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Edumacate me on HP Calculators #2834913
10/20/20 08:15 AM
10/20/20 08:15 AM
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Posts: 11,197
Taxes & Virus's R-US, NY
Dragula Offline OP
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Dragula  Offline OP
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I am a little confused by the HP estimates of my car depending which one I use.

If I put in my ET and weight with me in the car, I get like 628hp, I change it around and put in weight and hp to calc ET and I get like 780 at the flywheel...Who uses what, and what am I doing wrong?

Car with me in it is 3000lbs, and best 1/8th mile ET is 6.00 at 114.5mph.....Best actual 1/4 is only 9.66 with a 6.15 in the 1/8.....earlier in the season. Trying to figure out what the 6.0 is for HP


'71 Duster 400/512
https://www.youtube.com/watch?v=Znuo3jMUXTk (6.00 at 114.05mph)
https://www.youtube.com/watch?v=Y9hxSMAWoII (9.66 at 139mph)

'70 Cuda, Plan C....605 Hemi Street Car
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph)(823hp and still tuning)
https://www.youtube.com/watch?v=3zQEb9uxFng
https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)
Re: Edumacate me on HP Calculators [Re: Dragula] #2834935
10/20/20 09:18 AM
10/20/20 09:18 AM
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UK
rb446 Offline
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I use these 3 now, always used just the 1st one primarily which has worked out very close always>

http://www.wallaceracing.com/accel-calc.php >>... play with the hp no. to get your slip results, take note of deficiencies/gains at certain parameters. Generally this calc shows 1+mph to what my cars and our current car have run but thats down to the 60's of course.

>3000lb/input 688fwhp>

60 Foot E.T. : 1.32
1/8 Mile E.T. : 6.00
1/8 Mile Trap Speed : 113.20
1/4 Mile E.T. : 9.52
1/4 Mile Trap Speed : 141


http://www.wallaceracing.com/et-correction-eighth.php multiply hp shown x C/factor given

http://www.wallaceracing.com/et-correction.php

Fast uses the Moroso ruler which is as good if not better

Last edited by rb446; 10/20/20 09:29 AM.

1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: Edumacate me on HP Calculators [Re: rb446] #2834944
10/20/20 09:34 AM
10/20/20 09:34 AM
Joined: May 2004
Posts: 11,197
Taxes & Virus's R-US, NY
Dragula Offline OP
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Dragula  Offline OP
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Well, when I plug in my info it tells me 625hp....lol


'71 Duster 400/512
https://www.youtube.com/watch?v=Znuo3jMUXTk (6.00 at 114.05mph)
https://www.youtube.com/watch?v=Y9hxSMAWoII (9.66 at 139mph)

'70 Cuda, Plan C....605 Hemi Street Car
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph)(823hp and still tuning)
https://www.youtube.com/watch?v=3zQEb9uxFng
https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)
Re: Edumacate me on HP Calculators [Re: Dragula] #2834952
10/20/20 09:49 AM
10/20/20 09:49 AM
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Portage,michigan
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B3422W5 Offline
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Originally Posted by Dragula
I am a little confused by the HP estimates of my car depending which one I use.

If I put in my ET and weight with me in the car, I get like 628hp, I change it around and put in weight and hp to calc ET and I get like 780 at the flywheel...Who uses what, and what am I doing wrong?

Car with me in it is 3000lbs, and best 1/8th mile ET is 6.00 at 114.5mph.....Best actual 1/4 is only 9.66 with a 6.15 in the 1/8.....earlier in the season. Trying to figure out what the 6.0 is for HP


For comparison sake, the guy who bought my old car went 9.62@ 140. Car weight with him was 3220.
It made 708 on the dyno when Best Machine did it. That time was on super stock springs, so pretty crude suspension.
Figure 220 pounds less weight, about the same mph, probably an honest 660 ish horse
When i had the car( few less go fast goodies) went 135@ 3350. Back then several guys had a thread on here, they were checking ET/ MPH against Moroso calculator
That 135@3350 was 640 ish.
Again, your weight, likely somewhere right between 640 and 700ish

Last edited by B3422W5; 10/20/20 09:51 AM.

69 Dart GTS, performance upgrades in progress
11.26@ 118.40 best so far. Stock 360 shortblock with eddie heads.
3310 race weight
Re: Edumacate me on HP Calculators [Re: B3422W5] #2834970
10/20/20 10:28 AM
10/20/20 10:28 AM
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Las Vegas
Al_Alguire Offline
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MPH and weight will give you the answer to what HP you REALLY make. Its math and physics. How much HP does it take to move a given weight in a given time frame.

HP = (MPH ÷ 234)³ × Weight

Re: Edumacate me on HP Calculators [Re: Al_Alguire] #2834991
10/20/20 11:00 AM
10/20/20 11:00 AM
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Posts: 13,295
So. Burlington, Vt.
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fast68plymouth Offline
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When my friend went from an auto trans to a manual in his GTO stocker it picked up about 5mph in the 1/4, which shows an almost 60hp gain in a trans swap.

One takeaway there is........ the calculator results will only be as good as what the weak link in your combo is.

His current Firebird Stocker will outrun the calculators in any kind of normal air.

When you really want to know how much power your motor makes, you bring it to a reputable dyno service.
If the car doesn’t run what it should, based on the power numbers....... start working on the car, and leave the motor alone.

Quote
HP = (MPH ÷ 234)³ × Weight


That works out fairly close for speed compared to the Moroso chart.

