I'm looking forward to it too but it's at least a year off I think. Moving the manifold gained me.....0 cfm. It sure looks good now though. I'm sure the problem is up by the guide, I did a little work up there but didn't have a chance to check the flow. I'm having trouble getting the waves out of the port too. I need to get in there with the rubber backed sanding drums of some kind I think....that and get figure out whats up with the guide area and fix it.
At this point I am so impressed by your dedication to optimum design all I can do is pray that someday I have the scratch to have you build one for me... "looks good" You're darn tootin' it looks good! It looks fantastic. I have no doubt that you will soon find those last few cfms. And all this and you don't even have an outer space f1 dyno-room complete with TWO nerds, probably French-speaking nerds at that, reading gauges! Amazing!
It still true....... I took a few minutes tonight with the drum sanded and got the waves out of the port, cleaned the the inside radius on the bottom a little plus yesterday I did a little work evening tings out......for a net gain of 0 cfm. The head is starting to confuse me a little bit honestly. Normally when you do something there is a result, good or bad. It's very unusual to keep doing stuff and getting no change at all. clearly everything thing I've touched is already working better than whatever the problem is......I'm just not sure where the problem is since I think I've touch just about everything. Strange. I was supposed to be doing something else today so I didn't spent a lot of time. Hopefully tomorrow I can spent an hour or 2 with it and figure out what the issue is....it sure looks like it should be working.
Maybe, I haven't tried another head. In the interest of saving time I've been only using the 151 and 171 cfm calibration plates and then only checking the head at .500 lift since work done up on the manifold rarely has much effect at low lifts. Now that I have cut valve seat I have been checking the flow at 0 lift to be sure there are no leaks anywhere and tonight I did go ahead and loo at the .400, .450, ,500, .600 lift and saw about what I expected to see with anything above .400 only gaining 2-4 cfm per step. Tomorrow I'll do a full calibration and full flow curve...then grind something. I'm thinking the area right below the guide looks too high for the new port angle...I'll probably add a little clay first though and make sure the flow gets worse before I grind.
Not a very productive night and I finished up with a 1.5 cfm loss....now I know for sure where not to grind. My seat ID should be right, but my valve is a bit small to cut the top of the seat to the right profile so tomorrow Ill make 33mm test valves and re-cut the seats. If I can't get it sorted out by the end of the week I may say the h*ll with it and open the seat ID to 29mm and a 34mm valve and call it plenty good enough and move on.....this is getting annoying honestly and I cant stay stuck here and expect to ever finish this thing.
After thinking on it overnight 34mm valves are going in today and whatever they flow they flow. I've already got 750hp of air and that will go up with the new valve size. The seat cutter I have will allow me to us a 28 - 29mm seat ID with the 34mm valve so velocity will still be great. Enough screwing around, I've got an engine to build.
I made the 34mm test valve tonight. Oddly enough if I click the "auto calculate valve size" button in my simulation software it suggests a 34.17mm valve.....hmmmmm Tomorrow I'll cut the seats for then and see what I have.... I may have to weld up where I ground last night to get the flow I lost back, I hate when that happens. Image Unavailable, Please Login
exactly! I shot another email to the cam guy and asked if there was any chance the Easter Bunny would be bringing cams my way. He said there was..... I think it's time to settle on the 54mm TBs and pay for them so I can mill the big fat staft thin (I'll bet that will buy 1-2 cfm) ......and find 10 more.
Those are some massive valves! One thing that concerns me is the lack of metal where the valve meets the upper edge of the head? Look at the difference between the modified cyl and the one next to it. Thin metal gets hot faster. Could this be an area for getting very hot, brittle or burning out? Just an observation? Joe Image Unavailable, Please Login
It is a concern, but it should be fine I think. The valves are just sitting there at the moment, there is still alot of work to do before they are actually fit. Tonight I'm going to "cut seats" to do some flow testing, but there aren't actually any seats at all in the head to cut, the valves ar sitting on the aluminum head material and that is what I'm cutting the seat profile into. The flow testing will tell me how deep to set the valves into the head (you can see the stock valve is sunk into the seat a bit) and that will tell me how to install the real seats. As the valve goes deeper into the head the thin spot you see will get much thicker and things should look a lot better.
Copper conducts heat twice as well as Aluminum. Perhaps O-ringing the heads would help if that would be an issue.
I probably will end up o-ringing the heads, but seal them more than to help with heat. The water/cooling system will keep the engine and heads plenty cool over-all, the concern is local hot spots. If I leave the outside edge of the valve out in space like it is in the picture it will get very hot and most likely fail. Once I sink the valve into the heat a bit the outside edge will be full in concact with the head and not subject to hot spots.
I think what Joe was concerned about was a possible hot spot, not on the valve, but on the thin bit of head material between the edge of the valve and the "corner" between the combustion chamber and the sealing surface. However, on second look, I don't think that will be an issue as the thin part only appears to be thin if you disregard all the metal behind it in the plane of the sealing surface. A copper O-Ring to help there would have to be oval instead of round anyway.
The valve are set about where they want to be, no more hangin over the corner of the head. I left the seat ID at 28mm for now, it was actually a tad biiger before after all the grinding and sanding. I welded in where I ground last night and made the head unhappy, then ground as fast as I could to get everything looking like it would want to look. It's up 1/2 cfm from where it was before I screwed it up last night. I'll play a little more tomorrow night before I pull the trigger and go to 29mm on the seat...or maybe I'll just cut the seat ID....I need to think a bit.
