Eliminating the secondaries
 

I am going to remove the plenum on my 91 to replace the injectors. While it is off, I am going to install Jerry's new and improved fuel pressure regulator. I also want to remove all the secondary stuff to make the car simpler. I know Marc has a DVD which describes the removal process but I am wondering if there is a DVD that shows the secondary removal process. Dynomite describes the process with some pictures but I would really like some more detailed information. Perhaps once the plenum is off, his descriptions will make more sense to me. Thanks in advance, Perry

Re: Eliminating the secondaries
 

No videos that I am aware of. Too many old guys here (till now) that can?t handle a smart phone. The references you mention are very good though. Don?t forget you will need a Haibeck chip to handle the secondary delete in the ECM. Member Domenic Sorresso (Xfirez51) also does them. I have mine deleted, Dominic did the tune. Runs seamlessly! Nice not to have the secondary system issues worry.
H
:cheers:

Re: Eliminating the secondaries
 

I still have my secondaries.. they still work fine

Re: Eliminating the secondaries
 

Ditto.... Mine are working as theyre supposed to as well. Im not sure why so many guys dislike one of the features that makes the LT-5 special... :o

Re: Eliminating the secondaries
 

The simplest thing to do is just tie wrap them open and modify the calibration. That was my first step, then I removed throttle plates and kept throttle shafts in open position again w tie wrap. When I had heads ported. We took out everything.

Re: Eliminating the secondaries
 

Ahem


http://www.zr1.net/forum/showthread....ht=secondaries


Get rid of them if you are in there.


GC

Re: Eliminating the secondaries
 

Just because you had a screw loose (LOL) doesn't mean we all do :-D

However, while apart that is a good thing to inspect

Re: Eliminating the secondaries
 

Unfortunately 2... One per head

Re: Eliminating the secondaries
 

Mine are still working, with the MS-Pro (Megasquirt) ECU.

I gave my car to them (DIYAutoTune) a few years ago when they were working on the LT-5 tune. Before I gave my car to them I had disabled my secondaries. They asked me to put it back together, which I did, because they wanted to control the secondaries.

I realize this is apples to oranges, but my car made more horsepower when they were done.

Re: Eliminating the secondaries
 

If I could figure out a nice dash layout with aftermarket gauges I think it would work well with the DIY Autotune set up

Re: Eliminating the secondaries
 

Thanks guys. So I take it there are no videos or DVD's. I am sure I can figure it out with the info I have. Just thought it would be easier with more pictures.

Re: Eliminating the secondaries
 

My car came with Marc's 510 package and the secondary delete. I have some questions about it. I was going to call and talk with Marc about it. I usually think of something later that I want to ask. Like how do the fuel pumps work? Normally the car would run on the primary pump until all the injectors come in play and the secondary pump comes on. So how do the pumps work when you are running on all 16 injectors all the time? How or what is done concerning the pumps?

Re: Eliminating the secondaries
 

Think of the secondary pump as an auxiliary pump. It comes on when the ECM calcs a need for additional fuel. Otherwise, whether on 8 or 16 injectors, the motor uses the same amount of fuel and the primary pump can supply that amount. If you're running 16 injectors, the fuel delivery is basically shared equally by both injectors.

Re: Eliminating the secondaries
 

That's what YOU think! :p

Re: Eliminating the secondaries
 

My Secondaries are in super shape and my FULL POWER switch is working fine.
I did replace all secondary vacuum system for $100.

New Secondary Port Throttle Vacuum System

Yes........that is what I think :D

I think it is a bit foolish to eliminate one of the most unique and selectable and functional options for the LT5 (The Full Power switch on the console).....

And just because you do not want to do a simple fix but rather do a more complex "fix" eliminating the secondaries :cheers:

Re: Eliminating the secondaries
 

Xfire, thank you I wondered if anything was changed with the delete. I read Marc's article about going with a single pump if your sending unit is in bad condition. I saw a nice reconditioned ZR1 sending unit recently on eBay for around $475.

https://www.ebay.com/itm/90-95-ZR-1C...0/264751696997

Re: Eliminating the secondaries
 

No, I know they work fine. They will work fine until they don?t work fine

Same with my fuel pumps

Re: Eliminating the secondaries
 

With a 350, I've never been a fan of deleting the secondary port throttles because it degrades dirivatility and decreases torque output on the low end.

