i'm pretty confused!! hmotorsonline.com rates an h22 as having 200hp, but loads of people who are posting up their dyno results on this site are getting much less than that so...whats going on??? how much hp does it really have??

 

Well the rated horsepower is at the flywheel - the numbers on a dyno(stock) should be less because of the power loss....i'm really not great at words, so i'll let someone else explain. But they will differ because of the model of the h22 i.e. JDM or USDM....

 

That is flywheel power holmes. The Dyno's people are posting is wheel hp.

 

Couldn't have said it better

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by idle &raquo;</TD></TR><TR><TD CLASS="quote">i'm pretty confused!! hmotorsonline.com rates an h22 as having 200hp, but loads of people who are posting up their dyno results on this site are getting much less than that so...whats going on??? how much hp does it really have??</TD></TR></TABLE>

There is speculation as to how much drive train loss there is from the crank to the wheels. Some say 15% my tuner tells me 21% Hope that helps you understand the number differences, also the different engines and different years will change numbers a bit.

 

Stock h22 in a prelude should make ~150whp and 190-200 flywheel hp. Manufacturers quote flywheel numbers because they're bigger.

 

Wheel hp is more important to know than crank hp ratings.

It takes power to move the mass of axles, hubs, driveshafts, wheels, etc. WHP ratings take an account of all these things to see how much HP is actually LEFT to move the car.

 

The 200 hp is at the crank. Theres drivetrain loss when you dyno the car. Automatics lose more hp than manuals. The numbers you get from the dyno like 170hp is the hp to the WHEELS.

 

I think my IQ level just decreased by 20 points after reading this and three other threads before it.
If you take a shaft and spin it at a constant rate you make x power... If you understand that then what would happen when you add gears to the shaft and still spin the shaft at a constant rate -- the amount of energy/ power is decreased porportional to the rotation of the gear that you added... which would reduce the amount of power that is put through the gears. Most all cars up to recently have been rated at crank horsepower or the amount of hp at the crank shaft.. the drive shaft plugs into the transmission which contains gears and thus decrease the amount of horspower put down to the wheels so you can estimate about a 16-20% power loss due to the transmission gearing.

 

So you are saying that the transmission's gearing is literally gearing down the horsepower 20%?

I am just rying to understand what you mean...

Pirate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by specialedition &raquo;</TD></TR><TR><TD CLASS="quote">I think my IQ level just decreased by 20 points after reading this and three other threads before it.
If you take a shaft and spin it at a constant rate you make x power... If you understand that then what would happen when you add gears to the shaft and still spin the shaft at a constant rate -- the amount of energy/ power is decreased porportional to the rotation of the gear that you added... which would reduce the amount of power that is put through the gears. Most all cars up to recently have been rated at crank horsepower or the amount of hp at the crank shaft.. the drive shaft plugs into the transmission which contains gears and thus decrease the amount of horspower put down to the wheels so you can estimate about a 16-20% power loss due to the transmission gearing. </TD></TR></TABLE>

Um...you lose power from turning the drivetrain. Ever wonder why AWD has more drivetrain loss than FWD? Because there's more **** to move. Why the **** would you intentionally drop 20% hp through the drivetrain? You wouldn't. Drivetrain loss is ONLY because there is **** that has to be turned. That's why your 50lb "rims" make your car slower than equally sized 11lb wheels.

 

WAIT WAIT I want to hear his answer. Let him speak, don't bash just yet. I want to see exactly what he means...

Pirate

 

no dude I said that you will lose 16-20% due to the rotational force of the gears within the transmission which takes energy to turn -- the gears within the transmission take force to make them move the crank numbers are not the same as what is put out to the wheels ... maybe wheels and tires have a little bt to do with it but not as much as the loss in energy that occurs in the drive train -- has any one ever had physics?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by specialedition &raquo;</TD></TR><TR><TD CLASS="quote">no dude I said that you will lose 16-20% due to the rotational force of the gears within the transmission which takes energy to turn -- the gears within the transmission take force to make them move the crank numbers are not the same as what is put out to the wheels ... maybe wheels and tires have a little bt to do with it but not as much as the loss in energy that occurs in the drive train -- has any one ever had physics? </TD></TR></TABLE>

No you didn't say that. You said that the gearing reduces power. Which isn't true. It's ******* stupid. Wheels and tires don't have a "little bt" to do with it. They have a lot to do with it. They have lightweight rims for a reason.

