[stout95]

How close are the hp/ tq numbers on dashboard in b/e.

[cgrey8]

They are only as accurate as the numbers going into the equations (MAF flow values, RPM, BSFC, etc). The main component that is guess-work is the BSFC value. You can guess at that value, but unless you have that value actually measured from a dyno, you don't really know what it is, thus the HP/Tq values will be equally as accurate.

The one thing the HP/Tq values should do is indicate a rough ballpark. If you are seeing 300hp in BE, then that would tell me the engine is outputting somewhere in the 275-325hp range assuming the BSFC is at something reasonable for the engine. If you want conservative numbers, put larger numbers in for the BSFC.

[stout95]

Okay i was curious. i recently did a gt40 head swap on my 89lx auto car. messed with the tune a bit did some datalogging. and on my wot horsepower was at 318. torque was at 346. seemed really high for what is done to the car. thanks for the reply

[copcar]

Actually that may be right on the money. I'll explain.

In most cases on these forums the hp/tq is rwhp (hp/tq as the engine is installed in the car through the transmission and full exhaust and air box). Lets take my car for example. I make 311 and 340 to the wheels. Common accomodation for parasitic loss through a manual transmission is roughly 13-15%. Lets be optomistic and say 15%. So my engine's hp (311) divided by .85 gives me roughly 365 fwhp. Were this engine on an engine dyno the numbers would look quite different. Usually the Front Engine Accessory Drive is removed and instead an electric water pump is the only thing bolted to the engine. The pump is run by the dyno and not an alternator so the drag of the alternator is lost as well. Add to that a less restrictive exhaust and sanitary lab conditions and my engine may look more like 395 hp. The power isn't lost, rather it is used to overcome pumping inefficiencies and the parasitic drag of the FEAD. This hp must be accounted for in the mathematics of setting the engine up in the beginning. Your engine may very well be making that hp, it's just that a percentage is being getting eaten up by parasitic losses.