Now that we both have a better idea how we come across out dyno numbers, I have one other question.

I obtain all my dyno numbers using fourth gear. I have found some people use fifth. The hp readings between fourth and fifth are about the same but I have found fifth gear always renders higher torque readings than fourth gear.

What gear do you use for reporting your numbers?

 

Hi.
Elementally that doesn't make sense to me... Torque at a given
RPM equals horsepower. You can't have more or less torque
without also having more or less horsepower at the same time.
From what I have heard, the reasons to choose one gear over
another for a dyno run have to do with getting a long enough
pull to get a good range of measurements, and avoiding wheel
slip on the drum. These suggest using a taller gear. Also, the
higher gears in a tranny tend to be more mechanically efficient,
so you lose less power to internal friction. Usually one of the
higher gears in the box is a one-to-one ratio, making this the
simplest and most efficient. I seem to recall Stephan mentioning
something about the amount of cooling he could provide causing
him to stay in 4rth...
Joe

 

Joe,

I believe Stephen uses fifth gear. Maybe he can give us his input. I do not know the physics here. I have no idea if there should be a difference, however I have observed it. The torque has always been a little lower in fourth gear than fifth.

 

I typically use 5th, however only see more power in 5th, not TQ as compared to 4th.

 

I concur with Todd. The TQ numbers are constant. When I do a pull in 4th the HP is slightly lower than 5th. TQ does equal HP so if the TQ is constant then you can calculate HP based on those numbers. You create maxium load as well as a long enough run to stabilize the rollers and ECU to to stop over spinning the wheel. Also the ratio is closest to 1:1

 

Torque is what is the different on my car. Your cars probably have stock gearing and the heavy dual mass flywheel. My guess is this has something to do with it. At least it is good to know.

 

Peak torque on our stage 4 happens at about 4200 RPMS and Stage 4 GT at 3700 RPMS. My guess is that it you not making as much TQ is not the reasons that you mentioned, but probably differences in your tuning vs. our tuning.

 

Sorry that has been gone for a while. I swapped that after my run with Yeager's boy.

 

Stephen,

What differences did you notice with your single mass versus your dual mass flywheel?

My fifth gear ratio is .968 while fourth gear ratio is 1.174. What are the stock gear ratio's?

 

Stock ratio for 4th = 1.12 and for 5th = 0.92

 

Thanks Dock for grabbing those numbers.

As far as the clutch, I have a special made disc and pressure with the L/W flywheel. Overall it is pretty normal. If I didn't mention it no one would probably notice if you lug it down while pulling away from a light it has a small tendency to shutter. Not enough to notice really unless you have been around this stuff. The disc we have made is pretty good about keeping it to a minimum while using Kevlar. You can also attribute some of it to the L/W setup as the dual mass is designed to take vibration out of the driveline.

 

Stephen,

I'm using 3 five inch carbon ceramic disks.

 

I remember.... You also indicated that the shutter was bad enough that parking on a hill backwards was difficult. The one I am running have been run in cars we have built making 700HP and it is still pretty user friendly while making the grade for holding HP. Pedal effort is near stock. Not sure it would hold 800 though. We can always have the PP remade again if it doesn't.

 

The "backing up the hill to park" problem was present with the Sachs and the Tilton clutches. I believe it is a result of the single mass flywheel.

The single mass flywheel also has a problem of stalling the motor if the motor is reved up a few times and you stop reving. The cure is not to bleep the motor.

 

No, that can be corrected in the software...