inferno94

iTrader: (2)

How accurate is it? I've not dynoed my car so I'm wondering how reasonable a figure it offers. I assume any figure would be off the crank and subject to a ~15% drive line loss?

This is all assuming correct info is given to MLV to start with I realize.

EG, today it told me my car made 340hp at ~6800rpm and 16psi.

ianferrell

2560 can't make 340hp, definitely not with a NA head and not at 16 psi... That said, you can use the number like you're supposed to use a dyno... relative numbers, i.e. if you play with timing and get the number higher, you're actually making more power.

edit: To be fair, a 2560 can probably make 340 at the crank, when perfectly tuned, but it'd probably be happening at a higher amount of boost. You probably have a gear ratio or tire size wrong, or you put the weight of the car as being higher than it actually is... there's a lot of room for error with these calcs.

inferno94

iTrader: (2)

I know power #'s are for comparison on the same measuring device but was wondering if there was a general consensus that it was say 10 or 20% high etc kind of like people have rough calculations to go between different brands of dynos.

Actually you were right on the slightly off #'s, I have the weight at 2350lb (car has all oem equipment including air, spare, me, jack + everything added etc) so too light and the tire size was undersized at 22" vs 23.1" actual. I did however have the gear ratio and rear (4.1) right as checked at using this FM page and used 2nd gear (6sp) to do the run from a roll.

Simply correcting the tire size raised the calculated hp to 359 hp, the weight with gas and me is probably closer to 2600lbs but I left it at 2350lbs. I know the hp # has to be higher than actual.

ianferrell

Ahh, cool. IIRC, one of the main things it doesn't account for is drag, which should make it read lower than actual. That's not a fixed percent thing though, When I played with it, I got numbers that were pretty inline with where I think they should be... But I put a bit of effort into making all the variables I put in realistic, and have only ever looked at it in 2nd.