quote:
I finally got in touch with Neil Ruegsegger, PhD to talk to him about
oil. As I mentioned, Neil works at the Chevron Richmond, CA research
labs, is a tribologist (lubrication scientist, his specialty is
filtration) and owns a Pantera.
We talked for about an hour discussing many things. His opinion is that
you may be able to run a synthetic oil a little hotter, but not much.
He's had experience is with a number of racing teams. There they try to
keep the oil temps below 220. He said 250 is getting pretty hot. Above
that, you start to risk engine damage. Another reference on the web
(sorry I lost the link) suggested max temps for conventional oil of 240
deg and 260 for synthetics.
My guess that if you can run a conventional oil at 300 deg then
a synthetic might be good for 325 is a bit optimistic! The delta may be
about right, but both temps may be 50 or more deg high. I had based my
300 deg temp estimate on the Olds III-D test in which an oil is run for
64 hours at a 300 deg in an Olds V8 engine. In order to pass,
the viscosity must increase no more than 375%. Typically a
synthetic will thicken only 10% or so. I figured that if a conventional
oil can run for 64 hours at 300 deg, then 30 min at Silver State should
be no problem. What I didn't know then was the Olds III test is run at
100 HP and unknown (probably fairly low) RPM. This is a far cry from
running flat out at SS.
Although Neil didn't know one way or the other (probably because the
racing cars he's worked with have oil coolers) I've seen many references
to the temperature lowering capabilities of synthetic oils. This may,
however, be only for the primarily di-ester based synthetics (such as
AmsOil) and Polyol esters which apparently have both lower friction and
better heat
transfer characteristics. The numbers I've seen mentioned are a 20 to 50
deg reduction in engine oil temperature. While 50 deg seems a bit much
to believe, there appears to be a basis for the reduction. In a really
excellent document by Hohann van Rooyen "Performance Fluids for Modern
Cars"
http://www.nac.ac.za/~TJVANROOYEN/Lubricants.htm, (who appears to
work at the South African National Accelerator) he states that ester
based synthetics have a 10% better heat transfer capacity than
conventional oils. This document is one of the best I've found so far.
It's 93 pages long and has a lot of good technical info.
AmsOil has a number of testimonials to it's temperature reducing
capabilities. One of the more believable ones is from a Balcones
European Motors in Texas where they reported a 20 deg drop in their own
SCCA Porsche 911 racer with AmsOil 20W-50 over Mobil-1 and that a
customer reported a 35 deg drop.
http://www.amsdj.com/products/heat.html. What this means, of course, is
that you should be able to run at higher power and RPM at the same
temperature and that if the safe maximum temp is also raised, there is
even more to be gained.
Neil didn't have anything good to say about Red Line. He mentioned that
while he was working with the Nissan raging program they tested three
cars in the same race (may have been Daytona, I can't remember). One had
Redline, another Mobil-1, and the third Chevron's top conventional (I
think he said Delo 400). The Redline engine "grenaded", Mobil-1 finished
but bearings were badly damaged while the Chevron oil did great. It
should be mentioned that this was in a 900 HP 2.5L V6 with very good oil
cooling and probably has little to do with running Silver State in an
uncooled Pantera.
Bottom line is I now think that 275 - 280 might be a relatively safe
upper limit for a quality synthetic. This is partly based on Pedro's
comment that Larry Stock has been running at 280 deg without apparent
problems. It would be interesting to know what oil Lary was running. I
assume he was running a synthetic. If he was using Mobil-1, then there
may be some additional speed to be had by switching to AmsOil.
BTW, Neil is building a very special 4.6L Cobra engine for his Pantera.
Custom crank, cams, pistons, intake, etc. It is designed to run to at
least 8500 RPM. If he can keep it breathing he should be able to get
something like 500 HP out of it.
--
Sincerely,
Richard Barkley
To Ski or not to Ski, that is the question!
Richard Barkley
(310) 373-6695 (home), 813-2432 (work)
E-mail:
[email protected] (work),
[email protected] (home)
Mammoth Condo 2BR+loft/3Bath - Horizons 4 #186 (760) 934-6758
Condo web address:
http://home.earthlink.net/~rbarkley
