MG Sports Cars

Thanks for the advice Bill. I have the lifter valley pan and what I think I'll do is sandwich that between the heads and the intake. If I could get some triangular cross section aluminum bar stock (90*, 45*, 45*) it would make it easy to match the runners and install the injector ports as I'd have a horizontal top surface and a vertical to the inside. Then just 8 rectangular sections with some of the top cut off and build up from there with the side and end walls should very nearly do it. Of course machining the ports in the bar stock might not be all that easy and it would add a little weight, but not as much as that brass plenum I had on the other motor. Come to think of it, I know a guy with a waterjet machine who could nicely slice a section of square stock diagonally. If I can't buy it that way.

I need to get some materials on hand and see what works and I can go from there. Still working on a deal on a TIG too, may go to an auction next week.

Jim

I've been working out the details. 19" of 2-1/4 square stock will make the side pieces, drill and cut the ports and then saw it on the diagonal using my table saw. 2 x 1-1/2 x .125 tube for the runners, send them all the way across to join the sides, angling them so they all fit in and cutting the tops off about an inch past center. this gives good port separation except on 2 and 1 so angle 2 farther towards 3 and possibly flare the opening on 1 a bit. Even with that the flow through the center of the intercooler will be somewhat greater than at the edges so I'm thinking of placing a diffuser plate below the blower. Made of perforated stainless and with a gap at the ends and a smaller gap at the sides, this should even out the flow over the area of the intercooler core with a bias towards the ends, hopefully just the right amount to offset reduced flow along the end walls. Getting front/rear balance even is a bit trickier. The blower discharges towards the front. The diffuser plate can be slanted down to the rear to shift flow in that general direction, or a better solution may be to angle the core (which leads back to the heat-pipe design) but there's still the bypass to deal with, which unlike in the M90 fires straight down and not into the discharge port. This means that for unboosted operation this port needs to have it's flow directed towards the front of the plenum.

Side walls of the plenum will be 3/16" aluminum with roughly a 5" rise above the runners to the blower flange. A little taller than the old design. A mating plate there will match the blower discharge port and allow removal of the core. The core will be roughly 8 x 10 x 1-1/2" with better than twice the area and volume as the old design. The mating plate will have a deflector attached to the bottom for the bypass.

That's the design as it stands now. There will be some refinements as it progresses, such as revisiting the heat pipe theory and design, location of the sneeze valve, thermostat, injectors and regulator but the basic design work is done, supplies are ready to be ordered, etc. Material costs will be $150+ not including the intercooler core. A new 9" nose for the blower will be required, and probably a support plate, as well as a new look at the accessory drive. I'm shooting for boost in the 6-8 psi range on a 10.6:1 CR and based on my earlier work I believe that can be done without melting down the engine. The key to success is that the car is simply too light to allow continued heavy boost for more than a few seconds at a time. That amount of boost will make enough heat to allow the intercooler to help out so that will definitely be a part of the design.

More later.

Jim

Today I split the large square bar stock (2-1/2") and cut it down to near size. I did this on my table saw. below is the setup:


With a good sharp carbide tipped blade and slow steady feed this works quite well and is often a better way to cut rough stock sizes than other available methods. It throws hot chips though and you want to be very careful to avoid kick back and not crowd the blade.

So far here's how it fits:


The ports will run horizontally through the triangles and I'll probably have Steidle Fabricating cut them on the water jet machine.

I have stock for the runners and the blower mounting flange:


but I may have gone 1/4" tall on those, measuring on the angle instead of on the vertical, depending on the way I run the ports. If so I'll need shorter tube stock. I would also like to leave a gap below the runners, but we'll see.

Jim

RE: With a good sharp carbide tipped blade and slow steady feed this works quite well and is often a better way to cut rough stock sizes than other available methods. It throws hot chips though and you want to be very careful to avoid kick back and not crowd the blade.

That's for aluminum or other soft, non-ferous metals, right Jim?

Quite correct Rob. The critical element is tip speed for the cutting teeth, but with aluminum and a light feed it's difficult to go too fast. Some of the others, particularly copper, brass and similar alloys may be quite tricky and any steel is going to burn or break the teeth.

