Combustion chamber in the wrong spot??

[Maintenance Chief]

I don’t think it’s a volume thing as much as a direction thing. Less swoop blowing the charge flat across the piston underneath the remnants of the spent charge once the bore is widened

I have seen where people put an angle in a upper port ? Or just flatten it off at some precision.

 

[huskihl]

I have seen where people put an angle in a upper port ? Or just flatten it off at some precision.

Yep. Just have to be careful about popping through the casting on top

 

[Nutball]

Whenever someone wants to try one. Sleeves are staying put, and sizes are getting hit. Even better just going a couple mm oversize.

I wouldn't sleeve a 58mm, Hyway makes a plated one for the 395, so you could probably get away with boring and plating an OEM cylinder that starts out with much bigger transfer tunnels than the Hyway.

 

[Red97]

Whats your take on the port volumes being reduced by over boring? I mean ive got some old 10-10 's that are factory over bore (.020 and.030) and the absolutely feel strong.

Not really sure, most all I have done have been these "extra" cylinders +3-4mm is a large jump. So it is hard telling what all is going on.

Like Kevin mention the direction/control isn't as great and some abrupt walls vs nice cast radius.