Torque loss through the drivetrain...how much?

[updaboost]

Ok, so I know ours S4s lose about 20% to 25% hp through the drivetrain but how much torque do we lose??? Is it 10% to 15%??

[mike-2ptzero]

The dyno uses tq to get hp so the loss should be the same. I have never seen anyone use a different driveline loss for tq vs hp.

[MadMAXS4]

HP is derived by calculating torque at a specific RPM multiplied by a constant rotation velocity (5252rpm). Here's the Math for calculating Hp via given Torque at a particular RPM:



That's why you see on dyno graphs the Hp and Torque lines cross at 5252rpm every time. If you don't, someone is lying So, the percentage loss of horsepower is directly correlated to the amount of torque lost. You can determine the drivetrain losses via peak horsepower rating/production then base that off the factory crank ratings (assuming stock conditions) at the peak HP RPM to determine drivetrain losses as an average throughout the rev-range by dividing the actual wheel horsepower results over the factory crank ratings (again assuming stock performance.) It will result in a number <1.00, 1.00-result = drivetrain loss percentage.

[GVR4-201]

Yes, the math works out so that you have the same percentage of loss from bhp/btq to whp/wtq.

The dyno uses tq to get hp so the loss should be the same. I have never seen anyone use a different driveline loss for tq vs hp.

[SilverSurferS4]

I just dyno'd my s4 last weekend, its completely stock i just did a few base line pulls. I made 214awhp, and 250tq on the first run. 207 awhp and 240 tq on the second run. 199awhp and 235tq on the last run. So its clearly not a big loss on torque as opposed to hp i guess.

[10SecS4]

I just dyno'd my s4 last weekend, its completely stock i just did a few base line pulls. I made 214awhp, and 250tq on the first run. 207 awhp and 240 tq on the second run. 199awhp and 235tq on the last run. So its clearly not a big loss on torque as opposed to hp i guess.

Lemme guess, you dynoed on a Dynojet?

[TalipseAWD]

holy crap, 10 lbs of torque drivetrain loss. Thats Crazy

[SilverSurferS4]

Lemme guess, you dynoed on a Dynojet?

Yea mark.. it was on a dynojet. it was at ics performance out in CT last weekend, I decided to see what power the S4 puts down and just ran it, i was with my friend who was getting his subaru tuned over there... maybe the dyno is very forgiving.. lol... so whats a more realistic wtq that a stock s4 should put down? for now all i can go by is the numbers i saw my car put down...

[TalipseAWD]

Yea mark.. it was on a dynojet. it was at ics performance out in CT last weekend, I decided to see what power the S4 puts down and just ran it, i was with my friend who was getting his subaru tuned over there... maybe the dyno is very forgiving.. lol... so whats a more realistic wtq that a stock s4 should put down? for now all i can go by is the numbers i saw my car put down...

ICS
Im gonna dyno my stage 1 there so I can get over 300whp :p

[SilverSurferS4]

ICS
Im gonna dyno my stage 1 there so I can get over 300whp :p

Lol, what am i missin here guys!! fill me in! Is ICS a bad shop or something?
I do know they charge a arm and a leg for their work though! lol

[YZracer]

ICS is a great shop I've had no problems with them at all. George and Brian are great guys. They have done my a lot of favors and always keep their word. I don't know why you guys would be giving them a bad rap. I have to defend them because ever since Speedtechnik did the crappiest work I've ever seen, ICS has been great.

[TalipseAWD]

ICS does good work.
But almost everyone who goes there/went there will tell you they charge an ARM and a LEG for everything they do.
they told audisport he needed an axle instead of a ten dollar CV boot.
they tried to charge me $950 in labor to replace one axle and brake pads all round on my 1990 Eclipse GSX. like six years ago.
Speedtechnik has a worse rap than ICS, thats why speedtechnik is closed at the moment.
There are so many choices for shops in the Fairfield county area, yet people seem to always go to places that charge a ton more money than everywhere else then defend the shop?

[SilverSurferS4]

No No NO! We arent saying ICS is a bad shop or giving them a bad rep! George is a good guy and they do very good work from what i've seen last weekend. However I know they may charge a arm and a leg to do work, but hey you have to pay for quality work "you get what you pay for".... if not then do it yourself.... like me! lol... My questions are directly related to their dynojet... you guys seen the #'s my stock s4 put down there, im just wondering if the dyno is giving accurate readings or not, maybe i should be putting down less tq to the wheels, i dont really know, thats why im curious...

[mike-2ptzero]

No No NO! We arent saying ICS is a bad shop or giving them a bad rep! George is a good guy and they do very good work from what i've seen last weekend. However I know they may charge a arm and a leg to do work, but hey you have to pay for quality work "you get what you pay for".... if not then do it yourself.... like me! lol... My questions are directly related to their dynojet... you guys seen the #'s my stock s4 put down there, im just wondering if the dyno is giving accurate readings or not, maybe i should be putting down less tq to the wheels, i dont really know, thats why im curious...

Might want to do a search and see what other people have put down with stock S4.

[sean1.8t]

isn't normal stock whp on an S4 around like 180? i forget

at least something you might see on a Mustang..

[mossback]

Dyno's vary, it only makes a difference if you test on one dyno, then test on another, you won't be working on the same delta. Test dyno A, make car changes, test again on dyno A. Don't go to dyno B, its an incorrect result.

Dynojet, mustang...the numbers are just numbers a base line of power. One is not better in the scheme of things, the car is what the car is, but if you are tuning, tweaking, stick to the same dyno and try for the same kind of weather, to many variables otherwise.

[aysix]

Dyno's vary, it only makes a difference if you test on one dyno, then test on another, you won't be working on the same delta. Test dyno A, make car changes, test again on dyno A. Don't go to dyno B, its an incorrect result.

Dynojet, mustang...the numbers are just numbers a base line of power. One is not better in the scheme of things, the car is what the car is, but if you are tuning, tweaking, stick to the same dyno and try for the same kind of weather, to many variables otherwise.

Word, should have told them that ten years ago!