Thread: Top end speed
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Old 01-19-2008, 08:36 PM
Hal Copple Hal Copple is offline
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Join Date: Jun 2000
Location: Rock Hill, SC
Cobra Make, Engine: Superformance, 396 CI
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i am no drivetrain or gearing expert, but from what i understand if a driver wants to hit such and such mph at top end, then gear the car to put that speed at the engine's peak horsepower rpm.

ie, if you want 160 mph then gear the car to put that speed at your hp peak. My car with its present gearing has a theoretical top speed of about 195 mph at 6500 rpm engine redline, but my car would not pull that rpm in fifth, and it is about a thousand rpm beyond my peak hp point too.

Many cars will top out in a lower gear than than an overdrive top gear. I just read that the upcoming big engine Corvette (Blue Max or something like that), is geared to be the first Corvette to reach maximum speed in the top gear.

The amound of power to push thru the wind resistance increases exponentially as speed starts to increase. I head that back in the earlier NASCAR days, every mph over somthing like 180 or something like that took another 50 horsepower.

A GT2 Porsche can reach 199 with 520 hp, it takes twice that to go 210 mph.

When my son Chris and I did our standing mile with the East Coast Timing Association, a few years ago at the abandoned Maxton NC airstrip, it was a frightful experience. The path down the airstrip is about 15 feet wide at best, chunks of concrete missing and patched, scrub pine trees about 5 feet from each side of my car.

I told Chris when he ran, to absolutely not go from full power to hard brake without feeding in some gentle deceleration transition. So what did i do, with the end of the runway trees fast coming up.

Stand on the brakes as hard as i could!!

Bob Olthoff told me that many rookie drivers complain about front end lift in the Replica's. His opinion was that they were just inexperienced.

On the straight on the South Course at VIR, i hit something like 145 mph or so, it seems really fast to me, but my car seems rock steady. I am probably too much of a novice to even know of my front was off the ground.

I will say that braking for the right hander at the end from that speed comes up faster than one thinks, with so little experience braking from those kinds of speeds.

all the best,
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