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wheel horsepower vs. ET #2005331
02/04/16 04:43 AM
02/04/16 04:43 AM
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cincinnati ohio
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mcat4321 Offline OP
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what ET did your wheel HP get you, and at what weight?

Re: wheel horsepower vs. ET [Re: mcat4321] #2005332
02/04/16 04:50 AM
02/04/16 04:50 AM
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Bend,OR USA
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Cab_Burge Offline
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560 RWHP in a 3450 lb Duster wth driver through the full 3.0 exhaust system ran mid tens at 180 ft above sea level in decent summer weather at Woodburn, OR. Density altitude varied between 750 to 1500 Ft. morning to afternoon. That motor made over 700 HP on a engine dyno at 2500 ft altitude, lots of ways to slow street and strip cars down work shruggy

Last edited by Cab_Burge; 02/04/16 04:50 AM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: wheel horsepower vs. ET [Re: mcat4321] #2005345
02/04/16 08:48 AM
02/04/16 08:48 AM
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Chandler, AZ
Duner Offline
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I have dyno charts showing RWHP - but the numbers are overly optimistic / false when compared to actual timeslips. Since all dynos are different, I assume the one I was on would be considered "happy" or "not stingy". LOL It worked well for a tuning tool, but that's about it.

With that said:
705rwhp only produced 10.51 @ 130.13 mph at 4190# in my truck.

Last edited by Duner; 02/04/16 08:49 AM.
Re: wheel horsepower vs. ET [Re: Duner] #2005351
02/04/16 09:16 AM
02/04/16 09:16 AM
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Hot Rod Ridge
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Originally Posted By Duner
I have dyno charts showing RWHP - but the numbers are overly optimistic / false when compared to actual timeslips. Since all dynos are different, I assume the one I was on would be considered "happy" or "not stingy". LOL It worked well for a tuning tool, but that's about it.

With that said:
705rwhp only produced 10.51 @ 130.13 mph at 4190# in my truck.



Wallace racing calculators say you make 711 HP at 130mph and 4200 pounds

Re: wheel horsepower vs. ET [Re: mcat4321] #2005353
02/04/16 09:29 AM
02/04/16 09:29 AM
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UK
rb446 Offline
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This one says something different

http://www.wallaceracing.com/hpcalculatorquarter.php

Your HP computed from your vehicle ET is 643.53 rear wheel HP and 715.04 flywheel HP.
Your HP computed from your vehicle MPH is 665.06 rear wheel HP and 738.95 flywheel HP.

I always used this one for all my calcs for the race cars I ran, always came out spot on but was fly HP...

http://www.wallaceracing.com/accel-calc.php


1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: wheel horsepower vs. ET [Re: mcat4321] #2005364
02/04/16 10:02 AM
02/04/16 10:02 AM
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Hot Rod Ridge
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ET has little to do with HP and everything to do with putting the power to the ground.

Re: wheel horsepower vs. ET [Re: mcat4321] #2005366
02/04/16 10:11 AM
02/04/16 10:11 AM
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UK
rb446 Offline
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Yes I know that thanks, thats why I always used the 2nd Wallace link I gave and just input weight and change hp figs till you get the ET/mph you actually ran, but that is fly hp. Its only a guide but as said it came out spot on with actual numbers I ran and fellow racers cars I knew ran even on the short times.

example>
'69 Cuda in sig. 3000lbs/600hp/32" tyre/4.88's>
60 Foot E.T. : 1.38
1/8 Mile E.T. : 6.28
1/8 Mile Trap Speed : 108.15
1/4 Mile E.T. : 9.96
1/4 Mile Trap Speed : 135
1/4 Mile Trap RPM : 6,899

my 60 was 1.388 and trap rpm was 7200 with vert slip

Last edited by rb446; 02/04/16 10:23 AM.

1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: wheel horsepower vs. ET [Re: FastmOp] #2005370
02/04/16 10:42 AM
02/04/16 10:42 AM
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usa
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lewtot184 Offline
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Originally Posted By FastmOp
ET has little to do with HP and everything to do with putting the power to the ground.

this. if your looking at horsepower then look for mph.

Re: wheel horsepower vs. ET [Re: mcat4321] #2005372
02/04/16 10:46 AM
02/04/16 10:46 AM
Joined: Oct 2015
Posts: 561
UK
rb446 Offline
mopar
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UK
thats exactly what I just said wasn't it.


1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: wheel horsepower vs. ET [Re: lewtot184] #2005377
02/04/16 10:53 AM
02/04/16 10:53 AM
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Val-haul-ass... eventually
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BradH Offline
Taking time off to work on my car
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Originally Posted By lewtot184
if your looking at horsepower then look for mph.

+1.

The Moroso HP calculator is supposedly based on RWHP... Then again, the results it gives aren't far off from the crankshaft HP #s seen from the Superflow engine dyno that Porter Racing Heads uses.

I did one chassis dyno session years ago w/ my 4-spd A12 RR and the results were around 290 HP for a 3800#(+?) car & driver combination that ran about 110 MPH at the same event.

On the other hand, the engine HP for my Challenger on PRH's engine dyno was about 610 for a combination that ran 10.5s at 126 MPH at 3755#, after the full exhaust and engine accessories were bolted on.

Let me know if you can make sense of it all.

