Unable To Develop High Boost.

[J-Boy]

Hi guys, we have some issues with the GTR. It can't develop boost more than 0.6 to 0.7bar(on twin 34 n1). However, the car drives absolutely fine within 0.6bar, all readings are as should be. We have tried to look fer many possibilities, firstly the most possible being a leak somewhere. All hoses and pipings dont seem to have any leak at all. Both turbos tested flow the same and flow very well when testing the flow out of the turbos directly. We have tried tightening the actuators more than it should be to push 1bar, but it still does not push more than 0.6bar. At first we were told that the boost solenoid of the old hks evc had gone, so a brand new avc-r has been put in, but it DIDN'T solve anything. Only thing we are onto is that the outlet side of the front mount intercooler doesnt seem to be pushing out air as strong as from out of the turbos. Could it be a clogged or leaking intercooler core? How should we go about testing it(pressure test?) n who is a good person to sort this out in brisbane?

The last track day we had quite a lot of blowby and oil did splutter out of the catch can and maybe it clogged up the intercooler? We saw decreasing max boost on the track that day from like 1.3bar dwn to 1.1bar, then down to 0.7bar and ever since it seems to be clogged and cant develop high boost. That said, i dunno if the oil is the cause of the boost problem. However, car drives absolutely normal when we put it back on stock 0.5bar of boost ever since then cuz the problem is still not sorted. I don't recall anything coming into physical contact with my frontmount to cause a crack etc at all. Im running out of answers to this boost problem. Wot other possibilities can there be fer the cause of not being able to hit high boost???

Need some help urgent in brisbane! Recommendations for someone who knows turocharged skylines and track cars very well and is free to get this sorted out will be greatly appreciated!!

Edited May 28, 2007 by J-Boy

[Strik3r]

like you said, check intercooler and piping for blockages/leaks. Also make sure the BOV isnt leaking air.. maybe its getting weak and is opening and letting out air before it should !

[R31Nismoid]

Yer, BOV leaking or something in the I/C.

I've heard of unfortunate incidents where plastic/rags end up in I/C's and cause problems like that

[J-Boy]

Ok so i gather that you guys think its a leak as well? I havent checked the BOV and wastegates, will get them checked together with the intercooler core. Anyone thinks its something else??

[fEkuaR]

Based on that information it could be worth taking the intercooler physically off the car and having a look at it internally. You would think the car wouldnt idle properly or run so perfectly if it was a blatant leak.

[J-Boy]

Yeah im planning to have the intercooler off and checked, wot kindda checks should be done on it? And wot kindda remedies are there for a clogged intercooler core, or is it only thru replacement of the whole core itself?

[fEkuaR]

Well that would be depenadant on whats causing the block if that is infact the issue.. If its a damaged core you would see damage on the outside of the cooler. So i wouldnt expect that to be the case. If it is infact experiencing a large pressure drop across the core you all of a sudden you should be able to get an idea whats causing this restriction by examining it off the car.

[J-Boy]

Well latest update is that we think we are finally onto something and might get all this sorted out. The intercooler was pulled off and tested, it was perfect. What we found was that the 3.5" metalcat had its internals all melted due to a very rich tune n trackwork and was causing a big blockage. The cat has been replaced and the car will be going onto the dyno tomorrow to confirm if everything is sorted out or not. Hopefully thats the end of all this boost drama. I cant believe after all the time checking n changing hoses n checking everything under the bonnet that it mightt possibly turn out to be the cat giving me problems.

[ish]

LOL i was going to suggest an exhaust block but thought it way to obvious....

Dont ya hate that J-Boy. You combe the cars induction system for a problem and it turns out its just constipated.

[J-Boy]

Yeah well hopefully its all sorted out tomorrow, but sheesh this was surely missed from the start, what a bitch having gone thru so much checking. That was prolly why the car was driving perfectly fine i guess. Seems like the MetalCat can't handle too richly-tuned track gtrs. It just lasted me slightly more than a year I think ill just go de-cat on the circuit.

[ish]

yes on Drag night l... i had a replica flange to flanged straight though made up... i learnt after filling the cat up with lead on AVGAS

[J-Boy]

problem solved!! 1.35bar, 336rwkw~ 1858N.M before correction~ Feels good to be back on boost~

[xRHETTx]

Yeah well hopefully its all sorted out tomorrow, but sheesh this was surely missed from the start, what a bitch having gone thru so much checking. That was prolly why the car was driving perfectly fine i guess. Seems like the MetalCat can't handle too richly-tuned track gtrs. It just lasted me slightly more than a year I think ill just go de-cat on the circuit.

Wouldnt it be a too lean running GTR? As the car runs leaner, the exhaust temp increases. As the car runs richer, the extaust temp drops. Or have i got it wrong?

Rhett