GT40 quarter miles

Hi guys, has anybody run their Gt40 through the quartermile?
it would be interesting to compare engines, times and speeds?
And,to put most modern cars in their place!
 
Bob, My car is pretty far away from being able to participate in the quarter mile. But I for one don't anticipate any 5,000 RPM launches...
It seems I remember a hand lettered sign on an ERA @ Lime Rock a while ago that indicated the car did the 1/4 somewhere in the 11's. It had a 351 with Webbers and a ZF, although the owner told me that his transaxle was not the Pantera style, but was out of a different car. Of all things, I think I remember it having an adapter plate!! Brian
 
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I recall a few weeks back attending a vintage and classic car sprint here in Perth, where one of the locals had his GTD running. Some of you may know of Cossi and his twin turbo 302ci.

He managed a time of 12.3 from memory but this was a soft start, no wheel spine etc as the road surface was new and pretty "Green" I can easinly imagine mid 11's with more agressive starts. Unfortunately he was beaten on the day by a two week old Porsche (only 0.1 of a second though)
Cheers,
RV
 
If you guys are now considering drag racing the GT40's, we better have a lesson in burn outs




IMSA
Terry Teadtke
 
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Imsa, that is a very toasty, sorry I mean tasty picture you posted!

Cosi's car is awesomely powerful from what I have read. But he will still suffer from the same problem of how to put it down to the tarmac. His time of around 12.3 does not surprise me in the slightest. That is a typical time at the Brighton Speed trials for a dry run by the top guys. Wind direction and weather play a big part in good times over here. Also the road surface is a public road for 99% of the time and is a bad surface.

Absolute best times recently have been at about 12 secs dead. Paul came closest to a sub 12 two years ago with a 12.01. How annoying! Terminals are up to 140 mph. Our top guys run between 500 and 630 proven bhp.
Newcomers like to be below 14 secs for their first runs and regualrs like to be in the mid to high 12's. Any terminal over 120 mph is good. My best is 12.63 and terminal of 127 (different runs!).

Now when I wrote about this a while back, Ron Earp was surprised and thought these times were slow. We have been doing these runs now for 10 years plus as a club. The problem is putting power down for traction. The road does not get used all year except for this day so there is little rubber down. Also no one uses chemcals on their tyres or runs drag tyres. LSD's are only starting to be used now so maybe that will improve times. I hope not as I don't have one.

A good time is all in the start. You want as little wheel spin as possible without bogging down the engine. It is more difficult to do than say especially when you have 10,000 people watching you!

The US contributors talk a lot of mid 11's. I think that there has been only one post of an ERA claiming this. Are these figures coming from actual runs or computer simulations? One member here did the computer calc thing and came out with mid 11's too but in practice it is different for some reason. If they are genuine times from runs, what is the weight of the cars and do they do anything other than turn up and drive? Our cars are not prepped as 1/4 mile specialists and over half drive on the road to the Speed Trials. If there is a secret please email me privately so the other guys don't see what it is!

The only general rule of thumb is that sticky slicks can give you 1/2 second improvement off the line. And less weight is more important than high BHP, although high torque goes down well as that will pull you through the last 400 yards of a 1/4 mile!

Malcolm
 
I have been known to drag race my Mustang Cobra from time to time.
If GT40s are seeing trap speeds approaching 140 mph then the launch must be horrific...like a 60-foot time around three seconds. I realize (realise for our UK frinds) that the limiting issues are (1) traction, (2) gearing and (3) drivetrain durability (clutch, transaxle, half shafts), and I can certainly appreciate the reluctance to abuse a GT40 off the line at the risk of replacing a $12,000 ZF.

That being said, I feel that with minor modifications, a GT40 should be able to run in the 11s consistently with a 60-foot time around 2.0 seconds. Those modifications would include an extra set of rear wheels outfitted with drag radials or better, ET Streets or slicks. A few extra ponies wouldn't hurt either.


I believe the supercar benchmark for acceleration was set by the Porsche RUF 911 CTR, which I recall claimed an 11.3 ET at 132 mph. That's what I'll be shooting for.
 

Ron Earp

Admin
I agree that the limiting factor in quarter mile ETs is going to be traction. But, the trap speed doesn't lie - with a given weight and hp your trap speed through the quarter is fairly consistent.

So, when I see the 3000lb 600 hp latest and greatest "Insert name here" from "Insert your favortie supercar company here" pull a 12.7 at 115 mph I kind of wonder if it really does have 600 hp. (Yes I know the difference between crank and wheel hp and which is calculated using the formulas).

The fact is a lot of it doesn't add up.

In the cases above it does add up - if you fellows are getting terminals in the 127-140 range then you've certainly got the power, just not enough traction to get the low ETs.

Ron

[ March 21, 2002: Message edited by: Ron Earp ]
 
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Another interesting thread...

What it points out is that how a car is set up is extremely important to it's
intended usage. The EXACT same car with
a given horsepower can be set up through
tires, gears, suspension, etc to maximize
it's top end speed OR to minimize it's 1/4
mile time. You can't cover both.

Skinny front tires and drag radials are great for 1/4 mile runs, but you wouldn't want to do any serious road rallying!
And we all know the affect of gear ratio
changes.

