Hello,

I recently came accross a discussion on the forums here about a "soft burn", lean burn concept. Really interesting. And it got me wondering what the maximum compression ratio or more specifically maximum pressure a standard A series can run before mechanical failures. For argument sake lets assume that fuel/ design will allow us to avoid detonation. I have searched but couldn't find anything specifically discussing this. It might be an interesting project to build a "soft burn" lean burn A series running a compression ratio of say 16:1.

I understand that the articles I read were written about race engines and had the intake specially designed for intense swirl. I'll be interested to hear what can be done.

In A series race engines, standard rods & crank are being used with as much as 14-1 compression.

Tom

Thanks, that's pretty impressive really.

compression ratio and cylinder pressure are two entirely different things, but they work together. another important factor is squish hieght - the distance between piston crown and head. you have to be careful how close the piston comes to the head, to much gap = detonation, not enough = piston hitting head.

Obviously you read my thread on the round port heads :))
The old one Larry Widmers Soft head
Im glad someone else read it.

Great info the Soft head designs by Larry Widmer.

If Larry designed the A series to run a soft head if would run at 23:1 with 91 octane
fuel as this is what he has done with other engines. However working out the camshaft
timing of his engines are secrets that Honda own now hence he only plays with Hondas now.

The speedway guys are running 14:1 and more but Methanol is in the air.

I sure did, there's another interesting technology for lean burn based on ultra high energy sparks http://www.leanburnignition.com/LeanBurnLives/ignitions.html, at least I think that's the one I remember reading ages ago.

I sure like the idea of the soft burn concept, almost achievable to the person in the shed.

check out the singh lines and dimpled surface modifications
these additions would cure camshafts with crazy timing that
dont idle as well.

The 2 stroke lean burn engine could work with the 2 cylinder
A12 someone made a few years ago :) the A6