Date: Sat, 22 May 2010 21:00:48 -0700
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Re: Optimum WBX rpms; was RE: 4 speed/5 speed shifter
In-Reply-To: <01c001cafa1c$100769b0$6401a8c0@PROSPERITY>
Content-Type: text/plain; charset=ISO-8859-1
Oil temps will climb rapidly as you increase speeds...I don't have all the
engineering data that my engineering buddies use but when running my stroker
928 in open road races at very high sustained speeds...the difference
between say 165 miles per hour and 185mph caused my oil temp to climb. I've
forgotten the numbers but as you approach 200mph the amount of power needed
to increase your speed even slightly is HUGE... Many regular 928s would
easily run 165 all day long with just 300+ RWHP.. but to get through 200mph
took over 400hp and a tailwind...this is at 6000' elevation...
Using the same engine I ran the same identical course at a target speed of
145mph (your goal is to get your target average speed over a 100 mile
stretch of Nevada highway) and used 11 gallons of race fuel. I went back in
a higher speed class (185 max 165 target speed) and barely made the course
on 16 gallons...That indicates how much harder the motor was working to get
an extra 20mph at that high rate of speed.
I imagine a Vanagon's aerodynamics are a bit worse and drag increases even
quicker as speeds go up than it did on my old GT Porsche..
My Oil temps in road races on courses like Road America or Willow Springs
or Phoenix were often in the 230+range even with a full external cooling
system and 16 qts in the system..I had no oil temp gauge when the car was
still configured for highways..
Don Hanson
On Sat, May 22, 2010 at 7:02 PM, 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
>
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