MM 1 Shelby 0, What a race

[Tom Doan]

Shamu VS Shelby,

Sunday I'm out front weeding the lily patch when I hear a Mustang coming up the road, I look down the road and It's a white Shelby, and my next door NAIGHBOR is driving it!!! Dang. After months of us looking at It down at Crystal Ford he makes the jump.Our pea brains drain down to our right foot.
I figure I'll let him get a couple of hundred miles on his new toy before we tangle. I show him how to turn off the traction controll and he is much happier.
Last night I'm taking my sons buddy home and I spot Greg way ahead of me out tooling around, takes awhile but I work my way up to him at a light and say lets go to the secret spot. I drop off the kid and it's out to 3 lanes wide of clear road with barriers on both sides so we won't go into on coming traffic if we screw up. Jump into the left turn lane to let the traffic clear out and on the signal we U-turn and slowly line up and get ready to run, the light is holding up traffic behind us, we look for cops and this guy in a Ford pick up starts beeping his horn, jumping up and down and is giving us the thumbs up, he is first in line at the light and he knows what is going to happen.
Stock Shelby with 413rwhp VS Shamu with 404 rwhp, 2007 5.4 Cobra VS 2003 4.6 Cobra, I figure we are pretty even, I weigh more and am running a 2500pi convertor with 3:27 rear gear, he is a old school stick jocky and is good on the shifts, I lock out overdrive and smile at him to hit it.

Dead even at launch, top of first gear I start to surge by 6 feet then he hits 2nd and he jumps like a bullfrog, I hit second and start to creep ahead he hits 3rd. and jumps again, man that thing has some torque, I hit 3rd. at 90mph and bye bye I'm gone, Shamu's got LONGGGG legs and I'm running away. Thank you Dennis, I love my set up, and it does just what I want and how I want it done, you might beat me to 100 but after that I'm just getting started.

Greg's my buddy and I know we will messing with his car, he's been eatting my dust for years but that will change.Tom

[sdacbob]

Good run, congtats!

[Bluerauder]

:laugh: I hope this \/\/\/\/ is not a colloquialism :laugh:

...I'm out front weeding the lily patch
Nice story, Tom. :2thumbs: I just love to hear a happy ending. :D

[Raudermaster]

Nice kill! Did he know how fast your car was before hand?

[Tom Doan]

Oh yeah he knows, he lives next door and has been driving my Mopars,Audis,Saabs,Mustangs ect. for 15 years and running around in Shamu since the day I brought it home. He will at the Stafford show and drove his '63 Comet convertable last year, but I think that will change this year. Peer pressure still works even after age 50. Tom

[OneBADLsE]

exellent kill!!!! WE NEED THAT ON VIDEO! People would be jealous, LOL

[offroadkarter]

Yes PLEASE Get a video!

[Tom Doan]

The vid is for you young'ns to do, I can't even do pics here yet, old compuit dinosaur here. But it was fun with both cars pulling back and forth. I would need a cam'corder mounted on my head rest to film shooting out the window to show the fun and I wish I was watching my gauges to see the RPM, fuel pressure ect. to learn something. This ain't over. Sugestions are welcome.Tom

[Kennyrauder]

There is a Shelby 07 Cobra new in town. I'm sure it's real quick. My Marauder is around 440 RWHP but traction is my problem.... gonnna try to suck him into a 15 mph rolling start. I really think my Marauder will make him sweat or a possibleee kill .Reinhart Vortech, air to air, PI 3000 stall. 410 gears, metal metrix D/S Kooks. Magna flows, ETC. I am not afraid !!!!! I will hunt this Pony .

[DEFYANT]

A tuned Shelby will send most of us packing :(

Tom, you have lots of options still. I'd be looking real hard at a Whipple for that car!

[Tom Doan]

Ummm.. a Whipped cream instead of an egg beater on my motor. I have the Eaton becuse it has more low end torque and my car is set up for it with the T/C and rear gear. Kenny Bell, Whipple, Maugenson are a options and I have allready done a Vortex hair drier with bigger numbers, how much rwhp/rwt do you want and at what rpm do you want it, they all go fast. My rwhp is 404 but rwt is 444 at real low rpm, I had Dennis tune it just for me to give me the grunt at 1000rpm, we did other pulls that had more at 6200rpm but I don't drive at 6200. The stock Eaton is good to 17psi with reliableity declineing after 16psi on a stock Cobra motor, I'm running 14.5psi. All the other blowers will beat the Eaton112 after 3600rpm but till then I'm making more torque and this is where I spend 99% of my time, I got so much grunt and gear that I'm driving around in 2nd. most of the time with "drive" being an overdrive to me. When Dennis had it on the dyno 5000rpm was way over 140mph in third gear. This car feels like a big block for smooth manners in daily driving. BUT you are making me want to do Shamu2 a real killer whale.

[Tom Doan]

People put too much faith in the Peak Horsepower number. Engines spend very little time at their peak power point, with the possible exceptions of boats at cruising speed or NASCAR racers on banked ovals where all the horsepower is going to overcome a quasistatic fluid resistance, either air or water.



