What gear should I run?

Just recently bought a 280" Mike Bos dragster. 526"KB with DMPE M4 1471 high helix blower running an ATI Superglide 4 with a 1.80 first gear. 34.5 " Mickey Thompson's. I bought the car from a guy in Tennessee that ran all 1/8th mile Pro Top Outlaw stuff, car currently has 4.11 gear.

I intend to run NHRA Top Dragster (1/4 mile) and want to keep the RPM down as much as possible going through the stripe (around 8000 RPM). I am not trying to set low ET, just looking for a fat, happy and consistent 6.20 bracket car. I have talked to Strange and Mark Williams and have been told I need everything from a 3.40 all the way up to a 3.89 ratio.

Please help!

 

I run a 4:10 and very happy, I have tried a 4:30 and also a 3:90 i run a 526 going through the lites around 8,900 to 9,200

 

Thanks for the reply. What kind of incremental times are you running? Do you run a 2 speed glide? I was shooting for closer to 8200 through the lights......

 

That is Rocky's old car....runs well. Just stay with 4.11 (save some money) and take some pully out of it.....run appox.20% od, and shift it at around 8000 rpm's and it will slow down enough. I race a similar combo to this with a two speed glide (small shaft). But if you have a 3.89 rear as a spare throw it in the car and run it, with the 1.80 low gear the car will calm down on the starting line alot.

 

5.90 1/4 mile 8700

 

gear ratio

Try this equation. Put in your desired MPH and solve for gear ratio.

8200(rpm) X 34.5 (tire dia) x 2.96
______________________________ = Gear Ratio

1000 X MPH


or 837.384 / MPH = gear ratio

it will get you very close

Ed Urcis CP-Carrillo

 

As light as that car is, I think it will run out of gear with the 4.11 in the 1/4. Unless Rocky changed cams, I think he was running a pretty mild setup, somewhere just over .700 lift, trying to stay away from spring killers and keeping the car fairly low (8000 rpm)maintenance. I'm with Jody on gears, think a 3.89 would work well. Blown 5402 (Jimmy Kyle) probably knows the cam and rpm range that was in the car when Rocky sold it. The Batmobile was/is an extremely nice piece, good luck with it.

 

I run a 452ci hemi with a PSI D, Coan convertor, a 3 speed Lencodrive, 3.89 rear end and Hoosier 34.5 tyres. We're currently hitting the limiter (8600 chip giving an actual 8400 limit according to the data) pretty much on the stripe. Data tells us we're getting about 9% slip in the convertor, and the mph calculates out to about a 11% tyre growth...

I'm considering going to the 36" tyre or a 3.70 (or maybe even a 3.60 rear end) to get mine back towards an 8000 limit.

 

3:70 to 3:90 gear for that Hemi Motor

The motor you have will pull a freight train to 8000rpm and then runs out, but is very low maintenance. It will pull a 3:70 gear, but the gear of choice would be a 3:90 at legal top dragster blower overdrive for the 1/4 mile. Let me know if I can help any, Jim from TN 931-580-8804

 

thanks to all

thanks for all your help folks, have a 3:89 0n its way. Hope to meet all at a track somewhere first rounds on me. thanks Dan