Automatic vs. Manual. = Reduced HP?
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From: vancouver, BC, Canada
Automatic vs. Manual. = Reduced HP?
Is this true that simply having a Automatic in the car reduced HP?
Looking at the HP rating of 1986 - 1990 (single exhaust). The LB9 hp decreased as much as 20-hp simply by opting for the Automatic Transmission rather than the Standard tranny.
But the way my understanding is, this is not possible. How can a transmission (from standard to auto) decrease the OUTPUT of an engine?
Looking at the HP rating of 1986 - 1990 (single exhaust). The LB9 hp decreased as much as 20-hp simply by opting for the Automatic Transmission rather than the Standard tranny.
But the way my understanding is, this is not possible. How can a transmission (from standard to auto) decrease the OUTPUT of an engine?
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From: Mooresville, NC
In the case of an LB9, the cams were different. The 5-speed LB9 got a much bigger cam.
That's just the case here, obviously, on an engine dyno, an engine makes X amount of power. Put it in a car, it still makes X amount of power, just more/less at the rear wheels (auto vs. manual).
Are there any other examples you can think of?
-Corey
That's just the case here, obviously, on an engine dyno, an engine makes X amount of power. Put it in a car, it still makes X amount of power, just more/less at the rear wheels (auto vs. manual).
Are there any other examples you can think of?
-Corey
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From: cinci
it doesn't "decrease" an engine's output, just sort of "loses it" along the way
usually, the rule of thumb is 18-21% drivetrain loss for an auto, 12-15% for a manual
that's a reason you always see similarly equipped cars consistently dynoing better with the manual (assuming neither is a lemon or a factory freak)
auto just sort of acts like another accessory like a/c or alternator, w/e, that just drains some power
usually, the rule of thumb is 18-21% drivetrain loss for an auto, 12-15% for a manual
that's a reason you always see similarly equipped cars consistently dynoing better with the manual (assuming neither is a lemon or a factory freak)
auto just sort of acts like another accessory like a/c or alternator, w/e, that just drains some power
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From: vancouver, BC, Canada
Originally posted by unvc92camarors
it doesn't "decrease" an engine's output, just sort of "loses it" along the way
usually, the rule of thumb is 18-21% drivetrain loss for an auto, 12-15% for a manual
that's a reason you always see similarly equipped cars consistently dynoing better with the manual (assuming neither is a lemon or a factory freak)
auto just sort of acts like another accessory like a/c or alternator, w/e, that just drains some power
it doesn't "decrease" an engine's output, just sort of "loses it" along the way
usually, the rule of thumb is 18-21% drivetrain loss for an auto, 12-15% for a manual
that's a reason you always see similarly equipped cars consistently dynoing better with the manual (assuming neither is a lemon or a factory freak)
auto just sort of acts like another accessory like a/c or alternator, w/e, that just drains some power
If it were at the engine, then the transmission would have nothing to do with it since it's being recorded at the engine and not AFTER the transmission % is removed.
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From: Springfield,OH. U.S.A.
Converter slippage accounts for most of the power losses, the lock up convertors are more efficient than nons.
I still don't think it's as bad as most calculate.(maybe 5% less)
I think MOST of the power differences, as Rippin92RS said, is due to the fact that a stick can stall however much is needed, so automakers put larger cams in them.
Ofcourse having tighter gear ratio's helps too!..
I just LOVE
the 1 to 2 shift in my 700r4...drops right out of the power band...
I still don't think it's as bad as most calculate.(maybe 5% less)
I think MOST of the power differences, as Rippin92RS said, is due to the fact that a stick can stall however much is needed, so automakers put larger cams in them.
Ofcourse having tighter gear ratio's helps too!..
I just LOVE
the 1 to 2 shift in my 700r4...drops right out of the power band...
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From: cinci
Originally posted by camarosource
Then would that not mean the HP rating would be calculated AT the wheels.. after the differential. The engine itself produces XX amount and then XX% is reduce with auto = XXHP reduction. That would mean it's RW HP would it not?
If it were at the engine, then the transmission would have nothing to do with it since it's being recorded at the engine and not AFTER the transmission % is removed.
Then would that not mean the HP rating would be calculated AT the wheels.. after the differential. The engine itself produces XX amount and then XX% is reduce with auto = XXHP reduction. That would mean it's RW HP would it not?
If it were at the engine, then the transmission would have nothing to do with it since it's being recorded at the engine and not AFTER the transmission % is removed.
i think a lot of other companies go by the rwhp and that's what i was thinking of
sorry about that, thanks for the correction
T56 
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