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Old 09-25-2003, 06:35 PM
Super Streeter Super Streeter is offline
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Actually newer car have more drivline loss/Any automatic overdrive trans takes more power to turn then a th400,and a th350 or powerglide take even less then the th400.Newer cars are faster in box stock form then hteir older counterparts because tires are better today.Newer engines are making more horsepower then theri older counterparts too.Dont buy into the horsepower numbers either.A box stock LS1 camaro is rated at 300 hp,but ill usually make that at the wheels,the engine is making closer to 400 hp in stock form.
An automatic trans skews the horsepower and torque curves on a dyno because to some xtent convertor slippage cost horsepower,but increases torque.when running a high stall drag car on a chassis dyno,you would be surprised at some of the torque readings that are built as the convertor approaches stall speed.The slippage tends to scrub some horsepower off though.
an automatic tans suffers the most loss because it has more rotating mass in high gear then a manual trans.Most automatics have all or most of the internal parts required to make all three gears working in motion when the car is in high gear.Conversely,a stick trans has only the required parts moving in any gear.A planetary trans like a lenco is more like an automatic since the gears are aligned sequentially from front to back,every time the car upshifts it is spinning all the parts that made the lower gear{S} work and the parts that are needed for the driving gear.Lencos consume a lot of horsepower,but make up for it with the lack of a torque convertor and clutchless shifting.In reality,if you can make a real stick trnas work in your application it will be faster then a lenco,but a clutchless shiftng conventional stick trans doesnt really exist,but rather such transmissions are really standard transmissions that have ben modifed to shift as effortlessly as possible,and through loose clearances and trick sliders they can make a tans that can be forced to change gears without using the clutch,but is very hard on components and doesnt last long.The only way to calculate driveline loss is with both chassis dyno and engine dyno testing under exactly the same conditions.In reality,in car engine testing also takes into account cooling system and air intake shortcomings which also hurt performance,which means it isnt just about the moving parts.I figure that even the best auto trans race car looses about 20% in the driveline,an that would be in a typical 7000 rpm bracket car with a glide,lightweight convertor,light driveshaft and a 12 bolt.Anything bigger of heavier will add to the loss.There is no way of knowing where you are at power wise,but I have done a lot of testing in my car and have backed it up with some deskdop software.My engine came off the dyno making 680 hp and went into the car and put 490 to the rear wheels.It ran 10.60's at 126.5mph in a 3550# car.My desktop software puts it down as 515 rear wheel horsepower and 730 at the crank,which is similar percentage wise to what I have as actual numbers.This is in a very efficeint stocker style drivline including a lightweight stocker style convertor,and low pressure powerglide,a steel driveshaft,as well as a 12 bolt with a drilled spool and 33 spline axles and with centerline wheels.As a point of interest,my desktop software also said my engine would be spinning 7400 at the shift and in the lights,but the engine runs best when shifted at about 7100 and in the lights at about 7200,so I saved a miniscule amount of power by not spinning 200 rpm more then I had to.It all adds up.So get it on a chassis dyno and make some pulls.


Another thing to remember is that power adder cars loose less power in the driveline since the rpm range is the same as an N?A car,but the power is much higher.Since the driveline loss is dependent on component speed as it relates to ineria as well as to frictional loss,both efects are less percentage wise when the power goes up and the rpm stays the same.
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