Rogue_Ant

O-trim is referring to the turbine wheel. It is a T4 turbine, but not overly big - kinda between a T3 Stg III and Stg V. I guess you could think of it as a Stg IV.

TonyG

The trim is the size of the exhaust wheel and the size of the turbine exducer (where the exhaust exits the turbine). O trim is smaller then P trim, etc... You have the a/r ratio and the trim size which make up the turbine spec for a given turbine wheel.

I changed the cross over because of the turbine bolt pattern and the fact that the SFR header uses a 4 into 1 merge collector, thus cannot bolt up on the other end of the factory cross over pipe either.

I don't remember what the back pressure readings were. This was 7 years ago when we built the first 4 into 1 header.


The SFR Header (which I designed, and the first one built is on my previous car BTW) improves performance several ways:

1) Improved "off boost" TQ by the nature of the tuned length of the runners. Improved TQ, means more TQ, which means more exhaust gas, which means faster turbine spool (sooner in the rpm band that is...).

2) Equal length runners balance the reversion across the cylinders

3) Merge collected collector for better scavenging (see #1).


JME reported a 50Hp gain on his 3.1L race engines (measured on an engine dyno). SFR supplies him his headers as well as a a few other big name 951 engine builders.

Here's the car's old web page:

http://www.tonygarcia.org/red-951-2.html


Hope that helps...


TonyG

TurboTommy

Interesting, Tony; thanks

I know on a NA engine, tuned equal length headers are desirable for scavenging purposes; but how could they contribute to scavenging on a turbo engine when exhaust pressure is almost always higher than the intake manifold pressure?

333pg333

Tony, you did 1:32s at Button Willow in your old car. What sort of times are you doing in the current one bearing in mind that you have a lot more experience and car development since then?

TonyG

It wasn't Buttonwillow. I was Willow Springs Raceway.


Currently I run low-mid 1:29's with stiffer suspension, much wider tires. I am running NT01's 275/315 now (since then I'm now running 315/315 NT01's). I was running Hoosier 245/275 R6's then.

Then the turbo 4 make more top end power than the LS1 too.

As far as experience goes.... I had been running that track for 20 years before the previous red 951 that you see the pic.

My a close friend that I've been racing with and against for many years, with his modded 996 with 996 GT3 motor, bone stock GT3 suspension, close ratio trans, guard gt diff, yoko slicks, full aero, and gutted ran a 1:23.5 on the same track.


TonyG

333pg333

So what if you had your old 4 banger in your current car? What is going to turn faster times?

Also in regards to your friends modded 996 eclipsing your times by approx. 6 seconds. You have mentioned to me in the past that you could easily increase the power of your motor, but you don't want to go so ballistic as to blitz the field, or something along those lines. I know you weren't saying this in an egotistical way, but I wonder just how far your friend might be ahead if you had a warmer LS motor or dare I say it, a properly built 4 cylinder??
...oh, and a dry sump system plus slicks...

Tayloray

Alright so i'm stuck again, this time on the bottom shock mount bolts. i've tried breaker bars, impacts guns. and they will NOT budge, not even a tiny bit.

Tayloray

Okoay, i got them off, but the suspension only dropped maybe 1/2 inch. i have all the bolts clarks said to remove out, and it won't go any lower.