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Alex Denysenko
Co-Administrator and Moderator

NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl

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Alex Denysenko
Co-Administrator and Moderator

NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl

I've also read that lower temperatures accelerate wear. My machinist said the same thing. He indicated that the cylinders that show the most wear, are the ones at the front of the block where the cooled water first enters the engine. (the temperature differential could be a factor here, who knows)

I've seen engineering graphs that also support higher temperatures.

I've not done any tests myself, just passing along (parroting) what I've read.

Good Luck!

Ask some S/G or S/C (Q/R and S/R to you IHRA types)why they switched over to alcohol?

Ask some of these guys/gals how long their engines used to last when they had them set up to run at 200 degrees+ all the time for consistancy. 150-200 passes and the rings were history. Cylinder walls were egg shaped and bearings were toast. (oil has come a long way since the 80's also)
These guys and 90% of the bracket racers kept TRW in the piston business.

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Alex Denysenko
Co-Administrator and Moderator

NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl

quote:

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Originally posted by Ryan Wilke:
We all know that fuel is better atomized at higher temps, allowing it to burn more completely,

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Read near the bottome of the below address.

http://www.tpub.com/engine2/en2-47.htm

Here is a graph from the below sight...

http://performanceunlimited.com/illustrations/thermostats.html

The following is from the below address... (an excellent read)

The graph of cylinder-wall wear rate versus cylinder wall temperature tends to be bathtub-shaped, with wear increasing sharply at each temperature extreme (as you'd expect). But while two of the oils turned in very similar wear performance, one oil stood out as protecting the engine against wear at the extremes of temperature. That oil was plain SAE 30 (Straight-grade 30-weight). At either extreme of temperature, the maximum wear rate with 10W-30 was more than double that of the straight SAE30 oil. (The worst performance was turned in by straight 10-weight.)

It is important to understand how a multiviscosity oil is made. A 10W-30 multivis oil (for example) actually starts life as a 10-weight oil. Prior to fortifying the oil with additives, it consist of a straight SAE 10 base stock. Viscosity-index improvers and pour-point depressants (waxy long chain polymers) are added to give the oil added thickness at high temperature, When the 10-weight base stock would otherwise thin out terribly. The reason VI improvers work is that they change shape, depending on temperature. At low temperatures, they collapse into little balls of yarn (or at least, that's how you can picture them); at higher temperatures, they unfold into long, spindly, spaghetti-like molecules that behave a lot like normal oil molecules. At lower temps, in the collapsed state, the ball-like forms act like little ball bearings, easily sliding past each other. This is what allows the combination of a thin base stock (SAE 5, 10, or 20) and VI improvers to act like a thin oil at low temperature, but thicker oil at higher temperatures.

The trouble with VI improvers is that they are not shear-stable; they break easily once unfolded into the long, spindly, spaghetti-like form. They also combust easily, to form soot and other byproducts. And according to SAE 951035, they don't lubricate as well as an SAE oil of similar grade

http://www.eaa49.av.org/techart/str_oil.htm

This is all stuff I from a www.google.com search. Take it for what it's worth. I realize some of it doesn't have good references, and may be part of an advertiser's propaganda, but you see it all the time. The avaition stuff seems fairly well grounded... Personally, I wouldn't want to run an engine at either extreme of temperature. By 'extreme' I mean below zero, or 300+ degrees.

Good Luck!

quote:

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Originally posted by Rustang:
Doesn't cooler temps aid atomization and higher temps aid vaporization?

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...I don't think so.

Actually, I think that atomization is more dependent on the delivery process. In other words, atomization is more dependent on what the nozzle spray pattern looks like & what the velocity of the air thru the carb and then thru the manifold runners. If the air/fuel mix isn't kept moving fast enough, some of the fuel will actually drop out in the runners. Some time ago, somebody offered intake gaskets with fine screens installed in them. It was claimed that the screens improved atomization of the fuel and thus promoted a more complete combustion & providing better gas mileage.

While vaporization is primarily dependent on temperature. The warmer the incoming air & fuel is, the more likely the fuel will vaporize. In addition, heating of the passageways add to ensuring the temps stay up. Fuel that is being atomized at the point of delivery (carb port) will continue becoming smaller droplets in the air stream until it's vaporized. Ideally, all of the fuel should be vaporized by the time it reaches the combustion chamber. This provides the best conditions for a complete burn, thus, you get all the energy/power out of the fuel delivered. That's why FoMoCo used ducts to carry heated air to the carb and used coolant-heated plates beneath the carb to heat the mixture as it traveled out of the carb and into the intake.....