Driveline loss is the power lost to friction (mostly). Spinning weight takes hp so turning the flywheel is a power loss. Driving the alternator, the power steering pump, the water pump, etc. costs engine hp. The transmission gears turn creating friction and power loss. The Ujoints also use hp when changing the angle of the power direction. The trans pushes the gear oil at high speed causing another power loss while lowering the friction loss of the gears and bearings rolling and rubbing. The rear axle changes direction with a Helical cut gear and that costs hp. Then there's the little things like overcoming the drag of the disc brake pads and the rolling resistance of the tires.
Anyway, there's a lot of hp lost to all the different systems. Too many too list, but they're mostly small losses. When all the different losses are added up the driveline loss is usually a percentage of engine power. Vipers usually have a low loss of about 18%. Most two wheel drive systems lose about 23-25%. My Stealth is an All Wheel Drive and rates about 30% driveline lost. Hope this explains what you wanted to know.
Another question if you dont mind of course, but why does the viper have a lower power loss then others?
They have less loss than most 2 wheel drives because they were designed to have less as that increases power to the wheels. Superior designed drivetrain, eg. aluminium driveshaft, less power accessories. Automatic transmissions are famous power robbers, but you won't find one in a Viper. Less weight of the car means lighter parts can be used without compromising reliablilty.
The entire purpose of the car is to go fast, so the driveline gets a better design than most.
Sean Roe dyno'd his World Challenge engine on the stand, then bolted it in the GTS racecar and did a rolling dyno pull. The ACTUAL net driveline loss was 12.7%.
Sean Roe dyno'd his World Challenge engine on the stand, then bolted it in the GTS racecar and did a rolling dyno pull. The ACTUAL net driveline loss was 12.7%.
A few years ago, I remember dyno operators doing "coast downs" to measure drivetrain loss. I haven't heard of that much lately.
Roe's method was by far superior by comparing engine dyno numbers and rwhp.
Good info.
S.
A few years ago, I remember dyno operators doing "coast downs" to measure drivetrain loss. I haven't heard of that much lately.
Roe's method was by far superior by comparing engine dyno numbers and rwhp.
Good info.
S.
Im just curious what causes the powertrain loss in a car, more specifically the viper.
If this is the wrong place please excuse me Im new to these forums.
side note.....also, as you may know....superchargers use small amounts of HP. Some people use turbo's over super for that simple reason, even though you'll probably get a little more punch at the low end with a super.
side note.....also, as you may know....superchargers use small amounts of HP. Some people use turbo's over super for that simple reason, even though you'll probably get a little more punch at the low end with a super.
I wouldn't say small. Superchargers will use over 100 HP.
side note.....also, as you may know....superchargers use small amounts of HP. Some people use turbo's over super for that simple reason, even though you'll probably get a little more punch at the low end with a super.
Nope, match the turbo to the correct engine size and you'll have "punch" all over. For example a "smaller" GT 35R on a Viper will give you good low end but really die out on top end. A 76 is good all around strong power with some motor work to go with it, however I'm an 80's man myself.
Throw in the weight of the rear wheels and tires and you'll see a drop between an SRT10 Ram and SRT10 car on the dyno with identical engines... different gearing confuses the results - but the net result is still a drop in rwhp to the truck
Sean Roe dyno'd his World Challenge engine on the stand, then bolted it in the GTS racecar and did a rolling dyno pull. The ACTUAL net driveline loss was 12.7%.
Nope, match the turbo to the correct engine size and you'll have "punch" all over. For example a "smaller" GT 35R on a Viper will give you good low end but really die out on top end. A 76 is good all around strong power with some motor work to go with it, however I'm an 80's man myself.
Nope, match the turbo to the correct engine size and you'll have "punch" all over. For example a "smaller" GT 35R on a Viper will give you good low end but really die out on top end. A 76 is good all around strong power with some motor work to go with it, however I'm an 80's man myself.
I have the GT35R's on a built engine and don't notice a die out at the top end. The AEM logs from the track show constant acceleration in every gear and the boost stays the same from 3K to redline. I expect the bigger turbos to pull harder through acceleration and run cooler. But I don't see a drop at 20 psi.
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