During the 20 years I owned Barney, my purple '95, the two times I had trouble with the SPTs, I repaired them rather than eliminated them.

For a 368...maybe, bigger than that, yeah, I'd get rid of them along with appropriate cal changes.

Re: Eliminating the secondaries
 

Couple of things from 11 years and counting, driving w/o SPTs...

Drivability:

1. From off idle (<~1%) to WOT, there is zero hesitation or lag. Throttle response is instantaneous and continuous from the instant the pedal meets the metal (or anywhere in between): nothing for me to dislike about deleting the secondaries there. As for throttle response, it is a subtlety I think is unmistakable, but perhaps has to be experienced to appreciate.
   
2. Parts that don't exist seldom break and they don't cost much! The second time my SPTs hiccuped, and this was before Jerry carried replacement parts, BTW, OUT they came; never to return.
   
3. Valve "coking", primarily on the SPT valves, is non-existent! This. like my primary valves were prior to the secondary injectors running full time, is the result of fuel always being sprayed on the (back side) of (all) the valves. That said, if one presses the accelerator above 25% or so while in FULL POWER mode (w/o having deleted the SPTs), and then one backs off to maintain a prolonged highway speed, one achieves the same thing, i.e., flushing the secondary valves and thus reduce the heavy coking that typically forms on the secondary valves.
   
4. Torque* In (stock LT5) NORMAL mode vs. the FULL ENGINE POWER mode, the torque is only ~10% more than the FULL ENGINE POWER mode, but ONLY to around 3000 RPM. Between ~3000 and 3900ish the torque advantage of the NORMAL mode drops to zero (difference). Above that point the FULL ENGINE POWER mode provides greater torque.)

Far as the intact SPTs vs. secondary delete practice goes, for the more aggressively ported 350 cid or one with 368+ cid, I have no primary/secondary comparison data to share.

That said tho, apart from this "delete" discussion, I do have the stock LT5 and (aggressively) ported "before and after" (Dynojet) data on my 350 cid LT5.

The pick-up in torque at WOT in the "after" scenario clearly mitigates or negates entirely the ever smaller (below 4000 rpm) torque advantage present in the NORMAL switched position.

All in all tho, aside from the unnecessary complexity of the SPTs AND the uniqueness OR "NCRSness" AND the advantages of deleting the SPTs, you'll have to decide. My wife's ZR-1 does not have SPTs, but is not ported to the point where reinstalling them wouldn't be practical if someone wanted to do so. But, I like the reliability and drivability that having deleted the SPTs provide. So, I'd never consider reversing the delete procedure.

Below is a Dynojet graph of an LT5 slightly modified by Lingenfelter (specific mods unknown). From this graph one can get an idea of the differences between the NORMAL and FULL ENGINE POWER settings. Also I included the "before and after" graph results of an Excel spreadsheet showing the FULL ENGINE POWER plots for rear wheel torque for my ZR-1 in stock and fully ported configurations.

:cheers:

Re: Eliminating the secondaries
 

I removed the plenum yesterday and replaced all the injectors along with Jerry's improved fuel pressure regulator. All the secondary vacuum lines, reservoir, solenoid, actuators, etc. were also removed. I am going to wire the secondary linkage open after I determine the best way to do it. Any suggestions there? I was figuring to wire or use plastic ties to tie the linkage lever to the original canister mounting bracket. Is that how you guys have done it? I will reinstall the plenum today while waiting for my recalibrated prom from Marc which will be here tomorrow.

