Question about trap RPM

68Coupe · 07-16-2009, 01:10 PM

I bracket race and usually run 1/8th mile, thinking about going to a 1/4 track.
car runs 6.90's @98 MPH just wondering how many RPM's i will pick up on the back half have heard from 500-1200

greg fulk · 07-16-2009, 05:07 PM

what gear & tire size you have?

68Coupe · 07-16-2009, 07:32 PM

4.56 and 28x10.5 slicks

bill dedman · 07-17-2009, 02:11 AM

Wallace calculators (an online drag racing calculator page)
http://www.wallaceracing.com/Calculators.htm
says if you're going 96 in the eighth, ideally, you're going to go 120 in the quarter.

It also says that 120 mph with a 28" tire and a 4.56 gear is 6,600 rpm. If you have an automatic, it will be more; how MUCH more will depend on how much converter slippage you have at the finish line.

These numbers are, of course, "ballpark" figures; don't trust them to be 100-percent accurate, but they will probably be fairly close to reality when the dust settles.

Hope this helps!

Mike Taylor 3601 · 07-17-2009, 08:28 AM

There is old formula gear ratio X mph X 336 divided by tire height= RPM
accurate on stick. Auto allow for converter slippage.
Mike Taylor 3601

rayfin · 07-18-2009, 08:28 AM

4.56 and 28x10.5 slicks

Been there....6000-6500 RPM in the traps. How many rpm's are you turning now?

greg fulk · 07-19-2009, 08:55 PM

you'll be fine!

07-16-2009, 01:10 PM	#1
68Coupe Junior Member Join Date: Nov 2008 Posts: 83 Likes: 0 Liked 3 Times in 3 Posts	Question about trap RPM I bracket race and usually run 1/8th mile, thinking about going to a 1/4 track. car runs 6.90's @98 MPH just wondering how many RPM's i will pick up on the back half have heard from 500-1200

07-16-2009, 05:07 PM	#2
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: Question about trap RPM what gear & tire size you have? __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"

07-16-2009, 07:32 PM	#3
68Coupe Junior Member Join Date: Nov 2008 Posts: 83 Likes: 0 Liked 3 Times in 3 Posts	Re: Question about trap RPM 4.56 and 28x10.5 slicks

07-17-2009, 02:11 AM	#4
bill dedman VIP Member Join Date: Feb 2002 Location: Conway, AR Posts: 1,739 Likes: 0 Liked 6 Times in 4 Posts	Re: Question about trap RPM Wallace calculators (an online drag racing calculator page) http://www.wallaceracing.com/Calculators.htm says if you're going 96 in the eighth, ideally, you're going to go 120 in the quarter. It also says that 120 mph with a 28" tire and a 4.56 gear is 6,600 rpm. If you have an automatic, it will be more; how MUCH more will depend on how much converter slippage you have at the finish line. These numbers are, of course, "ballpark" figures; don't trust them to be 100-percent accurate, but they will probably be fairly close to reality when the dust settles. Hope this helps! __________________ Bill Last edited by bill dedman; 07-18-2009 at 08:23 PM.

07-17-2009, 08:28 AM	#5
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,362 Likes: 336 Liked 279 Times in 96 Posts	Re: Question about trap RPM There is old formula gear ratio X mph X 336 divided by tire height= RPM accurate on stick. Auto allow for converter slippage. Mike Taylor 3601

07-18-2009, 08:28 AM	#6
rayfin Member Join Date: Mar 2009 Location: sioux city Posts: 134 Likes: 1 Liked 0 Times in 0 Posts	Re: Question about trap RPM 4.56 and 28x10.5 slicks Been there....6000-6500 RPM in the traps. How many rpm's are you turning now?

07-19-2009, 08:55 PM	#7
greg fulk VIP Member Join Date: Jan 2003 Location: jackson Posts: 1,165 Likes: 0 Liked 5 Times in 3 Posts	Re: Question about trap RPM you'll be fine! __________________ Greg Fulk 308 308X P/SA "ALL AMERICAN"