Liquid cooling Lycoming conversion

[averyrm]

The one liquid cooled ram 414 I knew of was quite the hanger queen. More problems then solutions with the liquid cooling.

 

[sky37d]

I looked at a 414 Series V. The liquid cooled engine. This is what I know.
When Continental set out to make a liquid cooled engine, they decided it should help with shock cooling, steady engine temps, all the plusses. What they didn't do was completely re engineer the engine. Also, they don't produce in the volume that auto companies do.

RAM was contacted by Continental to develop an aftermarket installation for the liquid cooled engine, and they chose, wisely, the 414.

In the intial applications, RAM had problems with cooling, and it took them a while to solve that problem. Then they had problems with longevity. There were engines that needed complete overhauls after less than 600 hours. That wasn't a RAM issue as much as it was, and is, a Continetal issue. There was a long time where RAM would not do another Series V installation, only maintaining the existing fleet. The Voyager engine was also used in the Extra 400. Another short lived aircraft.

If cylinder tolerances are held like they are in auto engines, the liquid cooling solution is a good one, especially for turbo charged engines, and engines that fly high.

Continental has apparently solved the quality issues with the voyager engine, because there are not airplanes out there approaching TBO, with no issues.

Liquid cooling makes sense for turbo engines. Not much sense for non-turbo engines.

 

[A Squared]

I looked at a 414 Series V. The liquid cooled engine. This is what I know.
When Continental set out to make a liquid cooled engine, they decided it should help with shock cooling, steady engine temps, all the plusses. What they didn't do was completely re engineer the engine.

Yeah, and that was (one of the reasons) why it died a quiet, lonely death. One of the benefits to a liquid cooled engine is the compactness. Air cooled engines have to have the cylinders far enough apart to get sufficient fin area to get rid of the head. Air is a fairly poor carrier of heat. A liquid cooled engine can place the cylinder bores much colser together, you only have to have a narrow cooling galley between the cylinders. Why is that a benefit, other than the obvious one of size? Bottom end weight. LOnger cranks and crank cases are more flexible, so for a given number of cylinders and a given amount of power the crank and crank case has to be thicker (heavier) to give the same rigidity, there has to be more main brearings. Compare a 4 cylinder lycoming to say a Subaru engine, the crank is much shorter, heck, most V-8's are about the length of a 4 cylinder aircraft engine. So by just putting liquid cooled cylinders on an air cooled bottom end, you lose the benefit of having a shorter, lighter, stiffer, stronger bottom end. In short, all of hte disadvantages of air cooling, all of the disadvantages of a liquid cooled engine, and none of hte advantages of either. OK that's overstating it a little, but screwing liquid cooled cylinders on a air cooled engine is always going to be a bastardized affair. The best liquid coolled engine is going to be one that was designed from scratch to be liquid cooled