I just stumbled across this thread early this morning.
Flee,
Thank you for your vote of confidence. Over the years, we have seen the crap valve jobs come down the pike. Our shop does things to a cylinder head many don't even know needs done. We aim to not just keep, but improve our reputation.
Newlite,
We have modified our approach over the years. We still do plenty of efficiency builds, but as of late, we are building much more innovation and power. The good thing is, you can have your cake and eat it, too. Fuel economy and big performance do not need to be exclusively independent of each other; they just can't be done at the same time... We have found some parasitic drag reduction tricks that are very unique. Sometimes, it's not making power, but keeping from using it up the wrong way.
FUB,
I know we have had our disagreements and respectfully, I have to disagree again. The exhaust port is so poor that is it hard NOT to improve it, even for a stock-built engine. Intake swirl can be improved also, but bottlenecks in the exhaust are just wrong and always will be. Here is an old pic of Matt Whitbread's, which really does not do justice to how bad the exhaust port really is:
http://i702.photobucket.com/albums/ww29/mrwhitbread/head8.jpg.
This really doesn't show it all, but that port is a restriction. When we first started attacking it, we got reports back of with reduction of exhaust gas temps with the same build parameters. Nothing wrong with that...
Evaporating fuel?? We are talking about a diesel. There is no evaporation, but the swirl is very important as it literally 'bends' the flame path and keeps it from hitting the combustion wall as quickly. But there is no 'evaporation'. That is gasser talk.
To all:
You can talk all day about seat angles, incident of opening, swirl etc, but if you got a potato stuffed into the exhaust pipe, it still won't run.
Porting changes based on purpose, but all one has to do is feel the square corner on the inside turn of the exhaust to know something is very wrong. I have been told I'm wrong for fixing that, but then in later years of VW engines, VW fixed that issue, much as I have been doing.
From the point of the seat to the turn in the exhaust, it narrows down, causing increased heating inside the port, increases turbulence and reduces flow. Also, there are right angles in the intake port where cracks emanate from that will crack into the water jacket on highly modified engines. We think this is a case where 'leaving that alone' has very negative effects.
Lately, we also got criticized to what we refer to as a 'port match'. Well, it isn't exaclty a 'match' we do, but a technique we learned from an expert who has four record-setting cylinder head porting jobs to his name. Most recently, was with Dart. He pointed out some improvements that I needed and explained some very interesting principles, which we apply. One was about 'reversion', which I will not explain here, but it is a real eye-opener for effect and simplicity.
As for our ability, we are only limited by our imagination and the time in a day. We are going to take a huge step to overcome our personal shortcomings that we can't make a longer day, but sure can use it more efficiently. We will be announcing our latest big improvement within a couple of months. It is a large step in the right direction for us.
As for cylinder head work, you realize, Mozambiquer, you live relatively close to me; about 3 hours away? Come on down. I'll show you around. Nothing really to brag about, but we do make a lot of work go in and out.
