Which one of these combustion chambers you like the best?

[boss]

Cubic_Cleveland, the gasket is for a 4.155 bore, i have learned from the 4V feuling heads that unshrouding a 4 valve chamber like a 2V could actualy screw it up 2V and 4V are diffrent animals on this.

lada ok, i have LOTS of info/pics on Feulings 4V heads as im heavy into them along with the old billet 32V Dominion sbf heads. I have a few sets of ea and are in the process of 3dscanning/redesign/cading a new 4V Cannonball Clevor billet head baised on the old Dom heads. was thinking of doing the same to Feulings heads afterwards for 4cam XL apps.












so any questions on the 4v Feuling stuff just ask.

[lada ok]

WOW great work mate !
I'm thinking you have a flow bench ?
I've done plenty of 2v heads, but I maybe about to do a 4v
There has been lots of great discussion over the last couple of days on 4v flow, .... fella's are popping up out of the wood work all over the place.
have you come to any hard and fast rules on intake csa, angles, valve sizes, divider length /shape
Ta ... robbie

[boss]

depends on 4v app you are talking about, pushrod or ohc but combustion chamber wise, imo Stars chamber is the standard shape to start with.

http://dragbikelive.com/news/12087/hot- ... have-pics/


heres some other billet v twin race versions

[lada ok]

Ta boss

[Cubic_Cleveland]

Interesting to know boss, thanks.

[ShΣtland]

This has been a very interesting thread for me. Regarding the question of trading off squish with boost in a pent roof chamber, there has to be something said about exaggerating the scenario to arrive at an answer. There would be nothing more exaggerated on this topic than the 60-80 psi boost F1 engines of the 1980s. BMW ran a fairly conventional 1980's vintage pent roof combustion chamber in their engines, and they ended up with a shallow dish design with peripheral squish band.

bmw piston.jpg
While they would have had a need for a relatively low compression ratio, they also would have had to run large piston to bore clearances , promoting piston rock, as well as excessive fuel to keep the piston cool. Under these extreme conditons I can visualise the shallow dish would promote squish only where it was needed, while promoting mixture movement towards the spark plug and away from the cylinder walls. It would also reduce the chances of trapped volumes forming around the intake side of the piston due to piston rock. All of these features would contribute to lessoning the chances of preignition or detonation.

What book is this please ? Thanks