average hp loss stock?
#1
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average hp loss stock?
after reading the flame fest that was the 'how much horepower does your n/a make' thread i was wondering...
with all these 150whp and 160whp cars, how much is that over stock? Miata's consistenly dyno 23hp below stock so it's generally accepted. I know our drivelines are similar to their's, so i was curious. This goes for both S4s and S5s.
if i could afford a dyno, i'd go check myself, but well....
with all these 150whp and 160whp cars, how much is that over stock? Miata's consistenly dyno 23hp below stock so it's generally accepted. I know our drivelines are similar to their's, so i was curious. This goes for both S4s and S5s.
if i could afford a dyno, i'd go check myself, but well....
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Other variables:
which gear (4th bypasses the countershaft)
tire pressure
Ambient air temp
barometric pressure
altitude
intercooler heat soak
dyno calibration
mineral or synthetic gear oil
which gear (4th bypasses the countershaft)
tire pressure
Ambient air temp
barometric pressure
altitude
intercooler heat soak
dyno calibration
mineral or synthetic gear oil
#6
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Originally posted by hIGGI
anything between 10 to 25%
20% is pretty normal even for new cars
anything between 10 to 25%
20% is pretty normal even for new cars
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#8
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Its impossible to tell you the number. All cars will have a different number. even a few degrees in temp can change the results. The only stock dynosheet I can remember seeing is the one from mazdatrix and that was like 110whp or something similar which is a huge loss from 146bhp. I had seen a thread here with a large scan of that sheet but I think it may have been deleted.
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thank you, since loss isn't measured in percentage, care to give me an actual number?
drivetrain losses is actually measured in %. It is a form of mechanical efficiency.
A 1000 hp car will lose about 200 hp through the drivetrain and a 100hp car about 20hp.. percentages might not be "the" number but it's far more accurate than any "actual" numbers.
#10
After wasting the better half of my life browsing this site I have come to the conclusion that a health stock rx7 N/A will dyno, on average of corse, 115-125 s4 ; 125-135 s5
The highest N/A dyno sheet I have ever seen on this site was a highly modded s4 making 168 at the wheels.
The highest N/A dyno sheet I have ever seen on this site was a highly modded s4 making 168 at the wheels.
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Originally posted by 13bpower
After wasting the better half of my life browsing this site I have come to the conclusion that a health stock rx7 N/A will dyno, on average of corse, 115-125 s4 ; 125-135 s5
The highest N/A dyno sheet I have ever seen on this site was a highly modded s4 making 168 at the wheels.
After wasting the better half of my life browsing this site I have come to the conclusion that a health stock rx7 N/A will dyno, on average of corse, 115-125 s4 ; 125-135 s5
The highest N/A dyno sheet I have ever seen on this site was a highly modded s4 making 168 at the wheels.
and as far as a percentage, explain to me, using science/math how a 300hp supra dynos 260 at the wheels. but then once it's modified and dynos 860 at the wheels it really makes 1000hp by your logic? the drivetrain hasn't changed significantly, it still produces the same amount of drag.
#13
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We have drivetrain loss because of friction.
Friction is normally measured as a coefficient. its a multiplier(or divider whichever way you want to look at it....)
take your hands and start rubbing them against some cloth. getting warm eh? rub em HARDER. More heat? same principle.
Friction is normally measured as a coefficient. its a multiplier(or divider whichever way you want to look at it....)
take your hands and start rubbing them against some cloth. getting warm eh? rub em HARDER. More heat? same principle.
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he is correct, but to add another variable to this equation: Not all cars are rated at their exact factory rating, first there exists a difference fromthe factory, quality control can be an issue and in some cases differen horsepower and torque by a significant amount. (ive seen as much as ~20whp on LT1 camaros, but that quality control isnt as good as foreign cars.) second, often cars are underrated, I believe the supra TT was rated at 320 stock, yes? LS1 camaros are underrated by around 10 hp or so. SO basically, unless you take your engine out and dyno it, then dyno it through driverain under same conditions, youll never know.
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but people have done that, specifically with miatas, and turbo/supercharger/na they still give a 23-25 hp difference.
and if you wanna talk drivetrain loss, the 350z in this months super street dyno'd 235 whp. down 50, pretty sad. the nitrous kit they installed bumped it to 350 though
so by my method it makes 400 now, by yours it makes ~430. i don't believe in free HP so i'll stick with mine.
and there's no increase in friction, so the hand warming idea, although suitable for the wintertime, is invalid.
and if you wanna talk drivetrain loss, the 350z in this months super street dyno'd 235 whp. down 50, pretty sad. the nitrous kit they installed bumped it to 350 though
so by my method it makes 400 now, by yours it makes ~430. i don't believe in free HP so i'll stick with mine.
and there's no increase in friction, so the hand warming idea, although suitable for the wintertime, is invalid.
#16
Former Moderator. RIP Icemark.
Originally posted by 13bpower
After wasting the better half of my life browsing this site I have come to the conclusion that a health stock rx7 N/A will dyno, on average of corse, 115-125 s4 ; 125-135 s5
After wasting the better half of my life browsing this site I have come to the conclusion that a health stock rx7 N/A will dyno, on average of corse, 115-125 s4 ; 125-135 s5
I normally figure 25 to 30 HP loss on a FC or NA/NB drivetrain.
