C5Z Track Toy

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Re: C5Z Track Toy

Postby Cincinnatus » Tue Jan 04, 2022 5:35 pm

Very nice! I'll admit to being jealous. You doing all the tuning? I'm still learning but have a 5.3l I built with an ls3 cam and t56 I'm putting in a 92 Camaro. I've never tuned, just got swaps to run standalone with stock tune. My engine used e40 ECM but I think I'm going to try to get it to work with a p59 and use hptuners rtt. I have 6.0l block and 6.2l rotating assembly and l92 heads but the tuning is my biggest hurdle. I've built engines, but never tuned with a ECM. You should post some pics. I'll start a thread soon of my projects. Btw, the c5 clutch pedal going to floor has happened to 2 cars I've worked on. One the master cylinder seemed to fix. The other was only under hard acceleration, and I think it was the stock self adusting pressure plate. We replaced the clutch assembly, and the problem never recurred. Enjoy!

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Re: C5Z Track Toy

Postby Tre-Cool » Tue Jan 04, 2022 10:53 pm

Having a C6 Z06 myself, I had the clutch master cylinder fail. Working on it was a mission compared to a commodore.

1 of the main reasons i have been putting off doing a cam install in it because so much shit is in the way to get the harmonic balancer off.

I don't envy the guys putting it back together

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Re: C5Z Track Toy

Postby Cincinnatus » Wed Jan 05, 2022 6:41 am

Slave cylinder way worse than master. Tre_cool, did you get your heads rebuilt? I googled and it's the hollow exhaust on the ls7 that breaks. The intake is titanium but they coat it so it won't gouge the guide. They claim extending guides into the port .25" stabilizes valve enough to prevent the premature guide wear, and using bushings on the rockers. Also they use solid stem exhaust valves.
Wrenching is an acquired skill. I have a lift, and you just unbolt everything until it comes apart. 40 years experience helps a bit.

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Re: C5Z Track Toy

Postby NSFW » Wed Jan 05, 2022 1:23 pm

The shop that's doing the installation will also be tuning it. I will probably tinker with driveability and idle stuff, just because I'll have a lot more time to fine-tune that kind of thing, but I think a dyno is pretty much required to tune a naturally aspirated engine for peak power, and I have no experience with that, and this motor is too expensive to learn on. :) So I'll be leaving the high-load / high-RPM parts of the tune alone, unless I see a knock problem in the data logs.

All of my tuning experience is on my Subaru, and tuning that one for max power is relatively easy since it's so knock-limited - I just added timing until it knocked, then backed it down a bit where necessary, and road tuning works fine for that. Plus I'm super slow at tuning and I don't want to wait that long for my C5. With my Subaru I would usually do a few pulls, and then go home and study logs for an hour, tweak the tune, and reflash/retest the next day, so it took a lot of iterations.

I had the clutch-pedal-stuck-to-floor problem a few times, and I think you're right about the self-adjusting thing. GM issued a service bulletin about the C6 (which had the same problem), saying that it was an interaction between the master cylinder and the self-adjust mechanism. I had a new clutch put in (RPS BC2), with a new OEM slave, and the problem never came back. (Still using the same stock master cylinder.) It's got about 15 hours of track time now with 3-4 shifts per minute without missing a beat.

Some pics:

DrySump1Small.jpg
DrySump2Small.jpg
RainyTrackDaySmall.jpg
Please don't PM me with technical questions - start a thread instead, and send me a link to it. That way I can answer in public, and help other people who have the same question. Thanks!

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Re: C5Z Track Toy

Postby vlad01 » Wed Jan 05, 2022 7:19 pm

100% agree, dyno is the way to tune correctly on NA or any engine really.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: C5Z Track Toy

Postby Tre-Cool » Wed Jan 05, 2022 10:29 pm

Cincinnatus wrote:Slave cylinder way worse than master. Tre_cool, did you get your heads rebuilt? I googled and it's the hollow exhaust on the ls7 that breaks. The intake is titanium but they coat it so it won't gouge the guide. They claim extending guides into the port .25" stabilizes valve enough to prevent the premature guide wear, and using bushings on the rockers. Also they use solid stem exhaust valves.
Wrenching is an acquired skill. I have a lift, and you just unbolt everything until it comes apart. 40 years experience helps a bit.


mines an 09 with 42k km's on it. had 40k when i got it. figured if valve seats where stuffed by now i'd know about it. When i get around to doing cam, I'll do heads then.

For now, i've just put an aftermarket master in mine.

I have a mate with similar year with a magnuson blower on it. we did a pump upgrade on it so we can run flex fuel/e85. makes 660whp on my dyno. Complete stock motor/exhaust too.

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Re: C5Z Track Toy

Postby In-Tech » Thu Jan 06, 2022 7:12 am

Sounds neat NSFW, just for my own curiousity, further cam specs with a screen shot of the dyno sheet would be really cool :)

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Re: C5Z Track Toy

Postby NSFW » Thu Jan 06, 2022 1:08 pm

The cam is 239/251 @ 114, +4. "HUC" lobes, originally created for marine performance engines.
This is the milder, broader-powerband of two options that Golen offers for 454s.
The torque peak ended up somewhat higher than I had hoped, but I'm not going to complain just yet. :)

golen-454-dyno.png
golen-454-dyno.png (101.65 KiB) Viewed 1206 times
Please don't PM me with technical questions - start a thread instead, and send me a link to it. That way I can answer in public, and help other people who have the same question. Thanks!

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Re: C5Z Track Toy

Postby In-Tech » Fri Jan 07, 2022 4:53 am

Thanks, I am building a 430 in LS for a completely different environment(Off road race truck) and I appreciate the knowledge :)

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Re: C5Z Track Toy

Postby NSFW » Wed Apr 20, 2022 1:10 pm

For no particular reason... here's everything I think I know about the returnless fuel systems in later C5s.

I gather that the main problem with the returnless fuel system is the regulator, or specifically the regulator's ability to bypass. In other words, as your fuel pump gets beyond a certain size, the regulator can't bypass enough fuel, and your fuel pressure starts increasing.

600whp is apparently right around the point where you need a fuel pump that moves more fuel than the regulator can bypass. Some people do OK, some people report problems.

I want to minimize surprises during the engine swap, so I'm starting to convert to a return system. OEM fuel rail, regulator in the engine bay, bought an aftermarket filter to replace the stock regulator/filter. Keeping the stock supply line, adding a return line that will connect where the stock regulator's bypass line connected. Racetronix wiring.

I haev a hunch that one could keep the stock regulator if you convert to a PWM fuel pump controller. Pantera EFI makes one for $200ish, and I almost bought one... I'm guessing it would solve the regulator bypass problem if the pump is only running at (for example) 25% at low throttle, and ramps up to 100% as MAP and RPM increase. But I don't want to be debugging the fuel system at the same time as doing the engine swap.

The other suprise while I geeked out on C5 fuel system is that the Aeromotive 340 pump has a terrible reputation in the GM world. Meanwhile everybody loves them in the Subaru world, including me - I've had one for about 40k miles with no issues. My only guess is that the pump is happy at 43psi (Subaru) but not at 60psi (GM). It was tempting to get one of those pump and run it at 43psi, since my injectors are oversized anyway. But, as much as I want to try to test that theory... I also don't want to bet my new motor on it. :)

So I am going to be using a Walbo / Ti 450 pump.
Please don't PM me with technical questions - start a thread instead, and send me a link to it. That way I can answer in public, and help other people who have the same question. Thanks!

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