Doing a little math (GT40 quickness)

[Darrin]

After stumbling over an old thread or two talking about the quickness (or lack thereof) of the GT40 in general, I got to wondering why this is the case. Is it that most of the replicas are just under powered compared to modern super cars?

I mean think about it. We have a very light car with most of it's weight very close to the drive wheels and even a, relatively, sleek design that isn't too bad at high speed drag. All things considered, these cars should be very quick, like the Ford GT, yet I think only one member has his car in the low 11's in the 1/4 mile.

Now my goal in building my replica is to have it perform as well as the current year ZR1, or at least reasonably close. So I did a little math using the new ZR1 in comparison to my planned project.

Initially my thought was a centrifugal supercharger (Paxton in specific) feeding a Coyote (actually, the Aluminator version of it). Looking at the numbers though, I am not so sure that would be needed to reach my goal of ZR1 like performance. Now I am thinking that may not be the case at all.

Of course we know that traction control has a lot to do with quickness in these cars, but given the tire I will be running (Gulf version...tire will be a 305) I think that hooking up won't be such an issue (not that I plan to drag it much at all...maybe just once to set a benchmark).

Anyway, here are some numbers:

The weight of the two vehicles is like this (the 225 is the driver's weight)

ZR1 3353 + 225 = 3578
GT40 2350 + 225 = 2575

The rear wheel horsepower of the two cars is this:

ZR1 525 rwhp
GT40 455 rwhp

Note that I got to the 455 mark by going conservative for what I saw on some sites showing the Coyote with the Boss intake and larger throttle body but retaining all of the exhaust and emissions equipment. In short, I think this will be quite low for what a the engine will actually make. Here is a good article though: 2012 Boss 302 Intake Test - 5.0 Mustang & Super Fords Magazine

So, doing the math we have this:

ZR1 = 3578/535 = 6.687lbs/hp
GT40 = 2575/455 = 5.659 lbs/hp

My little GT40 even normally aspirated should be able to accelerate every bit as well as the ZR1 assuming proper hookup at the line and good gearing.

Thoughts?

Side note: Ford did a little trick with the GT giving it a first gear that allowed the car to hit 60mph without shifting. May consider doing that as the Audi tranny guy here offers custom 1st and 2nd gears. I bet a GT40 replica with 455rwhp and that gearing could hit 0-60 in 3.5 seconds or less).

 

[Mike]

My GT40 is as fast to 150 as my Ford GT with a pulley and tune was. The GT with a supercharger came out of the hole quicker but fell off a little on top. These cars were never designed to be drag racers. If that is what you're after there are far better platforms. Compare 60-130 times. I think you'll find a GT40 will hang with most modern supercars.

 

[Jim Cowden]

Darrin

I recon you are over thinking all of this.
455 rwhp is plenty, its about the package,how it goes around a corner and how it gets out of a corner.

My 40 has just over 300 at the rear wheels and it goes hard but corner speeds will blow you away.

At one race track I go to they often let me run with race cars and my 40 is more than capable of keeping up with 5-600 hp sedans.
Its how it uses it.

Just my opinion.

Jim

 

[roaldin]

In a recent standing start speed trial my car came second by 1 kph to a V8 supercar - aussie reference. Daylight came third.
My car was unchanged throughout the event and in complete road trim, it even had full tanks.
To my knowledge the race car changed to qualifying tyres, adjusted its aero etc - including removing mirrors and made numerous other adjustments.

As for traction control, electronic gearboxes etc, they didn't help any of the modern supercars that finished behind me.

Not quick... Pffft... Quick enough.

Unless...
If you're talking quick as in drag racing ET then I have no idea, I never found a way to be interested in drags.
I think the suspension, chassis etc are probably better at doing what the car does 99% of the time than the single task of getting it a quick start.
I know my car has outrun a car that does 11 second quarters but beyond that I have no idea and even less interest.

Tim.

