Thread: Big turbo build head question. Could get interesting.

Ok so the head im using for my big turbo build is a de head which is esentially the same as a det head minus the sodium filled exhaust valves.

Now the question i have is the quench area of the head a bad thing in big builds. i know most of the heat during combustion gets transfered to the pistons but i would think some of it would still go into the head. as well. Probably not as much as the force is being punched down.

Do people do work to this area of the head to trim it down some or get rid of the quench area completely. Ive seen mazworx do it on their ve head on their big build. But havent really heard from anyone else. I would also thing because it has a sharp edge to it that might be a bad thing as far as preventing detonation and the quench area period being there might not help any with preventing detonation.

Just looking for some experienced opinions on this. Im debating whether i should do a little dremel work on that area to kind of get rid of it or at least take away the sharp edges. This to me would also help exhaust and intake flow around the valves better as it may be a smoother transition. What do you guys think?

I have done some combustion chamber welding and reshaping in VE/DE heads but mostly just B/K series heads. I dont do it that often though because of the time/cost involved. The best way to do it is by removing all the valve seats before you start. I modify the quench and reweld and reshape it around the contour of the valves. this can give a 10-15% gain in flow on both the intake and exhaust valves. This also helps increase the burn rate because you are basically shrinking the combustion chamber. You should also do this to the sides of the chamber, between the IN and EX valves. If/ When shaped right, again, you can gain flow and increase the burn rate.

Most of the cylinder heads where they cnc remove that quench area is because in part of the piston design. when part of the piston bowl is extended beyond that quench area, it does no good to keep the burn contained to the middle of the chamber, the burn goes right under the quench. Also, the stock quench area does somewhat impeed air flow on both IN and EX and needs proper reshaping (not just grinding and removing all of it away) to gain flow.

I have pics of a few parts i need to take for some people, i will see if i can take pics of the latest head that i've done.

Im necessarily not just saying remove the whole thing but take away the sharp edges and give it some roundness which should help with flow. Cuz im sure if you take off enough your gonna have to get into welding. Which is way farther than i wanna go with it just looking to make the head a little more flowing but more so to make it less prone to detonation.

If your not going to remove the whole thing, then you need to clean it up a lot. If you grind a bit of it away, then make sure its smooth. if you have a lot of rough edges after grinding, then you will have hot spots for sure. worst case, just remove all or most of it.

yeah i would be using a dremmel with one of those nice bits to start off then use a stone bit to make it smooth as hell to prevent hot spot.

How much will that add to the combustion chamber if i do remove most or all of it. Im trying to debate this also cuz i wanna end up with an 8.5:1 motor but if i remove most of the squish area of the chamber thats gonna lower it even more. So i might go with 9:1 pistons instead to make it closer to 8.5:1. Also might use the 1.3mm cosworth gasket also to help bring it closer to 8.5:1 with 9:1 pistons

Mike Kojima did a home port on his inexpensive motor build. He also wrote it up for Turbo and that whole series was online.

Inexpensive motor build part 1 - SR20 Forum