust and chips.

[Top Toy]

Head porting generally includes opening up both the intake and exhaust runners as well as unshrouding the valves in the combustion chamber, all of which require removal of the engine to get the heads off. If you're careful not to allow any metal bits to fall into the valve pockets, you can match the IH and head ports without removing the heads, but the benefit from that mod alone is pretty small.