josh7owens

How come our 60' times are so "slow"? If you look in the "drag racing" forum they have time slips on stock cars with 2.0 60' times on street tires.

imstimpy

Your experience is quite different from mine. The tires feel the same up through 170*F (we've run them in the dead of the Texas summer without spraying). I spray them around the 140*F mark, just to keep them from getting too hot. We haven't found a magical temp but have seen that breaking for lunch (read: cool everything) then coming back will always yield a faster time.

We ran the tires back to back to back this weekend in 100*F ambient on a sealed lot. Our fastest runs were when they were the hottest at 130-140*F and everything else was heat-soaked. We sprayed twice, around runs 8-9, but they were plateaued. Temperatures were taken with a needle pyrometer.

daverx7

Yeah, exactly what I experience... except I have a cheap gadget to measure the temps.

Abide

I'd imagine mainly due to setup and surface. Ive cut a few 1.9s in my dragging days. But that was running with far less camber and lower tire pressure on a surface that was coated in VHT and hot rubber from many a night. (havent done a pro solo yet, just speaking from normal autox launches and drag experience) You also have to launch PERFECT on the strip. too high and it just spins to low and it bogs. On most autox surfaces ive run you have a pretty good lack of traction that leaves room for error where you can get em to spin easy enough that you dont overdo it. That makes it much less difficult to bring the rpm to where you want it to get moving and stop the wheelspin.

I'm sure someone else can probably come up with other reasons. a 2.2-2.4 doesn't seem half bad though

daverx7

I launch my S at the autocross and pro's in a way that preserves my differential, minimizes bog, plus my setup is totally focused on handling and not straight line. So, I am happy to get 2.3-2.4's. Of course I would like to get what the MX-5's do, but it is what it is...

-Dave

///MIKE

Launch was uphill the whole way... that's why.

marcrx5

And 5000' elevation.

george34

I would agree that it's mostly because of camber and the drag strip being conditioned.


Looks like the 60' times at lincoln were in the 2.3's and 2.4's so this past weekends 60' times might have been .1 second slower.

Zeus2k

I would imagine stiff suspension that most are running doesn't help matters either. I am betting if you are running 2.0 60' at the drag strip you are airing down the rear tires doing a pre launch burn out to get the tires sticky etc etc. While dropping a couple tenths off the launch would be nice, setting the car up to do so is going to hinder it for the rest of the course.

That being said launch control sure would be nice for consistency.

PilotSH

Before I start, to give some background info on the weighing, we weighed on the official SCCA scales, back to back to back. The pavement was on an incline, so I don't know if that might have slightly affected things, but prolly not by much. Ok, so here are the weights:

Thorne's CR: 2579 (4 bars of fuel)
Carpenter's 05 AP2: 2666 (half tank)
Melchior's AP1: 2588 (4 bars)

Figure in about 18 pounds of gas more for the CR and the AP1 to get to half a tank and make fuel equal. Please read the following notes however on the prep level of each car:

Mods:
Thorne's CR: there are definitely places that Thorne's CR can lose more weight. It still has the radio system, and the AC components inside the dash. Still has the stock passenger side seat. Easily 25-30 pounds of more weight he can remove. Weight savings come from: aluminum bodied shocks, CCW wheels (16-17 pounds), titanium exhaust, HFC, header, intake, racing drivers seat, rear sway removed, very worn tires (almost to wear bars), crossdrilled rear rotors. Gendron front sway added some weight.

Carpenter's earlier AP2: Looked like pretty much all the weight savings possible was done to the car. It had both seats swapped out, as well as the lightweight buddy club wheels (16 pounds). Could have prolly saved a couple more pounds with a titanium exhaust, but other than that, about as light as it's gonna get. This is about what I expected compared to Thorne's car. Almost a 100 pound difference once Thorne gets the rest of the weight out of his car. The 06+ AP2s are even HEAVIER, so I'm figuring those are at a 100+ pound deficit. I'll let him chime in more about his car.

Melchior's AP1: This car was prepped very similarly to Thorne's car (came from the same tuner, SCR). Pretty much the same mods, with the exception that this car had lightweight pulleys, which prolly knocked off another 5 pounds. MY2000, which was the lightest of the AP1s. This was the big shocker. Can't understand why there is such a big weight difference between this car and Carpenter's car. But what this proves is that the CR is even lighter than the AP1 but with tons more power.

Well, there you have it. Same scales, same day, same time. The CR is about 100 or more pounds lighter than the AP2, and although an AP1 is closer to the CR's weight, it has nowhere near the power. If you guys think 100 pounds is "driver noise," I guess all the guys in SP swapping out dashes, trim pieces, tops, etc for a weight savings of a couple pounds here and there are just nuts. Just what we needed, another class that will be dominated by the CR...