earlyapex

Chance,

Are you converting the cab to a coupe?

Tom,

Looks like you cut off the roof as well as the dash. What else came off the car?

Flying Finn

Very interesting info, thanks for sharing Tom!

DrJupeman

Chance, what happened to the chick in the bathroom avatar? She was there for [i]a[i] day...

chancecasey

The car will remain a cab until I can afford to buy a fiberglass roof. I decided the bathroom pic might be going a little overboard and I should probably leave more to the imagination.

Tom are you going to the next T-Hill race with PRC?

TheOtherEric

I've posted before that I think the 6th-power-rule works pretty well for weight or hp changes. It predicts a 2.4 sec improvement for Tom. That means that another 1.1 sec was due to the gearbox (that's probably a stretch IMHO).

Tom W

Eric: The roof came off to facilitate the removalof the old "bolt-in" cage and fabrication of a decent cage. Given the weight differences (58 lbs for the gutted sunroof to 38 for the non-sunroof donor to about 15 for the fiberglass roof) we changed the roof too. Everything not required was removed (original wiring harness was a big weight loss). We missed you last week - Is the car fixed yet?

Chance: Infineon this week but not TH at the end of the month (I'll be in Maui). The GT fiberglass full replacement roof works, but, like most GT Racing fiberglass parts, requires almost a complete re-do to get it to fit and work well.

Photos of the three versions of the Turtle and it's transformation are here: http://gallery.mac.com/tomllama

mark kibort

Tom,

I did the same test with adding the wieght at Sears Point. I put in 200lbs (a passenger) and tried to run a hot lap. It was in a nasa time trial day. You usually can predict my times with in a few tenths at laguna or sears. 200lbs was worth 1.5 seconds. Im sure i could have cut it down to 1 second if i was in a race, but it would have been unconfortable. I dont think 100lbs is worth 1 second. probably a little less. after all, remember pobst and galati at road america a few years ago in the RS6 audis? they were running 275lbs rewards weight and still ran a 2:14.xx there!!!!! dont think without the 300lbs they would be 2:11, but im sure they would have been faster, no doubt. It probably also depends on the track. Sears will pay the biggest dividends, while laguna might not be so different.
Im running near the same times as your Mark 2 car, with 1:47.9 being my best at Sears, but generally im in the 1:49s, and at Laguna, always in the low 1:39s.

I cant believe the "Turtle" is that light! thats awesome. 2200lbs now, and over 300hp? sounds like a low 1:30 car at laguna

By the way, the gearbox will usually always be a rounding error at best. especially since it will help you and hurt you depending on which track you visit. However, the closer ratios of what you did with the 6 speed would be more noticable than what my biggest competitor in a C5 corvette idid in SCCA ITE racing. He changed his gear box, as others i have competed against have. when thats the only change, rarely do any better lap times come of it. However, it might make it more compeitive during the race for a more optimized "launch" or run down a particular straight. in the end, the differences are usually slight.

When you start hitting turn 8 at t-hill at 100mph, as you can do easily now, you will shave another second off. I think the 2200lb (empty) POC 911 with 330 engine hp (saw the dyno) did a 1:55 , so im sure you can be in this range no problem now. 2300lbs???? that is so light! good for you !
mk

Tom W

Mark: I'm looking forward to Infineon this weekend, it will be another fun test. The trouble it took to get to 2150 empty was extreme (as was the cost) but I wanted to be competitive in the class and the cars built for the class that use an older chassis have a much easier time of it. The 964 tub is a lot heavier but a lot stronger. When they cut the roof off, the doors on my car still worked fine. In an older 911 tub, the car would have sagged too much for them to operate. Part of what got me to 2150 was a fiberglass roof - it saved about 70 lbs in the end (it replaced the front cowl, the pillars and the roof).

