Ok so say a car makes 230whp on a Dynopack stock and then makes 414whp. The stock crank hp is 287 so 230 is about 80% of that. Would that mean that my 414whp is like 520 crank hp? (287 * .80 = 230, 520 * .80 = 416) The reason I ask this is because my car doesn't feel like it has 500+ hp (even though it supercharged and only makes this from 6000 and up lol). Never has. Doesn't even feel like it's making 450hp. And yes I know the torque is linear because of the supercharger and all of that. Is my way of looking at this dyno correction off?

 

You might just be getting use to the power and that's y it doesn't feel like u have all that hp. Thats what happened to me (quick). After not driving it for awhile, when i did drive it it felt like it was a rocket... Now that im building i haven't driven it in so long that my other slow **** cars feel like rockets..lol.

 

Same thing happens to me...i have to remind my self every now and then... and i do that by reving to about 4000 slowly on the road and then punching it. That reminds you exactly how much power you have

 

a few trips down the drag strip will remind you. or just drive without the cog belt for a few days. i could never believe how much different the car was without the belt.

Also your crank HP is way over 500 then bc the supercharger is very inefficient. prolly closer to 550 crank hp.

 

So all those hp rating we find on magazines like Road and Track and Car and Driver, that's all in crank hp, right? The sometimes also seem to call it bhp...

 

brake horsepower is same as crank hp

yes, they always note chp or bhp, not whp.

 

Some folks like to use a % to calculate backwards to get a bhp number from a whp but this type of calcuation ignores the physics of what going on from the flywheel to the wheels.

Using your example, your baseline dyno gives 57bhp loss to the drivetrain (this is the friction and inertia of the transmission, driveshaft, differential, axles and wheels). Now if you drop in a new powerplant, i.e., supercharged 3.5l 6 cyl, what has changed in the drivetrain? Nothing. It still takes the same 57bhp to overcome the friction and inertia. In other words, drivetrain loss is a constant, not a variable.

So your engine is really making approx. 470 bhp, which is probably closer to what your butt dyno is telling you.

 

Intersting point....hmmmm. Makes sense but I always thought the % was based on the total horsepower. If I had to guess yea my car does feel like 470hp more than 520 hp.

 

how many 500 hp cars have you driven to compare it to?

again, the losses from the SC are not constant nor linear. higher rpm, exponentially higher the loss. So you max hp is your max loss. I still say you are way over 500 chp

 

Not many, I guess I just always thought 500hp was a ***** ton of power and it just doesn't feel like a lot now that I have it. I think part of it may be the linear torque and power curve of the supercharger though. I have gone up against some 05-09 Vetts (Which have about 440hp) on the highway and pulled away from them pretty well so I guess that confirms my doubts. I guess it's just never enough.

 

so does that mean we should be able to take out a stock gt-r rated at 480bhp? If so, then that's a damn good especially when we didnt pay +75K for one, lol

 

+1...

 

if we had awd and lighter cars, then sure

 

On the highway I'm sure some of us could (not me lol) but GT-R's are more like 550hp.

 

DING DING DING!!

That is the very reason I dislike centrifugal superchargers. I don't like waiting until redline for all of my boost.

 

Centrifugal SC - 'nuff said.