Jim

Looking good Jim! Are you going to make it an open individual runner type of manifold?
Table saw, your a braver man then me! Looks like it did a good job. They always make me a little nervious when I use one.

Bill

A guy who's not a little nervous around a table saw is likely to lose a finger. Or worse.

Bill, I'm still working out the details but I'd like to have an air gap below the runners, and then have IR's across the middle. The tube I have for that may be a bit tall though and I haven't decided whether to cut it down or use another approach. I'll know more after the gaskets come in this week and I cut the ports in the lifter valley pan. The ports through the triangular blocks will most likely be angled upwards towards the center and that will affect the height of the ports, and the vertical location isn't set either. I want to leave enough material above the runners to cut injector ports. Then from that point on it will be a build up of 3/16" plate with the 3/4" flange at the top.

Jim

As a long time user of table saws who still has all of his fingers (knock on wood!), the safest blade to use for this purpose has zero hook angle. Most wood cutting blades have a 7-10 degree hook angle, and tend to grab the stock as it is being fed. Some rip blades have even 20 degrees of hook angle and would be a poor choice for cutting aluminum.

Jim, You have a PM.

More progress.





The neat thing about this is that the work was done with nothing fancier than a drill press and a jig saw. No special jigs or tooling, no cad/cam files. Just lay it out, drill the holes, and connect the dots.

I cut the ports undersize so that I can come back with the die grinder and match them to the heads. The easiest way to do this would be before the short block and heads are assembled, with just the bare parts. But I'm way beyond that point so it'll be a lot of bench work and test fitting.

Jim

Finally, more progress. In order to take a clean-up cut on the 45* angles cut on the table saw I had to do a lot of other work. Purchase and set up a TIG welder (Yay!) so I could weld mounting ears on the ends of the wedges (I got an ESAB L-Tek 306, a good heavy duty industrial machine with 380 amp capacity second hand for about $1800 after everything was set up including foot pedal, chiller, and Argon). Then the main belt on the Moog Bridgeport broke so I had to rebuild the head. But the good news is that it is now semi-operational and usable for less demanding manual jobs. So here is the result:



The next task is to transfer the ports from the valley pan and then decide how I want to cut them out. Hopefully that will involve a little less extraneous work.

Jim

Oooooo, Bridgeport mill!! Me want one of those!!!!!!!!!!!! Make all kinds of shiny metal things:-p

It's taken me decades to get it Bill, but the price was right. It was an old Moog Hydraport NC machine that ran on paper tape, pneumatics, and had hydraulic actuators. Quite a monstrosity really. I stripped all that off and threw it away and have converted it to ballscrews and servomotors. I have one more servo to mount and a bearing clearance to sort out, and then I can begin to sort out the servo drive and control packages, which I have yet to obtain. But I'm hoping that over the next year or so I can get that part done. In the meantime it has some limited capabilities as a manual machine. One of the thorniest issues is, oddly enough the drawbar for the spindle. Moog used a proprietary quick change with a floating drawbar. Replacing that with a more modern system is neither simple or easy.

Jim

A little more on the intake system:









The ports are now roughed out. Once more the small bench mill was pressed into service and it did the job well. A bit of fine tuning with the die grinder and the pieces will be ready for bolt holes and injector ports. In case anyone is wondering about the 'mickey mouse ears', that is material left for the injector velocity ramps which will accelerate the boundary layer over the tips of the injectors, thereby preventing low velocity aerosol (fuel droplets) from stagnating on the back side of the injector tips. Just remember, you heard it here first.

Jim

Nice stool.

I sanded the top of it. Looks better, don't you think?

Another.

That's amazing Jim. I am envious of your skills!!!

Good work Jim. I wonder if anyone, in our group, has made a fiberglass/composite manifold? The first Huffaker 4bbl. was made of f-glass with clear resin. I'm told they put a fluorescent dye in the gasolene and shone a strobe light on it at various rpm. to check out the "action". We all like crafty, roverman.

I think that would be a great idea. So far I've not heard of anyone doing it though. Probably not the best for a blower mount so it won't be me, but I could see a real nice piece in carbon fiber, say for the 340 with TA heads for instance. Now that would be sweet!

Jim