tecknomage

any one know of any good BHP to RWHP calculators or the average equation?

and any info you can give me to increase my understanding would be great.

from what I know BHP is engine HP and RWHP is the hp at the rear wheels.

and if you want to make it simple what’s the FWHP the HP and the RWHP

I've read on many web sights that the BHP is 146-150...

any help / insight is much obliged

ty

RexRyder

iTrader: (10)

its kinda impossible to get the exact amount because some ppl dont have p/s, a/c, etc. so there arent any calculators. just subtract 20-30 from bhp.

FWHP is hp at the flywheel.

146-150 is about right for a new engine. but these cars are like 18 years old man

BlaCkPlaGUE

I always thought that BHP was FWHP, even though it stands for brake horse power. Confused as hell...

ch0g0nda

BHP is brake horse power and is used to measure power at the flywheel.

gingenhagen

rwhp = rear wheel horsepower = measuring the wheels on a chassis dyno

fwhp = flywheel horsepower = measuring the flywheel on an engine test stand or dyno

bhp is brake horsepower = SAE gross horsepower = industry standard before 1971 (but still used in UK) = horsepower at the flywheel with no accessories (e.g. a/c, alternator)

SAE net horsepower = hp = used today = horsepower at the flywheel with accessories

fwhp usually refers to sae net horsepower
rwhp is roughly 18-25% less than flywheel horsepower

but as an example...
1972 cadillac was measured at 400 hp by SAE gross hp standard
1973 cadillac was measured at 235 hp by SAE net hp standard

RexRyder

iTrader: (10)

BHP could also be British HP

gingenhagen

That's when it gets tricky, 'cause british HP is just another way to say hp, which is just another way to say 500 ft-lb/min or 745 watts. At least I know all the cars in the US use SAE net hp, but when the overseas cars read 200bhp, is that 200 SAE gross horsepower or 200 SAE net horsepower...tricky...but then again I don't know if they follow SAE standards

gingenhagen

I just did some quick number crunching with the car specs on supercars.net, which uses bhp for their car specs. I found that bhp on their site equals hp which you see thrown around every day, which is the SAE net horsepower standard specifically. I think all the car manufacturers use the SAE net standard, so all "official"info you'll see will be SAE net standard. Or maybe that's just their site.

But then, when people go dyno their modded cars, there might be a difference between whether you used a chassis dyno or just a dyno on the crankshaft/flywheel/whatever. Then that's 200 at the wheels vs. 200 at the crank which would have that 18-25% parasitic loss when measured at the wheels I quoted.

But then again, I'm no expert. I might be completely misunderstanding everything. Just little bits of info and research I gleamed. Anyone back me up/correct me?

sudseh

gingen: basically correct except that for the fwd cars out there, fwhp could mean front wheel horsepower...

ch0g: bhp as brake horsepower is measured usually at the driving wheels (losses from drivetrain are taken into account)

suds

Tessai

Edit - Double Post

Tessai

Hrm, I always took BHP to be Base HorsePower, equalling FlyWheel HorsePower... learn something new every day.

Guess the easiest thing to do is use HP for flywheel and WHP for wheel horsepower, that way no one gets confused over FW being flywheel or front wheel.

tecknomage

so 146 HP to 150 HP at the rear wheels or at the flywheel

sudseh's got me re-bogeled again

Mint87RX7

whats the difference between horsepower and torque? lol ive never REALY known the difference

Snrub

iTrader: (1)

Power is force per unit time. Torque is force applied in a circular motion. When you hear a manufacturer claim like "146hp," it's @ the flywheel, not at the wheels.

I think often sites like supercars.net use BHP and SAE net HP interchangably. With today's cars having pretty minimal accessory drag on the engine, wouldn't BHP and net HP be pretty darn close? eg. If you remove the air pump from a FC it's debatable whether it's even measurable by commonly available equipment.

I always thought that FWHP stood for front wheel hp, as in a front wheel drive car's equivilant to RWHP.

jarred

to clear up the first post...s4's had 146hp and s5's had 165hp in SAE net standard

rayden

there isn't really a difference, it's just the where it is in the rpm band. this is because hp = tq multiplied by rpm divided by 5250. this is why you will always see the two lines cross at 5250 rpm on dyno charts. there is a chance i could be wrong here, don't take this to be fact. i'm 95% sure though. can anybody correct me or back me up?

$150FC

That's not right. BHP is horsepower at the flywheel, not the driving wheels.

Rayden, you're correct.

tecknomage

this is off a mustang forum but it explains HP and TQ http://www.mustangsandmore.com/ubb/D...orqueVsHP.html


and so i'm guestamating that the n/a S4 rx7 has about 120 hp at the rear wheels ?