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Rear gear ratio dragster
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DRR All Star
posted
This is unchartered territory for me. Small block rear engine 4 link car. Ran 7.9's with 8000 trap speed.

Added boost, took some test squirts at 10 psi. With terrible tire shake it ran 1.15 60', 4.797 1/8 and 148 mph. Obviously once I knock out the tire shake, the time will improve. I ran out of gear in the 1/4 and was tickling the rev limiter way early so coasted.
Wallace racing predicts 183 mph from that 1/8 mph. I'm shooting for low 7's out of this combo bracket racing.

It has a 4.30 gear and 107 rollout tire. I don't mind 8000 mph trap speed. I was showing 10 percent converter slip where I was letting off just after the 1/8th.
Initially I was thinking 4.10 would be my switch to gear. I'm still there 80%. Am I going to regret it? I can't think that this small block will be happy with anything number under 4.0. But I would prefer to not do this twice.
I don't need to rotate the earth and this is not a max effort build.


Just say NO to socialism.
 
Posts: 3659 | Location: Illinois | Registered: July 08, 2004Reply With QuoteReport This Post
DRR Sportsman
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If I remember correctly my nitrous dragster was 4.10 gear and originally had the 2534 tire. Thinking that was around 107. I don’t remember ever going over 8000 at the stripe and it went 200 with that 2534 tire (204 with a taller tire). That converter was decent but definetely wasn’t a new age overdrive deal.
 
Posts: 787 | Location: my own little world | Registered: July 20, 2005Reply With QuoteReport This Post
DRR All Star
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quote:
Originally posted by BJs Wild Ride:
If I remember correctly my nitrous dragster was 4.10 gear and originally had the 2534 tire. Thinking that was around 107. I don’t remember ever going over 8000 at the stripe and it went 200 with that 2534 tire (204 with a taller tire). That converter was decent but definetely wasn’t a new age overdrive deal.


Perfect! Thank you!


Just say NO to socialism.
 
Posts: 3659 | Location: Illinois | Registered: July 08, 2004Reply With QuoteReport This Post
DRR Sportsman
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Some random thoughts on this:

You probably would benefit from a dump valve to loosen converter for spool/launch.

This will allow a more efficient at the stripe % of slip.

300-500 less slip would be a ton of MPH
 
Posts: 575 | Location: New Jersey | Registered: April 26, 2001Reply With QuoteReport This Post
DRR Sportsman
Picture of David Gerard
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quote:
Originally posted by Greg Kelley:
Some random thoughts on this:

You probably would benefit from a dump valve to loosen converter for spool/launch.
MPH


Any recommendations for the brand?
 
Posts: 225 | Location: Fullerton, CA | Registered: June 08, 2008Reply With QuoteReport This Post
DRR Pro
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Got mine from Abruzzi


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2016 Miller

http://www.killerrons.com/
Rolla Competition Engines
 
Posts: 1078 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR All Star
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Well now I understand why my math wasn't working. At some point I had put the 4.56 gear in the car. Thus too much gear with boost. It even shook the tires leaning on it some. The 4.10 should calm that right down. I see when I was running it past the 1/8 mile, that the converter was tightening up nicely. Of course the gear change will spoil some of that.
Thus far I'm not having a lot of trouble making boost within 1 second. Of course, I'm only running on about 8 psi right now. So the dump valve may be just the ticket. Do you dump for the entire time you are on the brake? Or do you stop dumping before the release?


Just say NO to socialism.
 
Posts: 3659 | Location: Illinois | Registered: July 08, 2004Reply With QuoteReport This Post



DRR Sportsman
Picture of N2Ofrog
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I have an Abruzzi dump valve for sale if anyone is interested.

Best way to reach me is text at 440-554-3052.

Thanks
Scott Wasko
 
Posts: 900 | Location: Columbia Station, OH | Registered: January 05, 2001Reply With QuoteReport This Post
DRR All Star
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I used this valve.
https://www.surpluscenter.com/...-Valve-9-5112-NC.axd


Just say NO to socialism.
 
Posts: 3659 | Location: Illinois | Registered: July 08, 2004Reply With QuoteReport This Post
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