RomRaider

On a mustang dyno I am throwing down 400+ ft/lbs of torque to the rollers.

Why does the romraider dyno show only 270 ft/lbs tq?

I am running 305/30/18 wr710 kumho rain race tires.

Bad computation by romraider?

Bueller?

A log might help with the appropriate car and environmental details it was taken under...

BTW: It's just a tool like anything else, it works best to evaluate relative change as you tune.

Is mustang the type that outputs "wheel torque" instead of calculated engine torque? If so, the number is completely meaningless, arbitrary and misleading (the dyno number, IF mustang is that dyno type). Post the graph.

Okay, here are a couple of dyno graphs for reference. The first one is my baja turbo. look at the numbers it puts down. Now my STI is way more torquey and powerful than the baja but look at the huge difference in numbers.

I am at a loss of words. BTW yes a mustang dyno shows power/torque @ the wheels, not the crankshaft. What does the romraider dyno show? @ the crankshaft or @ the wheels?

Thoughts??

This is my 19 psi E85 map on this dyno run. I changed the gear I was doing my pull in from 3 to 4 and the numbers seem better.

What do you think??

The RR Dyno is an estimate at the wheel as no drive train losses are used to even attempt an engine output calculation.

You don't understand. Measuring power anywhere is fine, you just get X % loss, maybe 5 - 40% depending upon who you ask, worst case being some 4wd systems. Measuring torque, directly, though, and stating it on a chart is just stupid. The torque number needs to be engine torque, calculated from RPM and power, with at-the-wheels losses, obviously.

On an imperial graph such as yours, hp and tq must cross at 5252 RPM, or one of/both of the curves are wrong. The mustang software would appear to be fundamentally broken.

Often people post plots with HUGE torque figures, bragging about it, but the curves are just plain wrong. They usually don't like it when you point this out.

Fred

How does it work? I mean, from fuel flow and afr and timing you could maybe take a stab at engine power/torque, but you'd need to use gear/speed/acceleration to do wheel power/engine-torque-with-losses. One of the other of these? Or something else?

This statement is only true if both power & torque are plotted with the same scale on the range axis.
With the RR Dyno this is not the case, so rarely will you see a 5252 cross-over.

Thanks for the link. And of course, you're right! Tricked me, fair and square. I assume that the above graphs are RR, then? Is there an option for matching scales? Maybe there should be? Or even default? The fact that they always include the same value in both plots for any engine revving past 5k pretty much says both will be well scaled if you use the higher of the two. It would therefore only be bad if the engine revved way more than 5k as the torque would then be squashed a lot.

This invalidates my comment about mustang's above, I think. It wasn't at all clear from the posts that they were from RR and not the dyno, the opposite if anything. Apologies for the, at least partly, erroneous post!

Fred.

Yes RR Dyno.
I was planning a fixed scale option. It is the way it is now for metric units, then you need individual scales for a decent view of the curves.

The above are rr dyno plots.