CSX3170 gets killed in autox

[snakeeyes]

Originally Posted by Cobra #3170

We carry 200 lbs of ballast and it does not hurt, in fact the car is faster weighted up because of 200 TW tires.

It’s ironic with a lightweight, high-hp car, isn’t it? I spent a great deal of time sweating blood to make my Beck Lister as light as possible when I was building it. She ended up at 1,976 pounds with a half-tank of gas so I was happy with that. In multiple track days the best lap I ever ran was with a 240-pound passenger, LOL. Don’t know if that’s a reflection of my need to cross-weight the car, if the extra weight helped the tires get up to temp, or if I just drive faster when I’m trying to impress.

Regarding aero, when I was tracking my Lister a lot I didn’t want to drill a bunch of holes in the body. I ended up mounting an APR wing to the roll bar (my bar extends the width of the car unlike a typical Cobra single-hoop design, so it was easy to do), making a splitter out of some high-impact material, fabbing a defuser from sheet metal, and then adapting some generic canards. The splitter and defuser bolt on but they’re both on the underside of the body where you’d never see the holes. The only visible holes are for the canards, and they’re pretty tiny. My “aero package” was all seat-of-the-pants but the car got faster afterwards, whether that was a reflection of aero benefits or just my increased confidence in it.

[Cobra #3170]

Originally Posted by snakeeyes

It’s ironic with a lightweight, high-hp car, isn’t it? I spent a great deal of time sweating blood to make my Beck Lister as light as possible when I was building it. She ended up at 1,976 pounds with a half-tank of gas so I was happy with that. In multiple track days the best lap I ever ran was with a 240-pound passenger, LOL. Don’t know if that’s a reflection of my need to cross-weight the car, if the extra weight helped the tires get up to temp, or if I just drive faster when I’m trying to impress.

Regarding aero, when I was tracking my Lister a lot I didn’t want to drill a bunch of holes in the body. I ended up mounting an APR wing to the roll bar (my bar extends the width of the car unlike a typical Cobra single-hoop design, so it was easy to do), making a splitter out of some high-impact material, fabbing a defuser from sheet metal, and then adapting some generic canards. The splitter and defuser bolt on but they’re both on the underside of the body where you’d never see the holes. The only visible holes are for the canards, and they’re pretty tiny. My “aero package” was all seat-of-the-pants but the car got faster afterwards, whether that was a reflection of aero benefits or just my increased confidence in it.

What tires were you running? In the past I found that running on Hoosier A6 or A7 at lower weight helped but with 200 TW you don't get the mechanical grip from the tread rubber conforming to pavement irregularities.

I can't do any aero on the Cobra because I don't want to spoil the original appearance. I did put a large wing on my 2005 Ford GT, added a much longer front splitter with shields for the front tires. I also lowered it about 2" and added full contact skirts to seal the diffuser air using conveyor belt material.
The car was scary because it stuck so well I could not sense the limit and I know if exceeded it would just let go. I ran it at Big Willow and found that it was 10 miles an hour faster around turn 2 than it was with out the aero upgrades. I am sure a really good driver could have gotten into the low 20's with it. It just scared me though, here it is on the front straight at Willow

https://www.youtube.com/watch?v=RsQoE1T-aNs

[snakeeyes]

That GT is a bad bear! Nice video.

I was doing a mix of AX and track days with my Lister. I tried R6 Hoosiers but the tire I actually liked the most was the Kumho V710, which I guess is now supplanted by the V720. It seemed to offer the best combination of predictability and grip. It also wore like iron but with a 2,000-pound car tire wear was never going to be a big issue. I was using the same tires for AX and track days.



I certainly understand not wanting to touch the bodywork on your car. Before I settled on a roll bar-mounted wing, I was looking into fabricating one that actually mounted inside the trunk. But that would be difficult with a Cobra because the trunk lid is cut so far down into the rear bodywork; on the Lister the opening was at belt-height so it was a more viable option. I don’t know how you’d be able to mount a splitter on the front, given the oil cooler opening on the chin, and you’d have to run your support stanchions through the fresh-air vents or something. Not easy!