Make some runs with the boost at different settings, i.e. 2, 3, 4, 5, 6, 7, and 8psia. Leave the vtec setpoint and all other variables alone. Graph the data by logging it through your EMS for each run. As the boost goes up, if the problem gets worse you have too restrictive of a turbine or exhaust. Yours appears to be a turbine issue, what is your a/r for your compressor side? This problem can be multiplied be by going too large here. I had this same problem on one of my cars.

 

i'll try to get the dyno graph from my tuner, but we did like a good 10 runs, above 2 runs at like 3psi, 4 run at like 4psi, and 4 more at 7 psi

 

are you sure that VTEC is coming on?? I had the exact same problem. as soon as i hit 6K, the car wouldn't make power at all. try to listen to the engine on the dyno and see if vtec is kicking in.

let me know if that's the problem and i can help you out

 

damn Tom hope you get this figured out...


D.

 

do you have a 3mm HG? just curious as to if all of the vtec pins were replaced upon reconstruction of the head.

 

The longer duration, higher lift of the larger VTEC cam is actually detrimental to making big power on a very restrictive exhaust/turbine combination. My GT30R with a 0.48 A/R turbine housing and an InlinePRO manifold doesn't make additonal power with the VTEC cam coming on until 7000+ RPM. The more restriction downstream of the engine, the higher the pressure in the turbo manifold. A more open cam profile allows the high downstream pressure to propogate upstream of the engine during overlap, heavily restricting the flow capable through the head.

Very low restriction setups like Full Race and Lovefab result in relatively low turbine manifold pressures compared to less efficient log manifolds. The Rev Hard manifold is one of the least efficient designs on the market, hence the large restriction. Couple that with a medium sized turbine housing and a small downpipe and there you have it...loss of power in VTEC.

 

i mean we can hear vtec kick in on the dyno and the gauges show an constant 85 psi right when vtec kicks in so i'm pretty sure vtec is still active even though i T off the oil pressure sensor.

I was thinking either get a new manifold preferably an inline pro, or getting a large a/r housing for the turbonetics turbo.

what do you guys suggest?

no i'm running on a stock motor thats never been tampered with.

 

Keep your turbo and housings and get an Inline manifold and Inline 3" downpipe. The housing is the least of your restrictions.

 

lol i was hoping you wouldn't say that lol b/c i know i would have to notch my frame!!!

Also here is some pics of my manifold and downpipe if it helps.

 

Try the downpipe first. Everything else should be ok.