Horrible Dyno Numbers inside.....

[01yellerCobra]

Mustang Dyno's typ read 10% lower than a dynojet....but the OP stated he already knew that. The Dynojet therefore should be reading 10% higher than the mustang dyno. Since it's 10% down on the dynojet, he's actually 20% down..which is piss poor. The ambient temp should not make any difference, nor the humidity, nor barometric pressure, since ( if it was done right)..it should be sae corrected, to factor in temp /humidity / pressure.

It also depends on when the dyno was calibrated. If ever. I had a car make the same horsepower on a Mustang dyno and a Dynojet. Two different areas of town. Two very different times of year. And naturally both operators said the others calibration was messed up.

Once again, dynos are tools. Numbers shouldn't be taken seriously.

 

[Pentalab]

It also depends on when the dyno was calibrated. If ever. I had a car make the same horsepower on a Mustang dyno and a Dynojet. Two different areas of town. Two very different times of year. And naturally both operators said the others calibration was messed up.

Once again, dynos are tools. Numbers shouldn't be taken seriously.

Agreed. Everytime I ask about how they are calibrated, (what the actual procedure entails).... or how often they are calibrated, I get a blank stare.
Our local Dyno operator owns a chassis dyno, and tried to calibrate it so it reads the same as a dyno jet.

IF they were all calibrated correctly, you would always be seeing the same hp /tq results, SAE corrected.... from coast to coast, regardless of temp / pressure / humidity. If the engine /blower /ic /HE is one big heat soaked mess, then all bets are off, since the timing is pulled, and it drops like a rock. Even that can change depending on fuel used..and the tune. A 91 tune ( with 91 fuel) will pull timing well before the same 91 tune... but using 93 octane.

So its a useful tool, provided you use the same dyno each time.... and its calibration hasn't wandered off, or been re calibrated..between the times you use it. You may as well just roll race it, say in 3rd or 4th gear, starting at 20 mph, then time how long it takes to hit redline /rev limiter / 100 mph. Quoting max hp at one rpm, then max tq at another rpm is useful info.... but is really cherry picking imo. That's sales BS, esp when quoted at the crank. If it's a DD, what to look for is the entire graph, from idle to redline, or more specific, the area below the curve.

 

[BruceH]

A Mustang dyno is calibrated with a weight. I've seen it done.

Dynos are different. That's about all there is to say about it. You can guess all you want but different dynos will have different numbers, there isn't a set % of difference between different brands.

330 - 340 is right on par for Hot Rod cams and LT headers with a decent tune. FRPP Hot Rods make good power provided the tune is on.

You won't see any gain with the 62mm tb. There isn't enough airflow through a 281 inch motor to warrant it. All it will do is reduce the air velocity to the motor and make it less stock like in smoothness and driveability due to more airflow per degree of blade opening.

The FRPP intake manifold won't help until you have sufficient airflow. I doubt that your current setup can take advantage of what the FRPP intake offers. In fact, I'd guess that your torque below 5000 rpm took a decent sized hit because of the manifold.

IMO your car will be more driveable and make more useable power with the stock intake manifold and cmcv plates. At least that's been my experience. It's an expensive lesson.

 

[dre256]

My last car, Pontiac G6 GTP, spent a lot of time on a dyno (mustang never has been on one) to get as much power as I could out of the turd 3900 V6. Tuner did a lot of fine tuning to it. It was a mustang dyno, but dyno is only good for same day comparison and best it did not get unbolted from it, make the changes and rerun. As my dyno numbers would vary as much as 30 HP over a coarse of a month. That is a lot for a car only putting down on my best dyno run ever 235-ish HP. Only quarter mile tells the truth of your mods. Worst numbers I ever put down was 200-ish. But car wasn't any slower. Still was a 14.5 @ 99 mph.