I have a 1956 341cid DeSoto Hemi, and speed parts are way out of my budget, but it is sooo cool. I was thinking about fabbing my own intake manifold for it and was wondering if there are any books for reference or guidelines when one goes about building an intake manifold. I would be building it out of .125" aluminum with thicker stuff for the flanges. Anyone taken on a project like this before, or should I hold out for a hilborn setup? Am I totally crazy?
Your not crazy. There are books and lots of articles out there. If you want some basic theory check out this site: http://www.newcovenant.com/Speedcrafter/ Its a free site. The "engine" section as well as the "tech" section have some good basic ideas on manifold theories. The "calculations" section in the tech area has some more theory and calculations behind intake area, port volume and runner length. Another great site for folks wanting to really build power to go with all that chrome is this one: http://theoldone.com/ If you can look past the import engine stuff and get into the technical whizzbang aspects of the articles and how they apply to the old iron you'll be flying in no time. These articles are good at getting you thinking in the right direction but they still don't cover the (important) relationship between intake runner tuning and piston speed near TDC, how stroke and the rod length to stroke ratio effects piston speed at TDC, and how camshaft timing and intake runner tuning interact. Also, Chrysler did ALOT of manifold tuning in the 50's and 60's on the hemi motors. I'm sure there has to be hemi specific information on the runner length and port area, etc, etc of the injection and 'ram' type imtakes they built for them. Two other sources of these types of calculations are the books "How DeskTop Dynos Work" by the makers of Desktop Dyno and (I believe) the "AutoMath" book also covers intake runner calculations. Of course you can avoid all this brainiac stuff by finding a manifold you know works well and copy it in sheetmetal yourself. Single plane manifolds are the easiest to copy. If getting every last HP out of your specific combination isn't critical then building a "close copy" of your favorite should be good enough. Good luck! -Bigchief.
Just saw this over on Fordbarn: [ QUOTE ] Posted by Erik - Vancouver WA from cache-rm01.proxy.aol.com (152.163.253.1) on Saturday, April 03, 2004 at 8:13PM : I was at the Portland Swap meet yesterday and met Ken Austin. He is a custom intake manifoldl/pattern maker from Newberg Oregon. He makes dual and tripple '49 - '53 Lincoln manifolds. They run from $400 to $750. He will also make custom Ford flathead manifold w/ your name on it. I'm going to have him make me a dual high rise for my 59A. He only wants about $400 for his custom manifolds. He also makes manifolds for V8 60s (Duals, triples & blower base) & Arduns. His company is "The Rod Shop", Manifolds by Ken Austin, PO Box 111, Newberg, Oregon 97132 (503) 349-1360 [/ QUOTE ] I don't know if it helps or not, but it was interesting to me - may be of help to someone out there... Didn't realize iceberg had it posted already! Should've read it all first!! Iceberg's Post
As we speak, I'm building a 2x4 crossram for my 392. Nice thing about Hemi's is that the intake is seperate from the valley pan. Makes it much easier to make your own intake. -Jeff
You guys are awesome. I was thinking about making a 2X4 crossram that has the carbs sitting over the valve covers or in that general region. Thanks again for the info. If and when I get cracking on this project you guys will be the first to know.
Go to the scrapper and get a flat piece of half inch steel. Screw it to your welding bench. Lay out your intake gasket and scribe around it. Drill and tap the bolt holes for studs. Bolt it down. You'll have a nice little "table" for welding. Easier and less clumsy than doing on the head. You can buy the mandrel-bent tubing "bends" in the diameter that you want. Make a similar "top plate" by scribing around a carb(s) gasket on to quarter- inch steel plate. I guess you could use aluminum too but that kind of welding is less accessable sometimes... Seen plenty of these fabbed manifolds and there is something real cool about them...
My dad is getting a lincoln tig, and I fully intend to practice often with it. I am going to sell one of my motorcycles to get a water cooled torch setup for it, so I can weld for long periods of time. I hear ya about the aluminum though. I had wondered about using sheet and then making a rectangular runner out of it or using tube, hammerformed to meet the intake ports shape. What do you guys think about that part. Tube or sheet?
Forming your runners in two halves and then welding them together allows you to build runners that are tapered. I went to my site's page on racing engine parts, looked under intake manifolds, and came up with the following manufacturers of sheet metal intakes that will give you some ideas: http://www.bennettracing.com/ http://www.epdracing.com/ http://www.hogansracingmanifolds.com/ http://www.kenlowe.com.au/ - sheet metal blower manifolds http://www.rancefi.com/ - parts for building sheet metal manifolds http://www.rehermorrison.com/ http://www.sonnysracing.com/ Pay particular attention to what Hogan's does. While most of the companies above only do their sheet metal intakes as tunnel rams, Hogan's does a variety of styles, and they'll make about anything you want. They seem to be the most popular sheet metal intakes in drag racing. Forget steel plate, unless you just want to experiment. That baby elephant could stand losing some weight. I'd use 3/8" aluminum for the runner bases, and then use a fly-cutter in a mill to take them down to around 5/16" after it was all TIG-welded. Dave http://www.roadsters.com/
If you are going to use round tube for the runners, you may be able to make a die to go from the round tube to the square intake ports. I did this when making the headers for my BBC and it worked out pretty good. Take a chunk of steel bar about the size of your intake port and a few inches long. On one end of it mark the inside diameter of your runners and then grind it so that it gradually transitions out to the ID of your port (minus the tube thickness). Since you are doing a cross-ram, you can probably do this over a couple of inches length. When it is the right shape, sand it to a smooth finish. Then coat the die in grease and press it inside the tube you are using for your runners. I got this done at an exhaust shop (using the machine they use to expand the end of exhause tubing), but you could probably use a hydraulic press as well ? You are limited to doing this with straight pipe, but once you have the shape formed, you can cut and weld bends on like you are building headers.
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