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Discussion Starter #21
I think you would see a dramatic improvement with a 3000-3500 stall convertor and 3.73...you have the right tires they just grip too much to let the motor rev ...4500 is way too low a shift point also...you could see 11.89
Not sure what you mean by shift point. I do have the rev limiter set at 6000
 

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I think he went through the big end at 4500 if I understood correctly. Meaning he could go to a lower gear ratio without riding out the rev limiter.

I think fixing the traction problem first then looking at the gearing would be the proper order of operations. Being able to launch the car harder will make big gains down the track.
 

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Try to keep your starting line rpm down. Bringing it to 2400 and hitting it is counterproductive. 1. It takes your suspension out of the equation with the chassis being loaded. 2. It keeps your converter stall lower. Short explanation there is stall speed of the converter and flash stall. You could actually raise the stall speed 100-200 by letting the engine run at the converter. Think of trying to push a heavy weight if you stand next to it compared to you running at it.
 

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Have you described the engine/car somewhere else?
I could Gonkulate it pretty easy but need a lot more detail.
Cold air / cowl induction?
Carb?
Intake?
Heads?
Headers?
Open or size mufflers & type?
Cam specs, .050 duration, LSA, advance, roller of flat, mech or hyd, gross/net lift?

Any dyno results like peak torq at RPM and peak power at RPM?

What RPM is the trans shifting at, 1-2 and 2-3? Guessing 5800?

x2 what bracket said about not loading it on the converter, if you already are spinning that's the wrong thing usually.

I guessed at your combo and a 3.73 gear made it about .12 sec quicker but that's a sloppy guess without the above info.

One easy thing to try would be, start off in 2nd gear, then just shift 2-3 at the usual (5800?) RPM.
When I did that in the Gonkulator it spit out this:
2.27
6.42
9.53 at 81.1
14.29 at 103.7
Point is, starting in 2nd gives you an easy but extreme way of testing the low-end of the car - how much does a really tall gear (eg staring off in 2nd) hurt it? Once we know that, gear changes can be gonkulated more accurately. A lot easier than swapping gears!
 

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Discussion Starter #27
Should be shifting between 5,500-6,000 RPM depending on the cam specs. If you drive on the street more, I'd go with 3.73 ratio, if more for the track go with 4.11.
More street than track. Also, it's an automatic. Can't remember which way you you're the screw for adjusting shift?
 
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