 

[Steve26]

I'm running a 302 with around 400HP and a Porsche 930 transaxle. My car will do 58MPH in first gear at 6300RPM and just short of 100MPH in second at the same RPM! I have never run the 1/4 but I have chedked the 0~60 several times and am always under 4.0 seconds. I can't even began to think how fast this might be with 450+ H.P. at the rear wheel would be like, you really need to pay attention when driving mine because things happen very fast!!! Just some real world numbers to think about. Just one more thought, you might want to think about what you are going to do to an Audi box at the numbers you're talking about and Drag racing 1/4 mile type runs? You will KILL it very quickly. I would look at a 930/G50-50 or something similar. Just my $.02

Steve

 

[Darrin]

... Just one more thought, you might want to think about what you are going to do to an Audi box at the numbers you're talking about and Drag racing 1/4 mile type runs? You will KILL it very quickly. I would look at a 930/G50-50 or something similar. Just my $.02

Steve

Take a look at this thread: http://www.gt40s.com/forum/gt40-tec...7568-has-anyone-destroyed-01e-their-gt40.html

That said, I won't be drag racing the thing more than once, perhaps twice to satisfy my curiosity.

 

[Darrin]

Unless...
If you're talking quick as in drag racing ET then I have no idea, I never found a way to be interested in drags.
I think the suspension, chassis etc are probably better at doing what the car does 99% of the time than the single task of getting it a quick start.
I know my car has outrun a car that does 11 second quarters but beyond that I have no idea and even less interest.

Tim.

Yes. In the US, 0-60 and 1/4 times mean more than I think they do abroad. Although I have never been into drag racing much, I am curious to know what the car would be capable of with respect to acceleration.

 

[Darrin]

Darrin

I recon you are over thinking all of this.
455 rwhp is plenty, its about the package,how it goes around a corner and how it gets out of a corner.

Agreed. It is plenty and is what I will go with to start at least.

As for over thinking...I'm an engineer. It's my nature.

 

[Ian K]

My little GT40 even normally aspirated should be able to accelerate every bit as well as the ZR1 assuming proper hookup at the line and good gearing.

Emphasis on the important part ...

Ian

 

[Ron Scarboro]

I was trying to get through the article to see what other mods were made to the engine. From the ford website:

M-6007-A50NA* is 412hp. At the wheel that'd be 350 +/-. Adding a BOSS intake makes 444 as in the part below?

M-6007-M50B* is 444hp. At the wheel that'd be 375-385. How'd they get 455 to the wheel? I may be missing some mods to the standard Coyote engine.

Also, for everyone who gets a motor with an engine dyno HP, that is GROSS horsepower as was measured in the 60s meaning it is running no accessories other than a water pump on a big pulley. You need to haircut that 15%-20% to get SAE (running real headers, flywheel, AC, alternator with a real pulley etc) then account for another 15% in driveline losses.

So a 500hp SBF is really +/- 425hp making +/- 365hp at the rear wheel.

 

[Darrin]

I was trying to get through the article to see what other mods were made to the engine. From the ford website:

M-6007-A50NA* is 412hp. At the wheel that'd be 350 +/-. Adding a BOSS intake makes 444 as in the part below?

M-6007-M50B* is 444hp. At the wheel that'd be 375-385. How'd they get 455 to the wheel? I may be missing some mods to the standard Coyote engine...

Besides the Boss intake and new throttle body, two other things that I know of. One, it was tuned and picked up some from that. Other than that, Ford, for whatever reason, has greatly underrated these engines. They all seem to produce much more from the articles I have read. It seems to be in the neighborhood of 30 HP for the stock Coyote, and more than that for the Boss version.

For example, this was typical of what I found researching:
http://www.youtube.com/watch?v=ZUSFCCKZGmc

and this:
http://www.musclemustangfastfords.com/tech/mmfp_1106_boss_302_intake_manifold_tests/index.html

 

[roaldin]

Yes. In the US, 0-60 and 1/4 times mean more than I think they do abroad. Although I have never been into drag racing much, I am curious to know what the car would be capable of with respect to acceleration.

Drag racing seems to me to be at least as dependent (and probably more) on traction and launch as it is on real life acceleration.
As far as acceleration is concerned, my car was 1 kph slower at the end of a standing 600m-700m (not sure of this distance) than one of Australia's fastest circuit racing cars. He was on qualifying slicks and had all the other things modern race cars have - eg sequential gears etc, I was on 8 year old r-spec Kumhos with no electronics, H pattern box etc.
I think it reasonable to suggest that he probably launched better than I but somehow I still managed to accelerate to virtually the same speed by the finish line.
Acceleration is just fine.
Launch (or whatever it's called)- not really something the car is designed to do and in reality it doesn't mean much anyway, unless you get your kicks dragging kids and grannys from light to light. ;p
IMO 0-60 and 1/4 mile are ALMOST meaningless numbers that at best give an indication of actual performance but no more. The fact that people care so much about them and they have become the be all and end all in some peoples minds tells me more about the silliness of humans than anything else.
You guys are great for that -simplify and distill: NASCAR and drags, two great examples.
Peak horsepower figures are another example - no-one cares what the torque curve is like, just the peak HP number... Crazy.

