Damian

iTrader: (89)

As the topic states I have found my problem. My heads/cam car is having some SERIOUS detonation problems. Something to the tune of bring my timing below 20* max advance. The car is making about 80 rwhp than it's suppose to, and falls completely on it's face after 3200 rpm's.

The shop who widebanded the car seems to think I am running to much compression, and to low of an LSA. The motor is right around 11.3:1 comp and a 230/230 110 cam. They think that the 110 LSA is causing to much cylinder pressure. They also think my cranking compression is way to high. Most of my cylinder PSI #'s were in the 225-227 neighborhood. They also think it's in the tuning as well.

Here is the car's setup:
TEA 5.3 Heads, milled .020
Comp XE-R 230/230 .595/.595 110
Grotts
MTI tuning
Blah blah

The car runs like absolute ****, and doesn't make **** for power right now. Above 3200 rpm's, it's lucky to see 20* of timing. The ping is so bad, it threw off the dyno reading.

Any opinions are appreciated...


Josh

Ron@Vengeance

iTrader: (51)

Thats a boy, resortin to da ole internet. I knew ya would come back Josh

Goodluck man

LS1derfull

You should be ok on paper, but your cylinder pressure readings are high. Is your cam advanced? What is ICL? Your air/fuel may be way off also.You may have more than 11.3 to 1, have you verified it?

BLK02WS6

iTrader: (2)

What head gaskets are you running? Maybe you can get thicker Cometics and drop compression a little.

Or consider a cam change.

Joe Kizzire

What he said....

Ron@Vengeance

iTrader: (51)

Compression ISNT his problem, the camshaft may be. Theres ALOT of heads/cam guys running 11.5:1 and higher on the street with NO issues. I vote for a slip and slide Just keep it dot to dot

dug

iTrader: (10)

Make sure the pcv system isnt suckin oil into the intake. Oil will lower the octane rating of fuel.

SLowETz

iTrader: (12)

Josh...got KR??? Can't see 11:3:1, and a 110LSA being the problem (w/good gas). Cylinder pressure does seem a bit high as LS1derfull said, but not convinced that's the root cause of the prob. Lot's of others running that combo w/out issue. Are you running an adj. gear set/zero'd out/dot to DOT? Put some Race gas in it(see if that helps the detonation)and wide band/tune again. I still say it's in the PCM. What about the welding issue? May be wrong but thought you're suppose to disconnect the battery before welding on the 98's ....keep at it dude....you'll get it right

CAT3

iTrader: (9)

What A/F ratio are you at, or were you?
Agree race gas, and try again.
Was pinging audible, or just the fact KR took your timing?
Definatley d/c the battery before welding..gremlins ouch.
11.3:1 Compression shouldnt be that bad other than the whole octane issue.

Good-luck.

Damian

iTrader: (89)

Ron, I'm scroungin for answers dude so lick my brown eye. BTW you've been asking a question or two yourself lately so STFU :p

LS1drful, the cam does not have any advance ground in, nor is it advanced in the motor. It's on a 110 LSA, and 110 ICL. The shop I took the car to seem to think thats to low. I do not remember the A/F. Compression was calculated using deck height, how much the heads are shaved etc...It came out right at 11.3:1 on the calculator.

I am running an 02 GM aluminum gasket.

Mike, it's not the PCM. I wish it was that simple. Tuning? Maybe, but the PCM itself is fine. Jayson ok'd it, and I also had a buddy of mine put it on the scanner at a GM dealer.

I'll try some race gas, but I do not think thats going to clear it up. I dont think you guys really understand how much this car is pinging. I'm talkin.....It throws the dyno off!

cablebandit

iTrader: (37)

call ARE and see if they can give you some advice. That's alot of cranking compression

MattG

What octane fuel do you run? What is your max timing set at? How much KR are you getting? You will definitely need to know your a/f ratio to cross that off the list. If you run some 110octane unleaded race fuel do you still get KR? Does the car come alive with Race Fuel?

These are all things you are going to have to investigate into before you will ever find a solution. In my opinion 11.3 CR is quite high for a car that is probably only run on 91-93 octane, especially if the max timing is set around 29-30+ degrees.

Vengeance Racing

Well Well Well

I have seen this twice before once about a year ago on a certain Pewter TA. Wish a shop a ***** could help ya out but I am sure you have it under control.

Best of LUCK

ChrisB

I would suspect that your static CR is a bit higher than 11.5:1 - where the chambers actually CC'd, or is that an estimated value? The cranking compression, as was mentioned, is *very* high - I don't doubt that you will have difficulty on pump gas that high.

I wouldn't try thicker headgaskets as that will just increase your quench - so you will lower your compression a tad, but probably have just as much knock.

You might try ordering the same cam, but on a 114 or even 116 - that should help reduce your dynamic compression - and would let you know quickly if it was due to the cam profile or not (though I suspect it is more likely a combination - the 230 duration should be enought that the 110lsa isn't giving you too much cylinder pressure. Did you degree in your cam to verify the specs?)

