Is this good dyno numbers?

StrokeThis347 · 04-22-2013, 07:02 PM

Quote:

Originally Posted by G37Sam

That's a huge misconception IMO. You do know your diff ratio is not 1:1 right? And your wheel diameter alters both speed & torque. If you want to know "true hp" pull the engine out and strap it to an engine dyno. That's why dynos are a tuning/comparison tool not a "how much power is my engine making" tool. It gives a good idea but should be not taken religiously IMO.

The real concern should be, do you really want to be doing close to 150mph on rollers without the air flow to keep the tires temps down?

For the amount of time your at this speed tire temps are not even a consideration.

Of course your differential is not 1:1, you just want a direct drive or as close as possible through your transmission to get the most accurate numbers. But yes a dyno is a tuning tool.

If your concerned about wheel diameter changing your HP numbers, use a better dyno such as a eddy current dyno not inertia.

The 1:1 is a "industry" standard, every tuner/dyno shop I know along with any tuning classes you can take will tell you to dyno in a 1:1 ratio or as close to it.

G37Sam · 04-23-2013, 02:24 AM

Quote:

Originally Posted by StrokeThis347

For the amount of time your at this speed tire temps are not even a consideration.

Of course your differential is not 1:1, you just want a direct drive or as close as possible through your transmission to get the most accurate numbers. But yes a dyno is a tuning tool.

If your concerned about wheel diameter changing your HP numbers, use a better dyno such as a eddy current dyno not inertia.

The 1:1 is a "industry" standard, every tuner/dyno shop I know along with any tuning classes you can take will tell you to dyno in a 1:1 ratio or as close to it.

That is true, but what I'm trying to say is, even if you dyno at 1:1 gear ratio, your torque is still multiplied by 3.3 through the diff. So the whole attempt to get "accurate engine ratings" is now off anyways, so you might as well tune in a slightly lower gear. When tuning my car on the dyno we spent at least 2 hours on the dyno, and had to stop every now and then to get fluid temps to cool down so it's safe to assume the tires were also getting too hot.

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