I was wondering the difference, my engine is supposed to have 200Hp H22A. Is that the same at the wheels? how does it work? someone help me out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rival12 &raquo;</TD></TR><TR><TD CLASS="quote">I was wondering the difference, my engine is supposed to have 200Hp H22A. Is that the same at the wheels? how does it work? someone help me out</TD></TR></TABLE>

I found this doing a google search. It will give you a general idea to start.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Horsepower measured at the wheel will be lower than what's measured at the crank for one simple reason. Drivetrain losses. Losses from friction, inertia, etc.

Typical losses for manual trans FWD cars is from about 10-15%, and RWD generally 5% more than that. It largely depends on how far the drive wheels are from the crankshaft, where transmission types, clutch, flywheel, driveline and axle weight's and design will have effects. The closer the drive wheel to the crank, theoretically the less loss due to friction. Looking at it another way, the more bearings there are supporting gears, shafts, etc, the more losses there are.

Also, these losses are a percentage of power, not an absolute. Just because a car loses 5hp between the crank and the drive wheel, doesn't mean if you build this motor to 300rpm you will still lose only 5hp. Much of these losses are friction. Friction increases with the square of speed.</TD></TR></TABLE>

Raz

 

200flywheel hp would most likely yield 170wheel hp. Rule of thumb is 85% I believe. You lose hp from the fly to the wheels due to inefficiency.

 

15% loss with manual
20% loss with automatics.

 

approx ofc

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ogbusboy &raquo;</TD></TR><TR><TD CLASS="quote">15% loss with manual
20% loss with automatics.</TD></TR></TABLE>

thats interesting that there is more loss with automatics

 

Not really when you think about it...they dont call it slushbox for nothing. The transmission is built to shift smoothly from point to point without driver control and there's a LOT of power loss in between.

I hate my ******* automatic.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by accordselux &raquo;</TD></TR><TR><TD CLASS="quote">Not really when you think about it...they dont call it slushbox for nothing. The transmission is built to shift smoothly from point to point without driver control and there's a LOT of power loss in between.

I hate my ******* automatic.</TD></TR></TABLE>

i feel u on that one... automatics suck!

 

autos work by the engine turning the inner of the torque converter which gets the fluid moving outwards which eventually turns the outer of the converter which turns the wheels, this is why up until about 40mph the engine spins faster than the wheels

as for bhp vs whp vs hp at flywheel, hp at flywheel = bhp, whp = 85%ish bhp

 

Can you lower the loss even more with a lightweight flywheel and different pressure plate?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdmaccord23 &raquo;</TD></TR><TR><TD CLASS="quote">Can you lower the loss even more with a lightweight flywheel and different pressure plate?</TD></TR></TABLE>

No.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dmurphy2k3 &raquo;</TD></TR><TR><TD CLASS="quote">

thats interesting that there is more loss with automatics</TD></TR></TABLE>

Torque converter makes the difference. In addition to more drivetrain loss, the auto's suffer from horrible gear ratios if you want to go fast...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdmaccord23 &raquo;</TD></TR><TR><TD CLASS="quote">Can you lower the loss even more with a lightweight flywheel and different pressure plate?</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Justin Klemgold &raquo;</TD></TR><TR><TD CLASS="quote">
No.</TD></TR></TABLE>

I would think the lightened flywheel should lessen loss slightly, but the reason you'd use it is so that your engine powers up faster allowing you to make max hp faster.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Justin Klemgold &raquo;</TD></TR><TR><TD CLASS="quote">

Torque converter makes the difference. In addition to more drivetrain loss, the auto's suffer from horrible gear ratios if you want to go fast...</TD></TR></TABLE>

Seriously.

Auto =

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bishop Don A. Shizzle &raquo;</TD></TR><TR><TD CLASS="quote">

Seriously.

Auto = </TD></TR></TABLE>

Well if you're looking for performance then yes it does suck. I have a '01 EX Accord slushbox (in addition to the '97 that's H turbo) and I absolutely love it. Its nice to get in a car and just drive. Its my commuting/heavy traffic car and there is nothing like OEM comfort for around town. Its completely stock and staying that way.

 

Automatic is great for a bracket racer.....as consistent as water.


And yes, quite simply, WHP = horsepower going to the wheel after all losses are factored in. BHP = horsepower at flywheel, this is the number published/advertised.


(BTW, you can't just generalize and say all automatics lose X % of their horsepower and manuals lose X-Y %. All transmissions are different. I've seen losses as small as 8%, and some as high as 20%.)

 

good thread

Makes me realize how much more power my car DOES NOT have, haha good info.

 

Great avatar...really ******* great!

 

BHP stands for brake horsepower. All it means is horsepower measured with a brake dyno. Technically, you should say 'BHP at the crankshaft' or 'BHP at the wheels'.

WHP is wheel horsepower, & all by itself that term doesn't say whether it was measured with a brake dyno or an inertia dyno.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">BHP stands for brake horsepower. All it means is horsepower measured with a brake dyno. Technically, you should say 'BHP at the crankshaft' or 'BHP at the wheels'.

WHP is wheel horsepower, & all by itself that term doesn't say whether it was measured with a brake dyno or an inertia dyno.
</TD></TR></TABLE>

That is the best answer so far. You beat me to it by one post.

 

thanx for the info,

 

I wouldn't go as far as saying automatic trannies have crappy gearing. The Mercedes E55 AMG has a final drive of 2.65:1...that sucker has a pretty good top speed I bet. On the converse, my old Ford Contour had a final drive of 4.4:1, and my mom's Infinit I30t has a final drive of 4.2:1.

I think car companies try to pick FD ratios of 3.5:1 (ish) on automatics because they know people need something streetable. 3.0-3.5:1 generally balances acceleration with top speed.