Visceral

iTrader: (1)

The cranking compression big #s could be from a fast starter too... THey are sorta hard to move car to car.

My first amatuer step would be to go get a bunch of 104 unleaded and see how the car drives. If that solves your problem, you need to start thinking about what might be different than you have on paper. On paper, this combo should be fine with good, fresh 93 octane and cool heads. You did make sure the car isnt overheating, right?

How old is the gas in the car? Is this poor running something you've only seen wiht the tank of gas in the car now? I get crap-gas every once in awhile. Maybe someone put 87 in the 93 tank. Dunno. Get some race gas, make sure its the only thinkg in the tank, and then you will know where to start. If race gas doesnt solve it, you have a sensor/ignition problem most likely, or a radically goofy cam. I dont think the cam is the answer though because if it was off THAT much, you'd hit valves with pistons.

chris

CHRISPY

Try this:

1) throw in some 104 unleaded and redyno

2) get the car dyno tuned with LS1 edit and wideband. If it is knocking at 28 degrees advance on pump gas, keep adding fuel at wot and see what happens. If that doesnt work drop timing
3) Do you have custom pistons in the car? Are they in the hole at all? Doesnt take much of a mistake putting these things together to hit 12:1 compression

Good luck, Race gas first and proper retune on the dyno with wideband should be first thing to try.

Check fuel pressure at WOT to see if it is dropping, check LTRIMS for Vac leaks

Chris

Damian

iTrader: (89)

Matt, I run 93 octane, all the time. Not sure what it runs like on Racegas. I just got it dyno'd 2 days ago.

Chris, I'd like to try and steer clear of pulling these heads again. Not only will that be the third time, but I have head studs. The compression was estimated using all the # figures, deck height, milling, etc.. TEA milled these heads, I do not think they would make the mistake of milling them twice as much although it is possible. 116 LSA? Yikes....

To answer a pretty wide question, the car did sit for a good long while, but I have been through several tanks of gas since then. I don't think it's bad gas. Even bad gas wouldn't cause this much pinging.

The main thing I do not understand is how in the hell my cranking compression is so high? Most LS1's are usually in the 180-190 range.

I will try some racegas this weekend, but even if it does run better that still does not fix my problem. I can't pay 100 bucks a week to drive to work on racegas. Something needs to be changed or adjusted, but who the hell knows what at this point.

Thanks for the pointers, keep them coming if anybody comes up with something...

Damian

iTrader: (89)

PS- Mike I don't think you need to say anything about that little comment I made to you, after all the **** talking you've done. Hopefully it didn't hurt your wittle feewings to much though.

PS- MIKE STAY OFF THE DAMN INTERNET....

FrankSS

iTrader: (18)

did you assemble the short block yourself too? if you did, did you make sure the ring gaps were good? race gas should be your first step to see if detonation goes away. then if you can notice even a little less det. then go get it widebanded again and see what you a/f ratio is. may be lean to cause so much det., and is it gettin excessively hot? that is from lean condition too. umm....if all else fails reduce the timing in Edit to a reasonable level. hope this helps

99 Black Bird T/A

iTrader: (4)

A couple of comments...bear with me as it leads up to a point.

With my TEA heads and a 224 cam the P to V was tighter than it should have been. My 5.3's were supposed to have been milled .015 but when compared to another set of virgin 5.3's it was clear my 5.3's had been milled more than .015. Best guess was the person that had the 5.3's before I did had them milled at some point for clean up or whatever. When TEA did the heads they miled .015 combined with earlier cutting my heads had more than .015 off of them. This increased compression a little for my car and wasn't a issue. It's possilbe your heads are like mine.

Comp Cams has good quality but unless the cam is checked on a cam doctor, one really doesn't know what Comp sent. You may have had your cam checked, I don't know. I do know that Comp doesn't get these cams dead on spec from having my cam checked on a cam doctor. My cam was off a little about 1 degree tighter on LSA than advertised. SRP knew thats would would happen and ordered 1 degree wider so we'd actually get want we wanted. The cam had about 1/2 degree less advanced than we'd ordered. Since SRP degreed the cam in instead of installing dot to dot, it wasn't an issue. You may have degreed the cam in, I don't know but if your cam went in dot to dot, it could be off a little.

While neither of these things might matter alone combined maybe they could. A little extra compression from the heads combined with a cam that's LSA is actually 1 degree tighter than it should be, installed not exactly on a 110 centerline but more like a 109 centerline.

All my rambling add up to this: If you order 110 LSA you probably got a 109 LSA cam. If you didn't order any advance, the cams probably .5 to 1 degree retarded as Comp ground it. If the cam wasn't degreed it might be installed another degree out. Coulod the cam actually be at an effective 107 to 108 centerline and at ~ 11.5 to 11.6 compression?

Anyone know if a 108 centerline and 11.6 compression would yield a cranking compression in the 220+ range?

Do you have enough P to V to advance the cam 2 degrees and test?

All speculation but I thought I'd toss that out there. It's probably something simple like a clogged fuel injector.

Good Luck!