built ls2 something not right
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Joined: Jan 2017
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Also compression is on the high side. May need better gas to be consistently reliable. These computers are not known to reliably read ls2 knock sensors. I tapped the side of the block and used my ls1 knock sensors. Some say this works, my tuner stated it's pretty iffy but I'd rather have them than not the ls1 sensors were not designed to be mounted ls2 style and the ls2 sensors dont always play well with the 4th gen pcm.
edit: Just read that its a vet
edit: Just read that its a vet
Last edited by Bspeck82; Feb 6, 2021 at 06:01 PM.
it runs out good to 7k just didnt dyno good on motor past 5900 for some reason but still went to 6800 just fell off little . it didnt fall off on the nitrous to 6800 so its little something not just right the engine builder is good does lots of mountain motors and big time rap car stuff and been doing ls stuff for years but im going to go over with him on the pushpod stuff just to see if its spot on or off some. fuel is 93 pump
G Atsma i like the cam sound but the idle is about 950 and i would be fine with little more i think . i mean im not dead set on counting the chop if it was idle at 1200 still be good with me but i wouldnt turn down a smaller cam than the one i just got for it 231/240 114+2 if it still run out good or faster im open to that for sure and better street manners too cause i know if i change out the gear to 3.73 or 4.11 the street manners would be better but i like to keep the 3.42 but im sure the setup would make 450 plus with lot smaller probably.
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Joined: Jun 2016
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From: Central Cal.
Look, with your cam it's gonna chop no matter what.
Get it tuned correctly and with a manageable idle speed. The chop will be whatever ends up.
"Tuning for a chop" means compromising something else.
Use a cam that suits your primary use, NOT for how it sounds. As was said, a smaller cam might make it a far better driving experience and still naturally have the rough idle.
Don't compromise good running just to get it to chop.
Get it tuned correctly and with a manageable idle speed. The chop will be whatever ends up.
"Tuning for a chop" means compromising something else.
Use a cam that suits your primary use, NOT for how it sounds. As was said, a smaller cam might make it a far better driving experience and still naturally have the rough idle.
Don't compromise good running just to get it to chop.
Last edited by G Atsma; Feb 6, 2021 at 09:30 PM.
Originally Posted by spanks13
The cam is not too big for a drag race application, but it sounds like for quality of life you're going to want to go smaller. It would be great for a 416 and honestly I don't hate it in the LS2 if your priority is just high rpm power. Problem is, something is killing your high rpm power lol. A higher stall converter would be better for this combo - but it probably stalls a lot higher than 4000 on spray.
It should be in my opinion peaking around 7000 or higher and carrying to 7500 minimum in a 6 liter with the fast intake.
A couple potential issues - valvetrain instability coming in around ~5900 rpm point, or maybe over-scavenging the FAST102 intake long runners with a very highly excited intake charge. You have a really good collection of parts here. You should be trapping 131 NA, not on the spray.
If you're just going to swap to a smaller cam here maybe it isn't worth the deep dive to figure out the issue now. I'd take a hard look at your valvesprings when you're in there. Check for any broken springs or other oddities. Make sure they're shimmed properly and that your lifters have the right preload. Maybe consider a low lash solid roller setup which would allow you to go smaller on duration but still have awesome high rpm performance.
It should be in my opinion peaking around 7000 or higher and carrying to 7500 minimum in a 6 liter with the fast intake.
A couple potential issues - valvetrain instability coming in around ~5900 rpm point, or maybe over-scavenging the FAST102 intake long runners with a very highly excited intake charge. You have a really good collection of parts here. You should be trapping 131 NA, not on the spray.
If you're just going to swap to a smaller cam here maybe it isn't worth the deep dive to figure out the issue now. I'd take a hard look at your valvesprings when you're in there. Check for any broken springs or other oddities. Make sure they're shimmed properly and that your lifters have the right preload. Maybe consider a low lash solid roller setup which would allow you to go smaller on duration but still have awesome high rpm performance.
But imo the real issue is that peak at 5900 rpm. Here are some potential things to investigate. Some were mentioned already I think:
1. Intake tract. Is your intake hoses getting sucked in causing it to not get air?
2. Can you verify the throttle is opening 100% - not via tps, but by pushing gas pedal and seeing blade move.
3. False knock.
4. Real knock - use boostane to test this. Or 99 octane. Ls2 balancer sucks too. I didn't notice if you put the Ati balancer on but I have seen the stock balancer kill power and rpm on many ls2 first hand. If you can watch the motor run and see the balancer wobble, start there.
5. Plugged cats
6. As mentioned, valve float. Honestly though, nothing about your parts suggests float unless your pushrods are small OD.
7. Cam installed off by a tooth (advanced). Normally this would cause the car to feel very torquey off idle and in midrange. But will definitely kill ability to rev.
100% agree you should be trapping 130 on motor. My hunch is if you fix the rpm, the expected power will be there.
