http://www.gounitrax.com/UNITRAX/pages/ratio.html

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SCOOP

oddly obsessed with big scoops on little Mustangs

65 coupe,351w,C4,Big Boss 429 hood scoop,8" 3.40 TracLoc.

Lots of the big H.P. bowtie guys around here are running 4.30s. Don;t know if you think that might work in your car, but might be worth thinking about.

I'd gear it lower than that and let the converter eat.

3.9-1 with your big a$$ motor isn't out of line. Especially with the n2o shot! Good luck,

quote:

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Originally posted by jsracingbbf:
what about if they spray it a little bit? would a 4.30 make that much difference from a 4.56?

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To be honest, not many guys run nitrous around here anymore. There used to be alot, but now its big motors. Big torquey motors in light cars.

I assume you run alky, so are you going to enrich with alky or gas for the spray?

Seems like there are a couple schools of thought on that.

3.89 seems kindof tall, but who knows?

SLR= low gear X rear gear

Don't they say most short stroke/ high rev motors like 11 or so and long stroke/low rpm motors like 6-10?

Gear it for trap rpms and the SLR will take care of itself. Look at the high gear only 'glide cars, the converter is eating and the launch is mild. Not saying you should do that, but a low slr isn't all that bad especially with your big h.p. and torque numbers. Add a 500 shot and you're really off those SLR stroke/weight charts! Those charts were developed before aftermarket heads, and before nitrous. A 500 shot is like adding 2"s of stroke to your already wicked motor. Just something to think about.

It's apples vs oranges here since my dragster is much lighter, but I run a 4.10 gear. That's with a 33X16.5 tire.

Works great in my case for the 1/8. If I were racing on the 1/4 I would install a 3.90 gear. My converter is on the loose side (6100 on the brake) and with 4.10's it would turn a little more rpm in the 1/4 than I'm happy with.

Another apples vs oranges story: A buddy of mine has a 69 Mustang with a mild 460. It had 4.56 gears, C-6, 28" tire, 4500 PTC 10" converter. He races it in footbrake brakets around here. Last year we decided to take it to Bowling Green for the NMRA race and run brackets there. Since that is 1/4 mile we swapped the gears from 4.56 to 3.70. Those were the only gears we had. To our surprise the car only slowed .02 in the 60', ran the same in the 1/8 (7.20's) and we were now able to run the 1/4.

These big engines like to eat unless they are in a lightweight car like mine. (Mine thinks it's just an overgrown SBF, LOL)

Later,
David Cole

If you use the bottle taking off, you won't miss the 4.56's.

Weren't you having problems with traction after you got the fuel straightened out already? A 3.91 or 4.11 gear will make things a bit more manageable. (especially on the bottle)

I'd probably go with the 4.11 if you still want to run it much off the bottle. If you want to concentrate on huge bottled passes, the 3.91 might be the ticket.

I'd start off a bit less than 500hp though, regardless!

Good Luck!

LOL@ Mike saying "wouldn't start out @ 500hp shot right away" That's a huge understatement. Mike I had those Plates built to sell them, not run huge nitrous. I'm skeered of that Happy Juice.

I'll stick it on the car, maybe use one of the 4 timers in the delay box to run a 75-100 shot in high gear IF needed. It will STAY a NA car for the most part.