Ben

Here's another good one if you're through with that. About how it's useless to compare numbers from different dyno's, and how shaddy part makers can manipulate the numbers.
http://www.vishnutuning.com/dynos_dont_lie.htm

boostedwrx

iTrader: (27)

The stock WRX makes 165WHP. It would be sad if the same dyno that measured the claimed 195whp for the WRX also measured the whp for the EVO. If thats true, I bet the EVO really only has 200-210WHP. AWD cars lose ~30% HP in the drivetrain. Ask any VR4 owner, they lose even more. I pray the my Stage II WRX WON't be able to smoke a stock EVO, but its not looking very good.

gtr

iTrader: (6)

I guess only the MPH on the 1/4 track counts . All of us are awd "have traction" so fast trap speed wins. Evo VII gets 103mph. If we're 101-103 i'm

WestSideBilly

iTrader: (1)

Sorry, but Mr. Shiv S. Pathak doesn't know what he is talking about. Drivetrain losses typically stay fairly constant as a percentage, and the losses have little to do with heat (as it is merely a byproduct of friction in this case).

Ben

He's one of the best Subaru tuners in the USA and one of the technical writers for SCC. So far his credentials beat yours.

broeli

iTrader: (19)

Hp loss wheels to flywheel should always be used with %. The Evo has about 24% drivetrain loss..NOT a set hp loss.
Read this if you need clarification on why:
http://www.g-force-motorsport.co.uk/...detail%202.htm

MrAWD

I would be very happy to see the US EVO going over 100 mph at the track. The best that I did with my car (which was several modifications and years ago) was 100.5 mph and happened in 13.41 sec. The car with me was about 3300 lb and HP calculator that can be found over the WEB, showed 275 HP at the wheels.

So, if US EVO brakes that 100 mph mark, I would be very happy!


Fedja

Longfury

why don't we compare the Evo's wheel HP to the JDM Evo VII's Wheel HP???

Longfury

i know that each dyno is different but it would give us a ball park idea of where it stands

Ben

Yes that's the traditional view, but what Shiv has said is it's more accurately somewhere between the set HP loss and set % loss. HP loss is the conservative way of looking at it, % is the optimistic. Sure heat will go up if you increase the power going through a system, but not enough to account for the double HP lost you'd see with the % method if you were to double your HP output.

MrAWD

Well, he might be a very smart guy, but what he wrote in that article doesn't make sense. Even just from the mechanical point of view, he was wrong. 200 HP engine will spin everything in there at the higher rate then the one with 100 HP. There is a rotational mass that has to be overcome from every single part that is spinning in there and the faster you want something to change its speed, the more resistance you will get (Newton's law of inertia). I do agree that all of this is just approximation, but to use a constant losses is way off.

Now, I know that my credentials are also way off his, but it is up to you to believe in whatever you think is correct, not according to who wrote it!

Have a good one!!


Fedja

Ben

Yes, and I do believe what he wrote. I've seen plenty of the work Shiv has done with the Impreza, and everything I've seen from him so far is accurate. He's actually one of the best WRX tuners in the world, getting 350hp with stock internals and pump gas was unheard of before the WRX came to the USA. Anyway, the lost power has to go somewhere, it doesn't just dissapear. It's going to be lost as heat. Is the heat going to increase so much as to account for the 35 extra hp lost in his double hp example? I'd agree with Shiv that no it wouldn't.

evo_dan

The JDM Evo VII was rated at 246 hp at the wheels. We also know it's flywheel hp is around 315.

USDM Evo VIII rated 230 hp at the wheels. Around 300 hp at the flywheel maybe or 271 hp at the flywheel with less drivetrain loss or the dyno was wrong. Don't know.

Sweft

I don't know much about this but let me take a stab. I suck with cars this might be way off.

1) Theres the weight of the parts you have to move. This is a set weight, say its 10lb and that takes off ~30hp it will be 30hp at 500 crank hp and 30hp at 100 crank hp.

2) Now theres the friction involved. Say its 10% loss. It equals 10hp at 100 crank and 50hp at 500 crank.

So in the two examples. 100 crank loses about 40hp, and 500 crank looses 80hp. These numbers are way off, but i chose them as an example of what i believe happens.

Tell me if i'm way off.

MrAWD

Then tell me a simple thing about the moment of inertia that I mentioned up there. If the car is traveling at 60 mph and it takes 112 feet to make a full stop. How long is gona take it to do the full stop if it is traveling 120 mph now? The same?

Or another one...to accelerate 0-60 car one with 100 HP makes it in 10 sec. And we will assume that 80 of those ponies are getting the car there and 20 is lost in the drivetrain. Now, raise the power to the 180 HP! How long is gona take to get there? According to your interpretation of the Shiv, I would say 5 second, since all of the losses are already done in the first 20 HP and twice the 80 HP would get you there twice as quick!

Makes more sense this way?


Fedja