FWIW it seems to me that setting a car up to launch as well as possible is likely to introduce problems in vehicle dynamics in other areas where cars spend more of their real world time. I have driven a few modern supercars now that have very strange gearing, I assume to make 0-60, 0-100, 1/4 mile numbers more sell-able.

I repeat, acceleration is just fine.

Oh, yeah one last thing - The Audi 01E in my car seems to be coping just fine (as is the alloy block). ;p
If you're interested, best launch in my car seemed to be if I started in second.
Also Darrin, in the 01E thread I said my box was standard - not quite true, the diff' centre was made by pfitzner. The rest is stock though.

If you're wondering what a guy with so little interest in drag racing is doing in a standing start event then I should explain it is a historic event using the last remaining part of an old 50's -60's racetrack - nostalgia.

Tim.

 

[Jim Cowden]

Making mental note.

Dont bring up drag racing in front of Tim.

 

[roaldin]

I'm Tasmanian, you just need to remember which head doesn't like drags. You can bring it up with this one without fear Jim. ;p

Just trying to provide evidence that a GT40 can stay with or indeed beat pretty much any modern supercar in a realworld environment. They might beat a good GT40 to 60 with their traction control and electronic boxes and bias in setup towards silly arbitrary indicators (I have no evidence either way) but from there I think I have demonstrated that a half decent GT40 can run with and beat them.
Indeed with the same gadgets and gizmos it'd probably be even easier - although less fun.

Hope my comments above re' NASCAR etc were taken as intended - poke in the ribs.
My sense of humour has a habit of dragging my feet to my mouth... ;p

Tim.

 

[Jim Cowden]

Im with you Tim.
F**k all the gizmos it a mans car, keep them raw and drive it I recon.

What ever Darrin decides they are supper cars.

Jim

 

[Mark]

I'm in the boat with Tim & Jim.

Sounds like a reality tv series though!

 

[David in Durango]

The 1 mile (pavement) events have been my standard. At least there is a "timing slip" involved, one can at least pretend the mile event is fairly standard.

Someone ( google "60-130) have started measuring 60-130mph runs with a "v-box" and this has some one good feature - NO hard launches. Bad feature is it would probably be frowned upon to run these on public roads. Ya think?

Anyway, these two options pretty much negate the traction control needs.

Just a thought or two . . .

good explanation here . . .
http://www.dragtimes.com/blog/dragtimes-com-starts-accepting-60-130-mph-times

 

[Dave Hood]

As Michael points out, these cars were designed for endurance events. Tim, Marcus Ambrose is representing Tassie well in NASCAR. Are you in Launceston or Hobart?

 

[Darrin]

...IMO 0-60 and 1/4 mile are ALMOST meaningless numbers that at best give an indication of actual performance but no more. The fact that people care so much about them and they have become the be all and end all in some peoples minds tells me more about the silliness of humans than anything else.
You guys are great for that -simplify and distill: NASCAR and drags, two great examples.
Peak horsepower figures are another example - no-one cares what the torque curve is like, just the peak HP number... Crazy.

We in the US do tend to distill things down I suppose. We are kind of utilitarian as well...practical. There are reasons why we use those measurements:

0-60 makes sense as a measurement sense, at least at one time, 60MPH (1 mile a minute) was a common speed limit.

The 1/4 mile test stems from the days of the quarter horse.

We also calculate lateral g and normally run a car on a track to compare it against others.

As for NASCAR, well, it's much easier to set up an oval race track and for fans to see all of the race that way (although NASCAR does run a couple road races per year as well).

Yes, peak HP doesn't mean as much on the street as "area under the curve" but that concept never caught on and it's easier to remember a max HP than to plot out the curve to commit to memory. There is usually a pretty good correlation between max HP and how strong an engine is overall anyway (not always...usually I said) so it's not such a bad indicator.

I do agree we value HP in the US more than in other places around the globe it seems. Maybe that's because we make some reasonably good performing engines.

 

[Larry L.]

I do agree we value HP in the US more than in other places around the globe it seems. Maybe that's because we make some reasonably good performing engines.

"Too much horsepower is just about enough." - Carroll Shelby