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Daytona - 145 mph in a Gen3 SRF

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Needs a Life!!!

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Posted: Thu Oct 09, 2014 9:05 am

LeeHill wrote:Best I've seen documented is 137 mph - that was bump drafting from the chicane around to T1. The 145.9 in the Gen3 was without bump drafting. My best guess is that in equivalent conditions a Gen2 SRF would be at 133 to 134.

I saw those same speeds in a three-car, non-bump draft in the Tunnel Turn on the Pocono South Long Course in May, 2002. It was me, Mark Fickenscher and Chris Current. In our case, it was 135 MPH at the end of that course's extremely long main chute.

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Lee Spuhler Lee Spuhler's Profile Needs a Life!!! Posts: 211 Joined: Wed Dec 14, 2011 10:09 am	Posted: Thu Oct 09, 2014 9:18 am Lee, What were the wind conditions? I know a porcshe club guy that did a 160 plus in a turbo 944, the next day the wind shifted and he could barely hit 140. Just wondering if that 145 is going to be the norm or if it will take very special conditions to achieve. It's better to be last on the grid at a race track, than have pole position at the Funeral Home.
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LeeHill LeeHill's Profile Needs a Life!!! Posts: 418 Joined: Wed Dec 07, 2011 6:01 pm Location: Brandon Florida Chassis: 762	Posted: Thu Oct 09, 2014 11:27 am I don't think it will be the norm. Top speeds at Daytona are very weather related. During the Sunday race with 3 or 4 of us drafting (not bumping) we were seeing 138-140. Lee Hill SEDiv SRF 72
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Racer X Racer X's Profile Needs a Life!!! Posts: 766 Joined: Wed Nov 30, 2011 1:03 am Chassis: 098 Facebook Page: http://www.facebook.com/#!/denny.stripling	Posted: Tue Oct 14, 2014 4:04 pm Was just thinking about this and I wouldn't be shocked to see a Gen3 break the 150MPH barrier next season at Daytona with the 2015 GY's and their lower rolling resistance. Wow. ____________ Bay 12, please.
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LeeHill LeeHill's Profile Needs a Life!!! Posts: 418 Joined: Wed Dec 07, 2011 6:01 pm Location: Brandon Florida Chassis: 762	Posted: Tue Oct 14, 2014 5:08 pm Denny - could be but it won't be by much without bumping the rev limiter up. Lee Hill SEDiv SRF 72
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Needs a Life!!!

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Posted: Thu Oct 16, 2014 6:08 pm

What transmission ratio was everyone running? Seem like the "old" ratio would have more RPM's available at the top end, though I expect aero forces are likely to overwhelm the taller gearing. Alternatively, would the old 5th gear work? Hmm, two transmission final drive ratios and two different fifth gear ratio to play with... :-)

Bob Breton - SRF 51 - San Francisco Region

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LeeHill LeeHill's Profile Needs a Life!!! Posts: 418 Joined: Wed Dec 07, 2011 6:01 pm Location: Brandon Florida Chassis: 762	Posted: Thu Oct 16, 2014 7:08 pm Bob - we were all running the 3.85. I ran the 3.62 in August at Daytona and did 4-5 upshift at 124 mph at about the old turn 4 tunnel - and had 128-129 at S/F. 3.85 shifted mid-3-4 at 116 mph and and had 132-133 at the line. Both with no draft. With 3.62 - the car slowed to 123 before gradually accelerating. With the 3.85 it kept pulling. Lee Hill SEDiv SRF 72
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Needs a Life!!!

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Posted: Fri Oct 17, 2014 10:24 am

breton wrote:What transmission ratio was everyone running? Seem like the "old" ratio would have more RPM's available at the top end, though I expect aero forces are likely to overwhelm the taller gearing. Alternatively, would the old 5th gear work? Hmm, two transmission final drive ratios and two different fifth gear ratio to play with...

I thought the old fifth gear is no longer legal, right?

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breton breton's Profile Needs a Life!!! Posts: 767 Joined: Wed Nov 30, 2011 12:21 am Chassis: 595	Posted: Fri Oct 17, 2014 12:53 pm Bob, you're correct. Looks like the new Gen3 rules specifically call out just the .77 5th gear, while the SRF rules continue to also allow the .73. Looks like the 3.62 is good until 1/1/18. Bob Breton - SRF 51 - San Francisco Region
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Novice Typer

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Posted: Wed Oct 22, 2014 7:06 pm

Assuming a Gen3 is ~10% (1.1x) faster, and keeping in mind that kinetic energy increases by the square of velocity, that would suggest about 20% more kinetic energy that needs to be dissipated by the car and its contents when a Gen3 hits something at top or near-top speed, compared to a Gen2. I wonder if the chassis was designed with this in mind? Will Gen3 cars preserve the excellent safety record of Gen2 SRF's?

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