More boost, no gain

[cool 84]

The t-type has been stuck in the 12.8@106 range no matter if the boost is at 15-24psi, it makes no difference. Got it dyno tuned and it went from 260rwhp/300lbs (in 12.8 tune) to 345hp/460lbs by going from an off the chart 10:1 AF to 11.0 and 20psi. It has ported irons, 206-206 cam, TE44, and all the normal supporting mods. HP falls off at 4,200rpm real fast. Torque increases with boost, hp falls off at a faster rate with more boost but peak is about the same as low boost. AF is ok, timing is at 24, the numbers look ok. Any thoughts? 100lb Comp valvesprings.

 

[TurboJim]

Your engine is probably sucking more than the turbo can supply. I'd say that 44 is too small and you're probably WAY out of its effieciency rance at 17+psi. Go up to a TE61 or bigger.

 

[WarpSpeed]

How's your transmission? Think it might be "giving up" around 350hp, or so?.

 

[norbs]

I have run 120 mph on a te44 theres lots left in it. Its something else

 

[azgn]

flat cam?

 

[norbs]

thats what i was thinking, but didnt want to say it, but its making power on the dyno

 

[cool 84]

I thought about the cam but figured there would be some valvetrain noise. It also pulls 20" of vacuum. Trans fluid is still red and doesn't smell burned. With low boost it has a little more of a curve but at high boost there's not the normal hp curve, just a steady decline. No KR. Also installed a Ford FM and even with signifigantly decreased air temps it still runs exactly the same. Tried high octane/no methanol and pump gas/methanol and it still runs exactly the same. It falls off bad enough that when it makes the 2-3 shift, it actually pulls harder in third than the top of second. There's no cutting out, sounds normal even when the power falls off. My 84 GN had a very similar combo except with the hotair intake and went 110mph in total street trim so I know this 86 must have more in it.

 

[TurboJim]

Ok, then how about taking the air filter off to see if its getting sucked shut?

Jim

 

[ijames]

Was the cam degreed in? Power should stay flat at least, if not go up, to about 5000-5400 rpm with that cam and heads, so maybe the cam is installed advanced. Is the boost staying constant or is it falling off as the rpms climb? I "know" a 44 has lots more in it but maybe you have a bad exhaust leak/poor wastegate puck seal/some other problem?

 

[cool 84]

Boost stays constant. No catalytic convertor, 14" K&N that shows no sign of getting sucked shut. It makes good power for 15lbs of boost but it just doesn't pick up at all with higher boost. Maybe the cam is a little advanced I guess.

 

[S2V6RACER]

I say a mechanical issue. Seems you are building exhaust backpressure and loosing efficiency past 15psi..... That is why no gain in power. Check the cam.

Ted