A much more interesting measure and predictor of real acceleration performance is the integral of either the power or torque curve over the acceleration course, or “area under the curve”. This would typically include a range of RPMs as revs built towards and past peak power, pauses for shifts with brief periods of zero output, then a return to a lower RPM range and repeat.



For optimal acceleration you would ideally want a transmission that could keep the engine RPM constant at full throttle at the peak horsepower point. Unfortunately, no one has been able to make such a transmission that could work with any real power, and of course there is the issue of starting from a dead stop—transmissions are multipliers, and at speed=0, you have to either couple in at some very low RPM, approaching zero, or suffer some negative consequence like wheel spin, slipping clutch, broken clutch, driveline shock, transmissions breaking, engine bogging down, or stalling the engine. You are also limited by gear choices. You can add more gears in closer ratios to keep the engine close to its peak power range, but this is self limiting: more gears means more gear changes (during which power cannot be applied), more weight, and more moving parts.



People like the simplicity of comparison – “My car makes 300 horsepower!” but in fact this is an instantaneous snapshot that tells you very little about the real-world performance. Honda and Nissan in particular have exploited this human tendency: their engines make great peak numbers and compare very favorably with other manufacturers when that spec is published. They generally do this with highly optimized intake tracts and relatively large valves that make great peak horsepower at the expense of low RPM power. The downside is that they bog off the line and you have to shift often to keep the engines happy. On a racecourse, with a manual or semiautomatic transmission and a skilled driver, you can exploit that peak power. In a street car, the driver rarely bothers with that sort of optimization. That’s why a 260 horsepower mustang v8 feels so much better than a 260 horsepower Nissan v6: the mustang makes 80% of its engine torque through most of its RPM band—the torque curve is nearly flat. But the Nissan has a narrow peak range at high RPM. The extra 1.1 liters of displacement DO do something after all, even if the peak number is the same.

[Tom Doan]

For a street car, I’m with Thom on this – a wide power band with fat torque from 2000-6000 rpms is really what you want. That’s the Big-Block feel: long strokes and long rods mean long lever arms and lots of dwell time with the pistons near their peak cylinder pressure, which produces more torque. Unfortunately the big block era is pretty much gone, and we’re now in a much more complex time of either high RPM or forced induction engines. So transmissions are very important, shift patterns are very important, and for forced induction, boost curves and parasitic losses from driving the compressor factor in heavily. Big superchargers make power much like displacement increases, but they also have big losses: something like 50 to 100 horsepower is consumed just driving a roots blower. Positive displacement superchargers, like Eaton’s roots-style blowers, produce boost at just about any RPM and have a more or less square boost profile, the best shape for large integrations and hence acceleration. Centrifugal blowers have more efficient compressors that have lower parasitic losses, but they produce boost proportionally to their input RPM: ideally, they should have a transmission and rotate at a variable speed, but no one does that and consequently they have a boost curve that looks more like a triangle with the thick part at high RPM, and the torque and horsepower curves mirror that triangle. Even with the higher peak number, the area under the curve over the whole RPM range will be significantly less. Centrifugals make great peak numbers but make the engine even more “peaky” than it was before supercharging. This is why few manufacturers use them for OEM applications. It’s also why Thom could say his car is faster with a 404hp engine than it was with a 500 hp setup with a Vortech centrifugal blower.



So what does all this mean for our hypothetical racers? If Greg could graph his shifts carefully and possibly use a shift light to help time his shifts, keeping the Mustang close to its peak power all the time, high might well win in a repeat race. His car is a factory hot rod that has to have a published fat peak horsepower number, and as Pete observes it’s higher than Shamu’s peak and his car is at least a little bit lighter. Shamu has a boost curve that Thom massaged through MANY expensive iterations to match the car’s qualities. He’s got a blower that comes in with its boost earlier in the RPM range than most – all in by about 2000 rpms when the torque converter hooks up -- and makes its boost peak a little earlier than most would choose. That hurts his peak power number but fattens the area under the curve substantially. He also has a custom transmission and optimized shift points built into his transmission’s program. He figured this all out through trial and error in advance, both on the street and on the dyno, and now the car knows what to do. He just has to keep his foot down and watch out for excessive wheelspin. Thom has no company to answer to either: Greg’s car must be backed up by a factory warranty to protect expensive engine parts. Thom has his cash in the game and accepts the risks himself, and he has paid for that risk in towing and broken parts already.



A more interesting comparison will come when Greg’s car is out of warranty. 500 or even 600 horsepower is possible on the GT500’s with smaller blower pullies and some fuel and ignition tweaks. The Mustang, with more displacement, less weight, lower center of gravity, and lower frontal area has the potential to crush Shamu in the long run, but knowing Greg and also knowing the awesome performance he has in his hands already, I don’t think he’ll ever risk breakage with the same abandon that Thom does.

[Tom Doan]

I am not starting a supercharger war, I mean IT!!, this is one mans opinion that has driven all the different set up's I have gone through.Tom

[RCSignals]

thanks for the article Tom. Great stuff.

[Tom Doan]

So greg shows up at "church" this morning and Joe Walsh doesn't? Dang. Tom