A couple months ago a friend of mine bought a used bracket race engine.
Brought it to the dyno, it made 728hp.
A couple of weeks ago at LVD it went 9.10@145.88 at 2915lbs.
On the Moroso chart the ET shows 734hp, MPH shows 695hp.

If I use the above formula for speed it works out to 706hp.



68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Edumacate me on HP Calculators [Re: fast68plymouth] #2835045
10/20/20 12:33 PM
10/20/20 12:33 PM
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UK
rb446 Offline
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Using our cars details, 3800lb etc. our best et of 10.35@127+, we have run 130 once and some 128+'s.... 1.43>44 60ft's....the motor dyno'd@695hp@EDA

entering all our info into 1/4m correction calc
Your HP is 642.90 from your ET
Your HP is 578.05 from your MPH
Your HP Correction Factor is 1.05
Your Grains of water is 85.52
Your DA (Density Altitude) is 1,560 feet
Your DA (Density Altitude) is 476 meters
642.90x1.05 = 675hp.

Go to the http://www.wallaceracing.com/accel-calc.php calc enter 675hp/3800lbs you get>
60 Foot E.T. : 1.44
1/8 Mile E.T. : 6.54
1/8 Mile Trap Speed : 103.96
1/4 Mile E.T. : 10.36
1/4 Mile Trap Speed : 129
and we run with full exhausts, how much hp is lost there against the dyno's open hdr system

you should be able to do exactly the same thing with your car/parameters and get similar results.

Last edited by rb446; 10/20/20 12:53 PM.

1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987
Re: Edumacate me on HP Calculators [Re: rb446] #2835102
10/20/20 01:55 PM
10/20/20 01:55 PM
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Fulton County, PA
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CMcAllister Offline
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My Moroso dream wheel says 9.65 @ 3000 is 620 and should going 139.

1/4 mile MPH is a better number to use. If you MPH is much more, or less, than 139-140, you are missing something depending on which way it's off.

Trans, rear, converter can easily eat up 15-20%, depending on how good or bad they are.

Last edited by CMcAllister; 10/20/20 01:58 PM.

If the results don't match the theory, change the theory.
Re: Edumacate me on HP Calculators [Re: Dragula] #2835107
10/20/20 02:19 PM
10/20/20 02:19 PM
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Prospect, PA
BSB67 Offline
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Manual transmissions will mph better than automatics. Some TQs will eat more power than others. There used to be calculators that you needed to input the tranny type.

MPH is generally a better hp indicator than et, as et is also impacted by all the variables in the suspension, a lot.

The actual mph used in a calculator needs to be adjusted to standard conditions for comparison to dyno numbers.

The mph in calculators is net not gross like an engine dyno. Some adjust needs to be made there as well. The difference could be nearly zero in a race car, but sizable in a street car with exhaust and mufflers, water pump, fan, alternator, power steering pump air cleaner....

Re: Edumacate me on HP Calculators [Re: BSB67] #2835116
10/20/20 02:32 PM
10/20/20 02:32 PM
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fast68plymouth Offline
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The fact is, as converter, clutch, suspension, and tire technology has improved over the years....... if you make use of more of those technological advances....... you car can be quicker and faster at the same weight and power/weight ratio than it would have been 20-30 years ago.

Yet, the Moroso calculator has remained unchanged since its inception.

However, I still like to use it, along with good dyno data to determine if the combo is at least close to running up to its potential.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Edumacate me on HP Calculators [Re: fast68plymouth] #2835127
10/20/20 02:47 PM
10/20/20 02:47 PM
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AndyF Offline
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Very true. The NHRA guys running super lightweight 904 transmissions and 12 bolt drop out sections put up much better numbers than the bracket guys with stock 727 internals and truck rearends.

Re: Edumacate me on HP Calculators [Re: AndyF] #2835132
10/20/20 02:54 PM
10/20/20 02:54 PM
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fast68plymouth Offline
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In good air, but certainly not at all “mineshaft” air my friends Stocker will outrun the Moroso chart by about 10% on both ET and MPH.

In Vegas the numbers show within a few % of the STP dyno numbers, and that’s a track where his index is adjusted up by .19 in ET.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Edumacate me on HP Calculators [Re: fast68plymouth] #2835147
10/20/20 03:26 PM
10/20/20 03:26 PM
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Sure. The calculators are emperically derived. They are not based on a black and white physics analysis. Transmission and TQ are the best examples. Efficiency changes matter, e.g. more time in the peak power band, more gears, lighter weight spinning internals......equate to more average power to the tire and faster and quicker car without more power under the hood. Change the weight of the tires/wheels will change et and mph, possibly in opposite directions.

My point is, lots of variables, and even if you attempt to account for them, it's still an estimate. The calculators are tools, just understand their limitations, and why.

Re: Edumacate me on HP Calculators [Re: BSB67] #2835158
10/20/20 03:54 PM
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fast68plymouth Offline
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Quote
lots of variables, and even if you attempt to account for them, it's still an estimate.


Exactly.

If you play around with the numbers enough, in a few different calculators you can often come up with a set of numbers that make you feel okay about your combo...... as long as it’s at least somewhat “close”.

But....... if you’re trying to actually improve the performance of the car...... someone is going to have to get out there and work on it smoke


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Edumacate me on HP Calculators [Re: fast68plymouth] #2835161
10/20/20 03:59 PM
10/20/20 03:59 PM
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I'm not sure about them.

2950# and 162 MPH gave me a crazy number that mopars can't make







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