View Full Version : Need quick advice...Did i make the right choice for gears??


PRAY HRD
02-15-2011, 08:11 PM
Hey guys....

Ok after flip flopping about going with an FI setup, i can't swing it right now being jobless and it will have to wait. I'm sticking n/a with a max 150 shot for the few times i expect to see a track. I bought this car which ran a best of 10.84 @ 123, 1.48 short time at 3800 race weight. I'm hoping to get about 200+#'s off the car in the next month, mostly off the nose.

The rest of the setup is in my sig. I chose to stay with the 4.11's that are in the current 9" and go from there for a starting point with the same 28" tires. Will this be too much gear with the 150 shot or not? I've looked at the wallace racing calculator and it says this will get me to 138 at the same 6800 rpm shift point as the previous owner. Do you think this combo will get me above 140? Should i step down to 3.89's?

:bang: I want to get this right the first time! :bang:

Thanks!!

NHRAFORMULA00
02-15-2011, 10:32 PM
131-132 mph is 7100 - 7200 rpm in chris1313 car with the same gear and 28 tall drag radials and yank ss4000.

PRAY HRD
02-15-2011, 10:49 PM
That's off by a LOT from what the drag calculators say! They come up as 141-142 with 7000 rpm shift points with 4.11's & 28's. I Thought those were supposed to be pretty accurate?! :confused:

camscam02
02-15-2011, 11:23 PM
you have to also account from converter slip which will be anywhere between 6-10% usually depending on your converters efficiency, Slicks will also grow up to 1-1.5 inches so that will give you a little room. but you will probably only get to 133-135 with your setup at 6800 if I had to make an educated guess, you can run it to 7000-7100 if needed

PRAY HRD
02-16-2011, 08:27 AM
So would 3.89's be better? MWC is gonna kill me for as many times as i've adjusted my work order, adding and subtracting and changing items! Good thing there was a 2+ month wait!! LOL

Oh, and i have an FTI Converter too :)

NoMoreFWD
02-16-2011, 02:58 PM
131-132 mph is 7100 - 7200 rpm in chris1313 car with the same gear and 28 tall drag radials and yank ss4000.

That's 10% slip. Could use a more efficient converter.

PRAY HRD
02-16-2011, 03:03 PM
I'm using a 28" DR btw. So no growth to help out.

NHRAFORMULA00
02-16-2011, 05:45 PM
SS4000,its about as effecient as yank makes!! and those online calculators are more in line with stick cars.Whats most important is 60ft time(1.29) and shift extension of 800-1000 rpm on the shifts.

PRAY HRD
02-16-2011, 06:00 PM
After talking to MWC i'm starting out with a 3.73 gear since i don't know what the car crossed the line at n/a with the 4.11's.

Thanks for the input guys! Much appreciated.

NoMoreFWD
02-20-2011, 11:19 AM
SS4000,its about as effecient as yank makes!! and those online calculators are more in line with stick cars.Whats most important is 60ft time(1.29) and shift extension of 800-1000 rpm on the shifts.

I hear ya. Not bashing. Just seems like it's blowing through the converter some. Then again, a tighter converter might add a couple MPH, but hurt ET.