Burninoil
Registered User
anyone try enlarging the hole in the precups... thoughts?
just trying to get a brain storm going here
just trying to get a brain storm going here
scavenging
- Thread starter Burninoil
- Start date
Burninoil
Registered User
might help fresh air get in and exhaust out of the prechambers
Burninoil
Registered User
how much do you think you could do before loosing too much turbulence
f-two-fiddy
Registered User
The Guy that has the lowdown is at the 09 IDI rally(icanfixall). He'll prolly chime in after the 4th.
Burninoil
Registered User
maybe we can kick this thread off now?
icanfixall
Official GMM hand model
Yes, I can tell you something about this. First off you rally need the port turulance for better combustion. Seeing that all the fuel is injected only in the precup chamber. That determines what burns. The cups have a step that needsto be ter so don't smooth it out.Opening up the actual port can help but how much is a tuff quetion to ask. I opened up mu frst set andcleaned out the internal step. I went too far. If you try doing any port work on the cups stay only in the opening. Also keeping all 8 precup ports exactlly the same size without using an expensive comparator tool is going to be tuff. I had the use of one a work. You can get very close by CCing the cups too. I also enlarged the chambers in the head because the offshore heads were really ruff castings. I made a custom ball end mill for this cleaning u of th heads. It was 1.168 inches. I dropped my comp ratio just a little with it. That motor had the pistons all around 54 to 56 thousands up out of the block. Factory recommends the pistond to be only 31 thousands out of the block. I don't feel anyone should run as high as I did. very piston had an imprint of the valves on it when I checked the motor after I burned it down because of the freeze plug poping out. You couldsee the imprint but couldn't measure it. That was too close....
