Someone with technical, theoretical knowledge....help!!!!!!!!
Thread Starter
Racer
Joined: Mar 2001
Posts: 469
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From: St. Pete, Fl
Someone with technical, theoretical knowledge....help!!!!!!!!
Please help, I'm not an engineer! (although, I an a scientist ;). Anyway, How is the drivetrain loss calculated and do you know the actual factor of loss for the camaro and vette??? How much different? Where I can find it? I know thew rule of thumb is 15%/20%, but I'd love to know #'s. I'm in a debate and someone is telling me that although mu car put out 300.5 real wheel HP stock, it is not making 350 at the crank because the drive train loss is less than 15% for the Camaro. I will admit he is right if it is so, but I really want to know for sure. the Chevy dealer service told me 15-20, as does everything I have read. Anyone know the actual #'s ? Thanx in advance! :flag
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
Re: Someone with technical, theoretical knowledge....help!!!!!!!! (tslawsky)
I've seen many dyno readings of 2001 Corvettes (non-Z06s) that were up around 308-312. That's an 11-12% reduction for manual transmission cars that are 350HP at the crank (with all accessories). If you have more RWHP as your signature suggests, then you ARE putting out more than 350HP. In fact, if your drivetrain loss is 12%, then you're putting out 370HP at the crank.
Intermediate
Joined: Aug 2001
Posts: 39
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From: Wood Dale IL
Re: Someone with technical, theoretical knowledge....help!!!!!!!! (Dave68)
DAVE68 I GRADUATED FROM UNIVERSAL TECHNICAL INSTITUTE AND WE HAVE TWO DYNOJET CHASSIS DYNO'S MY HOT ROD U INSTRUCTOR TOLD ME DIVIDE BY (.8)
TAKE CRANKSHAFT HP. DIVIDED BY .8 SHOULD GIVE APROX REAR WHEEL HP
SAME GOES FOR TQ. :cheers:
TAKE CRANKSHAFT HP. DIVIDED BY .8 SHOULD GIVE APROX REAR WHEEL HP
SAME GOES FOR TQ. :cheers:
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
Re: Someone with technical, theoretical knowledge....help!!!!!!!! (youngvette97)
Here's how I came up with my estimation of 370HP:
First, I assumed a 12% drivetrain loss, based on GM's rated 350HP for an 01-02 coupe/vert and the rear wheel horsepower numbers I've seen for 6-speed dyno tests.
Next, I calculated RWHP of the Camaro based on the above drivetrain loss and the corrected RWHP that was listed as 326.1. The equation is:
X-.12X = 326.1
.88X = 326.1
X = 370
Your calculation assumes a 20% drivetrain loss and is actually the inverse of what it should be, given that much loss. In other words, if you divide the crankshaft HP by .8, you'll end up with more horsepower at the rear wheels than at the crank. So, if 20% loss is correct, then you would MULTIPLY the crank horsepower by .8.
BTW, 20% is more typical of cars with automatic transmissions and our friend with the Camaro has a 6-speed.
First, I assumed a 12% drivetrain loss, based on GM's rated 350HP for an 01-02 coupe/vert and the rear wheel horsepower numbers I've seen for 6-speed dyno tests.
Next, I calculated RWHP of the Camaro based on the above drivetrain loss and the corrected RWHP that was listed as 326.1. The equation is:
X-.12X = 326.1
.88X = 326.1
X = 370
Your calculation assumes a 20% drivetrain loss and is actually the inverse of what it should be, given that much loss. In other words, if you divide the crankshaft HP by .8, you'll end up with more horsepower at the rear wheels than at the crank. So, if 20% loss is correct, then you would MULTIPLY the crank horsepower by .8.
BTW, 20% is more typical of cars with automatic transmissions and our friend with the Camaro has a 6-speed.
Safety Car
Joined: May 2000
Posts: 4,810
Likes: 344
From: Albuquerque NM
Re: Someone with technical, theoretical knowledge....help!!!!!!!! (tslawsky)
The solid rear end on a Camaro is more efficient that the IRS on a Vette at transmitting power. All info I have seen peggs the Vette's loss at 15% for a manual, and I've seen 18 AND 20% used for automatics. For the Camaro I've seen 13% used for manuals. :chevy
