NaplesFL11GT

What is the real true RWHP of this motor? First I seen 395rwhp and now I am seeing 365-369rwhp.

Snakebite64

It all depends on what dyno is being used to do the testing.

Joe in Dublin

Dyno, which gear car is in, all the engines will be different, 412 is the minimum at the crank, some may make 430 who knows, 365 to 385 sounds like the range at wheels

Driver72

395 rwhp was an overly optimistic or not properly calibrated dyno.

In the SAE testing of the 5.0 Ford got 416 hp from the "crank".
They choose to rate it at 412 hp as the SAE gives manufacturers a 1% variance. Ford "legally" could of rated the engine at 420 hp as it's within the 1% range, but better to under rate than over.
Also keep in mind those are not well seasoned broke in engines, so you can "expect" to see a bit more when broke in, but it still has to be rated at a power level it can make even when "green".

On a manual rwd car with solid rear axle, you'll get 12-14% drivetrain loss on average.

Figure 12-13% then as a fair guesstimate for the Mustang.

416 true engine hp - 12.5% = 364 rwhp

Keep in mind every engine is slightly different and weather and break in miles and so forth will also affect the outcome.

So on a properly calibrated dyno with a properly broke in and running engine expect to see:

355 rwhp on the low side if you have a weaker running "green" engine
375 rwhp on the higher side if you have a strong running and/or broke in engine.

SpartaPerformance

Depends on dyno and correction factor, Dyno Jet usually will give you high numbers while a Dyno Dynamics wont. I would say 355-375 would be accurate depending on the above.

Gene K

True flywheel is 416 bhp.

Hard to say exactly. i dont know how much power it takes to drive the new manual trans.

Total SWAG on a typical Dynojet?
3.73 - 50 miles - bad end of tolerances might be 360 rwhp,
3.31 - 15,000 miles - good end of tolerances might be 380 rwhp,

I think Sparta's numbers would be pretty close if it wasnt for the Dynojets tendency to show less loss at higher hp numbers. In some really high power applications its rumored to actually have gone negative (Dynojet showed more than engine dyno) but I have not personally witnessed this anomaly.

NaplesFL11GT

Going to a lower gear kills that much hp? I knew it did but didnt think it killed that much.

ronniegibson1978

and then you gotta factor in how far above sea level you are..if you're in the mtns, you're gonna see like 20hp less than other places...elevation sucks

Gene K

Reread my post. Gears were only a minor part of the change. Most was just production differences and the difference between 50 miles and 15,000 miles. Power usually peaks between 10,000-20,000 miles.

Mike@DiabloSport

Here are some very real numbers for you, before and after being tuned on 93 octane, bone stock car.