SonexBuilders.net

Given how critical engine temps are with these, how come there's not much discussion about combustion chamber coatings and piston skirt friction coatings? Seems like it would be a no-brainer for these? I'm trying to decide what to build, and powerplant is a big deal... I'm a VeeDub guy, but not entirely sold on it (turbo only for me) - could affect my decision to build this or just go with an RV with conventional engine (yeah, I know its twice as much).

I think its because most people have managed to get their engines to cool sufficiently well without resorting to any of that. The AeroVee is a "KISS" (Keep It Simple, Stupid) sort of system. Complexity isn't added unless its necessary.

The complexity of a liquid cooling system for the turbo might end up being one of those necessities; but for the regular AeroVee there doesn't seem to be a need for anything other than a good pressure differential between the cooling inlets and the lower plenum/cowling-exits.

Just did the first engine run-ups on my Turbo this week and she ran nice and strong. There are some minor things to tweak, and I am concerned about post-shutdown heat-soak (in the absence of liquid cooling); but so far so good!

--Noel

Thx... keep us posted how the turbo works out...

I had the piston tops and combustion chambers ceramic coated, and the pistons already had an anti-friction coating. I've only got a couple of hours on the engine after new cylinders, and it still runs quite hot - #1 and #3 at 375+, even during +30 degree weather. I am hoping as it breaks in the temperatures will drop. Next step is to check the CHT gauges to be sure they are accurate.

Bob Hoover of VW engine fame often talked of the usefulness of ceramic coating the piston tops and chambers. I'm not sure I ever saw a real side-by-side comparison of how effective it was, though.

JerryCPP wrote:I had the piston tops and combustion chambers ceramic coated, and the pistons already had an anti-friction coating. I've only got a couple of hours on the engine after new cylinders, and it still runs quite hot - #1 and #3 at 375+, even during +30 degree weather. I am hoping as it breaks in the temperatures will drop. Next step is to check the CHT gauges to be sure they are accurate.

Hmm.. that's my worry. Lots of places say the veedub is only good for about 80hp from a thermal dissipation standpoint, and the turbo does 100hp... if its still getting hot with coatings, that doesn't bode well. As a race car guy, I'd be tempted by head work, external thermal dispersants, bigger oil cooler etc. lol. Need those water-cooled heads like you can get for Jabiru. Can I stuff a Gen3 2.0T in it? (just kidding - VW joke)..

Spinnetti wrote:Lots of places say the veedub is only good for about 80hp from a thermal dissipation standpoint, and the turbo does 100hp...

My understanding is that the limit on continuous power from the heads is ~60 HP. Reason being is that most of the aftermarket heads have the same amount or even less cooling fin area than the original heads that were rated at 60 HP for auto use. The race guys beat the heads up pretty good and then just rebuild or replace them. Seems that a lot of time, money, & effort is being spent to make the little V-dub engine do more than it can reasonably do.

JMHO,

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
166.7 hours / Status - Flying
Member # 109 - Florida Sonex Association

Cooling depends on airflow, though. Well-engineered aircraft applications should have far more cooling airflow than an automotive installation (rear-engined, no less) so it's reasonable to expect higher cooling ability.