More progress this past week, but I'm still behind schedule. I've been trying like mad to get the engine ready to go for a dyno session on the 20th and 21st, but I'm not sure if I'll make it. If I do, there is some chance that I can make one trip to the track, over the Labor Day weekend, to get a test run or two in before Drag Week. If not, then I'll go in cold again, like last year. I guess last year didn't work out too badly though...
FINALLY on Thursday last week I got my cylinder heads. Flow numbers for last year's heads vs. this year's are shown in the chart below:
The exhaust was basically the same as last year, but the intake flow is up significantly at the higher lift levels. I'm not sure what this will mean in terms of horsepower, because there is not a uniform increase at all lifts, just from 0.500" up, but I've got to believe that it will pick up at least 20-30 HP over last year. We will see on the dyno.
During the week last week I took care of a bunch of odds and ends that needed to get finished, and then starting on Friday I went full bore on the sheet metal intake. I was going to start working on the heads this weekend too, but I got so wrapped up in the intake that I focused all my efforts on that, with the result that it is now nearly complete; it only needs machining on the flange surfaces to fit down on the heads so the ports line up, and I need to have the heads on the engine for a test fit before I can determine how much to cut, so right now I've gone as far as I can on the intake. Here are some pictures I took along the way.
After getting both the plenum plates welded to their respective runners, I pushed the two plates together and did a little grinding to get them to fit together. Here is one of my test fits:
Here's a picture of the port plates bolted onto my jig. This is the fourth sheet metal intake I've built on this jig; I'm glad I took the time to make it, it has really come in handy over the years:
After putting the plenum plates and runners into position, I welded the runners to the port plates. This is kind of a trial fit process, where you tack one runner into position, then use clamps or bungie cords or some method to move another runner into position, tack that one in place, etc. etc. After a bunch of screwing around all the runners were lined up and tacked in position, so I finished welding the seams. My welding still sucks, but it will get the job done. When I was done with that I welded the bottom plate onto the intake, leaving the ends a little long so that I could trim them to fit the engine later:
Next I removed the intake from the jig and stuck the partially completed manifold on my smaller CNC machine to cut the holes for the fuel injector bungs:
I also machined each injector bung so that it would conform properly to the inside of the runner, to minimize grinding and port work that would come later. Then, I welded the bungs into position on the runners, tacking them first with the fuel rail and some old injectors in place. After that was finished up, I fabricated some brackets to hold the fuel rails in place and welded them onto the intake, so that the fuel rails would bolt on solidly. Here's a picture of the manifold with the fuel rails and injectors installed:
I got done with all that about midnight on Saturday. I was out at the shop again early Sunday morning, working on the plenum. Here's a couple of pictures of the plenum in progress, with all the sheet metal and the top rail tacked in place in the second photo:
It took me most of the afternoon to get all the plenum seams welded up, but I finally finished around 4:00. Then, it was back on the CNC machine for machining the top surface of the intake, cutting an O-ring groove so that it would seal to the top plate, and drilling and tapping the holes for the top plate. This machining operation is actually very tricky, because the manifold is not very rigid. I had to go very slowly, and machine by hand, to get the top rail of the intake machined properly. Took about 3 hours because I had to go so slow. After that it went a little faster, but I still didn't get done until 11:00 PM on Sunday night.
Tonight I spent the evening in the shop porting the intake, making sure the runner transitions were smooth and any welding bumps ground down. Here's a picture:
All that's left to do now is to trim the bottom plate, and the port plates, for proper fit on the engine, once the heads are installed. I figure I've got about 50 hours over the last couple weeks working on this intake manifold, and now that it is done I'm looking forward to making some progress on the engine. I will try to post another update next weekend.
