e34nication

It's in the 80's down here, so not too hot.

JBrown

man it takes that much work to get 400 wheel holy **** lol

Humboldtgrin

I don't know about your cylinder head but Lindsey racing stage 3 2.5L 8v head will flow just over 250cfm intake. A 2.7 head flows 263 stock and a ported 16v head can reach 350 cfm intake. Your cylinder head is the weak link is what I'm saying if you want more power, regardless of the porting and big valves. Your head will probably produce near the same power on a 2.5L with a matched turbo but not as nice of a power curve as you have. But you have a 3.0 with a ported/big valve 2.5 8v head which I would say you maxed out with 91 octane fuel. A smaller turbo would move that power curve down a bit. I would find a 2.7 head and send it to LR to work it over. You need more CFM flow in the cylinder head if you want more power and you could bring that boost down some. The 968 turbo rs has about the same power that you have and they use a stock 2.7 head. If you port a 2.7 head the flow will dramatically increase because it's already a big intake port head. You would need to modify the water port (LR could probably do that) and use 951 exaust valves or have LR work that side over too. George D I believe said he used white lighting ceramic coating on the inside of the exhaust ports on his 2.7 head to help aid with the heat so that maybe something to look into or ask him. Also did you get Alberts 2.5" header/crossover? That helps with exhaust back pressure if you already have a big turbo and exhaust from the turbo out. That's just what I see. It's an air pump and the head CFM flow is the major factor. I bet with a 2.7 head with a port and polish with modified water port would realy show what that 3.0 could put down. But with your ported/big valve 2.5 head your about maxed out IMO.

V2Rocket

I think those quoted flow numbers are pretty optimistic, based on other people's projects shared on here not getting those results on heavily worked heads.

Also, the 968 turbo used what was essentially a 944T head made to fit the 3.0 block (like what Lindsey does)...968T head had 944T-size intake ports and small exhaust ports.

Surely user 968TurboS (Raj) will be along soon, as he has some Rennlist alarm that goes off when people talk about the 968T, and he can set us all straight.


Dear Mr. Brown...I wonder what the graph would look like with the stock intake manifold back on it.

jmj951

Are you running a completely stock intercooler? If so, that's your bottleneck. A stock IC flows in the low 200cfm's.

JBrown

i have speed force racings front mount intercooler

Humboldtgrin

Realy? I thought the 968 turbo rs used the 2.7 head just like everyone else that wants to biuld a 3.0 8v turbo using the 104mm block. Isn't that the reason for using the 2.7 head on a big block turbo setup? I like to be set strait when I'm wrong thou. I didn't think Porsche altered the water port from a 2.5 8v turbo head to fit the 104mm bore big block. We can also ask Jason since he has one of the four 968 turbo rs cars.

And I totally forgot about the intercooler, that is very true. I was focused on the long block, exhaust and turbo. And I was thinking if the intake manifold was custom then the intercooler would have been addressed with an updated unit as well.
He beat me to my post, he does have a FMIC.

JBrown

Here are some photos

JBrown

And more

V2Rocket

Devon are you using the stock 951 throttle body?

JBrown

That is correct

Dave W.

Which fuel are you using?

jmj951

Not a fan of the intake manifold design. It doesn't take into account the pressure waves bouncing back and forth. In this design, the pressure waves basically go off in different directions instead of traveling back down the runners.

Edit: And, the plenum is enormous. Great for top end, but I'm really curious about how that would affect throttle response in normal driving situations.

333pg333

Nor of the air filter position. Be an idea to check out that vented LH light cover if you're going to leave it there. And/or some hood vents to encourage some underhood flow.

JBrown

93 Right now but going to add a meth kit in the spring