08'MustangDude

~+13 HP
~+17 Torque.

Dino Dino Bambino

I presume that's from the tune that you mentioned earlier. There's no doubt that the factory tune on '05-'09 GT models leaves a lot of HP under the table, so optimizing it for 91 or 93 octane gas and sharpening the throttle response can make the car feel like a whole different animal.

As for the HP measurement debate and which components produce HP losses between the crankshaft output and the rear wheels, various websites provide conflicting information that can confuse anyone new to the subject. I'm going to write an article that'll separate the wood from the trees and post it on my own Angelfire site.

08'MustangDude

The tune will add BHP, then the UDP will free some of that to the wheels, for +~13 HP and +~17 TQ for RWHP.
On top of the small amount of BHP added from the tune to the wheels. Without the Tune, it would add those
#s to RWHP with just the UDP kit.

I did the idle trim relearn process on my Mustang two weeks ago, when the battery was changed.
Big difference in launch with the 93 Octane K&N FIPK Tune. No, I do not run a K&N FIPK, but it
was the one that worked the best with my intake modification. I got 27+ MPG with this tune, LESS
with the Economy tune, so I stuck with it.

66and06stangs

So, what, or where, would you go for your tune? I bought a tuner for my 06 V6 that I sold a while back and it sharpened up the response quite a bit, but now I think I'm ready to tune my GT. Suggestions on what tuner, where to go, etc?

Norm Peterson

This isn't ever going to get settled until we start defining closer what "at the wheels", "at the flywheel" and "at the crank" mean. Otherwise, we're not talking about quite the same things.

What '08 is saying is that the HP input to the crank (from the combustion process, through the pistons, rods, and crank throws) remains the same. That's fine, and I'd be fine with calling that "crank HP'.

But the amount of HP that can be constructively extracted from the crankshaft for accelerating the car is going to be reduced by however much HP gets bled off through the parallel path of driving accessories, typically off the front of the engine. This would be flywheel HP, slightly less than crank HP, and affected by the actual accessory load. IOW, usable output from the crank. Let's not be interchanging these definitions of crank and flywheel HP, as it's only going to keep the confusion going.

Finally we get to wheel HP, which people do seem to be mostly in agreement about. But I'm going to specify that while wheel HP is directly related to flywheel HP, it's only indirectly related to crank HP. Picky? Perhaps. But I think the only way this can be settled is by getting picky.


It's analogous to series-parallel arrangements of either springs or resistors, for anybody who can visualize such configurations.


Norm

Dino Dino Bambino

Norm, I'll word it slightly differently but the essence is still the same.

SAE gross crank HP (before 1972)

This was measured at the rear of the crankshaft with no belt driven accessories attached, no air cleaner, and no exhaust (only stock exhaust manifolds or sometimes long tube headers).
Basically this was indicated HP (input crank HP if you like) minus internal frictional and crankcase windage losses. Nowadays this is only a theoretical number as it's no longer used.
Factors that can increase SAE gross HP include increased displacement, improved combustion efficiency, improved volumetric efficiency (better cylinder heads, cams, intake manifold, throttle body or carburettor), higher operating rpm, lower internal friction (synthetic engine oil, low friction piston rings, low friction bearings, roller lifters, roller rocker arms), and lower crankcase windage losses (good oil pan design, crank scraper, windage tray, lower viscosity engine oil, dry sump lubrication system, flat plane crankshaft).
These factors will also increase SAE net crank HP and Wheel HP.

SAE net crank HP (1972+)

This is measured at the rear of the crankshaft with the engine in an "as installed state" equipped with all standard belt-driven accessories, an air cleaner assembly, and a full exhaust system.
This was substantially lower than SAE gross crank HP but it was a proper reflection of real world conditions as opposed to the previously overinflated HP numbers.
Factors that can increase SAE net crank HP and Wheel HP without changing SAE gross crank HP include anything that reduces parasitic drag to the front of the crankshaft (deleting the smog pump, substituting the mechanical cooling fan for an electric unit, substituting the hydraulic PAS with EPAS or manual steering, deleting the AC compressor, substituting the belt-driven water pump with an EWP, underdrive pulleys) plus anything that reduces pumping losses (higher-flowing air cleaner assembly, headers, free-flowing exhaust).

Q. What is BHP (brake horsepower)?
A. It's the same as SAE net crank HP. The term brake horsepower is sometimes used interchangeably because engine dynos that measures crank HP have a brake to hold the engine at a desired steady rpm.

Q. What is flywheel HP?
A. This is a theoretical number as it's no longer used. SAE net crank HP is measured with an engine dyno connected via a driveshaft and driveplate directly to the crankshaft. Flywheel HP is basically the same thing but with the engine dyno driveplate connected to the flywheel instead of the crankshaft, thus yielding slightly lower numbers.

Q. What is PS?
A. It's metric horsepower as measured in Germany, is used in Europe, and is often used interchangeably with DIN horsepower. It's equivalent to 0.9863 SAE net HP so the quoted PS number is slightly higher e.g. 300 PS or 300 DIN HP = 296 SAE net HP.

Wheel HP

This is measured by a chassis dyno at the driven wheels and yields a lower HP number than the SAE net crank HP due to inertial, frictional, and windage losses in the drivetrain (flywheel, clutch plate, torque converter, transmission, driveshaft, differential, axle shafts, driven wheels/tires).
Factors that can increase Wheel HP without changing SAE net crank HP are a lighter flywheel, lighter clutch plate, lighter torque converter, more efficient transmission, lighter driveshaft, more efficient differential, lighter axle shafts, lighter wheel/tire combination, and the driven wheels being on the same end of the vehicle as the engine (i.e. front engine & FWD, rear engine & RWD) which reduces the number of drivetrain components.

08'MustangDude

I use a DiabloSport InTune1000. I don't "go" anywhere. Taking your car to
have tuned puts you at someone else's mercy. You can always have tunes
made for your car, for whatever tuner you use. I paid $100 for mine, and
there is one for $125, and $150 on FB Marketplace.

Dino Dino Bambino

Here ya go:

Internal Combustion Engine Horsepower: How It's Made and How It's Lost