see my sig for current gear, 60 and trap rpm what changes do you think would happen with 3.73? where do you think it would bump my trap rpm to with current mods car will pull to 5200 rpm

 

I think you will be better off with 3.42's.

 

I was thinking the same thing. With only a 5200 shift point and 26" tall tires (typical car tire height), you're not going to need a lot of gear. 3.42's should just about max you out at the finish line. A deep gear like 3.73 or even 4.10 will get you off the line quicker but you'll run out of rpm before you run out of track.

Now if you had some mods done and got it up into the low to mid 6000 range, then you could use more gear.

 

When I had a 383 SBC, I was shifting it at 6800 and only had 3.27 gears and 26" tall slicks. The car ran high 11's at 117 mph with 1.7x 60' times. The gearing was all wrong though. I was only crossing the finish at around 5500. Although I was slow out of the hole, within the last few hundred feet, the car got into it's powerband and would make a fast charge to the finish.

Switched out to 4.10 gears and a 28" tall tire fixed that problem and the car finally got into the low to mid 11's before I blew the engine.

 

thanks guys that's what i needed to know. i did not wan't to get to high a gear and have it fall hard on the big end. hard launches are cool but you need to finish the run strong to

 

i'd jump up to 3.73s and 28" slicks, should put more of a contact patch on the road as well. Plus you can see if the 3.73s are too much gear and just change tire height which is good for 7-8 MPH more at the end typically.

 

If you’re going through at 4700 now you’d be going through at almost 5400 with 3.73’s. I’d bet that anything that put you over 4800-4900 through the traps will slow you down, but you will launch harder so maybe you’ll break even as high as 5000rpm.

You’d probably run fastest with the 3.73’s and a 28 or 29 x 9” slick, and that would also make it more fun off the line on the street, but I don’t think you’d really like the 3.73’s for highway cruising unless you run really tall tires on the street.

 

well, i know the stock tpi is good to say 4500rpm - 4900rpm
i have a ported bigmouth manifold, gasket matched arizona speed and marine semi-siamesed runners, a highly ported and siamesed plenum with twin 52 throttle body and slp cold air. i would think that would be good to at least 5300rpm or 5500 rpm. the car is out on nice weekends only has not seen rain by choice in over 4 years so gear choice for highway driving is a moot point. as of this year i will be "trailering" (is that a word?) to the track. sorry for not showing full set-up first see sig

 

it doesn't change anything I said, you're still limited by your stock heads and/or cam.

If you want to go faster with them then you need to optimize for them rather then fighting them with stuff that is going to like bigger rpms