Can anybody throw out some rough rear wheel horspower estimates in say a 3600 Camaro for 14.0 to 12.0 quarters in half second increments. Just looking for general ideas. I relalize that there are many more variables involved than this. Thx! Tom
Horsepower vs. 1/4 times
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bowtie1Z28
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Can anybody throw out some rough rear wheel horspower estimates in say a 3600 Camaro for 14.0 to 12.0 quarters in half second increments. Just looking for general ideas. I relalize that there are many more variables involved than this. Thx! Tom
Dont know about rwhp, but my friends 70 chevelle is 3600+lbs and runs 12.0@112 with a 406 engine that dynoed at 440hp/500tq. Now in the car you have to figure it lows about 40hp or so, because of water pump, alt. and exhaust. So it takes about 400hp for you average 3600+lbs streetcar to go 12.0s, and with a 18% drivetrain loss that would be around 328+/-rwhp for a 12.0 car. A really well setup car (racecar) can do it with less hp.
Hope that gives you a ball park on a 12.0 car
Hope that gives you a ball park on a 12.0 car
When my wifes camaro had 325 rwhp it only ran high 12's, she now has 425 rwhp and runs high 11's at our altitude. I run 12.0's with my chevelle, never dynoed it but I have the same setup in mine as my wifes. So, I would have to dissagree with the 325rwhp for 12.0's at 112. I've seen some 12.0 cars here that run 107-109MPH that has lower HP but a lighter/better hooking car then ours. I'm thinking the 440HP you quoted was rwhp not flywheel HP.
Lee
Lee
Nope, 440hp was right off the dyno, before the engine went in the car. And I used 18% loss, because I hear thats about right for an automatic.
So no I dont really know what the thing makes at the wheels, but we know what the engine makes, and from that there are plenty of formulas to figure out what it should run, and its actually pretty close. Formulas say it takes about 390hp to run 12.0s - and like I said it probably makes around 400 in the car. So it all adds up.
![Image]()
So no I dont really know what the thing makes at the wheels, but we know what the engine makes, and from that there are plenty of formulas to figure out what it should run, and its actually pretty close. Formulas say it takes about 390hp to run 12.0s - and like I said it probably makes around 400 in the car. So it all adds up.
67RS - I have this little program that I've used for years and with accurate data it's really accurate. With out all the detail I plugged in 3600 pounds, 3.73 gears, 28" slicks, good traction, 3500 Stall and it computes et to be 13.27 and the rwhp of 300. If the gears and stall was optimized it would run 12.88. 440 rwhp gives me 11.88.
If I put in 112MPH with the same data as above it gives me 391 rwhp and et's at 12.13, with optimized gears(4.10) and stall(4000) it would be 11.94
If I put the data in for my wifes camaro it computes to 11.78 with 412rwhp with 11.63 being ideal. It so happens that she runs 11.7's 90% of the time and her best at our altitude was 11.62! Her rwhp at the dyno was 425!
Dont get me wrong, I'm not wanting a shouting match! I just know what it takes for my chevelle and camaro to run what they do and it doest seem possible to run 12.0's with 328 rwhp in a 3600 pound car, if so, I'm really screwed up with my two cars and there is a lot of et left on the table somewhere that I would love to have!
Lee
If I put in 112MPH with the same data as above it gives me 391 rwhp and et's at 12.13, with optimized gears(4.10) and stall(4000) it would be 11.94
If I put the data in for my wifes camaro it computes to 11.78 with 412rwhp with 11.63 being ideal. It so happens that she runs 11.7's 90% of the time and her best at our altitude was 11.62! Her rwhp at the dyno was 425!
Dont get me wrong, I'm not wanting a shouting match! I just know what it takes for my chevelle and camaro to run what they do and it doest seem possible to run 12.0's with 328 rwhp in a 3600 pound car, if so, I'm really screwed up with my two cars and there is a lot of et left on the table somewhere that I would love to have!