Re: Eliminating the secondaries
 

For the record Hib I had Marc remove mine on my '95 when he did his porting. I never had a driveability problem and the engine always seemed to have plenty of torque. Of course there were several variables involved besides the elimination of the secondaries. But I was happy with the way the car performed around town and on the track. --Bob

Re: Eliminating the secondaries
 

This is how I keep my secondaries open at all times after removing the vacuum actuators.

Re: Eliminating the secondaries
 

Sooo... It appears you removed the actuator(s) and replaced them with a flat tab bolt, yes? Nice. Oh, but to be safe, it might be worth considering to dab some BLUE lOCKTITE on the threads under the nuts to prevent them from vibrating loose, resulting in the secondaries (possibly) creeping closed insidiously. :-x

Re: Eliminating the secondaries
 

I used a 1/4'' threaded rod and flattened one end using a hammer then drilled a hole in it for the linkage pin to slip into. Loctite on the inboard nut might be a good idea. I used a nylon lock nut on the outside.

Re: Eliminating the secondaries
 

I like your solution and either locktite or a hole to pint he outer nut from backing off (like the crown nut setup for hubs (crowned nut is not really needed but the pin idea would work well)

Re: Eliminating the secondaries
 

The obvious advantage to doing what you have done (used a modified bolt to hold the SPTs open) or a zip-tie as many have done, is the ease at which it can be reversed at a later date.

However, maybe for the sake of discussion, in my research on laminar flow and reversion caused by obstructions, I opted to remove the SPTs and the throttle rod entirely and plug the (now) empty bearing recess with a (Dorman) freeze plug. Admittedly, I have no "before and after" data to document the improvement to be had by so doing - that and extending the tapering of the IH runner down to the injector boss - but intuitively I feel it helps (just like smoothing the outside radius of the curves in the intake runner has in the porting fundamentals).

But, increasing the porting modification beyond 36mm (in one fashion or another) has been shown to be beneficial to many of the porting schemes (including mine which are now @ 37.5mm).

Re: Eliminating the secondaries
 

I don't disagree, but if the goal is to allow for reverting to stock, I would do what Perry did. if the goal was max power and I was porting, then yes remove them cause once you port those butterflies will not do their intended function

Re: Eliminating the secondaries
 

And, point of (further) fact, the Gen-III LT5 went so far as to Siamese both runners (into one). And, with the help of some tricky (dynamic lift) lifter scheme and variable fuel pressure, a single injector was used instead of two. IIRC Graham (in his presentation on the motor at the 2016 or 2017(?) Gathering) said that this 350 cid motor made 550 chp on pump gas. My point is, performance improvements via porting developments pioneered by Pete Polatsidis and Marc Haibeck and others showed just how badly the stock LT5 was starved for air: acknowledged (IMO) by the changes Lotus made to the gen-III motor's intake plenum/heads: AND, NO SECONDARIES.

Note of interest: Someone correct me if I'm wrong, but I believe this gen-III motor was (IIRC) installed in a car owned by Graham Behan (former engineer for Lotus and Lingenfelter before going out on his own).

Re: Eliminating the secondaries
 

Paul, et al
Engine made 528 hp
Ken owns the car that this engine was installed in.
I will put more info on the fb page, including video

Graham

Re: Eliminating the secondaries
 

And this makes me shake my head when I read stupid comments on the C8 forum about how DOHC motors need to spun like a sewing machine to make any power. 528chp from a 5.7L NA motor. And one designed 30years ago.

Graham, what cams did u use for this?

Re: Eliminating the secondaries
 

Power peak was at 7200 rpm.
Cam profiles were Lotus prototype.
Around 12mm lift, I think the duration was around 280 total.
I will dig out the info to confirm, don't have it with me at the shop.

Graham

Re: Eliminating the secondaries
 

Thanks for the clarifications, Graham.:thumbsup: Much appreciated. And, if there are any dyno graphs available on that beast that you might have, I'll happily add them to my LT5 gen-III reference folder.:)

Paul.

Re: Eliminating the secondaries
 

Just to add...

With regard to coking on the valves, I should mention too that in addition to secondaries delete, the installation of an OIL CATCH CAN was a notable contributor to the reduction of valve coking.