G'day guys, wasn't sure what to name the title but the best to describe it.
I went for a odd setup on a RB26 rather than the typical setups people run just mainly out of curiosity.
Standard RB26DETT R33 GTR
BW EFR7670 IWG 0.92 A/R - for comparison similar size to a GT3076R
Split pulse manifold, using 1 Inch runners.
3.5" Dump, Huge Cat, exhaust etc.
Using Internal Bypass valve on EFR Turbo
Haltech Elite.
This setup I wanted to tailor it not for huge power but more so response.
The issue the dyno shop had and we couldn't quite find out exactly what is causing it, it just doesn't want to make any more power than
around 280hp at the wheels without showing resistance. What I mean by that is, going from 8 PSI at roughly 280hp, and doubling the boost to 16 PSI, it only makes about 40HP more and I did remember
the tuner saying timing had to be held back to stop it from wanting to ping. He also mentioned he did have issues trying to get it to hold the boost, and some time had to be spent
tuning to get it to hold the boost. At first he mentioned it would boost up to desired pressure, run and then just want to fall off no mater if we ran direct feed to actuator, used a solenoid controlled by the haltech or used a manual tee. After they spent some time tuning the boost control they were able to get it to hold 16 PSI but it took a long time to achieve that result, but cannot get any more than 330hp, raising boost more just results in minimal gains beyond this point, where as normally on their dyno a turbo of that size would make in the 400-450hp range.
Originally we thought there may have been wastegate creep or a intake leak - all that was checked and it doesn't appear to be the issue.
I'm wondering if anybody can give me ideas as to what may be happening, I can try post some sheets if that can be of help.
I don't think the turbo itself is way too small, as many people have run similar sized turbos on RB25's and RB26's without issue.
I wouldn't think the manifold is too restrictive as a few people have run manifolds with 1" Runners on similar setups. So the issue is
we can't pin point a reason why it's happening other than thinking the rb26 doesn't "like" this combination of parts I've put on for better words.
I do not know if a bad batch of fuel could cause odd things like this?
For now I will have the car at a lower power level just to drive it around a bit and when I have time I can get around to seeing what's up.
Cheers Guys.