Date: Sun, 23 May 2010 18:00:44 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Optimum WBX rpms; was RE: 4 speed/5 speed shifter
Content-Type: text/plain; format=flowed; charset="utf-8"; reply-type=original
Hi yes, I was thinking about this and I would say that increased load and
higher rpm in top gear, and thus a higher speed, would result in increased
oil temps, compared to say 10 % lower rpm and speed.
for sure there is a timing lag in heat removal, from change to change. Say
you're going 65, and you increase throttle opening, rpm, and speed.....seems
that more heat would get into the metal parts of the engine, and that heat
would work it's way to the radiator and be removed, and from one rpm/power
level to a higher one, there would be some lag, thus metal parts get hotter,
thus oil gets hotter , at least for a while.
Agree with you on that .
to simplify things, I was thinking steady state.
Say cruise on the level at 65 mph....on a hot day , ...see what that oil
temp is.
Then do the same thing on the same road, but at 70 mph .....and don't take
the measurements until it's been say 5 full minutes at a given speed.
Would the 70 mph oil temp be higher than the 65 mph one ?..
sure, I'd have to say it would be, but not by that much, not in steady-state
measurements, is my hunch.
But ...yes, you'd think there would be more heat generated, and it would
show up in the oil temp. though my hunch is it won't be that much
higher...after all, the coolant temp will be the same at 65 mph and 70 mph.
...and once that's stabilized in steady state ...
it would be removing heat from the oil via the coolant and radiator in the
normal manner....
if the cooling system can keep coolant temps at the same in those two
conditions, I would expect the oil temp to be nearly the same.
We'll have to take some temp measurements to see what we can see.
would love to see Frank G's comments ..he gets into a whole other level of
it ...very 'engineer mind' about it.
Scott
----- Original Message -----
From: "Dave Mcneely" <mcneely4@COX.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, May 23, 2010 5:33 AM
Subject: Re: Optimum WBX rpms; was RE: 4 speed/5 speed shifter
> Pardon my naivete. I thought the production of heat by work effort was
> simple physics. When I work harder, I get warmer and sweat more than when
> I work less hard. I believe the same is true of machinery (except for the
> sweating part). The heat is the part of the force applied that isn't
> turned into productive work. To the degree that that is true, wouldn't
> whatever materials were in contact with the parts developing the heat
> themselves become hotter -- including oil. We hope that most of the heat
> is collected into the coolant and dissipated via the radiator of course,
> but there is definitely a time lag in this. Not true?
>
> David
>
> ---- Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM> wrote:
>> hmmm,......could be.
>>
>> I don't see why increased windge from higher rpm in top gear would raise
>> oil temps.
>> Windage may be one factor in dry sump engines...and
>> for many performance cars the primary purpose is to lower the engine as
>> far
>> as possible in the chassis, lowering certer of gravity for better
>> handling.
>>
>> Be interesting to see what Frand G says on the subject,
>> and I'm sure he has posted on oil temps somewere in the past.
>>
>>
>> ----- Original Message -----
>> From: "Dennis Haynes" <d23haynes57@HOTMAIL.COM>
>> To: <vanagon@GERRY.VANAGON.COM>
>> Sent: Saturday, May 22, 2010 6:41 PM
>> Subject: Re: Optimum WBX rpms; was RE: 4 speed/5 speed shifter
>>
>>
>> It does. Even with high capacity oil coolers I see the oil temp increase
>> at
>> higher speeds over time, even with the water temp staying normal. Most
>> likely the problem is the increased windage from the rotating parts
>> sitting
>> in the oil. This is why many race engines run dry sumps.
>>
>> Dennis
>>
>> -----Original Message-----
>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
>> Of
>> Dave Mcneely
>> Sent: Saturday, May 22, 2010 7:56 PM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: Optimum WBX rpms; was RE: 4 speed/5 speed shifter
>>
>> ---- Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM> wrote:
>>
>> > I do not see any reason why 4,200 rpm would produce particularly
>> > higher
>> > oil
>> > temps than 3,800 rpm would.
>> > other than slightly increased load due to speed and aero drag ...
>> > I see no reason especially why oil temps would be higher with a bit
>> > more
>> > rpm.
>> > Scott
>>
>> Scott, maybe it's the slightly increased load.
>>
>> David McNeely
>
> --
> David McNeely
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