The heads went on the flow bench today. I was really pleased with the numbers that I was getting on the exhaust side. My intake numbers were OK, however I did expect better. I am going to abandon the 30 degree intake seat. In the lower lift ranges where the 30 degree seat should help I didn’t see the increase that I expected. My guess is that the shallow angle combined with deep pentroof chamber causes air to crash into the chamber wall. I will have some new intake valves tomorrow and they will go back on the bench towards the end of the week. All of my tests were ran with a 4.250 bore Exhaust @ 28 inches .100 46 .200 97 .300 129 .400 151 .500 162 Raising the port floor did not work, I lost between 5 and 15cfm at every area of the lift range. Intake @ 28 inches .100 60 .200 119 .300 162 .400 196 .500 211 I will see if the intake comes up with the 45 degree seat.
Hi 487, any news on the intake flow? exh. turned out good, hope you can get intake up to some good flow...good thread:gp:
I did get some more work done on the heads. I switched back to a 45 degree seat on the intake side and did some more work on the roof of the intake port. Using my cutaway as a guide I was able to take most the entire bend out of the roof. What I did not do, and it was recommended to me by users on this board and Mike Lewis (I live in Fresno and his shop is only a couple miles from my house) who flowed the heads the second time for me was lay down the SSR. I actually left it near stock with a slight back cut into the bowl area. There is actually a method to my madness here, my second set of numbers on the intake side looked like this: <o></o> <o></o> .100- 62.3<o></o> .200- 125.3<o></o> .300- 166.5<o></o> .400- 203.2<o></o> .500- 218.7<o></o> .600- 223.6 <o></o> What I also got a chance to re-investigate was raising theexhaust port floor. What I think happened on the first test was the clay did not stick well and started to blow up during the test causing some erratic numbers. My second test with clay in the port floor of the exhaust was: .100- 20.1 .200- 79.2 .300-130.9 .400-151.8 I had a 5 cfm gain at .100, 3 at 200 and after that it evened off with the standard port floor. I did a little more research based on what some of the Oldsmobile guys are doing and I am thinking that my short side radius is too steep to work with the raised floor. For my blower motor I am going back to the raised floor configuration. I think that I can make to work correctly but it will take more time then I have to devote to the project right now. For that project I really need to buy myself a flow bench, there has been a few SF-110’s on EBay fairly reasonable. When I started doing the heads for this engine I was not as concerned with the total number for airflow as much as I was with the relationship between the intake and exhaust. On a stock nailhead it is in the mid 60’s (percent of airflow intake vs. exhaust). In terms of domestic V8 engines that are typically modified for performance only a small block Ford has a ratio as low as a nailhead Buick. Anyone creditable who specializes in small block Fords will tell you that the exhaust requires major work to squeeze good power out of those engines. Most other engines are in the low 70’s (Stock small block Chevy) or even the 80’s (455 Buick, Big block Chevy). In comparison aftermarket heads have a ratio in the mid to high 70’s. An AFR 190 is pretty consistent at about 74-78% across the lift range. I might be on to something or I might not, really don’t know. I built this engine because I didn’t have enough time to build the blown 364 that I really wanted to put into the boat. Maybe in a couple of years when I get my shop built. When I build the blower motor I am going back to the raised exhaust port floor and I am going to finish offsetting the intake valves. I started doing this in 2000 because I wanted to build a pair of heads that would feed the stroker motor I had. With a .187 offset 2.11x1.77 Pontiac valves would fit, however you cut the side of the chamber into water and the bowls were way too thin to ever port enough to make them work correctly. With a .090 offset I should be able to get a 2.02x1.60 in the head, from my cutaways the heads are thick enough to make those valves work. If anyone out there has a mill, a DRO and is brave enough to try this before I get back to it send me a PM I’ll be glad to tell you what I figured out with my prototype years ago.
Hi 487, good work. Nice to see someone else spending the time on this stuff. Very nice exh. numbers. In my first post on this thread I mentioned the ssr to you. Good luck with this. Also when you get your intake flow where you like it then flow with the intake manifold on and stand back and say WTFo No: Lol, then the manifold work startsuzzled: Keep it fun and keep us posted Just wanted to add, lots of dyno threads on here now and they all have peak HP at around 4500-4800. Pem racing is the only one on this site that peaks above 5000, think it was 5200. I have wondered if its because of the cams or head flow or head flow % or all of it. Also I am starting to look at the mcsa. Its way small for the CI. Just my .01 cent I have been talking with Tom T. quite a few times about doing what you are talking about. But at this time I am still playing with a fairly stock combustion chamber. I think the dyno thread with the build from AMS engine shop, The roller engine might of used a 2.00 intake valve.
