Hey guys hoping someone can get me going on the right track heres what happened. Went to my buddies shop put the car on the dyno base line made 480 at 26psi. Turned the boost up, have a manual boost controller so wasnt sure how much at first was playing with it. Well second run car made about 460 at 6k on 30psi we shut down early just to play it safe because never had it up that high. On 26psi usually makes about 420, so deff saw an improvement. Next run turned it down a bit to 27 28psi, going through the pull car popped like a charge pipe blowing off. Shut it down looked it over nothing out of place kind of had us both scratching our heads. Idle fine, couldnt see any leaks, made boost fine no issues. Did a few more pulls kept making about 480 max. Turned the boost up to 30psi again, came up with the same power as with lower boost, 420 at 6k 480 at 9k. Tried again made the same pop and still nothing out of place. Turned boost down to 28 made a pull felt strong but only made 480 once again. Just ended on that note because something seemed wrong.

Whole time a/f seemed good went from about 10.9 to 11.2, boost holds just fine, spool time is normal, oil pressure is great. Looked it over today nothing is split or loose, did a compression test all good, plugs look great, timing belt is in place, turbo has slight shaft play but nothing bad at all, bov is good, wg seems fine. No oil water mixing just really stumped.

Not sure what could be going on here if any one has any ideas throw them at me im lost right now. Car has never done anything like this before so im real confused. And really dont understand why the car stopped making power.

quick run down on car
GSR with eagle rods cp pistons 9 -1 comp
GT35r 38mm tial wg 50mm tial bov
walbro 255 intank precision 1000cc injectors
tuned with crome

Any things im forgetting just ask not sure if im forgetting to point something out but any help is great.

 

Your sure your not blowing out the spark at 30psi? im not sure if that would give the "pop" sound, but its my first thought. Whats the gap on the plugs? these 7's or 6's coldness?

 

Sounds like a boost leak or maybe your BOV spring is too loose and anything over 26psi it opens and lets boost out. Also this has nothing to do with the problem, but why is it only making 480whp at 26psi on a 35r? Should be at least another 50whp

 

I was gonna mention plugs too, what's the gap? Is your ignition all stock?

 

Ignition is stock ngk 7s are gapped at .020 my bov has the white spring. And with the 35r its the smaller .63 a/r and were kind of conservitive on the timing its a stock sleeve block. Car is on 100 oct also. But yea I dnt understand myself why its not making more power. Always seemed low to me for the amount of boost I was running. Car did make over 500 on another dyno so could just be the dyno we seem to have all heart breaker dynos locally.

 

yea, that seems to be low on power.. but I agree, could be spark

 

Any suggestions on what to try to remedy that? Diff plugs better ignition or something not sure on this one

 

random silly thought... though it has nothing to do with the pop... does this car have a air filter on the turbo? is the turbo getting cooler air from away from the heat build up around the engine....

i have had a filter restrict how much power i ve made no matter how much i turned up boost, took it off, car came to life... also i have seen drastic diff between turbo sucking in hot air around itself vs running just a simple tube one ft away... made a huge diff on the dyno..

hope these help

dan

 

throttle opening all the way on full thr? TPS sensor reading look good? you hav ea log file to post? to see what the readings are during pop? what the exh temp on each cyl exh pipe after the run?

 

Is there any restriction on the exhaust or a crushed tube underneath the car and the back pressure is getting choked?

Also what type of dyno was it tested before and what type of dyno is being tested now?

 

Could be sucking air that's been burnt. Post pics of setup. And graph.


Could be ic setup, manifold, b16 cams. Ect..,

 

Unfortunately no datalogs or graphs from the runs was kind of a spur of the moment thing trying to get some more power didnt expect to have problems so im lacking on that sorry guys. Umm turbo has a screen no filter had large fan going moving a good amount of air. Exhaust is in great shape 3" back straight through muffler.

I need to look at the tps that was one of my thoughts, if say i go full throttle and it goes past what it thinks should be 100% will this make it read funny or not? Right now the tps is is fully one way but the car has been like this for prob 2+ years now with no problems if i move it it picks up a studder. I broke my volt meter so im stopping by my buddies shop tomorrow to look into that further. This was one of my thoughts but idk, the way its set up it will read as far full throttle as you can possibly make it, i could be ****ing up right there but thats where it has been for ever.

And both dynos i have been on are roller type dynos different brands though not sure what brands off hand though. But yea power always seems a bit low.

Other thing im on a gm 3bar map any problems you guys see from that at all?

Im to the point where i may try putting it on the dyno again see if it replicates not sure what else to do.

 

I would get an external coil

 

my guess would be detonation from too much boost for 100 octane and your getting detonation and probably lifting the head, therefore causing the pop. i had the same problem but there was nothing wrong and we check datalogg and we couldnt find no leaks or anything. for the ignition i recommend the big blue blaster coil from msd and at least a 6al ignition box. try some ngk 9's gapped to .025-.028 no lower than .023. dynos do read diffrent from company to company so dont go off of dyno numbers just dial in the a/f and timing and dont worry about numbers just use the hp as a refrence for the changes you make. my .02 cents goodluck with it

 

Running a 3 bar map, aren't you nearing the top of the scale on that thing at 28psi? Don't they read -1 to 0 ATM then 0 to +2 ATM? Correct me if I am wrong there, but I thought that was how it was divided up.

 

SPINNING ON THE DYNO I BET

 

you do have a point about the 3 bar it might be maxed out or throttle body not being open all the way or possibly tps is bad.

 

What kind of exhaust are you running?? Are you running a Flex pipe or not? We've seen in my car and couple others where the flex pipe will collapse and not making any power even if you max Boost

 

Was going to just ask the same question. hope you find out what it is

 

did it pop up top in the rpm's? for a few pulls on the dyno on my car it would pop at the end of the pull and it was blowing out spark. it might be the ignition. your gap on the plugs is fine i would say. also maybe try a different plug. i run ngk 8's in mine and they do very well.
i also think that seems a little low for power on that turbo at the amount of boost. to bad you dont have a sheet for everyone to check out and maybe help a little more.
but my guess is the ignition

 

There is a small flex pipe ill check it out i dont think thats the problem but doesnt hurt to check. And ill try a diff plug, if problem is still there ill try a better ignition set up. I deff dont see that i was spinning on the dyno my DRs were pretty sticky on the rollers.

Also seemed to pop like 6 - 7k both times so it would hold boost to that point then what ever is happening did.

And yea sorry guys for not having sheets or logs i hate being unprepared but just kind of is what is right now.

Do you guys think i should maybe try and start fresh on the tune and throw more timing it and try keeping the boost down? My tuner seems like to make power with boost more than timing thats just his preference i guess.

 

The stock ignition can handle around 500, your getting close to that. That why I recommend the external coil

 

Ok ill deff look into picking something up what do you guys suggest?

 

ignition issue, try another dizzy.

 

this. and it could vary. yours might be maxed out already. when others might make 550 on stock.
def try external coil. if the plug issue doesnt fix it.