[s-cars] Oil Temperature Question-How Hot is too hot

[Taka Mizutani]

IMO, past 150C is too hot, even with synthetic oil.

Two things I think you can do to help fix that issue- you need to put
the undertray back on the car. Most cars that have a undertray as part
of the design need the undertray in order to manage aero flow. IME
with my Miata, there is a significant difference in the cooling
ability with and without the undertray- by removing it, you actually
reduce cooling ability because the air doesn't go where it's supposed
to go. By reinstalling the undertray, you'll help fix that issue. You
also might want to consider doing some ventilation mods to move that
air through- putting vents in the front wheelwell liners might help-
the factory did that with the S4tt, I would think that this might be a
valid thing to do with the UrS as well. I'd put in some sort of
louvered setup so you don't get a lot of water getting kicked up into
the vented area.

The other option in terms of venting is a lot more radical- do what
they do with race cars and install a big vent just behind the radiator
and install ducting so all the air coming off of the backside of the
radiator gets ducted into the vent- take a look at a Subaru WRC car
for reference as to exactly what I'm talking about.

You can also vent the area by the EM and turbo- put big vents in the
pass. side wheelwell or vent the top of the hood above the EM and
turbo.

The second thing to address is the oil temp directly- install a larger
oil cooler. There has been a decent amount of discussion about using
the factory IC location and installing a bigger oil cooler right
there- then duct appropriately to make sure air gets to it and vent
behind the oil cooler- again, wheelwell vents seem to be the better
solution.

Doesn't anyone have a larger radiator installed? DeWitt makes a cool
radiator for Corvettes that has a secondary core that is used as an
oil cooler- just hook up the factory lines and you have a larger
radiator and oil cooler. You might want to see if they make a core
that can be adapted to fit- they are OE for Pratt&Miller C6R race
cars.

Taka


On 3/23/09, Manuel Sanchez <manuelsanchez at starpower.net> wrote:
> Fellow S-Heads,
>
> I was wondering what oil temperature might be considered too hot for
> our cars during a Driver Ed track session? I usually attend track
> events that are early spring or late fall, so the outdoor
> temperatures are on the cooler side, however "warm" days in April and
> November aren't unheard of.
>
> When I'm pushing the car hard, and it's warm out, I've seen the
> needle get a needles width past what would be analogous to the 3/4
> tank full mark on a fuel gauge, at the un numbered hash mark between
> 130 and 170 degree's (150ish). That's the last tick mark before the
> "ludicrously hot" measurement on the oil temp gauge.
>
> It's interesting to see how much of an effect the outdoor temp has on
> the oil temps. At least on my car, cooler track days show up as a
> noticeable measurement (lower) oil temps than if the day were warmer.
> I can't imagine what a summer track day would be like.
>
> I had a instructer once that suggested I back off because the oil
> temp seemed to be to high. Taking it easy did cool things down during
> the session.
>
> Under normal driving oil temps are normal and stay at the 130 deg C
> mark.
>
> My car doesn't have the undertray anymore due to the FMIC and LLTek
> bumper, so the ducting that was there is no longer.
>
>
> If I need more cooling, is there a "better" answer? Do those little
> electric fans really work or would they get cooked easily due to the
> proximity to the turbo and downpipe? Is a bigger oil cooler core the
> "better" answer? Do those heat sink things that you can wrap around
> an oil filter do anything measurable?
>
> Regards,
>
> -Manny
>
> 95.5 ur S6 Avant (mostly RS2'd)
>
>
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