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Tuning inconsistent between cylinders boosted LS wth oem pcm causes and fixes!
I have a turbo 5.3 camaro. Nothing crazy traps 153-159 trap speeds this summer @ 3,380 pounds.
I am still on the factory pcm and the car runs great. Really great. Cold starts, idling etc.
Anyways twice in a row the car has torched the heads. Once on the passenger side and once on the drivers side. First time it happened I was running quite a bit of timing but the car would go faster accordingly. About 21-23 psi and 19 degrees of timing. It would trap 153 on 21 psi with 19, 151 on 21 psi with 16 degrees. about 11.5-11.7 afr for both.
The first time it popped the gasket i hoped for a quick fix but for the first time in my life I had torched the head. A set of heads I had 25-30 hours porting and polishing into. I was pissed. All of the plugs looked great, no signs of det, and no other cylinders showing any kind of issues once opened up.
I was a little spooked so I pulled timing back to 15 degrees. Made two passes without any problems at the track or so it seemed. 8.80@15, 8.79@156 and then my third pass it once again popped the gasket. I was super pissed now. Plugs look brand new in all of the cylinders.
Got home and instantly tore it down. One entire side of the motor the headgasket looked brand new. Opposite side of where it popped through the head last time now has another torched head and gasket.
Im at the end of my rope with it. Im wondering if there is an issue with the pcm/wiring etc. If it is something I am doing I will be more then glad to correct my error but a single cylinder for no rhyme or reason is throwing me off for a huge loop. If it makes a difference or not it is revved to 7,4-7,500 peak
I street drive the car and track i for fun. I dont really want to spend $2,500 for a standalone but if that is going to keep my motor from doing this again I will gladly do it.
I'm no FI expert but maybe that's just too much pressure
for a stock style gasket and stock head bolts / number of.
Maybe you need to be O-ringed by this point? Looks like
the fire just found the easy way out and kept on digging.
What fuel, head gaskets, compression, cam? At a glance it looks like you are lifting the head from too much cylinder pressure or the heads are flexing though. Either way it doesn't look like anything a standalone is going to fix.
Ive had this up to 30-31 psi on the street but havent wound it out past 7kish or pushed it as hard as the track. So usually when I get to the track Im up around 7-7,500 for the entire run. So Im not sure if it is the extra load, extra little bit of heat, or just the fact that something is going wrong. At first I thought maybe an injector failed or it was too much timing. But the fact that most all of the other cylinders look perfect has me skeptical. The fact that it happened on two different sides of the motor for no ryhme or reason.
Makes me wonder if I am lifting a head in those areas and while under all of that load it is just blowing the spark to the edges of the chamber.
Either way I want to get it fixed.
I know people running 7's with similar setups but slightly lighter so I know it is capable.
Car is on e85
oem 3 and 5 layer headgaskets. happened with both.
Approx 10.2:1
ljms stg 2 turbo cam.
slightly ported 243's
aluminum block 5.3
Back pressure has not been monitored but shouldnt be crazy. 5.3 with a 1.32ar 96mm bullseye t6
I have definitely had headlift issues with the car in the past. I was really aggressive with timing but the car would always pick up mph. I just recently started taking timing out to keep from pushing water. Car goes as fast on more boost and less timing.
Convertor isnt tight enough. about 11.6% slip. Going to a better PTC unit this year.
Backpressure in one single cylinder? That makes no sense.
Im not blaming the rpm Im just saying the first time it happened I whipped its *** on the street for weeks. Went to the track and fucked it up first run.
Added the 5 layer gaskets and another head and it lasted a few more passes and did the same thing on the other side.
With that turbine and ar I shouldnt have any issues in comparisson to 6.0+ cube guys running this frame s400 chassis.
I'm no FI expert but maybe that's just too much pressure
for a stock style gasket and stock head bolts / number of.
Maybe you need to be O-ringed by this point? Looks like
the fire just found the easy way out and kept on digging.
I have done several 700+hp 4 cylinders in the past. Same scenario with them. Oring them and night and day difference. Im probably going to go for it while the car is done over this winter. Wont hurt.
It may be as simple as you are just exceeding what the setup is capable of holding. In my opinion that combo is making an awful lot of cylinder pressure for OEM 5 layer gaskets and ported 243s. I'd be doing thicker deck aftermarket heads and LS9 gaskets, make sure the block deck is flat as well. I didn't see any mention of studs either but make sure you are running good studs for a good clamp.
LS9 gaskets are 7 layer, I'd try those.
I lost the stock 5 layers, as well as the FelPro 3 layers.
I also had the heads surfaced then lapped smooth. Mine were cut too coarse when I was losing gaskets.
In fact, they looked like yours.
I'd get a machinists straight edge and carefully check the deck for flatness.
I guess you will be needing a head.
What AFR are you running?
Did you use the ls9 gaskets on an aluminum motor? My buddy tried them previously on an l33 turbo setup and they spit coolant out instantly. Switched them out for a set of fel pro's and been fine. there is very minimal amount of gasket material that touches the 5.3 sleeve.
It may be as simple as you are just exceeding what the setup is capable of holding. In my opinion that combo is making an awful lot of cylinder pressure for OEM 5 layer gaskets and ported 243s. I'd be doing thicker deck aftermarket heads and LS9 gaskets, make sure the block deck is flat as well. I didn't see any mention of studs either but make sure you are running good studs for a good clamp.
Absolutely, since it is winter I am tearing it all down and sending it out for a surface. In the middle of deciding if I should oring the heads and block and run copper gaskets or get an aftermarket set. Id hate to buy a set of $2k dollar heads and torch one for whatever the reason is. That would suck.
Did you use the ls9 gaskets on an aluminum motor? My buddy tried them previously on an l33 turbo setup and they spit coolant out instantly. Switched them out for a set of fel pro's and been fine. there is very minimal amount of gasket material that touches the 5.3 sleeve.
I am running low 11's afr. About 11.20-11.40
Yes, mine is an L33. As I stated, I had the heads machined and lapped to a very smooth finish.
i also went over the deck with a flat machined alum plate and 400 grit wet paper. Very carefully.
Although I now have ARP studs, I was using the China studs. Torqued to 80.
I fought the LS9 gasket being too big for good sealing, but it works. I know one guy running 30+ psi and it lives. LS1Nova
I would honestly run closer to 11 flat on the E85. I saw no perf gain going to 11.4.
I haven't gone as fast as you, but I will.
Yes, mine is an L33. As I stated, I had the heads machined and lapped to a very smooth finish.
i also went over the deck with a flat machined alum plate and 400 grit wet paper. Very carefully.
Although I now have ARP studs, I was using the China studs. Torqued to 80.
I fought the LS9 gasket being too big for good sealing, but it works. I know one guy running 30+ psi and it lives. LS1Nova
I would honestly run closer to 11 flat on the E85. I saw no perf gain going to 11.4.
I haven't gone as fast as you, but I will.
I agree that the power difference is minimal in that slight amount of extra cylinder cooling. Im still wondering if it is something else. I have tuned 160+ mph hondas and several 150+ trap turbo ls engines. Figures Id have issues that I do not have answers for with my own car.
01-15-2017, 10:05 PM
Tuning inconsistent between cylinders boosted LS wth oem pcm causes and fixes! 
