FYI: Exhaust radiant heat

[Toobuilder]

Originally Posted by SvingenB

Found an excellent article about exhaust systems for performance cars (F1). It appears coating vs HP is a bit more complicated. What counts is diameters and lengths to obtain the wanted inertial scavenging and wave scavenging. The material properties of the pipe is a part of the equation...

Yes. This is why simply making one change to a "well tuned" engine will require more tuning to optimize the "new" configuration. Simply coating/wrapping a set of headers (speaking about cars here) will almost certainly require an air/fuel ratio change and/or ignition timing. The sonic properties (i.e. tuning) of the pipe have changed due to the altered internal temperature. Race cars have different exhaust systems for different elevation race tracks. Same concept. An engine run at a high altitude track will have a different sonic wave speed than a lower altitude track.

There are practical considerations of course, but the more heat you retain in the exhaust for as long as possible, the better for engine power (if tuned for that, of course). For our engines which are not on the bleeding edge of tune, I'd opine the main benefit is the reduction in radiant heat in the engine compartment.

[RV8RIVETER]

Originally Posted by tclaire

Why would you have a loss in oil cooling? Was it a gain in hp
Tim

The decrease in oil cooling I was talking about was due to coating the intake tubes, my current thinking anyway. The intake tubes run through the oil pan and being coated removes less heat from the oil.

As for HP increase. No way to know, since I did not dyno before or after. The owner of Cradin, who coated my parts, has an engine dyno room and has told me he has dyno data to show gains. I didn't follow up as radiant heat reduction was my number one goal. I think there are HP efficiency gains to be had by coating the comb chamber and pistons to extract as much work out of the thermal expansion as possible, but how much, who knows.