[QUOTE=POLARBEAR666]If increased horsepower doesnt increase the speed you get from a given engine rev then how can a modified car have a higher top speed than a stock car if the gearbox and drivetrain are exactly the same. EG a 500hp 6 speed WRX vs a stock one. Who would have higher top speed? Higher Power per engine rev = Higher Speed. Therefore 100kph@3000rpm + increase engine power = 105kph@3000rpm is logical.[/QUOTE]

Because theres a point there isnt enough power to overcome the drag from the air. Extra power means a higher point where this will occur.

Its like putting two people on a bike. The stronger one will be able to make it go faster, but at the same speed both will be moving the pedals at the same rate.

LOL the stronger rider is using less of a % of his maximum force to do the same speed. This is like an engines revs. IF both engines rev to 7000 but one produces 30 more hp at every single rev point then it wont need to rev at 3000rpm to have the car travelling at 100kph. It might only need to rev at 2500rpm. If you modified the weaker engine so that it has 30hp more it would then only need to rev at 2500rpm also.
DRIVETRAIN REVS FOR A GIVEN SPEED ARE FIXED, ENGINE REVS TO POWER A CAR AT A GIVEN SPEED VARY ACCORDING TO HP/REV.

Go drive a v8 commodore thats doing 1500revs to do 100kph in its 1:1 gear ratio and then drive a subaru thats doing 3000rpm to do 100kph in its 1:1 gear ratio and you might understand what im talking about.

Anyhow the proof is in the physics, my car is travelling faster than before at the same revs or if you want to look at it another way it could travel at 100kph with less revs than before.

WE need a new thread so that the people who dont understand the difference between drivetrain and engine revolutions can be taught. Can we stick to external gate discussion from now on please.

[QUOTE=POLARBEAR666]Go drive a v8 commodore thats doing 1500revs to do 100kph in its 1:1 gear ratio and then drive a subaru thats doing 3000rpm to do 100kph in its 1:1 gear ratio and you might understand what im talking about.[/QUOTE]

Dude, they have different gear ratios...you cant compare them!!

As for your Engine RPM vs Drivetrain RPM theory, engine rpm is directly linked to gearbox input shaft speed, given that the clutch is fully engaged. THERE IS NO SLIPPING once the clutch is engaged (unless its fucked).

If you put the car in 5th gear at 100km/h, the output shaft of the gearbox will be doing the same speed whether you have 100HP or 500HP.

The gearbox will be spinning at exactly the same speed, as long as the gear ratios and tyre diameters and final drive ratios remain equal!!

My car has double its factory HP, and it still does the same speed in each gear at any given RPM.

[QUOTE=POLARBEAR666]If increased horsepower doesnt increase the speed you get from a given engine rev then how can a modified car have a higher top speed than a stock car if the gearbox and drivetrain are exactly the same. EG a 500hp 6 speed WRX vs a stock one. Who would have higher top speed? Higher Power per engine rev = Higher Speed. Therefore 100kph@3000rpm + increase engine power = 105kph@3000rpm is logical.[/QUOTE]

A stock WRX and a 600HP WRX, both with 6 speeds, same tyres and same final drive ratio, will have the same top speed, as long as the revlimiter remains the same. The 600HP WRX will get to the top speed much quicker.

More power does not equal more speed. Your limited to how fast your tyres are spinning, no matter how much power you have. If your engine redlines at 8000rpm, and it has 600HP, vs a stock engine that redlines at 8000rpm, the cars will have the EXACT SAME speed in each gear. More power per RPM means it will reach top speed QUICKER, but it will not go any higher than its given top speed as limited by its gear ratios. Even though it has more power, it cant physically go any faster, because the gear ratios dont let it do that. Its simple physics!

If a stock STi is doing 3000rpm in 6th gear, it will be doing exactly the same speed as a 600HP STi doing 3000rpm in 6th gear.

Simple as that, cant explain it any easier.

To even further debunk this "theory", explain me this....You say that "more power per rpm = more speed", but a 600HP STi doing 3000rpm with no load on the engine in 6th gear, is going to have no more "power" than a stock STi at the same rpm and load, in the same gear. How does that work then?

MORE POWER REV = MORE KPH FOR SAME ENGINE REVS. Examples.

Kei class car has engine replaced by a 6L v8. 3800rpm@100kph to 1500rpm@100kph
Subaru 2L is bored out to 2.5L. 3000rpm@100kph to 2500rpm@100kph
Subaru 2L is replaced by a diesel tank engine same drivetrain as above, 3000rpm@100kph to 390rpm@100kph.
Subaru 2L is supercharged to make 10psi where no boost was there before. 3000rpm@100kph goes down to 2200rpm@100kph.
Subaru 2.5L gets debored down to 2L, less power at each rev 3000rpm@100kph goes up to 3400rpm@100kph.

Why dont u try it out to get a real world result like my 5kph increase instead of heaping crap on a FACT! Take your intercooler pipe off the throttle body and put a pod filter on it. Now drive at 100kph and I bet you are doing a lot more revs than before to sustain the speed because the engiens power has dropped way down.

[QUOTE=POLARBEAR666]MORE POWER REV = MORE KPH FOR SAME ENGINE REVS. Examples.

Kei class car has engine replaced by a 6L v8. 3800rpm@100kph to 1500rpm@100kph
Subaru 2L is bored out to 2.5L. 3000rpm@100kph to 2500rpm@100kph
Subaru 2L is replaced by a diesel tank engine same drivetrain as above, 3000rpm@100kph to 390rpm@100kph.
Subaru 2L is supercharged to make 10psi where no boost was there before. 3000rpm@100kph goes down to 2200rpm@100kph.
Subaru 2.5L gets debored down to 2L, less power at each rev 3000rpm@100kph goes up to 3400rpm@100kph.

Why dont u try it out to get a real world result like my 5kph increase instead of heaping crap on a FACT! Take your intercooler pipe off the throttle body and put a pod filter on it. Now drive at 100kph and I bet you are doing a lot more revs than before to sustain the speed because the engiens power has dropped way down.[/QUOTE]

Simon,

[quote]Kei class car has engine replaced by a 6L v8. 3800rpm@100kph to 1500rpm@100kph[/quote]

The Kei class car with the 6L V8 will still be doing 3800rpm @ 100km/h, because of the [I]same gear ratios[/I]

[QUOTE]Subaru 2L is replaced by a diesel tank engine same drivetrain as above, 3000rpm@100kph to 390rpm@100kph. [/QUOTE]

If the engine is only doing 390rpm, then it wont even get to 100km/h, BECAUSE OF THE SAME GEAR RATIOS!!!!!!!!!!!!!!

I'm willing to bet that you get a pair of WRXs, lets say both 06 WRXs.....one with a tune and exhaust, and one with nothing at all, and you put them side by side on the fwy at 100km/h with the cruise control on. They will both be doing the same RPM!

horsepower doesnt affect your cruising rpm, its placebo.

Your wrong Stace,

My 800HP WRX, with 4 times the power of a stock one, does 4 times less rpm in 5th gear on teh freeway!!!11

750rpm in 5th gear ftw!!1

:rolleyes:

heh, sorry, i forgot about your wrx.

the only time ive seen this happen is when your towing a trailer with an automatic gearbox, or a noob riding the clutch with his foot resting on it :)