There's no way the drivetrain loss is only 15%. Just like the previous Evos, it's going to be around 24%, like others have said. Besides the impact of the weight of driven parts in the AWD system, there's no way you can avoid power losses in a drivetrain with a set number of gear meshes. Each time one gear transmits motion to another gear in the gearbox or in a differential, power is lost due to the efficiency of that gear type. An efficiency of 90-95% for a single spur gear or helical gear stage is excellent, and won't be improved upon.
Find a book or website about geartrain design to learn more.

 

12%-15% drive train loss on a AWD car is wishful thinking.

I've witness cars from TT S4 to Mazda Turbo GTX dyno on a Mustang AWD and they are all consistent with 24% plus drive train lost.

Some additional food for thought regarding the DynoJet roller type dyno.

DynoJet independent type rollers X2


Mustang AWD dyno chassis


"One of the reasons not to go with the AWD Dynojet is that there is no way to keep both rollers spinning at the same rate. The two rollers are two seperate entities with no central control system. With torque split changes, the front and rear axles will spin at differenct speeds. Center differentials don't like this one bit."

"The optional steady-state loading feature on the AWD dynojet is flawed for two reasons: 1) you can't measure torque or hp while the car is loaded to hold a certain vehicle or engine speed and 2) the holding system (called Dyna-Trac) only loads ONE roller, relying on the car's center differential to hold equal front and rear wheel speeds!"
Again, very bad for the viscous center diff!

 

Here you go...


Well, the original size is about 250k, but I have to degrade it a bit to fit into the 100k limit...sorry

 

Or this bigger one with lower resolution...

 

According to Sport Compact Car July 2002, a Euro Spec EVO 7 dynoed on a Dynapack at 247 to the wheels and ran a 13.4 at 103 on a bad clutch. Trap speeds only about 1.5 mph difference. Still would have to have both cars on same dyno and track at same day to compare.

 

Same SCC issue their project WRX with 218 hp to the wheels ran a 13.4 at 99.3. The evo, on a good surface with a great launch should be able to post low 13s

 

I don't think anyone saw this post because about 3 people posted at the same time and mine got stuck at the bottom of the previous page.

 

So there are now two seperate instances of Dyno info for the Evo VIII being posted on this site, correct? And both instances the US Evo VIII is posting numbers near 240 Wheel HP, correct?

If this is true, then regardless of the accuracy of any specific dyno, the evidence that the US Evo's hp is underrated is certainly building.

SC

 

I don't know about that... AWD cars lose a good bit more than 10-15% between the flywheel and gronud. 10-15% is more accurate for a FWD car, such as my VR6 -- average 13% loss.

IIRC, Claudius mentioned something about a 24% drivetrain loss on the Evo 6 and Evo 7. It is then logical to presume a similar loss on the Evo 8.

240 hp and 254 lb*ft at the wheels roughly translates to 298 hp and 314 lb*ft at the crank. That's pretty freakin good by all means!

EDIT: Someone mentioned how the curves are labeled incorrectly. I think they're right on. Max hp is usually around 6-6.5k rpm and max torque is much lower, around 3-3.5k. Just switch the numbers and you'll have a car that's just as good on paper.

2nd EDIT: Just saw the second graph with a different (correct?) scale. I'm confused now. Either way, it looks good.

 

It is so obvious from the graphs that air flow (or boost somehow) is so restricted after the 4k RPMs and once those are removed and car starts to breath the way it should, both curves will be much higher at the end. The max torque number will probably stay the same, but power should be up quite a bit!


Fedja

 

also, holding boost at 19 to 20 psi from 4,000 to 6500 or redline rpms should skyrocket the top end hp. factory boost is supposed to go from 19 to 16 psi. granted you have the fuel capabilities for that, im sure the 560 cc injectors are able to support that (id bet they can hold 25 psi stock bottom end). anyone have any guesses what flatening out the boost curve would look like?

 

Hi,

Well..... this has to be the longest thread I have read in awhile where someone was not called bad name Nicely done gentleman. (and ladies).


May I summarize?

1. We are under the impression, that this is a STOCK EVO 8? Correct?

2. The HP has been adjusted (SAE) for temp and pressure? Correct?

3. UK tuners state that the EVO drivetrain loss in the range of 24%? Correct?

4. Based upon the torque measurements (dyno) the max HP calculates out to 240 HP.

5. Given the 25% drive train loss, the crank horse power is 300HP plus? Correct?

We are claiming that the drive train loss is 60HP and if we modded our EVO to make 300HP at the wheels we would have 375HP at the crank with a 25% drivetrain loss? Correct?

I just have one question. Why does drive train loss increase with HP?

Speedlimit.....

 

u just brought up a good point...it is just about pointless to try to figure out the flywheel horsepower from a chassis dyno...the horsepower at the wheels is just that

unless u take the engine out of the Evo and dyno it and figure the loss in the drivetrain u will never be able to figure out the true flywheel power #'s from the chassis dyno #'s