eyecandy

iTrader: (19)

I need a little help here. I have been trying to describe to my dad how a rotary engine is better than a piston engine. The problem that I am having is how they get low compression after say 60-80K miles, and they will need to be rebuilt.

He has been telling me since the compression drops very quickly compared to a piston engine that the rotary engine is a WEAK enigne.

Bascially what I am asking is what causes the compression to drop quickly compared to a piston engine, and is there anyway to prevent/slow down the loss of compression?(i know they is more wear areas to consider) Also say you have an rotary engine with 120psi and other with 90psi, is there like a 30% drop in power?

Thanks!

peejay

Well I have an engine with 157k and good compression, and this is about half of the expected life for that engine (1st-gen) assuming the rest of the chassis is around that long.

I also have a strong 12A that I pulled from my last car at only 113k-ish because I had a ported engine that needed a home.

Project84

Not all rotaries lose compression after 80,000 miles. go to www.howstuffworks.com and show him how a rotary engine is more efficient then a piston engine. A 1.3 liter rotary does as much work or more as a 2.6 liter piston engine. The new RX-8 had the intake and exhaust ports moved so that the exhaust stroke doesn't overlap the intake stroke. (and though it is a rotary, it does go through all for "strokes", just like a piston engine)

The new RX-8 is putting out 255 horse power from a 1.3 liter rotary (non turbocharged) and 10:1 compression. Don't sound to weak to me.

eyecandy

iTrader: (19)

Thanks for the help but WE both know how the engine works and what it is compared to. I am just trying to explain to him how it is not a weak engine, thats the part I am really having trouble with.

12A's are of a different story, they are not making alot of power so they are not under as much stress.

Although the rotary is really not a 1.3 liter, Mazda has said it themselves that is should really be be displaced at 2.6 liters. And they just sate it at 1.3 to make it sound that mush more effeicent, it was a marketing ploy to get ppl to bu the cars(which I think it was VERY intelliegent). Even at 2.6 liters it is still a good engine though.

eyecandy

iTrader: (19)

Also when I am mean weak its not that they cannot make power, its the fact that they loss compression quicker than a piston engine. That is what I mean by weak.