 

becuase when hmotor says the 200 hp, its at the ctank not at the wheels like on adyno. 200 crank hp should be making around 170 at the wheels on a dyno with 15 % loss to drivetrain.

 

Mass is only a problem when comparing inertial type dynos.


Frictional Losses
tires on rollers (softer compounds have more friction, wider tires have more friciton, more sidewall deflection = more friction)
brake pads dragging on brake rotors
wheel bearings
axle joints
multiple bearings/bushings in the transmission
friction between teeth on trans. gears
friction of trans. shift forks on synchro sleeves
friction at point of articulation of trans. & input shaft at clutch disk
acessory belts friction
bearings

Pumping losses
Power steering pumping losses
transmission splashing tranny fluid around for lubrication
axles (pushing grease around)
bearings packed with oil/grease in general
air in and around pullies and inside transmission

Accelerating mass (rotational) (only pertinent on Dynojet dynos not dynapack where the load can be applied independant of acceleration)
mass of:
tires
wheels (and air in and around tires)
brake rotors
axles
little ***** and races of bearings
accessory pullies
accessory shafts, gears, armatures/wiring
mass of belts

Electrical losses
electrical load from ignition, stereo, lights, current eddies in the electical system


anyway you get the picture there are many many reasons to read less power. not just more mass of gears in the transmission

Pirate

 

maybe you should learn to read I said that gears ( a gear or a series of gears) when hooked up to a constant rate shaft will reduce the amount of power coming out the other side-- that is the concept and it applies to the drivetrain. The wheels are not where you lose the most power I quess if you ride on 18s or 19s but there is not much of a notable difference between the stock 15s and +1 16s.. You might dyno a couple of extra power outta the 15s but it is not that much of a difference unless you have a turbo or nos or some power added of some kind..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by specialedition &raquo;</TD></TR><TR><TD CLASS="quote">maybe you should learn to read I said that gears ( a gear or a series of gears) when hooked up to a constant rate shaft will reduce the amount of power coming out the other side-- that is the concept and it applies to the drivetrain. The wheels are not where you lose the most power I quess if you ride on 18s or 19s but there is not much of a notable difference between the stock 15s and +1 16s.. You might dyno a couple of extra power outta the 15s but it is not that much of a difference unless you have a turbo or nos or some power added of some kind.. </TD></TR></TABLE>

****. No. Wrong. The weight of the rim matters too. Ever notice how paper tends to be heavier than bricks? And yes, I know how to read. I read this:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by specialedition &raquo;</TD></TR><TR><TD CLASS="quote">the amount of energy/ power is decreased porportional to the rotation of the gear that you added... which would reduce the amount of power that is put through the gears.</TD></TR></TABLE>
Which is, pretty much, saying that different gearing ratios make the engine produce more or less power. Following your logic, you could theoretically make a civic a 9 second car just by putting some tiiiiiiny gears on it.

EDIT: Nitrous (not nos, you ******* idiot) or a turbo doesn't have anything to do with it. Shut the **** up.

 

wowzer...i posted this Q and left it for a few hours...when i come back theres a god damned war being waged but anyway cheers for ur help guys much appreciated

 

if you look at it from an energy standpoint, which would make sense since we're talking about power, in an ideal, no-slip, no friction, no deformation gearset, power remains constant. while gear #5 may have a larger radius, the amount of energy being x-ferred from gear #4 to #5 remains the same as long as crankshaft output is constant.

power is Force x velocity. translated into angular terms, power = torque x angular velocity.

angular velocity is defined as w = V/r, where V = linear tangential velocity of a given point and r is the radius. when you increase the radius of the gear, the tangential linear velocity of the gear's teeth increases in proportion to the increased radius. understanding this via kinematics is more complicated than it needs to be so, think of it like this:

kinetic energy in this case is defined as Iw^2/2. and being that in an ideal, closed system with no heat, sound, friction, or other loss, Iw^2/2 (gear 1) = Iw^2/2 (gear 2), where I = moment of inertia, w = angular velocity.

