Making LS7 more reliable and faster ? I hope so

[acammer]

Originally Posted by joelster

I do autocross, so my engine doesn't spend a whole lot of time at max rpm. A typical run only goes WOT for 2 or 3 short instances, and then you're right back on the brakes, hard. My engine is oversprung as it is. If it was a daily driver or an engine that I'd run 5000+miles a year, I would have a different approach for sure.

You're correct on the preload, I was simply going by the thread pitch, I totally forgot to multiply by the ratio lol. But factory preload at over a tenth is just nuts to me.

I see you're from GPI, they have an excellent write-up on what goes wrong with an LS7. I refered to that page a lot!

Yea, Aaron wrote that LS7 head article - really solid info in there. He's got one he did on Lifter Preload you might find interesting as well - although in talking I'm confident you've got a pretty good grasp on it all. Sharing below for reference. I see you're semi-local to me, I'm near Syracuse. Obviously, GPI is a remote gig for me, but I very much enjoy being a part of that team - great products and great people.

If you're ever out this way, give me a shout and we should connect for a bite to eat and you can give me the low-down on Auto-x with the 5th gen. I used to do some in smaller FWD cars I've owned, and I have my SS on Watkins Glen and PineView, but never autox - the visibility and weight lead me to think it probably isn't super competitive.

https://gwatneyperformance.com/lifte...ont-hurt-will/

[joelster]

Originally Posted by acammer

Yea, Aaron wrote that LS7 head article - really solid info in there. He's got one he did on Lifter Preload you might find interesting as well - although in talking I'm confident you've got a pretty good grasp on it all. Sharing below for reference. I see you're semi-local to me, I'm near Syracuse. Obviously, GPI is a remote gig for me, but I very much enjoy being a part of that team - great products and great people.

If you're ever out this way, give me a shout and we should connect for a bite to eat and you can give me the low-down on Auto-x with the 5th gen. I used to do some in smaller FWD cars I've owned, and I have my SS on Watkins Glen and PineView, but never autox - the visibility and weight lead me to think it probably isn't super competitive.

https://gwatneyperformance.com/lifte...ont-hurt-will/

5th Gen 1LE's are pretty good for autocross, Z/28's are better. Visibility sucks in both compared to Miata's and whatnot. My car is tastefully modded, and I've done very well with it. Other than the visibility and the fact that they punish tires, they are quite capable.

6th gen SS 1LE's are ringers in the F-Street class. They are neck and neck with the new Mach 1, and at most large events you'll see a bunch of them.

If I do an event with the Finger Lakes Region SCCA, I'll let you know. They race at the Seneca Army Depot which is 30 minutes from Watkins Glen.

[acammer]

Originally Posted by joelster

5th Gen 1LE's are pretty good for autocross, Z/28's are better. Visibility sucks in both compared to Miata's and whatnot. My car is tastefully modded, and I've done very well with it. Other than the visibility and the fact that they punish tires, they are quite capable.

6th gen SS 1LE's are ringers in the F-Street class. They are neck and neck with the new Mach 1, and at most large events you'll see a bunch of them.

If I do an event with the Finger Lakes Region SCCA, I'll let you know. They race at the Seneca Army Depot which is 30 minutes from Watkins Glen.

Keep me posted, Seneca Army Depot is less than an hour from my home. I have done events there in the past with other cars and they are typically a nice open course, probably well suited for a bigger, faster car that may be a bit lacking in agility for the low speed corners! I'm not too interested in trying to compete at a high level, I don't have the budget for all that, but it would be fun to just go out and put the car on the limit for a bit.

[void_kp]

another update. Car is almost done. map is not complete yet, at moment it's set at 21degree advance but it is "only" giving 520hp at wheels... everyone (me included) is expecting something around 550 given how extreme the cam is.

Tuner was not 100% confident this can be achieved with tune given current result. My suspicions are on the heads. The MAST Factory might not be fluxing that good.

anyway... we will see, before end of week I should have the final verdict. I don't care about HP, I just want to fix that valve problem with heads.

There was a problem with pushrods being too "thick" for the head, which was restricting oil flow into the head. That was a scary moment, now solved.

[joelster]

Originally Posted by void_kp

oh, another quick update that I forgot. The 2" Kooks headers didn't fit right away. they hit steering rack on one side and something else on the other side. They require modification to install (or to "bump" the headers).

They can't hit the actual rack, they hit the steering shaft. You have to remove the bolt on the shaft, pull the top part out, and then zip-tie it to the side during the install.

