Allrighty then!

My question to the “dyno numbers are the only ones that matter” crowd is this…. Which dyno? A Dynojet? A high reading Mustang dyno? A low reading Mustang Dyno? All three of these options will give me different numbers. Varying from 280 on a stock EVO X on TTP’s Mustang dyno:

https://www.evolutionm.net/forums/ev...one-stock.html

down to 211 on a stock EVO X on Buschur Racings Mustang dyno:

http://buschurforums.com/forum/showthread.php?t=21422

A 69 wheel HP difference on bone stock EVO X’s.

If you take an EVO to three different drag strips under the same weather conditions you will have very close to the same trap speed at each drag strip.

Now, lets go through the arguments against using drag strip numbers to estimate HP…

1. Track conditions make a huge difference in times! OMG!
Yup, your ET is affected a huge amount by traction conditions at the launch area of a drag strip… this has very little effect on trap speed. Any problems will give you a LOWER estimated HP reading.

2. Driver skill makes a huge difference in time AND trap speed! OMG!
Yup, bad launch will kill your ET and bad shifting can kill your trap speed… both of witch give you a LOWER estimated HP reading. In addition, using an EVO MR or Ralliart, much of the possible driver error is taken out of the process.

3. There is no correction factor used in this formula for standard temperature and pressure! OMG!

True, and this can lead to a higher or lower HP reading depending on track conditions… the person using these formulas should report altitude and temperature at minimum so concerned parties can factor this in… Also, at least one dyno operator I know of uses no correction factors on his dyno. Using the simple HP calculator and not using correction factors shows how much HP you made that day under those conditions, and is comparable to HP numbers obtained at the same track under similar weather conditions. My track is at 600 ft above sea level, and I reported temperatures with every post about my drag strip times.

4. Weight of the car makes a huge difference in HP numbers! OMG!

True. My vehicle weight is based on real world numbers obtained at a truck scale with a +/- 20 lb accuracy…. Not some numbers I pulled out of my @ss or from a magazine article. I even reduce the weight put into the calculations (thus reducing estimated HP) based on fuel level… not 100% accurate, but more accurate than the +/- 20 lbs I got on the initial vehicle weight from the truck scales.

I used my drag strip times and more accurately my trap speeds obtained at the drag strip to show how much improvement my car made between bone stock and in it’s current configuration, not to make wild claims about mega HP with minimal mods. The weather conditions for power productions were BETTER on my trip to the track stock (low 40’s temperature) than they were my last trip to the drag strip (high 50’s temperature).

I put a disclaimer in my original post about how these drag strip obtained numbers were not for comparison to any dyno, they were just for comparison of the same car at the same drag strip…. and I immediately started taking $hit for not using a dyno to get “real” numbers. When I pointed out my disclaimer the reaction was “oh, so you admit it… why did you post up this bogus information” <----this is the attitude and gist of the post, not the actual wording.

The simple HP calculator uses mathmatical formulas like are used for an inertial dyno. Accelerating a given weight to a given speed in a given amount of time using the vehicle being accelerated as the mass instead of a heavy roller. If you have accurate inputs (vehicle weight and trap speed) you get REPEATABLE results that are great for comparisons using the SAME METHOD… not for comparisons to somebody’s dyno numbers.

Also, <not trying to contradict my statement in red above... but here goes anyway > when dyno numbers from another car with an almost identical setup and virtually the same drag strip results are brought into the thread showing a 90 WHEEL HP gain, that information is ignored and I am repeatedly told that it is impossible to have made a 71 CRANK HP gain on my car with this setup. I am NOT saying my car would make the same HP on that dyno just because it has the same setup and ran the same trap speeds at the drag strip... just saying that if someone makes a claim of 90 wheel HP gains with the setup and nobody throws the BS flag, why is the BS flag being pulled on me for a claimed 71 crank hp gain on this setup?

After reading this post, re-read my original thread. Am I being deceptive in anything I said in my original thread? Nope. Am I trying to pass off drag strip numbers as dyno numbers? Nope. Am I showing my vehicles HP gain between when it was stock and as it sits in my driveway now? Yup, you got it. i take pride in the increased performance of my car, and resent having someone try and drag me down.


Draw your own conclusions.

Keith

 

In answer to #4, I don't think weight affects HP. It affects your trap speed, acceleration, time, etc., but horsepower could be estimated using weight as one of the variables in the equation.

In answer to what I believe your comments address: I feel that you are damned if you do and damned if you don't. If you post dyno numbers, someone will question their validity. Just search around these forums and you'll see what I mean. If you don't post your dyno numbers, then people will question the validity of your findings.

If we all just agree that you are estimating your gains after modifications and leave it at that, I think we will all be fine. Too many people either a) believe what is posted on the forums is gospel or b) believe that everyone is ignorant enough to believe a and as such need to be protected from this evildoer out to pray on the innocent.

Regardless, I say keep up with what you are doing. I find your posts thought provoking, if not directly informative, and I think you've added greatly to the community. So thanks.

BTW, if I remember my high school physics, the equation for determining force is F = MA. Off to do some quick estimates...

 

You are 100% correct, weight does not affect HP... it affects the ESTIMATE of HP calculated by this particular program. If you tell the simple HP calculator web site ( http://www.dsm.org/tools/calchp.htm) that your car weighs 5000 lbs instead of 3685 lbs and that you run a 13.2791 @ 103.90 you get very different results.

The correct weight yields estimate of 311crank HP by the ET method and 323 crank HP by the trap speed method.

Using the 5000 lb weight yields estimates of 422 crank HP by the ET method and 438 crank HP by the trap speed method.... so knowing the true weight of your car (with driver) is very important to these calculations.

Keith

 

keith,

I see your enthusiasm and i enjoy seeing new members on the forums who are involved and want to make it better, so congrats.

With that said, i think that posting these numbers, which the self contradictions that have followed hasnt made for a good thread.

There is no way, program or not, that you can accurately tell a power number based off your trap and eta. As many have said, weight, wind, humidity, temp, altitude, fuel, driver error, knock, you name it, it can all factor into the outcome, which simply makes this methodology silly at best.

Also, the dyno question is stupid as well. Go stock, then go back when your done tuning, get your gains, and be happy. IF you want a higher reading to make yourself feel better, be our guest dude, lots of people on the site have done it as there are a few vendors selling hopes and dreams. But if you want legitimacy and knowing what you really have, then base your current dyno numbers off one of 2 things. 1. your baseline or 2. a baseline of a stock ra on the exact dyno. those will be your only realistic sense of where you are.

thanks.