406shark

Hello,

I get asked how much horsepower my Vette has all the time. I alway's tell people, "I race a car not a dyno." They have got me thinking it might be nice to know what I have. I don't have the cash laying around or the time to go to a dyno. Can anyone give me an idea of how much horsepower my car has if I give you the ET/MPH/weight on my best run?


ET 11.90 @ 115.62mph
weight on that run was 3840 with me in car and half tank of fuel.

Thanks for any help.
Jeff

neoh77

http://www.speedworldmotorplex.com/calc.htm


You are making : 463 HP at the rear wheels and 547 HP at the flywheel

rough estimate of course, but a ballpark idea

Glensgages

http://www.smokemup.com/auto_math/index.php

using these calculations, 11.90 ET = 450 RWHP, while 115.62 MPH = 403 RWHP

'Generally', ET is a 'function' of applying (traction, gearing, etc.) the power you make, and MPH shows how much 'ompfff' you're making.

That's a good MPH for the ET; I raced a guy who ran 11.50s @ 115 MPH...

comp

on the links

Doug70vert

http://www.prestage.com/Car+Math/ET+...s/default.aspx

this formula calculates your engine at either

450 HP using ET and Weight
or
456 HP using MPH and Weight

Your car seems quite heavy. My 70 is only 3250 with me in the car.

regardless, that thing flys

vincevette78

Fevre

Under ET and weight it states the est is for rear wheel hp while the MPH and weight does not but both are very close. My guess for my hp was 375 and using the formulas for my mph (104) and weight (3500) is 307 which with 20% drive trains loss gives me 383 hp. I think the car weight stated above is high unless you got Oprah in the passenger seat. None the less that is a lot of hp.

Glensgages

406shark's '77 coupe has an advertised shipping weight of 3448 lbs, and if he weighs 200 lbs, that car is close to 3650, so 3800+ isn't out-of-the-question, but I agree;
that car is smokin'!!!


My '79 Z28 weighed close to 3800 lbs w/ a full tank of gas and me in it;
then, I added two 100-lb weights to the trunk, for added traction.
Still, it has trapped as fast as 109+ in the 1/4-mile...

MotorHead

If your in the 11's your making some power, I like to go to the dyno to see exactly what I have before and after mods, local dyno charges me 50 bucks for three pulls any time I want. Pretty cheap really since I am in there ofor over an hour. Some people say your dyno racing I just want to know how much power I am making and whether mods make any difference.

My car wieghs 3300 lbs with me in it (185) and 1/2 tank of gas, weighed it at a municipal dump, if yours wieghs that much time to go on a diet

To go 11.90 I need 390 RWHP

547 HP at the flywheel would be around 600 HP on an engine dyno, if that run was with mufflers, standard water pump etc. ? What are the specs on the motor ?

81ZZ4

Nice links.
I'm at 140 mph redlining 3rd which is sooooooo easy. :shocked:
Still have 4th to go
My 81 speedo only goes to 85. always wondered how fast I was going.

406shark

Thanks for the information everyone supplied.

I'm sorry...my car's weight was 3640 not 3840. Sorry for the fat fingers.

It is a pretty basic 406. It has 10.3-1 compression. Dart II Sportsman cylinder heads with minor porting. Crane cam with 238/244 @.050" and .502"/.516" with Roller rockers. Edelbrock Performer RPM Air Gap manifold. Holley 850 Double Pumper. 1 5/8" primary full length 4-1 headers. 3" exhaust with cutouts and Flowmaster 40 series Delta Flow's. Moroso 7 qt. oil pan (run with 5 qts at strip). Carter HP electric 7psi fuel pump. Moroso plastic Cool Can. Timing set at 35 degrees- all in by 3000 rpm. Pan evac system plumbed into header collector's.

Turbo 350 automatic. NO shift kit...just built right.
Torque converter that flashes at 3400 rpm.
Tranny cooler.

3.70 Richmond gears.
Rear suspension rebuilt.

P275-60-15" BFG Drag Radials mounted on spare set of Rally wheels, mainly used only at the strip. Firestone P275-60-15" for everyday use. Unless I'm in the mood to play around town. P225-70-15" on the front always.

When run at the track I uncork the headers, mount the BFG's, lower rear pressure to 23psi, raise front pressure to 40psi. Fill Cool Can with ice. Add 5 gallons of 110 octane for insurance.

I have a line-lock for burn outs.
I spin the tires enough to get them to start smoking, only at about 3500-4000 rpm, then release the brake, once she moves out of the water I nail the throttle to clean them good. Pull right to the line. Load converter at 1500 rpm to take play out of suspension and leave on the last yellow...hopefully.


Thanks again for the info.

Jeff

Glensgages

Alrighty, now.....

A 3640-lb car, running 115.62 takes 382 RWHP, and based-on 11.90 ET, you'd need 426, but even SMOKEmUP.com believes that HP/ET # is in-accurate.

Still, I'll bet it gives the ricers something to think about on the street...