[void_kp]

Originally Posted by joelster

they hit the steering shaft. .

this is correct

[void_kp]

got the car back.
First of all... the car sounds MEAN. Like, really loud (despite stock exhaust) and absolutely menacing.

here's a cold start (the 1st cold start I heard of it)
https://youtube.com/shorts/BhsriMgaqxI?feature=share

phone doesn't fully capture the chop

speaking about more interesting stuff...we were all a bit disappointed by the result. It's good but we were expecting more given how extreme the cam is.

car drivability is VERY low below 2000 rpm, engine picks up revs much quicker and sound is definitely insane above 3000 rpm. very race-car like. I couldn't pull gears to the end so i can't speak for perceived performance, but overall it feels a bit quicker.

I was expecting at least 550 at wheel... we are close, but both me and tuner were expecting more, with much less extreme cams they saw over 560 at wheel.

my theory is that there are 2 factors at play here:
1/ in washington state we only have 91, so a bit is loss due to "bad" fuel
2/ everyone else that changed to a similar setup also changed intake and 103mm CF. I did not. Maybe airflow is a constraint at high revs?

lastly, it would well be that the heads don't flow better than the stock heads, but it's unlikely to be honest.

I will post more as I will drive it, today I could only suffer in heavy traffic while I was bring it back home. Seattle is as bad as Los Angeles in that regard (no joking)

[CamayroZ]

High performance aftermarket is filled with overly optimistic hp/torque figures and backed by shops with optimistic dynos. This is what sells.

I think that you approached this in the correct way with before and after measurements. And you know that any dyno will have variations of +/- X%. You can run the same exact configuration two different days and get different numbers.

Personally, I think that a ~15+% gain after a tune and headwork is great. It will be interesting to get your impression about real world driveability since that is probably the most important measure.

The car does sound like a dragster! Enjoy it with the nicer weather.

[void_kp]

Originally Posted by CamayroZ

Personally, I think that a ~15+% gain after a tune and headwork is great. It will be interesting to get your impression about real world driveability since that is probably the most important measure.

The car does sound like a dragster! Enjoy it with the nicer weather.

Hey, thanks for the message.
I really don't mind about HP, but similar setups with less extreme cams gave 560+ on Z06 on the same dyno, tuned by same people. This is why we are a bit surprised by the result.
I don't need more power, I don't care... but this might be a sign of something being off.

One example could be a shorter pushrod ? or the insufficient air intake (i doubt it, but who knows).

Said so:
car drivability. Severely affected. Car refuses gas below 1900rpm, especially in high gears. It will stumble and buckle and requires VERY smooth accelerator action. Lowering one gear and getting >2000 is almost required in real traffic situations.

I was expecting this, so no big surprise there. Point is that less extreme cams give more power with more drivability (if this is the case), which means that combination of these pieces I've put together is not giving 100% of what they could.

I will keep driving it a few days checking oil pressure and oil temp. I want to make sure everything is fine.

Car sounds incredible from 3000rpm, like a real racing V8. Big cams sure deliver in terms of sounds on a pushrod V8

[void_kp]

Originally Posted by joelster

\You have to remove the bolt on the shaft, pull the top part out, and then zip-tie it to the side during the install.

I'd like to understand more about this. Is there a thread with pictures or some video or something else I can use as a reference?
is it possible to do it even after installation of headers?

[joelster]

All dyno's read different, but you did do a baseline before, and your baseline numbers were right were most others fall. If your baseline was 420-425~ish, then I'd say your new numbers are accurate. An MSD Atomic Airforce and a 103+mm TB will certainly add more power but that's a tough $1700 to spend along with another dyno tune. I don't know if they'll give you the 25-30hp that you're looking for. But they are pretty easy to install.

[void_kp]

update.

you provided 7.800 pushrods which is stock length for LS7
these aftermarket heads are taller than the LS7 so we had to measure for Zero lash on our measurements we got a 7.950 so we ordered 8.050 pushrods to give us .100 preload usually the pushrods measure out on the shorter side so i was hoping we would be around the .080-.085 preload but these pushrods measured long so we ended up a little heavier than i wanted closer to .115-.120 preload we can always order up a set of 8.025 that would get us back to below .100 preload witch is where i was hoping to be at

so next step is get to less preload using shorter pushrods.
We will also try to fix the problem of steering column hitting the headers... we will try both via releasing the top bolt and by shimming engine mounts (if push come to shove).

[joelster]

Originally Posted by void_kp

I'd like to understand more about this. Is there a thread with pictures or some video or something else I can use as a reference?
is it possible to do it even after installation of headers?

I did an install thread:

https://www.camaro5.com/forums/showthread.php?t=573885

I still don't understand why your headers hit, unless the cylinder head casting is different enough. I saw that the shop said that they were taller than the stock heads, needing different pushrods, so I believe your problem with your headers hitting may be because of your heads. My Kooks 2" fit just fine.

[void_kp]

Originally Posted by joelster

unless the cylinder head casting is different enough. I saw that the shop said that they were taller than the stock heads,

I am confident this is exactly the case. I still have my original heads... maybe in future I can have them ported, fix the valvetrain and use them instead.
Thank you for the installation post