Harrop 2015 TVS kit image..

[Blood]

Originally Posted by Irace86

Why run in two gears with two different tunes/fuels?

No idea. That's a question @moto-mike has to answer. But my understanding is that 4th is closest to 1:1 on AT cars, so that is the "best" for displaying actual power, though that doesn't explain why the pump gas run was in 3rd.

[Irace86]

Originally Posted by Blood

No idea. That's a question @moto-mike has to answer. But my understanding is that 4th is closest to 1:1 on AT cars, so that is the "best" for displaying actual power, though that doesn't explain why the pump gas run was in 3rd.

Yea thats what i thought too, that 4th gear was ideal for demonstrating power. In reality it doesnt matter for tuning, right? A tune could be done in any gear long enough to make corrections. But pick a low enough gear and the car will show inflated numbers on the dyno.

[armstrom]

Originally Posted by Blood

...my understanding is that 4th is closest to 1:1 on AT cars, so that is the "best" for displaying actual power

This myth has been around since the beginning of time. It is 100% false. Some gear may or may not be "better" for getting an accurate reading on a particular car or dyno, but the gear ratio being 1:1 has nothing to do with it. The only way to couple your engine to a dyno with a 1:1 ratio is to use an engine dyno. Any chassis dyno will only be able to measure the torque after it has gone through a series of gear ratios. Yes, the transmission gear selected is the first ratio, but not the only one. Next the power goes through the final drive ratio, then if you're on a roller dyno there's the gear ratio between the tire and the roller. Let's say you're in 5th gear on a MT car (1:1 ratio) your gear ratio between the engine and your hubs is STILL 4.1:1.

Of course, any dyno worth its price measures horsepower and then uses the engine RPM to calculate torque at the engine. Since horsepower is a unit of power (force times speed) it is not multiplied by gear ratios like torque is. Of course, there are parasitic losses that we're all familiar with. Perhaps a particular gear ratio is better than another by changing the rate at which the dyno is accelerated. If the gear ratio is too high (in a low gear) then the run from ~2000-7400RPM will take very little time so the dyno will take fewer samples when calculating horsepower. This is one advantage hub dynos have over inertia dynos, you can control the acceleration rate by varying the load and stretch out the elapsed time of the pull. However you will also notice many tuners claiming they can drastically change a dyno result just by varying the ramp rate.

[Wise]

Originally Posted by Blood

It's a bit higher, but the Cusco strut tower bar still fits. If this is the TRD one you have -- http://www.ft86club.com/forums/attac...0&d=1335026028 -- then I don't think it will fit.

Yeah I thought so. Shame I'll have to sell the TRD bar as it's a beautiful piece of hardware.