Last edited by Icemark; 01-29-04 at 10:30 AM.
#17
Former Moderator. RIP Icemark.
Originally posted by 1987RX7guy
Didn't Icemark do something like 170 to the wheels the other day
Didn't Icemark do something like 170 to the wheels the other day
#18
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Originally posted by projekt
but people have done that, specifically with miatas, and turbo/supercharger/na they still give a 23-25 hp difference.
and if you wanna talk drivetrain loss, the 350z in this months super street dyno'd 235 whp. down 50, pretty sad. the nitrous kit they installed bumped it to 350 though
so by my method it makes 400 now, by yours it makes ~430. i don't believe in free HP so i'll stick with mine.
and there's no increase in friction, so the hand warming idea, although suitable for the wintertime, is invalid.
but people have done that, specifically with miatas, and turbo/supercharger/na they still give a 23-25 hp difference.
and if you wanna talk drivetrain loss, the 350z in this months super street dyno'd 235 whp. down 50, pretty sad. the nitrous kit they installed bumped it to 350 though
so by my method it makes 400 now, by yours it makes ~430. i don't believe in free HP so i'll stick with mine.
and there's no increase in friction, so the hand warming idea, although suitable for the wintertime, is invalid.
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using science/math how a 300hp supra dynos 260 at the wheels. but then once it's modified and dynos 860 at the wheels it really makes 1000hp by your logic? the drivetrain hasn't changed significantly, it still produces the same amount of drag.
F=ma
since you have more power on the flywheel we know that "a" will definitely increase therefore "F" must also increase in order to achieve that particular "a". Keep in mind that you have to be accelerating to measure the peak Hp. You can't have constant speed to measure peak hp.
Also you Clutch efficiencies are given in percentages. Normal street clutches are rated at about 85%-90%?? while performance clutches 90%-95%??
#20
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loss @ X rpm will be the same regardless of hp, but @ different rpm's it changes? its been a while since ive had physics so hrm... can ya tell?
yeah the hp loss will be the same for the same acceleration. However, hp losses will be different at different acceleration rates.
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I knew I was pretty much correct when I factored drivetrain loss on my car. Since people always ask me how much hp it has. I say, "146hp to the flywheel, which gives me about 120hp to the wheels."
#23
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Originally posted by Slacker7
The drivetrain as you know it rotates. This rotation causes the drivetrain's rotational inertia or "effective" mass to increase as it spins faster.
F=ma
since you have more power on the flywheel we know that "a" will definitely increase therefore "F" must also increase in order to achieve that particular "a". Keep in mind that you have to be accelerating to measure the peak Hp. You can't have constant speed to measure peak hp.
Also you Clutch efficiencies are given in percentages. Normal street clutches are rated at about 85%-90%?? while performance clutches 90%-95%??
The drivetrain as you know it rotates. This rotation causes the drivetrain's rotational inertia or "effective" mass to increase as it spins faster.
F=ma
since you have more power on the flywheel we know that "a" will definitely increase therefore "F" must also increase in order to achieve that particular "a". Keep in mind that you have to be accelerating to measure the peak Hp. You can't have constant speed to measure peak hp.
Also you Clutch efficiencies are given in percentages. Normal street clutches are rated at about 85%-90%?? while performance clutches 90%-95%??
and there's no power on the flywheel. only torque and rpm are any mechanical parts' concerns.
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Originally posted by projekt
umm F=ma isn't a good comparison. the force will increase(power/torque), and the mass will stay the same so the acceleration will increase. you've just shown how more power makes your car accelerate faster.
and there's no power on the flywheel. only torque and rpm are any mechanical parts' concerns.
umm F=ma isn't a good comparison. the force will increase(power/torque), and the mass will stay the same so the acceleration will increase. you've just shown how more power makes your car accelerate faster.
and there's no power on the flywheel. only torque and rpm are any mechanical parts' concerns.
Sorry I couldn't explain it better.
But F=ma is the easiest way to explain it. In order for the engine to accelerate the car, it must first accelerate the drivetrain. Which takes up hp (which is proportional to torque). The faster you accelerate the drivetrain, the more hp(or torque) it takes.
Whatever power(torque) is not used is what you have to the wheels and that is what determines the car's acceleration.
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no, f=ma works, it just depends on what F you are calculating. If you are calculating F as the force exerted by the engine, then yes it is bad,however;
if you are calculating F as the force required to twist a drivetrain then it works.
F=M(constant)A(increases as engine produces more power). As the drivetrain accelerates faster, more force is required to do so. Thus as long as the mass is constant, more force is required to accellerate the drivetrain.
its proven, the more power you make, the more power you lose to drivetrain loss.
perhaps its not as noticeable between a 125fwhp miata and a 170hp turbo miata, but between a 275fwhp lt1 and a 450fwhp S/C Lt1 its quite noticeable.
if you are calculating F as the force required to twist a drivetrain then it works.
F=M(constant)A(increases as engine produces more power). As the drivetrain accelerates faster, more force is required to do so. Thus as long as the mass is constant, more force is required to accellerate the drivetrain.
its proven, the more power you make, the more power you lose to drivetrain loss.
perhaps its not as noticeable between a 125fwhp miata and a 170hp turbo miata, but between a 275fwhp lt1 and a 450fwhp S/C Lt1 its quite noticeable.
Last edited by Tsunami; 01-29-04 at 05:22 PM.