Technical info on ZR engine

[Konrad C]

I found this technical information on the ZR engine, with some keys points regarding the differences compared to the previous ZZ engine.

http://toyota-club.net/files/faq/12-11-01_faq_zr-engine_eng.htm

Some of the information I was aware of, but the offset crank is new to me. 

This engine to me has restored Toyota's reputation for reliability that blighted the previous ZZ engine. 

[TomdeGuerre]

It’s strange you should post that Konrad, I was just reading about the De-Saxe principle a couple of weeks ago. I’d never heard of it before but was led onto it by an article about Henry Ford using the principle on his V8 back in the 1930’s. I’ve actually worked on the old Ford V8’s (we had a breakdown truck with that engine in it and a customer who still ran an old V8 Pilot). They had two sets of distributor points with the dizzy facing forward into the radiator of all things and it had 18mm spark plugs. A “flat head” side valve engine with the Ford split valve guides – I could go on but it’s nothing to do with Toyota. 

The De-Saxe principle was supposed to be based on the idea of pedalling a bike, it’s easier to start moving off if you have the pedal a few degrees beyond “top dead centre” as any child who has ridden a bike will know. It seems one big disadvantage the engine has is vibration as the revs increase due to the varying piston speeds. You canny change the laws of physics Captain, as Scotty used to say on Star Trek. Still, if the design offers better torque at lower RPM that kind of offsets it. Same as the Atkinson principle Toyota’s using on some of their other engines, it has its disadvantages. 

Thanks for posting that, it was interesting to know.