Gone supersonic

I finally got around to putting on the supersonic head I got from a member on my '53. There is a noticeable change in the idle. I haven't driven it yet. The combustion chambers look the same, but the stock head is deeper than the supersonic head. I took before and after videos. I can't notice anything different in the videos though.

Supersonic on top, stock on the bottom. Now I should feel the power when I step on it. R)

 

Whooh. I'd be careful getting on the skinny....

 

The flat area over the piston,commonly caused "quench",is very important.It provides mixture turbulence to make a faster burn, make a bit more power and use less fuel and resist detonation.Does this area have less clearance when the piston is at TDC? We're talking about .035-.045 clearance to be most effective on OHV designs,I believe Flatheads respond the same....Higher compression is better,tighter quench is better,both are much better.

 

Like I said, the combustion chamber in the supersonic head is shallower than a stock one. I can't give an accurate number because both heads were decked and I do not know how much each one was. I know in the service manual, DJs have a slightly higher compression ratio, 7:1 instead of the the stock 6.48:1. I know it isn't much, but hey, every little bit helps!

 

Obviousely a higher compression cylinder head with the smaller cumbustion chamber............might want to back off your timing a few degress and sneak up on it.....High compression works well at higher altitudes, but at sea level may need a higher octane fuel. If there are no published numbers.............you could always pour the CC volumes in both chambers and then do a total swept volume calculation and come up with the before and after change.

 

I already installed it, so I can't compare them by CC.

No Patrick, I don't need them yet. I will need them when I paint the engine Chevy orange! :twisted: R)

 

were gonna need a smoky burnout video to be totally impressed.

 

r)

 

Thats a nice looking Supersonic head!

 

Can you tell just by looking if an L-head motor has a supersonic head? Is the word "supersonic" cast into it?

 

Yes it is.

 

Thanks Bill...