# Weight reduction = horsepower gain

Discussion in 'General Tech and Maintenance' started by humblegumbo, Jun 26, 2007.

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1. ### humblegumbo1595cc's of Mad Fury

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I am looking for a simple equation. Somewhere out there in the wild world of the interweb I know there is a straight forward equation for converting weight reduction to horsepower gain equivalent.

What I mean is this:
If I remove one pound of weight from my car, how much HP would I "gain"?

I'm putting my girlfriend on a serious diet. Last weekend she lost 30 - 40 lbs when I tore out all the underhood A/C components. The new headers and downpipe also helped. I'm looking into lightweight batteries and relocation kits as well.

Reasoning? It sure seems cheaper to remove "useless junk" (like A/C) than to increase hp. If I can get a pound for pound hp comparison, I can convert that into dollars. Everyone wants to know hp per dollar.

Maybe the cheapest way to go faster is to be skinny....

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2. ### eg6sirSupa ModModeratorVIP

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i've heard for every 10 lbs its like gaining 1hp

3. ### CRX-YEMSuper ModeratorModeratorVIP

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I've often heard that a weight reduction of 100 lbs. should reduce a 1/4 mile time by 0.1 secs

4. ### CRX-YEMSuper ModeratorModeratorVIP

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I think that's a stretch, removing his A/C system would then equate to a 30-40Hp gain.

I think that your an order of magnitude off on the ratio, 10lbs = 0.1hp gain, which equate to about a 3-4Hp gain which seems much more reasonable

5. ### phyregod!!YTINASNI

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Unsprung weight and rotating mass is worth 4 times that. So if you get a set of wheels that is 10 pounds lighter each, you remove 40 pounds from the car, but it will act as though you've removed 160 pounds.

6. ### eg6sirSupa ModModeratorVIP

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maybe thats what it was.. my mechanic told me that years ago.. he builds hotrod drag cars..

7. ### humblegumbo1595cc's of Mad Fury

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I'm serisously no math wiz, but break out your calculator for this one.

A ten to one ratio would mean that 30-40lbs would be 3-4hp....that does seem reasonable...

8. ### phyregod!!YTINASNI

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Thats what he was stating in the first place, except your math is off by one decimal point. 10 pounds = 1hp. so 100 pounds would be 10hp. and his AC system (40ish pounds total) would be like adding 4hp.

9. ### eg6sirSupa ModModeratorVIP

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i knew i was correct..

10. ### phyregod!!YTINASNI

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Its not an exact math, just very rough guestimates.

11. ### humblegumbo1595cc's of Mad Fury

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Now, I have heard that. Thank you HOTROD magazine. This applies to everything that the motor turns, which is why a lightweight flywheel would be a nice upgrade.

That still costs straight cash that my poor bank account can't support. Removing the passenger seat, for example, would be completely free, though.

Does anybody have a source for this rumored 10:1 lbs to hp ratio?

12. ### eg6sirSupa ModModeratorVIP

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nope.. i'm just going by what i was told by a hotrod builder

13. ### humblegumbo1595cc's of Mad Fury

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I won't trust that source unless he has a sweet mullet.

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14. ### eg6sirSupa ModModeratorVIP

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exactly why i said its like gaining 1hp.. never said you gain 1hp for every 10 lbs

15. ### jimboburgessGo fast, Go Cheap

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not only would loosing weight help you go faster but turn and stop faster too. the main thing most hondas have going for them is they are light weight, that's why a little b16 eg has a fighting chance against a 350hp monster that weighs sometimes twice as much.

here's a chart from super honda on free things to remove

Remove Spare Tire

Remove Jack

Remove Floor Mats

Remove Passenger Seat

Remove Rear Seats

Remove Muffler

Drain Washer Fluid

Remove Cruise Control

Remove Speakers

16. ### eg6sirSupa ModModeratorVIP

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mine has teh spare, jack, carpet, rear seats and panels stripped out.. no AC, no PS.. no glove box or gauge cluster bezel.. of course it'll all go back in once the car is painted.. and for shits and giggles i'll pull out the passenger seat and i can really feel a difference in how the car pulls.. which is a lot harder without that seat

17. ### CRX-YEMSuper ModeratorModeratorVIP

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eg6sir , you stand corrected, math > me today, I totally read your post wrong.

18. ### klyphDismemberVIP

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Actually, it is YOU who stands corrected. Again. Grammar>you as well

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hahaha..

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