[Judd]

I know this is a autoX/road course site but I though some of you might have some insight on this question so I decided to throw this out. I'm thinking about running my car at Maxton N.C. at the E.C.T.A. 1 mile event. I'm putting down around 540RWHP and right now I'm running a 4.10 gear which should max out somewhere around 165 or so. I should get to that which is cool by me since my tech speed should be 175mph. To go over that, I will need a real cage which I'm not willing to do right now.

Later, I would like to replace the gear so I can get some more mph but I'm a bit confused. I've heard that you really should do your best to run 4th gear {1:1} for top speed events because that is the most efficient but my my set-up would really be doggy with something like a 2.73 in the rear. I'm really thinking of running a good dose of nitrous in an effort to get to 200mph {one of my goals} and I think I should have the power to do it but just how much will running 5th gear hurt me? Sure would like to run a 3.42 or 3.73 so I wouldn't have to swap out axles all the time.

Also, I will be carrying a trailer with extra wheels, tools and possibly a bike so I really would like to keep a low gear.

[Blainefab]

I know this is a autoX/road course site but I though some of you might have some insight on this question so I decided to throw this out. I'm thinking about running my car at Maxton N.C. at the E.C.T.A. 1 mile event. I'm putting down around 540RWHP and right now I'm running a 4.10 gear which should max out somewhere around 165 or so. I should get to that which is cool by me since my tech speed should be 175mph. To go over that, I will need a real cage which I'm not willing to do right now.

Later, I would like to replace the gear so I can get some more mph but I'm a bit confused. I've heard that you really should do your best to run 4th gear {1:1} for top speed events because that is the most efficient but my my set-up would really be doggy with something like a 2.73 in the rear. I'm really thinking of running a good dose of nitrous in an effort to get to 200mph {one of my goals} and I think I should have the power to do it but just how much will running 5th gear hurt me? Sure would like to run a 3.42 or 3.73 so I wouldn't have to swap out axles all the time.

Also, I will be carrying a trailer with extra wheels, tools and possibly a bike so I really would like to keep a low gear.

I took a swag at your 4.10 baseline: 6600rpm 25.5" dia tire .74 5th gear = 165mph ???

Just switching to a 26.8" tire (275/40-18 ala C5) gives you 173.5mph, close enough to your tech speed for now. Your driveshaft rpm will be crazy high, so definitely get a carbon shaft - there is GP pricing available on the ACPT shaft.

With the tall tire and 3.73 you'll get 191mph in 5th. 3.42 goes to 208mph, given enough room. Getting there in a standing mile involves more than a gear chart, but it's someplace to start.

I wouldn't worry about using 5th - you'll need the higher acceleration rate that the 4.10 gears will give you in the lower gears until you start spraying it. 5th is only a little less efficient than 4th, the only difference is that in 4th gear the input shaft to main shaft bearing is not rotating. Both gears load path is via the countershaft. I ran a couple thousand miles of ORR in 5th > 150mph.