SBF Gear Recommendation Please

HR9121 · 09-07-2016, 07:48 AM

I would also think the standard gears would be fine also and I would think you would need the 4.56 to get you up in rpm power range also.
I ran a 302 in a fox body bracket car, it was only 2950# but ran a 30" radial like stockers run and ran a 4.88. It ran 10.50-10.60 and would trap at 6900-7200. With those little motors rpm's are your friend.

Chris1529 · 09-07-2016, 10:33 AM

what kind of RPM do think its going to run? I'd look at a 4.86 at least.
probably lean toward 5.14

FireSale · 09-07-2016, 12:32 PM

Quote:

Originally Posted by Chris1529

what kind of RPM do think its going to run? I'd look at a 4.86 at least.
probably lean toward 5.14

The Comp Cam that is giving me the mid 12's at 105 ish is a solid roller with a 3000-65000 power band. It's on the way out for another solid roller that will give me at least 7000 in the traps. I'm currently maxing out at 5500 when I hit the lights so I'm not using the power I have on tap. According to AFR the AFR 1399 heads I have will take up to a .600 lift cam. Looking at Crowers that are rated at 4000-8000 and 3000-7000 and Lunatis rated at 4400-7500 and 4400-7200. The Dynamic Compression Ratio from the Crower cams would be 8.9 and 9:1 respectively and the Lunati cams clock with a DCR of 8.6:1.

My block is the Ford Racing M-6010 BOSS302 4 bolt main rig. My machinist went nuts over it. Rods are forged Crower Sportsman from the Accepted Products list and the crank is a forged Eagle. I pulled the heads recently after a season of driving to the track and bracket racing and everything looks brand new.

The bottom end is underused.

I used gear calculators based on 7000rpm and 28 inch tires to determine speeds for gearing. I know it doesn't factor weight and HP, but it was all I could find to mess with. 4.56 gave me 128 and 4.29 gave 136. 136? OOPs too fast, scratch that. 4.86 yields 120 and 5.14 is good for 113.

Dale

Chris1529 · 09-07-2016, 01:04 PM

To run 11.00 or better in your car, its going to need to run about 119 MPH.
I think you will find that the motor will want to run at least 7500 RPM and that is taking it easy on it.
Even switching tires with differences in roll out will make a big difference in how the car performs or doesn't perform.

stang321 · 09-07-2016, 03:46 PM

I run an aluminum head 302 with 4.30 gear shift at 6500 traps at 6600 its runs 12.30s with a 26 inch tire I would go with 4.88 or 5.14 if you change to 28s

FireSale · 09-07-2016, 07:42 PM

Quote:

Originally Posted by stang321

I run an aluminum head 302 with 4.30 gear shift at 6500 traps at 6600 its runs 12.30s with a 26 inch tire I would go with 4.88 or 5.14 if you change to 28s

What is the weight of your car? Mine is 3355. It's a 68 coupe.

Last pass of the season I drew a 2016 Cobra Jet at 9:00 am in perfect conditions. Couldn't judge him with a 3 second lead and twitched off the gas at the 1000 foot mark. Blew by me in the traps but I got a 12.64 at 116 with my foot of the gas.

Dale

stang321 · 09-08-2016, 08:03 AM

my car weighs 3150 with me in it its an 88 hatch fuel injected the car is built for stock eliminator but I put in a bracket engine to more dial in chassis while I work on my stock engine combo it needs more converter for sure I run a 3000 stall with an aod with a manual valve body it 60 ft 1.75 runs 12.30 at 110 I want to gear change mine also and im thinking 88s with my 26x9s

09-07-2016, 07:48 AM	#1
HR9121 Live Reporter Join Date: Jan 2011 Location: New Bern, NC Posts: 3,467 Likes: 146 Liked 3,363 Times in 731 Posts	Re: SBF Gear Recommendation Please I would also think the standard gears would be fine also and I would think you would need the 4.56 to get you up in rpm power range also. I ran a 302 in a fox body bracket car, it was only 2950# but ran a 30" radial like stockers run and ran a 4.88. It ran 10.50-10.60 and would trap at 6900-7200. With those little motors rpm's are your friend. __________________ James Williamson W200 J/SA. SS/JA

09-07-2016, 10:33 AM	#2
Chris1529 VIP Member Join Date: Dec 2006 Location: West Virginia Posts: 1,366 Likes: 6 Liked 70 Times in 29 Posts	Re: SBF Gear Recommendation Please what kind of RPM do think its going to run? I'd look at a 4.86 at least. probably lean toward 5.14 __________________ Chris Bowman The Mountain State Mustang 1984 Mustang GT350

09-07-2016, 01:04 PM	#4
Chris1529 VIP Member Join Date: Dec 2006 Location: West Virginia Posts: 1,366 Likes: 6 Liked 70 Times in 29 Posts	Re: SBF Gear Recommendation Please To run 11.00 or better in your car, its going to need to run about 119 MPH. I think you will find that the motor will want to run at least 7500 RPM and that is taking it easy on it. Even switching tires with differences in roll out will make a big difference in how the car performs or doesn't perform. __________________ Chris Bowman The Mountain State Mustang 1984 Mustang GT350 Last edited by Chris1529; 09-07-2016 at 01:09 PM.

09-07-2016, 03:46 PM	#5
stang321 Junior Member Join Date: Sep 2011 Location: Belmont ohio Posts: 20 Likes: 47 Liked 0 Times in 0 Posts	Re: SBF Gear Recommendation Please I run an aluminum head 302 with 4.30 gear shift at 6500 traps at 6600 its runs 12.30s with a 26 inch tire I would go with 4.88 or 5.14 if you change to 28s

09-08-2016, 08:03 AM	#7
stang321 Junior Member Join Date: Sep 2011 Location: Belmont ohio Posts: 20 Likes: 47 Liked 0 Times in 0 Posts	Re: SBF Gear Recommendation Please my car weighs 3150 with me in it its an 88 hatch fuel injected the car is built for stock eliminator but I put in a bracket engine to more dial in chassis while I work on my stock engine combo it needs more converter for sure I run a 3000 stall with an aod with a manual valve body it 60 ft 1.75 runs 12.30 at 110 I want to gear change mine also and im thinking 88s with my 26x9s

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