hatch vs. coupe at the wheels

[asterox]

was wondering.. the 92-95 coupe is about 120 pounds heavier than the same year hatch

what hp loss/gain does this translate to at the wheels?

[PunkAlex]

The horsepower rating shouldnt make a difference if all of the variables are the same-tranny, wheel size, tire profile....weight has nothing to do with engine output. But you have to remember its half of a power to weight ratio, so its always important. The hatch would win because of the better ratio (assuming the people are of equal skill blah blah blah)

[knorwj]

if engine/drivetrain is the same then hp and tq should be the same.

the lighter car however will have a better power to weight ratio, therefore making it slightly faster. (less lbs for each hp to move)

[PunkAlex]

Originally Posted by knorwj

if engine/drivetrain is the same then hp and tq should be the same.

the lighter car however will have a better power to weight ratio, therefore making it slightly faster. (less lbs for each hp to move)

Originally Posted by PunkAlex

The horsepower rating shouldnt make a difference if all of the variables are the same-tranny, wheel size, tire profile....weight has nothing to do with engine output. But you have to remember its half of a power to weight ratio, so its always important. The hatch would win because of the better ratio (assuming the people are of equal skill blah blah blah)

[asterox]

thx guys, so on a dyno would both cars perform the same or would one have more 'actual' hp?

[PunkAlex]

In theory, yes, they should have the same whp.

[knorwj]

Originally Posted by PunkAlex

sorry not trying to steal your glory or anything, but sometimes these guys need to hear things more than once from different people.

[PunkAlex]

hah I was just wondering that one...

[leolo007]

a good thumbrule is 100lbs=10hp
now I think a good way to explain that is if you have a car with 200hp that weighs 2000lbs and another car weighs 100lbs extra = 2100lbs you would need 210hp to be as fast. Im know there are a lot of factors and this has nothing to do with any dyno results but just sorta trying to answer the question that was originaly posted.

[asterox]

thx that's what i was looking for, i definately want to get a hatch !!

[knorwj]

i've never heard of taking weight away adding HP? I have however heard that for every 100 pounds you lose your car will run .1 second faster 1/4 mile times. i.e if you run 15.5 and you lose 100 pounds of crap you will run a 15.4.

[PunkAlex]

Also, a 20 hp gain in a CRX would have a much larger effect than in a Supra because of the weight difference (I used supra as an example...yes i know its easier to get 20 hp out of a supra than a CRX...its a weight analogy!). So for every bit of horsepower you make, itll have a greater (and more noticeable) effect in a light car. Power to weight ratios are your friend

[leolo007]

Originally Posted by knorwj

i've never heard of taking weight away adding HP?

I didnt say your adding HP by taking weight away, I said its sorta like the equivalent of. Read my post carefuly its not that hard to understand. But like knorwj said you have to say things twice. Heres a different way of explaining it, theres a car that weighs 2000lbs and has 200hp and runs a 13.00 1/4mile, if you have the same car (engine, drivetrain, etc. that weighs 2100lbs and you want to run 13.00 you should have around 210hp
see how 100lbs=10hp, its just a thumbrule and its not equal, maybe I shouldnt have used equal sign, but its equivalent... get it?

[asterox]

I thought when people talked about hp "at the wheels" they were talking about effective horsepower... i.e. if your car were measured for power how many "horses" would it be equivalent to. If that is the case then reducing weight would make the car equivalent to more horses.. but of course the engine driving the car would stay the same.

[leolo007]

thats sorta what Im saying except the measurement of hp is a little more complicated than that.