Maximum safe cylinder head temperature (CHT)

[Fabian]

Btw, what's your cranking pressure atm with the "medium"?

I have no idea. i haven't bothered to check because i stopped experiencing detonation once reverting to the medium compression cylinder head.

I'll endeavour to do a compression check to give you some numbers.

 

[FurryOnTheInside]

haha I just wondered that's all. I know there's enough variance in engines and modded engines and environment that copying another's cranking pressure isn't neccesarily a good idea, nor would be assuming that swapping "a slant" to "a medium CR" would give the same outcome. I'm still trying to get my head to hold enough numbers at once to actually figure out what the increase would be for a certain decrease in volume .. I think I figured out how to seperate the piston to cylinder top clearance from the stated combustion chamber vol....... oops it's 3pm have to go and watch "A bike is born" on Tv... he's refurbishing a 1942 Harley somethingorother.

 

[Deleted member 12676]

Fabian, which head contributed to detonation?
Did you have a lean condition?

 

[Fabian]

Fabian, which head contributed to detonation?

The high compression specification CR Machine Manufacturing cylinder head and the high compression Rock Solid Engines cylinder head, and the high compression straight plug standard cylinder head.

Did you have a lean condition?

My engine is "always" jetted to perfection, plus i have an exhaust gas temperature gauge and cylinder head temperature gauge to make sure that things are operating where they need to be.

 

[Deleted member 22467]

If reducing compression got rid of the detonation do you think maybe higher octane fuels could have done the same?

 

[Fabian]

If reducing compression got rid of the detonation do you think maybe higher octane fuels could have done the same?

Yes, but i am using the highest octane pump fuel available, furthermore, i want my engine set up in a way that it runs properly on readily available pump fuel.

 

[Deleted member 12676]

I agree with Fabian. Any recommended setup should be able to work without "special" fuels.

Fabian, are you using the term "detonation" lightly in a way to say that the engine was making funny noises, or did you take it apart and note the loss of aluminum from the top of the piston?

 

[Fabian]

Fabian, are you using the term "detonation" lightly in a way to say that the engine was making funny noises,

That is correct.
If i even hear the slightest sound of detonation, the engine is switched off; preventing engine damage, then a lower compression cylinder head is fitted to fix the problem.

 

[Deleted member 12676]

Fabian you are throwing me off by saying the "high compression straight plug standard cylinder head" also causes detonation whereas to my knowledge all of the standard heads have low compression, around 90psi.

 

[Fabian]

Fabian you are throwing me off by saying the "high compression straight plug standard cylinder head" also causes detonation whereas to my knowledge all of the standard heads have low compression, around 90psi.

Watch this video again: