guys, set up as follows:
B18C1 84.5mm / 10.0 :1 CR
ported head with edlebrock mani/70mm tb
3" I/C piping with T1 I/C
FR Divided Manifold/ BW s372R with 1.10 Hotside
pro 1 cams

at boost of 28psi car was making 570 whp/410 ft lb.(i think this was kinda low). thing is that although boost was holding rock steady, after 7500 rpm a/f ratio was going from 11.5 to 10.2. needed to take out about 20-25% of fuel from 8000 and up to maintain a 11.4 a/f ratio. this tells me that around 7500 to 9200 the turbo is flowing less air than when full boost is attain up to 7500.
what can be the caused for this.

thanks

 

boost leak, cams not adjusted right, could be several things, did you have the Pro-1's degreed?

 

pro was not degreed. was goin to adjust on the dyno. so with a boost leak, the boost level would still show it is holding?

 

Pro-1's need to be adjusted properly before you start looking for the problem, they are not drop in cams.... well the new Version3's are but more than likely yours are not, if they are off you should see less than optimal numbers....

 

i'm guessing he is asking if they were degreed based on a non oem cams needing to be degreed to know when the valves open and close and how much if any you need to adjust the cam gears to get the most out of your cams.

Now i'm no expert on degreeing so i won't say anymore on it as someone with more knowledge should explain why it is needed to be done.

 

a/f ratio was going from 11.5 to 10.2. needed to take out about 20-25% of fuel from 8000 and up to maintain a 11.4 a/f ratio.

Maybe that is telling you something, cam related?head related? just a thought.

 

I think its cam related, and I think your best bet is to start there.....

 

I would check for exhaust leaks pre-turbo (manifold,turbo,wastegates) and boost leaks test to insure is not leaking at any coupling, BOV, TB, or even IM gasket. Check your valve clearances and copression/leakdown test. Hopefully one of those would give an answer.

 

what are you cam gear settings?

 

if boost is holding steady like he said? why would you recommend he check for leaks? thats makes no sense.

 

umm boost can hold steady with boost leaks, the bigger the turbo the easier it is to maintain pressure levels. I'm not saying that's the problem, I am saying just because it's holding steady that doesn't mean it's not the problem.

 

The only leaks that i'm seeing that could "hold back" power are very large ones. and to me 28psi is quite abit to be holding steady and have pre/post leaks.

Just another opinion over here.

 

ok opinion sure, facts are you're wrong.

 

You have to set the Lobe Centerlines then go from there man. You cant just "adjust" on the dyno lol..

 

And def those cams need some tweaking.

 

If the head wasn't ported or you had a smaller hotside I'd say you're flow restricted but from the sounds of it you're as wide open in all areas as you need to be... definately points to the cam timing.

 

How do you know if you have the version3s or the old style pro 1s that need to be degreed?

 

fellars, thanks for all your input. will check the cam timing.

 

+3 Intake, +4 Ex.

 

watching.. similar problem - different car, different setup but same symptoms. I too think it could be a boost leak (at least for my issue).

 

You can have a boost leak and still hold plenty of boost. You WILL make less power than if you are holding that same boost without a leak.

 

Get the cams degreed.

Dyno sheet???

 

will get someone to post the dyno sheet.

 

Those cam gear settings seem a little suspect.. If I remember correctly, the Pro1's require a 4 degree lobe separation..

 

well foud out that the map sensor (not used btw) casing I had on the TB was cracked. pulled it out and all around the casing was starting to open up. hope that is where the boost leak was coming from.