Who wants to help me pick shift points, stall, and gears? - Third Generation F-Body Message Boards

IROCThe5.7L · 08-27-2009, 02:20 AM

Hopefully I can provide you with enough information. The car is mostly street. I take it to the track once or twice a year.

Stock L98 bottom end (9:5:1 compression).
Holley Stealth Ram Intake
AFR 195's (New Eliminator Series milled to 62cc).
Comp cam XR276HR:

Quote:

RPM Range: 1900-5600
LSA: 110
Duration @ .050" Lift: 224/230
Valve Lift: .535/.544
http://www.compcams.com/Cam_Specs/Ca...?csid=188&sb=2

I was thinking 6100 rpm shift point (shifts at stock 5000rpm now)
2800-3000 stall
And a strange 12 bolt rear end with 3.73's (I'm told this is a direct bolt in).

There are two strange 12 bolts on summit. One says it's only for 1993-2002. The other says 1982-2002 (http://www.summitracing.com/parts/ST...ET&prefilter=1).

Well we all know if we put a LT1/LS1 rear in our cars it will stick out a bit. And I honestly don't like the way it looks. Will the 12 bolt do that too?

Thanks a ton!

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Stephen 87 IROC · 08-27-2009, 07:55 PM

That cam has an RPM range up to 5600. Why do you think you can shift at 6100? You'll probably be shifting at 5500.

Stall speed in the 2800-3000 range will work fine for the cam.

five7kid · 08-27-2009, 08:11 PM

Your shift point should put the engine at its max torque in the next gear. With a TH700, you may need to shift at different RPMs for 1-2 than you do for 2-3 (typically higher for 1-2 than for 2-3). But, I doubt it will be 6100 RPMs for either.

I would guess the rear end would be specified upon ordering, whether 82-92 or 93-02, disk or drum, gear ratio, etc.

IROCThe5.7L · 08-28-2009, 12:30 AM

I always heard to shift 500 rpm past your peak power. Kind of how a stock TPI makes it's max HP @4500 but it shifts at 5000 rpm. But does the 3.73's sound good to you guys?

xpndbl3 · 08-28-2009, 12:58 PM

i'd go a little bigger on the cam and grab a 3500 stall and 4.10s but it's ultimately up to you. If you want 6k+ shift points then knock the cam size up a little.

Stephen 87 IROC · 08-28-2009, 07:06 PM

Gearing depends on tire size and engine rpm range. You want to be at or just before your shift point as you cross the finish line in high gear. 3.73 gears will work for a 26" tall tire but for drag racing, you want at least a 28" tall tire. Again, it really depends on the rpm range of the engine. A shift point at 5500 needs different gearing than an engine with a shift point at 7000 rpm if both use the same size tire.

xpndbl3 · 08-29-2009, 12:17 AM

also 9" > 12 bolt bar none. Get an aluminum center if you're worried about weight and it'll be lighter than a 12 bolt and with drag brakes it's lighter than a stock 10 bolt

IROCThe5.7L · 08-29-2009, 12:43 AM

Damn, I was set on a 12 bolt. Hmm...is the 9" a direct bolt in also?

Since I am on the stock 74,000 mile bottom end, I didn't want to string it past 6000 rpm. That's why I figured the current cam could be shifted at 6000.

The most I'm going to do is throw a set of DR's on the stock rims.

Stephen 87 IROC · 08-29-2009, 01:39 AM

That weighs about 20 pounds. Aluminum bolt through Moser case, aluminum spool, aluminum daytona pinion support. I never did get around to installing the aluminum yoke. If everything was steel, it would be closer to 40 pounds. Hard to shave that kind of weight off when using a 12 bolt.

The Moser case isn't cheap but you can get an inexpensive Strange aluminum case which will easily survive your power level.