Stage 2 Cosworth Kit Preview!!!!

[weederr33]

Physics class, hell yeah!

[cdrazic93]

Originally Posted by bfrank1972

You know - I always thought of losses as a fixed % as well, but what he says does make sense. Then it struck me that we're talking about a pretty complex set of interactions, which is likely not fixed loss nor a fixed percentage loss... rather somewhere in between varying in a complex way. Then I turned to Google and found lots of articles about it, like:

http://www.superstreetonline.com/how...in-power-loss/

http://www.hotrod.com/how-to/transmi...in-power-loss/

I never said it is a fixed percent, I beleive its just a percent specific to the car. Like ultra maroon said, the more the load and the more the speed the less efficient the drivetrain components are. Thus increasing whp will decrease the efficiency of the drivetrain. I found that SAE paper that the superstreet article is talking about, but i didn't want to pay $20 to settle an argument.

As soon as I take my power train class I'll revisit this thread and shore up my findings.

[Deep Six]

SAE certified crank horsepower really has a single purpose: marketing new cars. Aside from that I really see no use for that data point. Wheel rated horsepower and torque is what moves the car and is the constant for measuring performance. So why do we even care if drive train loss is static or proportional to wheel horsepower?

[ajc209]

I'm not suggesting drivetrain losses are a fixed number, I am suggesting that they don't go up with power linearly. Drive train losses go up with doubling the stock power but certainly dont double.

[ajc209]

Originally Posted by Deep Six

SAE certified crank horsepower really has a single purpose: marketing new cars. Aside from that I really see no use for that data point. Wheel rated horsepower and torque is what moves the car and is the constant for measuring performance. So why do we even care if drive train loss is static or proportional to wheel horsepower?

Because I said the 85whp increase with stage 2.3 is likely to be close to 85 fly hp not 85 multiplied by a magical number.

[Deep Six]

Originally Posted by ajc209

Because I said the 85whp increase with stage 2.3 is likely to be close to 85 fly hp not 85 multiplied by a magical number.

My question is WHY does anyone NEED to know (guess) crank or flywheel horsepower after modifications when you already have the before and after numbers measured at the wheels.

[cdrazic93]

Originally Posted by Deep Six

SAE certified crank horsepower really has a single purpose: marketing new cars. Aside from that I really see no use for that data point. Wheel rated horsepower and torque is what moves the car and is the constant for measuring performance. So why do we even care if drive train loss is static or proportional to wheel horsepower?

I agree, its useless; that being said every single automaker uses it because its a nice number, and it makes the car sound more powerful.

[cdrazic93]

Originally Posted by Deep Six

My question is WHY does anyone NEED to know (guess) crank or flywheel horsepower after modifications when you already have the before and after numbers measured at the wheels.

its all up for debate and people LOVE debating on the interwebs lol

[ajc209]

It really doesn't matter.

[bfrank1972]

Originally Posted by cdrazic93

I never said it is a fixed percent, I beleive its just a percent specific to the car. Like ultra maroon said, the more the load and the more the speed the less efficient the drivetrain components are. Thus increasing whp will decrease the efficiency of the drivetrain. I found that SAE paper that the superstreet article is talking about, but i didn't want to pay $20 to settle an argument.

As soon as I take my power train class I'll revisit this thread and shore up my findings.

When you say 'a percent specific to the car', it sounds to me like you're saying car X has a 15% loss over the rpm range, car Y has 10% loss over the rpm range.

I think what these articles are saying - car X might have 20% loss at 2000 rpm, 15% loss at 4000 rpm, and 12% loss at 6000 rpm (don't take me literally on any of these numbers, just pulling out of the air for example).

[cdrazic93]

Originally Posted by bfrank1972

When you say 'a percent specific to the car', it sounds to me like you're saying car X has a 15% loss over the rpm range, car Y has 10% loss over the rpm range.

I think what these articles are saying - car X might have 20% loss at 2000 rpm, 15% loss at 4000 rpm, and 12% loss at 6000 rpm (don't take me literally on any of these numbers, just pulling out of the air for example).

Each design of the engine, transmission, differential all have different efficencies. I can bet you a DCT is more efficient then a 6 spd. And a torsen is more efficient than another kind. Also depends on the driveshaft the material used, the lubricant reccomended. Everything.

An EVO 8 will be less efficient than a Miata. A Focus ST might be more efficient than a miata.

All comes down to part design, lubricant used, and number of parts.

[bfrank1972]

Originally Posted by cdrazic93

Each design of the engine, transmission, differential all have different efficencies. I can bet you a DCT is more efficient then a 6 spd. And a torsen is more efficient than another kind. Also depends on the driveshaft the material used, the lubricant reccomended. Everything.

An EVO 8 will be less efficient than a Miata. A Focus ST might be more efficient than a miata.

All comes down to part design, lubricant used, and number of parts.

I understand and agree completely, I'm just thinking 'losses' for a Focus ST 6 speed transmission or a specific model torsen diff aren't fixed, but rather vary under different loads and rpms. Same for every other component in the driveline. But maybe saying a Focus ST 6 speed has total 15% power loss across the rpm band under WOT is a close enough estimate so that it doesn't matter? I think in the end when looking at dynos, it's all about relativity anyway (non-einsteinian) - the graphs mean the most when comparing the same car before/after mods/tuning.

[cdrazic93]

Originally Posted by bfrank1972

I understand and agree completely, I'm just thinking 'losses' for a Focus ST 6 speed transmission or a specific model torsen diff aren't fixed, but rather vary under different loads and rpms. Same for every other component in the driveline. But maybe saying a Focus ST 6 speed has total 15% power loss across the rpm band under WOT is a close enough estimate so that it doesn't matter? I think in the end when looking at dynos, it's all about relativity anyway (non-einsteinian) - the graphs mean the most when comparing the same car before/after mods/tuning.

Yes, the as vehicle speed and engine load increases so does torque and therefor friction. The more friction you have the more heat you have, thus higher drivetrain loss the higher in the RPM band you go. Another reason why it's good to have torque down low so its more useful than torque in the higher rpms.

[dirtymax]

CARB license and I am so in the cosworth club. Cant wait to get rid of this 100k warranty