I am having a very difficult problem.... After hitting the dyno... I have come to realize that I can only make power up to 6000 rpm... After that I drop... This is at 15psi with a Garrett GT35R turbo... Benson Sleeved 83mm LS/VTEC 9.0:1 Compression... 1000CC injectors, Walboro Fuel Pump, MSD 6A Ignition, MSD Coil, B16 Head with port and polish.. PFAB Log Turbo Manifold.. 3" Downpipe... Open exhaust... 2.25" intercooler piping... Skunk2 Valvetrain and GSR Cams...

Someone please help me out... Running Hondata S300.. Tune is on point, but the majority of my horsepower should be made once VTEC hits... it rises at 5000 rpm and stops at 6000. THen drops off... This motor is very capable of 700+ hp but i am no where near that... Any advice?

 

Post a dyno sheet.
Post your calibration & datalogs...

Was the car breaking up (miss-firing) ?
Who was doing the tuning ?
What air fuel ratios are you seeing at what load level ?

Have you done a boost leak test ?
Compression & leak down tests ?

 

Is the vtec working sounds like it's not switching over.

 

i have the same problem. i took apart the head and the shop that put the motor together didnt install the rocker assembly correctly. the rocker assembly pins were not inside the other rockers. also my cams became square? ihave no idea why. so i swapped out the cams and put a 6an vtec line instead of a 4an. i switched out the rocker assembly and now the car feels a lot fast but i havent taken it to the dyno. on the dyno my 84mm lsvtec made 240whp at 6000rpm and then it dropped to like 110whp by 6500rpm.

 

i and a few shops have been trying to solve the problem for over a year so if you figure out your problem let me know. my vtec is switching over btw.

 

I had the same problem with my set-up. 84mm LSvtec. T67.
Here is the dyno sheet: http://img182.imageshack.us/img182/1465/epson002si0.jpg

I parted out my set-up before i had a chance to try and fix it. I am building another set-up as we speak and im just going to use another head. I believe for it to be a oiling proiblem with the head. I figure i'll just get another one since ive tried to fix it 100 times.

Here are some things i changed for the better before parting it out though: I had both oil feeds coming from the GE sandwitch plate. I moved my turbo feed to the stock oil pressure sensor location, kept the -6an on the plate. I also replaced my rockers because they were worn pretty bad. The car felt better(a/f changed, so that means it was something), but parted it out shortly after.

 

Were you running ebay cam's, a friend had a problem with his cam's going square also.

 

i was running gsr cams. 2 sets of cams went square on me. so i changed the rockers and the cams. new cams are blox a's.

 

Make sure your LMAs aren't stuck or jammed up. I've seen LMAs freeze up and cause all kinds of crazy stuff to happen.

 

i am running GSR cams... i was also coming to a conclusion that VTEC was not engaging properly or something... it just doesnt rip at all... I was at 180psi across the board...

 

It could be the log manifold not flowing enough. Also, I have seen numerous exhaust flex colapsed and restrict the flow. Take the downpipe off and see if the flex is fine.

Adriano

 

i never thought of that... the downpipe is ok... flex is still good... im not sure why, but i dont think it the log manifold because when im driving it, it wants to keep building boost.. and pretty quickly for a gt35r...

bisi from bisimoto did my tune... a/f was at about 11.8 all the way down.. doesn't miss a beat... no misfiring

 

another thing to look for is under the center cam cap(bottom half) there should be a small round dowel pin and a tiny rubber grommet type seal. without this you will not have vtec either.

deffinetly sounds like no vtec, we just had the same thing happen last week. car would make 270@14psi with no vtec, then we trouble shot it and with vtec the car picked up about 100hp. you can also hear the tone of the low cam stop pulling and it really sounds like crap


some engine managements, hondata to name 1 will actually show it switching over to the high cam table because it is triggering it to switch over, whether it comes on or not mechanically is a totally different thing. alot of people assume that since it went to the high cam MAP that it went into vtec

 

no oil pressure to vtec solenoid at high rpms??

 

with my car vtec would sound and it wouldnt make power. like i said before check to see that you rocker assembly is put together correctly because the rocker pins lock during vtec. in my case the pins were not in the other rocker.

 

sounds like either somthing with vtec not engaging or somthing in the head isnt allowing it to...

 

probably isnt a problem but u might pick up a few hp's with bigger charge pipes.

 

post pics of ur setup. How is ur dumptube routed?

 

are you loosing boost?

 

what ls/vtec kit are you using? your not feeding the turbo and vtec from the same location are you? stupid question but did you plug the factory oil feed hole for vtec?

 

i am running vtec from the same place as the turbo feed. a 6an for the vtec and a 4an for the turbo feed.

 

from my understanding, you will have insufficent oil pressure to feed both, and vtec will not engage, or oil starvation to the turbo can occur. i may be way wrong in saying this, but thats what i have come to know.

 

be sure your flex pipe hasn't collapsed. someone said it earlier.

 

Pretty simple to diagnose a vtec problem. Turn it to 7k and make a pull. Turn it to 4k and make a pull. It'll be very obvious if it's mechanically working.

 

and what do you do if it is sounding but not making power? if its a vtec problem whats the next thing to look at to make the car run right?