Ace, Good analysis.I talked to several machine shops about my diesel engine, and I ended up doing the following mods to improve performance. (I should add that my goal was NOT speed, but efficiency; but in truth there is not much difference - more efficiency can translate into either higher speeds or more torque or more mpg, depending on other factors including your driving habits).The diesel head was ported much the way you describe, with the intent not of enlarging any particular surface, but to SMOOTH out the surfaces to reduce turbulence. Additionally the head was coated with a ceramic coating which disperses heat. The theory behind this is that the better the engine throws off heat the less energy it has to expend mechanically removing it via the exhaust chamber, or by the oil cooling system. Therefore the entire internal area of the exhaust port was coated to "throw off" heat back into the exhaust itself, rather than absorbing it into the head for the cooling system to remove. Additionally, the coatings made both intake and exhaust ports micro-smooth.Thirdly, the piston, bearings, crankshaft and flywheel were all balanced to witin a couple of grams. Again, any eccentricity in weight distribution not only damages the engine over time (by ovalling the bearings and machine surfaces themselves) but also is energy that is transferred into unnecessary vibration, instead of being channeled into the power output itself.I can't comment on the result in any way except to say that the engine seems to run exceptionally cool (max temp so far is about 170 degrees, but I'm not pushing it hard) and, for a diesel, very smooth. Although noisier than the gas engine, it does not offer significantly more vibration.Ace, you may want to comment more on these areas; I'm no expert, merely following the opinions of a couple of machine shop pros.
Last night I took off my intake manifold and saw how rough it was just inside. I was thinking about the turbulence. I was trying to come up with a way to smooth it without taking the engine apart. I guess I will learn how to take it apart and find a good machine shop. Thank goodness for the manuals (Snidal, Service, & Parts).Thank you,-Rick
I meant that I noticed the roughness in my inlet port. I like the suggestion about cleaning up the gasket too. I was trying to come up with a way to smooth the inlet port without taking the engine apart. It is a black box to me right now. But then many other things were too.Thank you for your technical input ace. I enjoy reading your posts.-Rick
Ace, I always enjoy your analytical discourses. I do have a question about this. It is my understanding that on the intake side one does not want a mirror finish. At low RPM that mirror finish will not provide enough turbulence to keep the fuel in suspension. This will cause puddles of fuel, an inconsistent mixture, and poor throttle response at low RPM. Certainly, as you mentioned, any large flashing or sharp angle that will disrupt flow should be removed. You mentioned using 220 grit paper. I guess my question is: Can you quantify the right amount of "rough" finish needed in the intake tract? Would your answer be Enfield specific or of general application? On the other (exhaust) side it is my understanding that a mirror finish will aid exhaust flow and minimize carbon build up. How much does this apply to the Enfield specifically, or for general application?
I would imagine, ace, that the ceramic thermal coating in the exhaust would be particularly effective on the Enfield head, as it tends to run pretty hot. As I said, it is keeping my diesel ridiculously cool...
Something I noticed when I ported my 04 is the rubber flange connecting the carb to the manifold. Inside is a internal flange that protrudes into the air flow (its there for the carb and manifold to mate up to).. I used my 60 grit "flapper" wheel to turn it down to match the complete intake diameter. Seems a shame to match all ports and leave this sticking out into the intake trac. Just my two cents.
Ace,i've noticed where the bowl meets the seat it is under cut slightly,any blending would need to be made on the sea itself,however that would turn the flow back slightly.Can epoxy steel be safely used on the Alloy to build it up so it blends in a nice straight line with the seat?the coinz.
add a modest intake extension between carb and head. Longer runners improve low speed torque and our machines engine fits the bill. These are available from at least one supplier of flatsides whose name escapes me right now.
Quote from: jonapplegate on January 02, 2009, 04:23:18 AMadd a modest intake extension between carb and head. Longer runners improve low speed torque and our machines engine fits the bill. These are available from at least one supplier of flatsides whose name escapes me right now.About how long would you suggest? I am going to put a 32mm flatside carb on and all I can find so far is a short rubber mikuni manifold. Everything I find seems to be 2" center-to-center and the bullet seems to be 60mm center-to-center. For me, I have decided not to port it or do the valve job yet, I want a reason to take the head off. Like maybe to celebrate 3,000 miles.Thanks,-Rick
doesn't putting a rubber hose between the manifold and carb cause two relatively large steps that would mess it up? Is it insignificant? I am thinking about filling in the gap with high temp silicon.-Rick