Lee
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MY 67 Chevelle with the old 10:1 355 ran 11.80's@113-114 and low 7.50's@91. Took it to the chasis dyno expecting to see ~350rwhp and got 315rwhp.Race weight was usually between 3350 and 3400 depending on how much gas was in the tank. Don't put much faith in the computer simulations. JMHO
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The most accurate hp calc's don't use et they use mph in the traps. The calc on www.smokmup.com is known to be fairly accurate. A 3600 lb car using 20% loss looks like this;
100 mph = Rear Wheel HP - 244.4 Crankshaft HP - 305.5
110 mph = Rear Wheel HP - 325.4 Crankshaft HP - 406.8
120 mph = Rear Wheel HP - 422.4 Crankshaft HP - 528
130 mph = Rear Wheel HP - 537 Crankshaft HP - 671.3
100 mph = Rear Wheel HP - 244.4 Crankshaft HP - 305.5
110 mph = Rear Wheel HP - 325.4 Crankshaft HP - 406.8
120 mph = Rear Wheel HP - 422.4 Crankshaft HP - 528
130 mph = Rear Wheel HP - 537 Crankshaft HP - 671.3
John, I'm not putting faith in computer programs, I have tons of data and pratical hands on experience. The program figured that you needed 350 rwhp to do that. What comes to mind is the day you dynoed the weather conditions were different, dyno calibration off, correction factor off, etc. I have dynoed at different days and seen ~15 rwhp different yet my track times are very very consistent.
Lee
Lee
I'm not saying to use these formulas or anything but I read this in a magazine.
Theoretical E.T.=[(weight/hp)^(1/3)]*5.825
Theoretical MPH =[(hp/weight)^(1/3)]*234
The article didn't say if it was crankshaft hp or rwhp. It must be rwhp, because realistically there's no way a 3600# car with 400 crank hp can run a 12.12@112.5. Unless it has the perfect gear/stall/traction...and the aerodynamics of an F-16. Okay maybe it could be crank hp...I don't know. Anyway these are some cheezy formulas for you to play around with.
![Image]()
Theoretical E.T.=[(weight/hp)^(1/3)]*5.825
Theoretical MPH =[(hp/weight)^(1/3)]*234
The article didn't say if it was crankshaft hp or rwhp. It must be rwhp, because realistically there's no way a 3600# car with 400 crank hp can run a 12.12@112.5. Unless it has the perfect gear/stall/traction...and the aerodynamics of an F-16. Okay maybe it could be crank hp...I don't know. Anyway these are some cheezy formulas for you to play around with.
So much of it is in chassis and hooking up. My friends Saleen ran 12.5 something and it only put out maybe 290rwhp max at the dyno, the car is more around 3000lbs but still it is an example of less hp turning a good time. The car pulls both tires off the line an inch or 2 on the launch.
net engine HP numbers
HP calc
http://www.dsm.org/tools/calchp.htm
hp = weight * (speed / 234)3
hp = ((speed * .00426)3)* weight
This method uses the weight of the car and the time it took that
car to travel 1320 feet (¼ mile).
The formula is: hp = weight / (ET / 5.825)3
12-1 lbs per hp
13.34 sec @ 102.25 mph
(12.6 @ 102.8 w/moroso power speed calc)
11-1 lbs per hp
12.95 sec @ 105.1 mph using both formulas above
(12.3 @ 105.6 w/moroso power speed calc)
10-1 lbs per hp
12.55 sec @ 108.5 mph using both formulas above
(11.95 @ 109 w/moroso power speed calc)
9-1 lbs per hp
12.1 sec @ 112.5 mph using both formulas above
(11.6 @ 113 w/moroso power speed calc)
8-1 lbs per hp
11.64 sec @ 117.1 mph using both formulas above
(11.2 @ 117.5 w/moroso power speed calc)
7.5-1 lbs per hp
119.9 - 430 hp using 1st formula
119.9 - 426 hp using 2nd formula
11.4 - 426.8 hp using et formula
(11.0 @ 120 w/moroso power speed calc)
7-1 lbs per hp
11,15 sec @ 122.4 mph using both formulas above
(10.75 @ 122 w/moroso power speed calc)
6.5-1 lbs per hp
10.87 sec @ 125.4 mph using both formulas above
Moroso Power Speed Calc uses 235
HP calc
http://www.dsm.org/tools/calchp.htm
hp = weight * (speed / 234)3
hp = ((speed * .00426)3)* weight
This method uses the weight of the car and the time it took that
car to travel 1320 feet (¼ mile).
