when people say stock horsepower, this hp is at the flywheel right?

[redbird94]

i was told that for say, my 94 formula when it was stock has 275 hp but that is at the flywheel and i only have about 190 to the wheels is this correct?

[immgeorge]

yeah, that's the way I understand it... A great deal of power is lost in the drivetrain. I believe automatics lose even more power than a manual would... Someone, correct me if I'm wrong...

[Jay 02 TA ws6]

You gotta have more than 190 to the wheels. That would be a 31% drivetrain loss.

Also, the 275 HP figure was probably underrated (they are in the LS1 f-bods, anyway).

[redbird94]

well i no i have more than that because my car isnt stock

[Dave M]

a stock 95 formula automatic should be putting down about 220 hp to the wheels (20% loss). LT1's are not really under-rated as far as I know. Stock LS1's have put down 300 rwhp, indicating they are indeed underrated. Kinda gives you a new appreciation for the guys who are putting big numbers down in RWHP when you see how much you lose through the drivetrain.

[Detroit_Bird]

Have you given her a tune up lately? You said she's not stock, could anything be installed wrong where it would eat horsepower(like headers eating through plug wires)? Maybe fuel pressure is lean?

As I understand it, the vette spec 300 horse mill is the same as an f-bod, only it breathed better. So, if you have the typical intake and exhaust mods you should have picked up about this amount, and so should put down near 240 horse to the rear.

[kwild]

when i dynoed my car stock i had 240 at the wheels and 285 at the fly wheel and i have a 94 formula. So, what that tells me is the LT1 was also underrated. If that helps there you go also my car had a fresh tune up right before the dyno and my car only has 68,000 miles so thats a big deal also. the more mileage the more horsepower you lose.

[Injuneer]

If you had it on a chassis dyno, how do you know you have 285HP at the flywheel? Some of the dyno programs will ESTIMATE the flywheel HP from the rear wheel HP, using GENERIC allowances for drivetrain loss. Do you have an A4 or M6? What did they tell you the ESTIMATED drivetrain losses were?

An engine does NOT necessarily loose HP as the miles build up. They might actually gain in net HP as they "loosen up".

Even if you had a 285HP flywheel rating, that is a 3.6% variance from stock.... certainly, not EVERY engine produced on a mass-production line is going to make exaclty the 275HP it is rated at. +/-5% wouldn't be out of the question. And of course, unless you used the EXACT drivetrain loss for your actual combo, you don't really know that you have 285flywheelHP. Its an ESTIMATE, unless you measured it on an engine dyno before you put it inthe car.

[kwild]

i did the dyno twice once on a chassie and the other on the computer that is how i found out how much HP i had w/ by the Fly Wheel. As for the Mileage statement a car w/ 60,000 miles on it will normally run better and get more HP out of it. As compared to a car w/ 100,000 or more miles on it that is all i was trying to get it at and normally that is true the more miles you have on the engine the more HP you lose.

[Joe 1320]

Originally posted by kwild
i did the dyno twice once on a chassie and the other on the computer that is how i found out how much HP i had w/ by the Fly Wheel. As for the Mileage statement a car w/ 60,000 miles on it will normally run better and get more HP out of it. As compared to a car w/ 100,000 or more miles on it that is all i was trying to get it at and normally that is true the more miles you have on the engine the more HP you lose.

This is only true once blowby starts. As a matter of fact as Fred pionted out, often a motor makes more power as it accumulates the miles. Timing chain stretch begins to retard the timing which is going to aid in upper end HP production and parasitic drag of the rotating assembly decreases. my LT1 with 133K miles is much quicker now than when new and the motor has only bolt ons with stock heads and cam.

[kwild]

but you up graded the heads and cams. which wear and tear with more miles. especially 100,000 miles on the same stock heads and cam.

[Joe 1320]

Originally posted by kwild
but you up graded the heads and cams. which wear and tear with more miles. especially 100,000 miles on the same stock heads and cam.

Mine are stock heads, stock cam. The only thing that was done on mine was new head gaskets. The originals were only partially blown, the head was not warped so it wasn't decked. Upon taking off the heads, even the factory finishing hone was still on the cylinder walls as of 110K miles. Lifters looked new, the motor was just breaking in! The car runs stronger at 133K miles than it did with 36K miles.

Matter of fact, a little type S Porsche Boxter found that out last night. You guys know I live next to the track and this past weekend was the Porsche club at the track. They have been all over town this past week. A few of them are really bad rides..... a few of them are simply posers.