GT40's were not constructed to win drag races, so no one should be surprised if their 1/4 mile times are poorer than what the engine dyno says.

That's the funny thing about drag races,
the winner is the one that gets there first....not the one with the most dyno HP
or highest top speed.

MikeD
 
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We measure the first 64 ft. If you can go below 2 seconds for that then you have pulled over 1 G in acceleration. The best acheived here is 2.17 secs for 64 ft. Normally we are around 2.3 secs. 3 secs is an appalling time and would mean rain had fallen.
Maybe a UK 1/4 mile is longer than a US 1/4 mile? Your gallons are different!

Malcolm
 
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Hmmm....time for a reality check I think. I wholeheartedly agree with Ron on this one, there is a lot of Barroom Horse Power talked about GT 40s.
My 2001 engine (302 0n 44 IDFs) was dyno tested at 350 bhp. My car did not have an LSD at Brighton and ran on Dunlop Historic treaded cross ply tyres. It ran 13.22 at 117mph.
Roger Burston's car has a 351 on 48IDAs which we reckon has about the same power as mine, same tyres plus a LSD. His first run was identical to mine and on the second run he did a 13.14 at 113mph. Both these cars were droven to the event and competed on the tyres they arrived on.
At the next level up, Paul Thompson drove Roy Smarts car which has a highly developed Fontana blocked engine, stroked to 350 with Kinsler injection. It hasn't been on a Dyno but we reckon it's good for a genuine 500+ bhp. This is a lightweight car with LSD and running slicks. The driver certainly knows what he is doing and Paul was the fastest 40 at Brighton this year with a 12.38 at 128mph.

I have not seen any results that show 140 mph terminals for 40s, Paul's was our fastest this year.

The speed trap doesn't lie, so use these facts to gauge some of the claims you may hear. My observation is that getting into the 11s is a whole different ball game from being in the mid 12s.
 
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I think we pretty much agree on this one
(sorry)...

The average (?) GT40 is plenty quick and
should wax 95% of the cars on the road today
in a drag race. But at the drag strip
running against purpose built cars,
it's at a disadvantage because of the chassis
layout and torque limited transaxles/driveshafts/CVs.

That's why Cobra's generally post better
1/4 mile times. Their chassis layout (and many run a solid rear axle)is more conducive to drag racing. And those with an independent
rear generally have stronger components
than most GT40's.

It would be neat to see what a GT40 could do
with a "superstrong" drivetrain. I guess
anything can be accomplished given enough
time and MONEY!

MikeD
 
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Andrew

You need to go back to before you were on the scene as an owner for the really fast terminals, all set by Tony Marsh with his highly tuned GTD Mk11. However do note that he has always run on street rubber ie 17 inch Pirelli P Zero's, which makes the times and terminals even more impressive.

In 1995 Tony's times were 12.45 in practice, 12.30 with 137 mph terminal and then 12.29 and 134 mph in the timed runs. They do not record terminals for practice but I recollect it being 139 but stand to be corrected. Hence use of wording "up to 140" before.

In that year Justin Bell in a road going Viper did 12.48 in practice, 12.33 with 118 mph and then 12.39 with 118 mph again. His practice time may have been quicker if he hadn't burnt rubber way down the track!

For comparative times, I see a Porsche 911 SC 3 litre did 14.76 with 100 mph. Ferrari Testarossa did 13.27 with 114 mph. Genuine AC Cobra (289) did 14.05 with 104 mph.

In 2000 Tony Marsh posted terminals of 135 and 134 mph, both times in the mid 12's.

The other best times I have recorded are Roy at 12.75 and 12.64, Paul corrected me on the 12.01 to 12.10 but he has done quite a few low 12's now, and Robin at 12.79 and 12.93.

For interest sake my best time of 12.61 (not 12.63!)was in 1993 but with a terminal of only 111 mph.

If you averaged out all the times our club has from over the years it would make depressing reading. My records show many 14 second runs and slower ones as well.

Malcolm
 
Hi all,

One thing that I have noted - especially looking at the logged data, is that times are dramatically affected by both poor launches and slow shifts. I know we all use variants of cable and rod change but I have data showing shift times ranging from 0.6s (poor) to 0.3s (good). This measurement is from lifting the throttle to planting the throttle and must be worth a couple of tenth's on say 3 shifts. Any comments?...

regards
Paul Thompson
[email protected]

ps- roll on the MOTEC launch control, traction control (aka Tony Marsh) and full throttle gearshift! (only kidding!)
 
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Hi Malc,
Point taken about Tony's car, however I think we should make it clear that this car is pretty unique in that it has a completely different engine and transmission from a "normal" 40 replica.
Tony runs a turbocharged Rover(born out of small block Buick) V8 with a Hewland racing transaxle with straight cut gears. He also has launch control, something over 600bhp and all the driving skills of an ex-hillclimb/formula 2 champion.
In no way am I knocking Tony or his car here. I am just old enough to remember being thrilled by him on the hills and think the car is a wonderful piece of engineering and his presence at Brighton is always wonderful. I just want to make the point that it could be misleading to use this car as a yardstick for GT 40 1/4 mile performance.
I for one am hoping to get into the 12s this year, can't wait for September 14th.
Andrew
 
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