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For just headers? Dayum! I don't think they're telling us the whole story. With stock exhaust? That's pointless with the headers.

:bsflag:
 

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Good catch. 222 is a pretty low number for stock HP. I believe most people are dynoing around 240 at least, which would mean these headers will probably deliver about 5-10 HP increase.
 

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The dyno might not be off. The car has 17s, which means there's a 50/50 change it's a sh!tty-matic, which would mean a lower max HP
 

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im raising it too. Cant ever go by a companies independent dyno test


:bsflag:
 

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For OPEN headers..............now go hook up the exh.


Stillen: 11.5 hp at @ 6200 RPM and 18.5-lb. ft @ 3800 RPM at the wheels.

BHP is at the crank (riight?...)

...is 21 at the crank like 11 at the wheels?....
 

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Avg HP loss from crank to wheels is around 20%. Or you could take 80% of crank HP and that's the wheel HP.
 

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Originally posted by DiRN@Oct 29 2004, 02:44 PM
No, BHP is the same was WHP

Actually, I'm about 99.9% sure BHP is measured at the engine... through use of an engine-dyno like this one:

WHP is just that - HP measured at the wheels (to account for drivetrain loss).
 

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• ACURA CL (HEADERS+INTAKE) = +30bhp, +16tq

• ACURA RSX (HEADERS+CAT-BACK EXHAUST) = coming soon
• HONDA ACCORD V6 (HEADERS+CAT-BACK EXHAUST) = +34bhp, +26tq
• HONDA ACCORD I4 (HEADERS+CAT-BACK EXHAUST) = +17bhp, +13tq
• HONDA CIVIC 4 CYL (HEADERS+CAT-BACK EXHAUST) = coming soon
• LEXUS IS300 (HEADERS) = +15bhp, +15tq
• NISSAN 350Z (HEADERS) = +21bhp, +15tq
• SCION tC (HEADERS+ EXHAUST+INTAKE+THROTTLE BODY)= +24bhp, +19tq
• SUBARU WRX/STI (HEADERS+DOWNPIPE+EXAUST) = +36bhp, +47tq


all these numbers seem very high

I say :bsflag:
 

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Originally posted by Jetpilot718@Oct 29 2004, 07:32 PM
Actually, I'm about 99.9% sure BHP is measured at the engine... through use of an engine-dyno like this one:

<span style="color:darkblue">Okay, I used my trusty buddy Google and found that you're right. BHP is measured at the "output shaft." (the crank)</span>
 

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May not be too much of B.S. there. I heard Crawford makes gains close to that with their headers.
Also I think teh car used by alphawerks had I/E
 

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Hey Tom when are we going to get to see Eminem?
 

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Originally posted by SmoothZ@Oct 29 2004, 03:06 PM
Avg HP loss from crank to wheels is around 20%.  Or you could take 80% of crank HP and that's the wheel HP.

Now I know you said AVG but...

This is a merely internet tribal wisdom. Without into getting into why, let's use common sense.

Example (using arbitrary numbers):

Take a 300hp engine HP rwd car and it dynos at say 240rwhp using your theory. No problem.

Now turbo or supercharge it and hypothetically add say 100 engine hp. This car would now dyno at 320rwhp using the 20% drive train loss factor. Does this make sense? Why should the driveline suck up an additional 20hp? No driveline changes were made! Assuming you did add 100hp then you should dyno at 340rwhp.

The reason is simple. It takes a certain amount energy to turn the driveline and some drivelines are more efficient by design than others, but the amount of energy that it takes to turn is a constant. If it takes 60hp to turn the driveline it will always take 60hp to turn that same driveline. Using an arbitrary rule of thumb to apply to all cars doesn't make sense.

BTW, BHP stands for brake horsepower.

Just my $0.02,
 

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Originally posted by thrlskr+Nov 7 2004, 07:42 PM-->
<!--QuoteBegin-SmoothZ
@Oct 29 2004, 03:06 PM
Avg HP loss from crank to wheels is around 20%.  Or you could take 80% of crank HP and that's the wheel HP.

Now I know you said AVG but...

This is a merely internet tribal wisdom. Without into getting into why, let's use common sense.

Example (using arbitrary numbers):

Take a 300hp engine HP rwd car and it dynos at say 240rwhp using your theory. No problem.

Now turbo or supercharge it and hypothetically add say 100 engine hp. This car would now dyno at 320rwhp using the 20% drive train loss factor. Does this make sense? Why should the driveline suck up an additional 20hp? No driveline changes were made! Assuming you did add 100hp then you should dyno at 340rwhp.

The reason is simple. It takes a certain amount energy to turn the driveline and some drivelines are more efficient by design than others, but the amount of energy that it takes to turn is a constant. If it takes 60hp to turn the driveline it will always take 60hp to turn that same driveline. Using an arbitrary rule of thumb to apply to all cars doesn't make sense.

BTW, BHP stands for brake horsepower.

Just my $0.02,

Based on your examples or counter argument, I still don't see your point on the 20% loss being an arbitrary formula. Nothings changed. The loss is a constant. There are several factors that could account for a difference of 20hp at the wheels.

Using your reasoning, say you have a car with 400hp at the engine (no FI, just stock). With an avg 20% loss, you're still going to get a result of about 320rwhp. Of course, the factors that could fluctuate those numbers by as much as 20hp would include barometric pressure, ambient temp, size and weight of the wheels, type of dyno, etc.

What does size or weight of tire matter, you might ask? Seems there is another internet urban myth about increasing your numbers by lightening the wheel weight. I believe Josh or Jay explained it to me once about inertia and the amount of energy it takes to get those wheels rotating.

When I said average, I did not know I had to clarify myself by stating that certain factors could change that formula, i.e. stock vs modified. I'm sure other factors could include the flywheel being changed and decreasing the size and weight of that piece to change the formula and numbers produced.

When you said that hypothetically we add FI and gain 100hp at the crank, that number is a variable and so is the output at the wheels. Why else do people add mods to their cars? To make it look pretty? No offense, but when I said an average of 20%, that would be the constant number in the equation whereas the rest of the numbers would be constantly changing. :cheers:
 
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