Competition HP to 1/4

[dsather]

I've heard many people make reference to a chart somewhere that will calculate how much HP you need at a given weight to get through the 1/4 in a given time. Where might I find this info??



Dennis

 

[MDW]

http://www.gofastzone.com/carmath/default.asp

 

[MMeier]

How about torque derived from HP and MPH?

 

[dsather]

HP

Thank You, that's exactly what I was looking for!



Dennis

 

[kaptn]

www.prestage.com/Car+Math/ET+and+Horsepower+Calculators/HP+from+ET+and+Weight/default.aspx

 

[Rhondasway]

Very interesting, but...

I was actually going to start a thread questioning the HP it takes to get the times I'm getting.

My highest dyno run was 467hp.

My fastest ET (same setup) was 12. 68 @104.

According to the first link, using weight (7000) and hp (467), my ET should be 14. 35 @ 94. 99...

Using the second link, using ET (12. 68) and weight (7000), my HP should be 679...

What's wrong here? Is it the diesel vs. gas torque diff's? Maybe my Air Bulldog hood is making that extra 200 hp on the track, eh?

At any rate, be wary of relying on calculations.



I'd also be interested in seeing some other guys' ET's, specifically with single turbos and preferably at NHRA tracks.

 

[DRAG DIESEL]

Here you go Rhonda,



13. 0 @ 106



By MPH @ 6750lbs is 627 hp



By ET @ 6750 is 607hp



I dynoed 431 @ PDR with just my big injectors, stock turbo, and stock cam plate.



so there you go, single turbo at NHRA tracks. Enjoy.

 

[c-hawk]

Haven't dynoed since I ran 13. 20 @ 101. 5. But when I was running 13. 96 @ 96, I dynoed @ 408/866 and 414/880. First numbers were at muncie, second set was at Kauffmans.



According to the hp calculator, when i was running 13. 96 @ 96, I had 490hp using e. t. , or 466hp using mph.



Later,

Chris

 

[csutton7]

cuz it's the tremendous torque we make that throws the calculations off would be my guess-or maybe we slip the dynos or maybe... ..... --chris

 

[Elite1]

Re: Very interesting, but...

Originally posted by Rhondasway

I was actually going to start a thread questioning the HP it takes to get the times I'm getting.

My highest dyno run was 467hp.

My fastest ET (same setup) was 12. 68 @104.

According to the first link, using weight (7000) and hp (467), my ET should be 14. 35 @ 94. 99...

Using the second link, using ET (12. 68) and weight (7000), my HP should be 679...

What's wrong here? Is it the diesel vs. gas torque diff's? Maybe my Air Bulldog hood is making that extra 200 hp on the track, eh?

At any rate, be wary of relying on calculations.



I'd also be interested in seeing some other guys' ET's, specifically with single turbos and preferably at NHRA tracks.

Rhonda, One thing I notice wrong in your formula... A Dyno measures what HP you are putting to the ground. So I would bet if you are Dynoing 467, I would bet your actual HP is about 550. Also wondering why your truck is so heavy,I weighed mine, my 4 door 1 ton is 6800 lbs. That is with 3 tool boxes in the back.

 

[Digger]

torque = hp/5656*RPM

 

[DRAG DIESEL]

Originally posted by DanHill

torque = hp/5656*RPM

I believe it is 5252.

 

[Rhondasway]

Re: Re: Very interesting, but...

Originally posted by Elite1

Rhonda, One thing I notice wrong in your formula... A Dyno measures what HP you are putting to the ground. So I would bet if you are Dynoing 467, I would bet your actual HP is about 550. Also wondering why your truck is so heavy,I weighed mine, my 4 door 1 ton is 6800 lbs. That is with 3 tool boxes in the back.

Aahh... Good point about the "rear wheel vs. flywheel"...

I don't know what my truck weighs (need to get it on a scale), but I tried using 6500lbs (the 'gravel pit scale' weight of my '97) also and it only changed the numbers minimally.

I know guys who have 3/4 ton trucks that weigh over 7000 (or so they claim). Could be some scale variation...

Maybe we should have a "weight day" at a neutral location. Imagine the ---->:-{} beforehand!!

 

[csutton7]

mine is 8000-8200 lbs--campershell, ladder rack, ladder bars and big frickin tires add up quickly-not good for racing-chris

 

[Dieselrod]

7120 lbs with me (170 lbs. ) and a full tank of fuel weighed at a cat certified scale. No tool boxes or anything like that. Just FYI!

 

[Elite1]

Re: Re: Very interesting, but...

Originally posted by Elite1

Rhonda, One thing I notice wrong in your formula... A Dyno measures what HP you are putting to the ground. So I would bet if you are Dynoing 467, I would bet your actual HP is about 550. Also wondering why your truck is so heavy,I weighed mine, my 4 door 1 ton is 6800 lbs. That is with 3 tool boxes in the back.

I'm just guessing that your (flywheel) HP is about 550. This estimate comes from the fact that the new 03' HO is advertised at 305 HP, but is putting about 260 to the ground on dyno's. If your HP is 467 to the ground using the same factor it comes out to about 550. If you enter that HP and 6500 lbs. it comes out to a 13. 26 1/4 mile. (pretty close to what you are running). The formula doesn't take into consideration rearend gearing or transmission mods... . I know you have run a best of 12. 68... but I'll bet a normal run is pretty close to their numbers... . 13. 26

 

[WAYNE]

These HP calculators can only estimate the "average" traction the vehicle could get , and you 4x4 guys (girls) are getting "exceptional" traction and throwing the numbers off.

 

[JRG]

Don't forget reaction time!



JRG

 

[dsather]

Reaction time

Clock doesn't start til your wheel trips the light so reaction time is not a factor except for the manual trans guys (shifting).