The formula is: hp = weight / (ET / 5.825)3
12-1 lbs per hp
13.34 sec @ 102.25 mph
(12.6 @ 102.8 w/moroso power speed calc)
11-1 lbs per hp
12.95 sec @ 105.1 mph using both formulas above
(12.3 @ 105.6 w/moroso power speed calc)
10-1 lbs per hp
12.55 sec @ 108.5 mph using both formulas above
(11.95 @ 109 w/moroso power speed calc)
9-1 lbs per hp
12.1 sec @ 112.5 mph using both formulas above
(11.6 @ 113 w/moroso power speed calc)
8-1 lbs per hp
11.64 sec @ 117.1 mph using both formulas above
(11.2 @ 117.5 w/moroso power speed calc)
7.5-1 lbs per hp
119.9 - 430 hp using 1st formula
119.9 - 426 hp using 2nd formula
11.4 - 426.8 hp using et formula
(11.0 @ 120 w/moroso power speed calc)
7-1 lbs per hp
11,15 sec @ 122.4 mph using both formulas above
(10.75 @ 122 w/moroso power speed calc)
6.5-1 lbs per hp
10.87 sec @ 125.4 mph using both formulas above
Moroso Power Speed Calc uses 235
Thanks John for backin me up. Like I said I dont know what it makes at the wheels?
All we know is the 406 makes 440hp on the dyno, so I'm just assuming a 18% loss.
Also there are class cars makin 532hp(flywheel) from a 350 that run 9.90s in a 3150lbs
(67camaro), if you take 532 and X it by .82 (18% loss) you get = 436rwhp, for a 9sec car.
So it all depends how efficient a car you've got. Johns chevelle is a good example, and so
is my friend 70 chevelle with the 406 - both run good for mild small blocks, and are set up
well. Most street cars arnt set up well anyway.
It usually takes way less hp to go fast then you think. I have seen cars makin 600+ rwhp
and cant run low 10s@130+, when my 67 makes that at the flywheel and does.
And dont forget all the exaggerated dynos out there too!
All we know is the 406 makes 440hp on the dyno, so I'm just assuming a 18% loss.
Also there are class cars makin 532hp(flywheel) from a 350 that run 9.90s in a 3150lbs
(67camaro), if you take 532 and X it by .82 (18% loss) you get = 436rwhp, for a 9sec car.
So it all depends how efficient a car you've got. Johns chevelle is a good example, and so
is my friend 70 chevelle with the 406 - both run good for mild small blocks, and are set up
well. Most street cars arnt set up well anyway.
It usually takes way less hp to go fast then you think. I have seen cars makin 600+ rwhp
and cant run low 10s@130+, when my 67 makes that at the flywheel and does.
And dont forget all the exaggerated dynos out there too!
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Thx!! That is some great info and I need to go and check out some of the links you guys posted!!!
Tom
Tom
Dang, I need to find out where that extra 100 rwhp is going on our cars!
I'm going to the dyno today with my friends 32 coupe that runs 9.0's, he's trying to get into the eights with his 3300 pound car. We know the exact weight of the vehicle, qtr mile times and now when we get the dyno numbers I'll see how they compare.
You guys need to help me find where the HP is going...seriously.
Lee
I'm going to the dyno today with my friends 32 coupe that runs 9.0's, he's trying to get into the eights with his 3300 pound car. We know the exact weight of the vehicle, qtr mile times and now when we get the dyno numbers I'll see how they compare.
You guys need to help me find where the HP is going...seriously.
Lee
Here's another example I just thought of - my buddy's "furd mustang"
![Image]()
He dynos his at the wheels, 347 - it made around 400rwhp, the car
is 3250lbs and ran a best of 11.36@121, (with that mph it should go 11.0s)
so even if we added 400lbs to the car it would still run about 11.7x's@117.
So its makin around 475hp+/- @ flywheel.
Still trying to talk him into putting a real motor in it - a SB chevy, like all the fast mustangs in Houston
He dynos his at the wheels, 347 - it made around 400rwhp, the car
is 3250lbs and ran a best of 11.36@121, (with that mph it should go 11.0s)
so even if we added 400lbs to the car it would still run about 11.7x's@117.
So its makin around 475hp+/- @ flywheel.
Still trying to talk him into putting a real motor in it - a SB chevy, like all the fast mustangs in Houston
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