Hi guys I was thinkin to lighten up my car, rear seat, spare tire,a/c pump and radiator, but before workin on it i just want to know how much "hp" could i get from these mods..

THANK YOU

 

It's my understanding you don't gain Any "hp" per se but rather you increase your 1/4 mile times because you're lighter. By eliminating your AC you reduce parasitic power loss caused by the AC pully always going, otherwise nothing would really gain you any real hp but instead simply lighten the load, every 100lbs=.1 is the accepted formula that I've seen. Of course I could be totally off base so please don't hurt me if I am

BTW rear seat+cushions=around 27lbs Spare Tire+jack=30lbs AC=30lbs so if you do all that you'll have about an extra .1

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84 stock Z-28 V8 305 H.O.
1/8 10.328@66.06
1/4 16.246@80.82 phear!

[This message has been edited by Inwo (edited September 19, 2001).]

 

.1 sec for no A/C? doesnt sound worth it; i think ill keep my A/C and just increase horsepower for the extra .1 seconds...

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1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."
"Ponies can run, but birds can fly..."

 

Pretty sure when you get rid of the parasitic hp loss at the AC pump you gain a slight amount, so if you race a lot then get rid of it, otherwise I say keep it :-P Of course someone else might have a totally different opinion, all I know is don't put it on when you are heading to the track or they won't let you race due to the condensation it creates (dripping water+spinning tires=BIG MESS)

 

The point is that i don't need the rear seat 'couse i 'm a poor lonley guy, i don't use the a/c couse i've got t-top .

I need a quicker acceleration from standing position so i thought : lighter car = better accelaration.

 

my car weighed 3180 with power windows/locks and all seats.

Removed
A/C, Heater, Radio

Replaced
Heads (aluminum), Intake (aluminum), water pump (you guessed it) and radiator (one more time).

 

I'm in the same boat as you, I ditched my AC (t-tops) and rear seat (left the backing in to make a "trunk" of sorts.) Never ran the car with the ac so I can't comment on how much power loss AC actually accounts for but I imagine that you'll get something out of getting rid of it, however be aware that your girlfriends might not appreciate having their hair messed up because the t-tops are off



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84 stock Z-28 V8 305 H.O.
1/8 10.328@66.06
1/4 16.246@80.82 phear!

 

Correct.

Approximately every 100lbs lost is .1 second off in the 1/4 mile but that is a rough estimate and is dependant on how fast or slow the car is to begin with, how heavy it was to begin with, the engine power band, etc etc.

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

And since the engine itself doesn't change HP from removing weight, you'll go faster. It's all a matter of power to weight ratio.

While it may take 800 HP to push a 3500 pound car into the 9's, it only takes around 300 HP to push a 1200 pound dragster into the 9's.

Sometimes it can be cheaper to lose weight to go faster than to make the engine build more HP.

When compared to other uni-body cars, third gen F-bodies are very heavy. Add in a V6 or 305 and you have a slow car.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block (times are for the current engine)

Best ET on a time slip: 11.447 altitude corrected to 10.99
Best MPH on a time slip: 119.42 altitude corrected to 124.86
Altitude corrected rear wheel HP: 493
Best 60 foot: 1.586

Racing at 3500 feet elevation with a typical race day over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

Also only takes 200-210 hp to run high 12's in a 2200 lb car plus driver. Must have traction though.

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86 T/A 5.0 A4 & 2.77 gear
15.62 @ 86 mph
93 Civic 1.6L
13.5 @ 100 mph