11 replies to this topic

[lm11m]

Would like to know what the top speed & (chip)RPM should be in 4th gear on a legal 99 / 1.8 / 4.30 gear on Hoosier SM 6s. We're newbies running Nelson Ledges in Ohio and are running 1.18 3s and having to pull 5th on the back chute in the 99 / 1.8. Our 90 legal 1.6 turning 1.20 0s will carry 4th clear through no sweat. Thanks in advance for any feedback!

[Ron Alan]

99 Rev limiter...7000rpm  I think speed is around 109-110mph?

 

1.6 Rev limiter...7200rpm  

[Danny Steyn]

Ron

 

In my '99 I cannot get beyond 107mph before the limiter kicks in at around 6950RPM

[Michael Novak]

You will have to be in 5th at Nelson's. The Flag stand 3/4 down the back straight is about the point if you get a proper run out of Carusel.

[Michael Novak]

You are doing pretty well if you are in the 18.3 range btw. Being a fast track the times drop down alot as it gets cold.

[LarryKing]

Have you tried using 5th in your 1.6 and compared lap times vs. using 4th?

 

I can leave my 1.6 in 4th on the back straight at NL without hitting the rev limiter, however my lap times are better if I shift to 5th. Roughly at the same spot as Mike mentions above.

[Ron Alan]

Ron

 

In my '99 I cannot get beyond 107mph before the limiter kicks in at around 6950RPM

In our 95 at 6900rpm(limiter) I think we are at 107-108mph on the rumblestrip. Was just basing my guess off this...dont have data to actually see this after the fact! I know there is a chart kicking around somewhere that shows each gear...based on math.

[HoneyBadger - BrianW]

Ron

 

In my '99 I cannot get beyond 107mph before the limiter kicks in at around 6950RPM

+1 That is what I see as well.

[Jim Drago]

I hear that on rev limiter a lot on 99 cars. I think it is a traqmate/dyno deal. On the dyno, the cars rev out at 7000 if you use electric eye to read RPM. If you sense off plug,coil wire sometimes you see less. No idea why.

I see close to 7 on my traqmate. Just looked at Road america and I see 6980 plus before shifting at 107.25 or so

[Todd Green]

I show 112.4 @ 7193 for my 1.6, but that is on RR's. I'm sure you can look up the rev/mile for both tires and calculate the difference. (I think the Hoosiers are a bit shorter and if you do the math based on the different rev limits it should be 110 mph or so.)

[Adax]

You will probably find this calculator helpful:

 

http://www.flyinmiat...ech/gearing.php

[Todd Green]

You will probably find this calculator helpful:
 
http://www.flyinmiat...ech/gearing.php

It would be more helpful if you could put in revs/mile or the tire diameter. Not all 205/50R15's are 23.1".