1/4 mile times

[ItBites]

My Cobra with IRS and a 3.08:1 gear cuts a solid 1.6 sec 60' time every run. Do not try to tell folks that IRS will not hook. I do not run slicks either. My 1.6 sec 60' times are on 275/40-17" Toyo RA1 tires (DOT road race tires).

I think most folks do not have a good enough tire for a launch (still you do not need drag slicks for 11 sec runs), they do not have the power they think (as-installed losses and lack of perfect tune), and they are not used to finessing a high-power car off the line.

I know my comments will make me popular, but as I've said before:

"The cheapest, easiest way to improve your car's ACTUAL (not bench racing) performance is to put on a good set of tires" - Then you have to actually go out to a track...

[jeffko]

I have to agree with Itbites with a couple of exceptions. Tires are very often overlooked and are one of the single most important components of any kind of racing. Most of my tickets show high 1s to low 2s 60' times with BFGs. My best time was 12.1 @ 116 with a 60' of 1.845 and that was when my IRS was a 3.47 open diff. Now it is a 3.64 IRS limited slip.

The chassis dyno shows the rear wheel hp and torque around 450. All the above was with a 750 demon that would not hold a consistent tune. I have now built an 850 with several different companies’ parts and now this thing is motorcycle fast. I can not tell you guys how important a good carb is and a major part of that is air bleeds. Make sure you get a center section with "screw-in bleeds" and get your air/fuel between 12.7 and 13.0, all the way through the curve if you want to race for the sake of a little economy.

How do I disagree....drag radial are the best tires to drag with. However, you can narrow that gap with exceptional street tires. My average 60' times are let's say 2 seconds, that's 4/10 slower than Itbites in sixty feet! That's nearly half a second. You can't spend 20% of your time on 5% of the track and expect a decent run. Spinning tires is for show, not for go. The other is the IRS vs. straight. IRS can perform pretty well but with all the uneven loading, wheel hopping and inferior energy transfer they can't compete. Straight axle dominates drag race and IRS dominates road race. I would say this though. IRS can do both road and track better than a straight axle can.

This is a good thread so let's keep it up.