Whp vs. Engine hp?

Pelican170

[QUOTE=Econ;1103368]well if HFC's and a CBE net around 15 whp

then

15 * (1+.17) = ~18bhp

about the same as a stock nismo

if you have a nice dyno and you get 20 whp

then
20* (1+.17) = ~23.4 bhp[/QUOTE

Nah thats not making sense. For example, fast intentions claims their hfc's with exhaust net a whp of 24... But a nismo with its exhaust and tune get 19 extra bhp? You see what im saying or not? No way a boost of 24 whp is only getting you 3-5 bhp... If you lose power at the crank than the bhp number is going to a good jump higher than the whp...

SPOHN

I only talk WHP numbers. Only the domestic guys talk in terms of crank HP. Guess it makes them sleep at night.

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Econ

Bhp = whp*(1+.17)

Whp = bhp*(1-.17)

Estimation Obvsiously. Its not perfect.

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2013 Fiat 500 Abarth
2009 Nissan 370z

onzedge

Must be that "New Math".

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Dizon248

You can't do that. When you use the 17% drive train lost, you can't convert back up 17%, you are using a different baseline and it will give you a different value.

So Whp = bhp*(1-.17) is right, but when you do Bhp = whp*(1+.17) you are multiplying by a different baseline. Try it. Say I have 300bhp and I multiply that by (1-0.17), I get 249. Now use 249 to multiply by 1.17, you get 291.33. You just lost 9HP from converting like that.

The right way is this, Whp = bhp*(1-0.17), solve for bhp now. bhp = whp/(1-0.17).

Summary

Whp = bhp*(1-0.17)

bhp = whp / (1-0.17)

4r3s

This as far as math equations go is correct, as far as the specific problem I can't say how accurate the equation is. The previous posts were really bothering me, yes, I am an engineer....

Dizon248

Yeap, I'm still trying to figure out what's up with the OP's post. 19bhp difference between the NISMO and the normal edition. The OP said people slapped on a NISMO exhaust onto the normal editions and only got 5whp. NISMO edition =/= normal + NISMO exhaust. NISMO edition probably has a tuned engine too to boost that bhp figure to 350.

The reason why I say that the NISMO editon =/= normal + NISMO exhaust is because 19bhp =/= 5whp. No way in f'ing hell.

kenchan

whp stands for whip hp, the amount of neck whip you get when you mash the gas in reverse and forward. you have to do 3 cycles and take the average to get the most accurate numbers.

Econ

your right,

i just based the formula off stock Z's 332 bhp vs 275 whp, which is a 17% decrease.

The formula would have to be weighted, so if you were doing individual mods you would have to increase the .17 (17%) to maybe .25 or .3


300whp would be around 351bhp using the 17% formula which sounds about right

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2014 Triumph Thruxton 900
2013 Fiat 500 Abarth
2009 Nissan 370z

Pelican170

Gotta be higher percentage than that since the nismo at 350 bhp isnt going to dyno at 300whp...

Econ

you're right it won't

350 * (1-.17) = 290whp

which sounds right (although i have no idea what a stock nismo whp is)

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2014 Triumph Thruxton 900
2013 Fiat 500 Abarth
2009 Nissan 370z

Pelican170

Actually, thats right around the mark. Ive seen around 284-286 average on dynojets from what ive read...

Pelican170

But its gotta be different for when bolt ons are being added because if you use that formula, the whp to bhp between the nismo and sport dont add up, unless im doing my math wrong again.

eksigned

I'm not entirely sure if I understand your post, but I just skimmed through it. Edit: I don't understand your post. Despite as some mentioned, drivetrain loss is mainly to blame for the difference you seen in crank versus wheel horsepower. Typically it's around 15% loss for RWD (has to send it all the way to the back), and a bit lower for FWD cars (less distance to travel).

I think someone mentioned whp from mods. Individual mods add a good amount, ie intakes, tps/hfc, exhaust. Put them together though, and they unfortunately don't yield the given whp added together. Understand? Stillen Gen3's add...what? 20 whp...supposedly? Pipes and exhaust add 27 whp (let's just say). The total gained doesn't equal 47 whp.

No idea if that even answered your question...

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Pelican170

Nope lol but thats ok. I agree with what your saying. To put it simply, if you add hfc's and exhaust that show dynos of 24 whp, what bhp does it convert to?