Combustion Chamber mods for FI

[DESRT10]

Anyone who has modded the combustion chamber for FI want to share pics of where they took metal out to increase the chamber cc's to reduce CR? Of course, will measure cc's to ensure consistent chambers across all cylinders.

I would like to enlarge the chamber a bit but still leave as much quench area intact. Can't really make the outer edge near the cylinder wall much larger, so only real option is the back wall. Taking it out adjacent to the exhaust would make it a bit similar to Stryker design (fast burn design to increase the threshold before detonation occurs). Also don't want to remove too much depth at any one location to make the wall to thin.

The other option is to sink the valves a bit, but how much can that be done before it affects flow. If do that, do our stock valve have hardened tips, can they be ground?

Thanks in advance.

 

[Greg Good]

How many CC's do you want to remove?

Never sink the valves.

 

[WOT]

I would guess that sinking the valves would hurt flow tremendously. I would unshroud around the valves as much as possible and keep as much of the quench wedge intact as possible. You might need a ruined head to cut on first so that you can find the thin spots and plot out your profile for the rest of the chamber.

 

[Greg Good]

This is how much you can open up a Gen 3 chamber. This particular set was done for increased swirl, and is on an N/A engine. The tuner installed domed pistons to get the compression back up.

This chamber also works well on FI. You can get the chambers up to 90 CC's without breaking through.

When valve seat work is being done, the only amount the seat should be sunk is to get the top cut of the three angle valve job wide enough, usually .075". Lots of heads have a narrow top cut, and are down on mid-lift flow because of it. This is the exception to the rule of not sinking valve seats.

 

[DESRT10]

This is how much you can open up a Gen 3 chamber. This particular set was done for increased swirl, and is on an N/A engine. The tuner installed domed pistons to get the compression back up.

This chamber also works well on FI. You can get the chambers up to 90 CC's without breaking through.

When valve seat work is being done, the only amount the seat should be sunk is to get the top cut of the three angle valve job wide enough, usually .075". Lots of heads have a narrow top cut, and are down on mid-lift flow because of it. This is the exception to the rule of not sinking valve seats.

Thank you, the picture is not showing up, can you resubmit it.

Thank you again, your expertise is great to have around here.

Bryan

 

[DESRT10]

Here is my dilemna. I am putting on ported heads and extrude honed intake with Paxton, with the bigger X-metal heat exchanger and top mount bigger intercooler (pics later). The black head gasket is no longer available, and anyways I would rather run tighter quench with a bit bigger chamber to reduce detonation. I have a stock bottom end (yeah I know), but from the research I have done, the ported 10s with Paxton result in reduced boost pressure. Makes sense, but they are still putting out decent power even with reduced boost. What matters is how much air/fuel is making it into the chamber. I am in the Stinker order for a bigger crank pulley. So with a thinner gasket (045 Cometic from Justin), I still don't want to be running too high of boost, so would like to mod the chambers to bring CR to low 9s. I don't want to be near 10:1 and boosting on top of that. I still want it to live on 93 gas.