The 300 hp is at the flywheel on the engine dyno at Jerry Woods. If you figure 12% drive train loss, about 265 hp at the wheels. With the new dyno at Thunderhill, I may do a few pulls next time I'm there to see what it gives.

The MoTeC wheel speed sensors (which depend on correct tire diameter) were telling me about 95 mph in turn 8. The Traqmate says a bit over 100 (IIRC) and 2.0 g's. I finally got the MoTeC i2 Pro to draw a track map, now I'm working on getting the numbers out of it (learning new software is never much fun). One thing I love about the MoTeC is it is programmed to provide a display of the minimum corner speed after every corner. It's great feedback while you are out there and much nicer than waiting until you come in to download data and review it.

mark kibort

I think you were out with us at laguna PCA a few years back, right? Wasnt this car more of a street car, but real fast? (i remember it also running the new Hoosiers at the time, i think R4s)
(EDIT: that was Henry Watts in a dark green turbo old 911)
(Chris Burns from POC was the one that had the 330 engine hp out of a 2200lbs chassis and ran a 1:55ish time at T-hill )

Anyway, sounds like you have done all the right things. I think the challenge is trusting the car can do much more than it could before based on the lighter weight. braking and cornering, besides just raw acceleration will be helped! (as you have seen)

Sears will be a great test too, because it is both a handling track, and a HP track!

It will be very interesting if you do a dyno, to see what the conversion factor from engine to chassis dyno is. the conversions are all over the map, but i would bet that its in the 265rwhp range as you mention

as far as speeds through turn 8, im sure you are more near 100mph anyway, as it really takes this kind of speed to run near 2:01 with the "Hill".

nice you can get the almost imediate feedback with motec. I still have to do some tedious video analysis to figure out whats going on after our races. It is ok for some basic information, but no where near as cool as the real electronic tools can be.

what is the event this weekend at Sears? PRC?

good luck and report back!

Mk

1AS

Nice work. If the 300 lbs equates to 3 seconds, losing another 2100 lbs would get you a car that weighs nothing and turns a lap at 1:38. What is the lap record? AS

earlyapex

Tom, the car blew a starter, which was easily replaced. Now for the bad news. The motor cut out on the in lap a Laguna Seca on Monday. I had to be towed in to the paddock where the motor fired up again. Something is causing the carb's to continue to pump gas into the motor off throttle. The motor gets flooded with gas and dies. The car is at Tim's to have the PMO's looked at. A plastic windshield will go in and he will also look at a sticky throttle for me. The car is down to 2150 with half a tank of gas. ATL is making a fuel cell for me and this should be ready at the end of the month. I will have Tony C mount a Sparco HANS seat and get a bead foam insert made. I've lost some weight and the Recaro SPG is too big for me now! Did I mention that I have a 3.8 RSR wing on order? With all these changes, I will still be a few seconds slower than you at TH. I do not have the budget for a new motor and transmission to make me competitive with real GT3 cars so I will always have at least a 50 hp disadvantage. I may still join you some day in PRC. SCCA ITE looks scary. My hat is off to you Mark!

Tom W

I believe the lap record for a "sedan" is 1:45.315 . We had two monster "super production" corvettes and a radical vying to set a new lap record at the NCRC/ARC event that I was at 2 weeks ago. I believe the one corvette did set a new fastest lap. I know they passed my like I was standing still.

The car/driver about to pass me is the one that set the new record.

Sean F

It looks like you're about to be eaten

race911

He looks like when I park the smart next to............anything. Whose Radical? Best I've done is a 1:50 flat, so absolutely even a 1.3L can be hustled around 2 secs quicker. With a built engine, let alone if it were an SR8, you're talking easily under 1:45. I think DSR's are around 1:42 now.

In any case, I think you'll be making yourself known to some real 993 GT2's, etc. that frequent our tracks. Now that you're on the track, I look out to my RSA carcass and see where that could head. Nah, no time for even what I've got.

DrJupeman

Ha ha, that was my thought exactly!