Real HP loss numbers

[Bruce Plecan]

-----Original Message-----
From: Shannen Durphey <shannen at grolen.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Friday, March 12, 1999 3:02 PM
Subject: Re: Real HP loss numbers

I was talking to the folks at Comp Cams and they had a Ford Cup Car cut
apart running a
Optitron motion analysis on the valvetrain.  Was real interesting watching
the valve's motion on a PC.  Oh, and the valve just barely even follows the
motion of the cam other then afor a moment at opening (at 9,000 rpm).   Yes,
was wayyyyy noisy.
Bruce


>Ahh.  There was an article (maybe super Chevy?) on valve spring
>testing done by Isky cams.  They use a block with no pistons or rods,
>no plugs, and power it electrically.  The cam, oil pump, and
>valvetrain are installed.  Oil temps still get to 210 deg even though
>there is no combustion taking place.  And the noise level was
>suprisingly high, too.  Gives a guy a little more respect for valve
>springs.
>
>Clive Apps Techno-Logicals 416 510 0020 wrote:
>>
>> >
>> > I have wondered about this myself.  I have heard anywhere from 15%
>> > to 25% in drivetrain losses.  What I can't figure out is where the
>> > energy is going.  If you have a 300HP engine with 25% drivetrain
>> > loss, then you are losing 75HP somewhere.  Since it doesn't just
>> > disappear, something has to be soaking up 75HP of energy.  My
>> > guess is that the loss would be in the form of heat which would
>> > mean of lot of drivetrain parts would have to be getting really hot
>> > (assuming the 300HP load on the engine).  Since I have only seen
>> > my transmission get warm, it doesn't really make much sense unless
>> > I just haven't had the load on for a long enough period.
>>
>> just estimate how much torque it takes to compress a valve spring
>> multiply x 1/2 revs x # springs X length of valve travel x
>> x losses in the vlave gear and add in the amount that it takes to
>> move the valve train components around
>> 15% sounds reasonable
>> on 300 HP that would meav that another 52 HP was being eaten by the
engine
>> to move the valves
>>
>> Clive
>>
>> >
>>
>> > I wonder sometimes if people don't estimate drivetrain losses on the
>> > high side because they don't want to admit that their engines aren't
>> > as powerful as they want them to be.
>> >
>> > Dan L
>> >
>> >
>