Darth V8r heads were built to work with the cam in car now but i can always get checked , i will check the pushrods to and make sure the are up to task . the intake track is ls2 tb not sure of size no maf and a haltech . will check throttle operation , i dont think i have knock ive never heard any but something to look into , dont have any cats in exhaust , and it really smells like gas when running too , not just cam gas smell or i guess it could be but its strong , also ATI damper , im sure the engine guy setup cam according to cam card but i dont have it anymore lost it or something you have any clues what it might look like i know the cam is for sure whats in first post and ground by comp . i really guess im going to have to start building them myself and checking everything just dont really have some of the tools needed , and i cant tune or have the stuff and if so it might never run again HAHAHA .i been leaving that to the pros.
Last edited by caviness; Feb 7, 2021 at 04:41 AM.
ok guys i went back to post 1 and tried to add anything i might have left off to try to give full info on everything thanks also i only get like 13 MPG so that sucks too
Last edited by caviness; Feb 7, 2021 at 04:45 AM.
G Atsma the cam i do like the sound but was not only reason it was supposed to make power the tune for chop you kinda lost me on that one i always have it tuned to run and how it sounds is whatever it turns out i definately didnt have it tuned to make chop or anything like that if thats what your asking me . i been on tech for lots of years reading and learning but i have really been going off what other builds kinda turn out to base my stuff im not so good at all the cam guru stuff and do talk to venders for info on that stuff but always like you guys input that know that stuff
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Who spec'd your cam? Just curious. Mamo can port your ls2 throttle body. Not that that is your issue by any means but something to consider moving forward. Are you running a maf tune or speed density? Seems some go speed density to wring out every last hp, not worth it imo.
Ls2 TB is 90mm. If everything checks out fine and you are getting low map at wot, that could indicate a larger throttle is warranted.
I have no doubt the heads, valves, springs, etc are fine. I would be more inclined to think with the 1.8 rockers you might need to jump to 11/32 pushrods due to flexion.
Good deal on the ati. That rules out a lot of bullshit. Ditto the cats.
Afr was spot on for the pulls?
I have no doubt the heads, valves, springs, etc are fine. I would be more inclined to think with the 1.8 rockers you might need to jump to 11/32 pushrods due to flexion.
Good deal on the ati. That rules out a lot of bullshit. Ditto the cats.
Afr was spot on for the pulls?
I’ll add to this discussion that the LNC box has the ability to cut individual cylinder ignition timing at high rpm, not just at launch, and if it’s not setup correctly, would do the very thing your experiencing here. Pretty sophisticated little device actually. Maybe disconnect the box and go for a drive?
I’d be curious to see the data log and the tune from the NA dyno run.
See what the timing is doing, as well as the AFR where it falls flat.
That cam has 19.5degrees of overlap at .050” so it’s no wonder it stinks and gets crappy mileage. Would also be curious what the plugs look like.
I don’t think he mentioned 1.8 rockers. That was Showdog.
The 90mm TB should be fine. A 102 might gain 10hp.
Those heads are nice. And have PAC .650 lift springs. Should be good. I’d still carefully inspect them.
Agree that this would be happier with a cam around 10 degrees smaller.
But really need to figure out why it falls flat at 5900
See what the timing is doing, as well as the AFR where it falls flat.
That cam has 19.5degrees of overlap at .050” so it’s no wonder it stinks and gets crappy mileage. Would also be curious what the plugs look like.
I don’t think he mentioned 1.8 rockers. That was Showdog.
The 90mm TB should be fine. A 102 might gain 10hp.
Those heads are nice. And have PAC .650 lift springs. Should be good. I’d still carefully inspect them.
Agree that this would be happier with a cam around 10 degrees smaller.
But really need to figure out why it falls flat at 5900
Agreed Ron. It would run better on a smaller cam. I just think Whatever is killing power above 5900, a cam swap willl not fix unless the cam is just way off on lsa or icl.
Number one stop looking at a new cam right now. Yes will a smaller cam idle better and produce more power down low yes. That cam can make some serious power at higher rpm so it’s not the cam that’s the problem here. I would like to know do you have short travel lifter from Johnson?? If they are short travel the preload will not be .035. I believe it should be .025. I have 2126lsr Johnson lifters. They are not short travel and the preload is .035. Def try to post and a dyno graph. Can help to tell if it is valvetrain instability. If not then I’d would like to see if it has knock retard next. But please at this time figure your problem out before changing the cam.
if i hade half yall tuning experence i would have a laptop and be checking but i dont and as far as tuners ive had 2 look and same power at both but dont want to talk about them cause im not bashng anyone of them i know there good i think it does need more street tuning time and ill have to get into the other stuff and check it out .thanks to everyone and its helping me figure out what i need to look at also if i log in on my phone can i post pic right off that ?
ok guys if i go buy tuning stuff hp or efi im not compering them just getting something to use even if just loging runs or whatever for extra help from guys like yall