Re: Re: Power vs quarter mile

From: TerribleTom (SilverEightynine@aol.com)
Date: Mon Feb 07 2005 - 18:38:41 EST


Josh Battles wrote:
>
> jon@dakota-truck.net wrote:
>
>> "Josh Battles" <josh@omg-stfu.com> wrote:
>> [...]
>> : Don't forget, Ron's truck is a 4x4 and thus has more rolling resistance.
>> : That may account for some of the difference in time between his and
>> Bernd's
>> : 2wd.
>>
>>
>> True. It would certainly add some weight which would show up in the
>> 1/4mi, but the hp and torque numbers given were both
>> rear wheel, so I would expect any additional resistance due to the 4wd
>> would already have been accounted for. So, I'm assuming Ron's engine
>> has a little more power than Bernd's
>> (at the time of comparison anyway) since the power numbers were
>> basically the same, but Ron's had to go through the transfer case.
>
>
> Not necessarily, Dakotas don't have unlocking front hubs. Granted, most
> of that extra drivetrain resistance is already accounted for, however
> the rolling resistance of the front wheels turning the diff and
> driveshaft are not, as the dyno only measures at the rear wheels.
> Correct me if I'm wrong, but when you're in 2wd, all it does is
> disconnect the driveshaft at the t-case.
>
>

In a 1/4 mile drag - you would see more rolling resistance in a 4x4 than
a 2wd due to that front drive train still moving with the truck even in
2wd. On a dyno - you wouldn't really see any appreciable difference.
However given that the transfercase still adds a few more cogs to the
works - you will have some - SOME additional power loss there - due to
the fact the internals of the transfer case are still gonna move - just
not the front drive shaft. The loss of power on a dyno with 4x4 vs 4x2
is neglagable.

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