but since we don't live in that kind of world, it ends up that the real equation looks like:

Iw^2/2 (gear 1) = Iw^2/2 + Losses to heat/friction/sound.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by idle &raquo;</TD></TR><TR><TD CLASS="quote">i'm pretty confused!! hmotorsonline.com rates an h22 as having 200hp, but loads of people who are posting up their dyno results on this site are getting much less than that so...whats going on??? how much hp does it really have??</TD></TR></TABLE>

Here you go bro hope this helps you out....Doesn't explain what others are saying but gives you dyno #'s on a stock 98 prelude..Hope this helps..

http://www.ntpog.org/dyno/index.shtml

 

Oh ok according to you then a 20 lb. piece of paper and a 35 lb. brick is going to give you a huge difference in numbers -- how much do you fiqure they will help out ? as much as a turbo or N2O (which is the correct term for Nitrous Oxide- NOS is a manufactuer) hell I may switch rims according to your theory then I would only lose 10% within the drivetrain... I do not care if you believe me or not but the same power decrease of approx. 16-20 % will still be there when your car is setting on a dynometer with 20 lb. rims or not. The power to weight ratio is important for times and how quick your car gets down the track ( CF hoods, Lighter front end, removing interior pieces, etc.) all make a difference in track times as far as helping the horsepower they are not going to give you 20 extra horses -- Ever wonder why a aftermarket exhaust on a camaro SS increases whp by 40 and on our hondas it only adds 8 whp (if that). What does this mean? I wonder maybe you should stop reading volk racings website or try not to believe everything that you saw in Too Fast Too Furious .....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by specialedition &raquo;</TD></TR><TR><TD CLASS="quote">Oh ok according to you then a 20 lb. piece of paper and a 35 lb. brick is going to give you a huge difference in numbers -- how much do you fiqure they will help out ? as much as a turbo or N2O (which is the correct term for Nitrous Oxide- NOS is a manufactuer) hell I may switch rims according to your theory then I would only lose 10% within the drivetrain... I do not care if you believe me or not but the same power decrease of approx. 16-20 % will still be there when your car is setting on a dynometer with 20 lb. rims or not. The power to weight ratio is important for times and how quick your car gets down the track ( CF hoods, Lighter front end, removing interior pieces, etc.) all make a difference in track times as far as helping the horsepower they are not going to give you 20 extra horses -- Ever wonder why a aftermarket exhaust on a camaro SS increases whp by 40 and on our hondas it only adds 8 whp (if that). What does this mean? I wonder maybe you should stop reading volk racings website or try not to believe everything that you saw in Too Fast Too Furious .....</TD></TR></TABLE>

You are so ******* stupid. You're telling me not to believe what I saw in some ricershit movie, yet you call Nitrous "nos"? And where the **** did the a/m exhaust and lightening bit come from? And there's a lot more factors to drivetrain loss than just gears. Yes, wheels matter. Lightweight wheels are easier to turn than heavy wheels. Any idiot knows this.

No wonder everybody makes fun of the honda community.

 

am i right in thinking lightweight wheels do not increase power??? well that's what i thought... it's like adding a lightweight flywheel... spins up faster but still the same amount of power right? oh well if im wrong.. im a noob...

 

Listen up bud-- this board is not about insulting people with different point of views than you -- If you could actually make somebody believe that light weight wheels make that big of a difference then why don't you sign up for http://www.nationalpreludemeet.com -- and I'll smoke ya with my 17s on all motor prelude and you can tell me how your 15s that weight 20lbs. caused you to lose --- weight makes a difference in power to weight ratio which is something honda engineers are good at... The power comparsion was just that a comparsion to let your stupidass know that power gains reflect other factors than just weight -- weight gets you there in steps but I seriously doubt if you would even get 3-5 percent gains out of light weight wheels. Money would be better spent elsewhere like a lightweight flywheel, or a N20 kit....