Re: wheel horsepower vs. ET [Re: mcat4321] #2005379
02/04/16 10:57 AM
02/04/16 10:57 AM
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UK
rb446 Offline
mopar
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UK
610fly hp@3755lbs = 10.67@126 according to my numbers

60 Foot E.T. : 1.48
1/8 Mile E.T. : 6.74
1/8 Mile Trap Speed : 100.91
1/4 Mile E.T. : 10.67
1/4 Mile Trap Speed : 126

just use this link, input your weight, if you know what the car ran change the hp numbers till you get as close as you can to those numbers and there's your fly HP

http://www.wallaceracing.com/accel-calc.php

Last edited by rb446; 02/04/16 11:03 AM.

1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: wheel horsepower vs. ET [Re: rb446] #2005381
02/04/16 11:02 AM
02/04/16 11:02 AM
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Posts: 15,439
Val-haul-ass... eventually
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BradH Offline
Taking time off to work on my car
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Originally Posted By rb446
610fly hp@3755lbs = 10.67@126 according to my numbers

60 Foot E.T. : 1.48
1/8 Mile E.T. : 6.74
1/8 Mile Trap Speed : 100.91
1/4 Mile E.T. : 10.67
1/4 Mile Trap Speed : 126

Pretty close... my 60-fts were in the 1.45s and my 1/8 mile MPHs was a tad higher, which helped chisel the 1/4 mile ET down about a tenth from your #s.

Re: wheel horsepower vs. ET [Re: mcat4321] #2005382
02/04/16 11:08 AM
02/04/16 11:08 AM
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UK
rb446 Offline
mopar
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UK
Yeah, I've been using this method for ages and it always gives the right numbers, on all my cars and and all others I've tried, but really its a way of finding the HP your making against your weight if you have your timeslips, the gearing tyre part is useful as well....quite simple really.

However this doesn't answer the ops question re RWHP.........

Last edited by rb446; 02/04/16 11:37 AM.

1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: wheel horsepower vs. ET [Re: rb446] #2005421
02/04/16 12:30 PM
02/04/16 12:30 PM
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oregon
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greendart408 Offline
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I tuned my car on a load cell chassis dyno multiple times, I made 588 rwhp, and at 3090lbs I went 9.55@139.99 with my w5 combo and a 727. The dyno I use imop is very close, track time proven.

Re: wheel horsepower vs. ET [Re: mcat4321] #2005563
02/04/16 04:55 PM
02/04/16 04:55 PM
Joined: Oct 2015
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UK
rb446 Offline
mopar
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UK
Yep thats 694Flyhp to get your numbers which is an 18% loss at 588....sounds about right, losses differ from car to car of course.

Last edited by rb446; 02/04/16 04:58 PM.

1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: wheel horsepower vs. ET [Re: rb446] #2005610
02/04/16 06:30 PM
02/04/16 06:30 PM
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Weddington, N.C.
Streetwize Offline
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The only thing about the 1/4 mile equation (if I remember right) is it's also based on a 'fixed' (assumed 'constant') .50 drag coefficient...(and, interestingly enough .50 c/d seems to be more or less average for a mid size late 60's early 70's car)

So, a theoretical 1968 and a 2002 Camaro at the same weight running the same ET and MPH (lets say 3000 pounds and 11 flat at 120 mph) might have the same "theoretical" RWHP and FWHP, but since the 68 Camaro has a c/d of ~.50 and the 2002 is only about .29, the 68 likely needs another 35 or so HP to push through the wind on the big end.

There is a frontal area 'compensation i.e. (< or >.50)factor' I found once on the internet, it may even be in the Wallace charts.


Last edited by Streetwize; 02/04/16 06:32 PM.

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Re: wheel horsepower vs. ET [Re: Streetwize] #2005652
02/04/16 07:37 PM
02/04/16 07:37 PM
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Posts: 1,969
Chandler, AZ
Duner Offline
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Sometimes the aero has more to do with mph numbers than we think.

On the calculators - I gained 40 hp by removing the spoiler off the back of my truck! I know. Trucks are supposed to have bad aero, but I'm TRYING to make it better.

Obviously I didn't GAIN horsepower, but I did gain MPH. In back to back runs the truck went 10.58@128 mph. Then I removed the spoiler and it went 10.51@130 mph twice back to back. So I put the spoiler back on and it went 10.55 @ 128 and change in slightly cooler temps than the first runs. I no longer run what I thought was a cool looking spoiler. It can't stay if it slows me down.

I previously had the truck lower to the ground by 2 inches with a different suspension setup and it didn't 60' very well like that... but it went 10.68@133.65 mph! So the aero plays a bigger part than I've read about for sure. I'm still working to get the truck low again - but 60' like it's supposed to.... then it SHOULD (coulda,woulda,shoulda) be faster and quicker! LOL

Too bad those calculators don't have any provisions for crummy aero.

Re: wheel horsepower vs. ET [Re: mcat4321] #2005726
02/04/16 09:36 PM
02/04/16 09:36 PM
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Pattison Texas
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this has a mph vs drag & hp

RB racing


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392

Re: wheel horsepower vs. ET [Re: mcat4321] #2005729
02/04/16 09:43 PM
02/04/16 09:43 PM
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Pattison Texas
csk Offline
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1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392

Re: wheel horsepower vs. ET [Re: mcat4321] #2005741
02/04/16 09:49 PM
02/04/16 09:49 PM
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Nebraska
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Is there one that calculates for elevation?


Mopar to the bone!!!
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