I know this isn't directly related to ecuflash, but I came across this old article that really is good. May even be a repost but worth it. This forum gets a lot of diy and new to tuning guys.
sort of a wake up call to some of us

Detonation and pre-ignition,

http://www.streetrodstuff.com/Articl...ne/Detonation/

 

this stuff should be stickied!

nice find - albeit a long read

 

I read this a long time ago. It was recommended by Klaus from Innovate. I re-read parts of it when you posted it. Always a good read.

 

good read! so i wonder why there is still so much hype over the hemi engines? and that point of EGT's dropping due to detonation is something new to me. good info.

 

He is talking about the old Hemi engines. From what I read, the new Hemi has a totally non-hemi combustion chamber.

 

cause hemi is the best combustion chamber design.

 

the article said it was one of the worst.

 

so it's not even a true hemi then, just a hyped up name mopar used to sell more vehicles?

 

Exactly. The new Hemi combustion chamber has nothing to do with the old Hemi combustion chamber.

 

very good read!

im surprised when on the topic of pre-ignition contributers he did not discuss carbon or machined edge hot spots???

very good read none the less, does he have a book available?

 

I guess i should've read that book first )

In any case hemi head is good because it flows good and spark is in the right location.
It's not so good because yes, you cant have too high of a compression.And new hemis are just flatter than earlier versions for that precise reason. to get more compression with less domed pistons.

Also the writer obviousely prefers GM.

 

yes any large bore engine is less resistant to dentination, like the auther explained the combustion chamber design amplified the effect.

that also goes for large bore engines with a dome style piston for the same reason.

a good example of this is looking at the power output of a small bore forced induction engine (busa turbo motor to be extreme) vs. a say hemi or big block tuned on the same fuel your power numbers become more similar from detination resistance.

this i know, is a somewhat poor and maybe exagerated example, but an EXAMPLE take it for what its worth not law

 

Yes it was back in the days of vacume ign advance

 

4g63 engines are hemi's

 

pentroof