What gear to run vs. starting line ratio

casrak7 · 09-20-2019, 12:28 AM

We are currently geared for 1/4. 4.56, 1.98 first gear Powerglide, 28x10.5 tire. roughly 750 hp. roughly 2800lbs. 418 cube small block. shifts at 7800 crosses currently at 8250. Not tuned. suspension not yet right. But he wants to set car up for eighth mile. SO we might as well have the correct gear in the car to begin tuning with.
So......our current starting line ratio is 9.03:1. Should we gear the car for max rpm to eighth and run 5.38 gear or so? Should cross at 7700+ (10.65 starting line ratio), OR concentrate on the starting line ration ONLY, and go by a generic starting line ratio chart I found which says to shoot for roughly a 9.5-1 starting line ratio......and put in say....a 4.88 gear for a 9.66-1 starting line ratio? Car is a stock suspension "style" 2000 camaro......with NO power adder
The moroso slide rule is spot on for our current and only trip to the drag strip in n the 1/4. It said 150 mph was about 8200. That's where were crossing now....8250. it says to cross at 7700 at 121 mph would require a 5.38. I just wonder if the 5.38 will create a "too aggressive" starting line ratio for BEST ET POSSIBLE.

PLEASE KEEP IN THESE THINGS...

we only run on hp only. No power adder.

We will only have a 28x10.5 tire (stiff wall)

We want BEST 1/8 mile ET as our ONLY concern

Car only has made three passes at track 1/4 Mile. 9.50 @ 150. Had lots of suspendion troubles....... But before tackling them.....I be want the correct hear in the car just in case the gear could potentially affect things.

Mike Pearson · 09-20-2019, 09:58 AM

Ideal would be to gear the car to be at max RPM at the trap. Given the small tire you have the SLR might make it difficult to hook. The Stockers are able to do it with a 9 inch tire.

Chevy55 · 09-20-2019, 12:38 PM

Usually best to leave everything right where it is but if you want to play then maybe a lower rear gear and a higher 1st gear ratio so you end up the same final total 1st gear ratio that you have now without upsetting the launch.

Doesn't seem worth it to me. JMO

Dan Fahey · 09-20-2019, 04:03 PM

Fix the suspension and safety of the car.
Tune the engine and suspension
For gearing
If you are Bracket Racing you have enough.

HawkBrosMav · 09-20-2019, 05:36 PM

I not completely familiar with SLR but if it's rear ratio times first gear ratio 10 seems a little low for most Stk S/S cobinations...

obviously with a longer stroke that would change things, but we have a 3 inch stroke... 2.92 1st gear ratio and 4.88 rear ratio on a 28 or 30 by 9" wide tire.. have zero issues hooking..

2.92*4.88=14.25 SLR I'm sure yours can be a little lower as I'm sure your stroke is bigger... but i wouldn't worry about it too much and I'd guess if you can make the higher SLR hook your 1/8th ET will be quicker..

09-20-2019, 12:28 AM	#1
casrak7 Junior Member Join Date: Jul 2011 Posts: 63 Likes: 0 Liked 3 Times in 2 Posts	What gear to run vs. starting line ratio We are currently geared for 1/4. 4.56, 1.98 first gear Powerglide, 28x10.5 tire. roughly 750 hp. roughly 2800lbs. 418 cube small block. shifts at 7800 crosses currently at 8250. Not tuned. suspension not yet right. But he wants to set car up for eighth mile. SO we might as well have the correct gear in the car to begin tuning with. So......our current starting line ratio is 9.03:1. Should we gear the car for max rpm to eighth and run 5.38 gear or so? Should cross at 7700+ (10.65 starting line ratio), OR concentrate on the starting line ration ONLY, and go by a generic starting line ratio chart I found which says to shoot for roughly a 9.5-1 starting line ratio......and put in say....a 4.88 gear for a 9.66-1 starting line ratio? Car is a stock suspension "style" 2000 camaro......with NO power adder The moroso slide rule is spot on for our current and only trip to the drag strip in n the 1/4. It said 150 mph was about 8200. That's where were crossing now....8250. it says to cross at 7700 at 121 mph would require a 5.38. I just wonder if the 5.38 will create a "too aggressive" starting line ratio for BEST ET POSSIBLE. PLEASE KEEP IN THESE THINGS... we only run on hp only. No power adder. We will only have a 28x10.5 tire (stiff wall) We want BEST 1/8 mile ET as our ONLY concern Car only has made three passes at track 1/4 Mile. 9.50 @ 150. Had lots of suspendion troubles....... But before tackling them.....I be want the correct hear in the car just in case the gear could potentially affect things.

09-20-2019, 09:58 AM	#2
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,445 Likes: 614 Liked 1,919 Times in 576 Posts	Re: What gear to run vs. starting line ratio Ideal would be to gear the car to be at max RPM at the trap. Given the small tire you have the SLR might make it difficult to hook. The Stockers are able to do it with a 9 inch tire. __________________ Mike Pearson 2485 SS

09-20-2019, 12:38 PM	#3
Chevy55 Banned Join Date: Nov 2014 Posts: 324 Likes: 625 Liked 179 Times in 89 Posts	Re: What gear to run vs. starting line ratio Usually best to leave everything right where it is but if you want to play then maybe a lower rear gear and a higher 1st gear ratio so you end up the same final total 1st gear ratio that you have now without upsetting the launch. Doesn't seem worth it to me. JMO

09-20-2019, 04:03 PM	#4
Dan Fahey VIP Member Join Date: Oct 2008 Posts: 2,128 Likes: 1,084 Liked 184 Times in 113 Posts	Re: What gear to run vs. starting line ratio Fix the suspension and safety of the car. Tune the engine and suspension For gearing If you are Bracket Racing you have enough.

09-20-2019, 05:36 PM	#5
HawkBrosMav Member Join Date: Apr 2009 Posts: 362 Likes: 6 Liked 302 Times in 73 Posts	Re: What gear to run vs. starting line ratio I not completely familiar with SLR but if it's rear ratio times first gear ratio 10 seems a little low for most Stk S/S cobinations... obviously with a longer stroke that would change things, but we have a 3 inch stroke... 2.92 1st gear ratio and 4.88 rear ratio on a 28 or 30 by 9" wide tire.. have zero issues hooking.. 2.92*4.88=14.25 SLR I'm sure yours can be a little lower as I'm sure your stroke is bigger... but i wouldn't worry about it too much and I'd guess if you can make the higher SLR hook your 1/8th ET will be quicker..