josh817 Posted August 19, 2009 Share Posted August 19, 2009 Excuse the use of Paint... To get you into the jest I will post this first: Yes, motorcycle carbs. But wait! I'm not a total noob suggesting motorcycle/mikuni carbs on an L engine! I had a different intention. Instead of having to cast all your stuff like Derek did, why not gather your supplies which should be relatively simple to find and TIG weld/bolt it together (or I guess you could make it out of steel and MIG?). Examine the super human skills: Ok so we have a regular old air horn, then comes the weird part. Get a cylinder, and then solid rod (we'll refer to this solid rod as a piston). Drill out the runner size through the piston. Now you attach your linkage to the top of the piston. Stock linkage to make things easy. With the arm swing, you can attach one of those adjustable pivot rods that you see on a standard Weber DCOE linkage to the top of the piston. This way, when you want more throttle, the piston is pushed down within the cylinder, and more of the hole is exposed for air to flow through. After it gets through that mess, you come to your runners which have injector mounts on them, like Derek's setup. Now the runner on the injector side will be tapered for that venturi affect. I thought of this with an N/A motor in mind and not forced induction, sorry guys. The book Tuning BL's A-Series Engines by David Vizard shows a chart of several carb combinations and how much they flow. It says that a Dellorto D.H.L.A. 45mm carb with 38mm venturis will flow 245 CFM per barrel. Whats the most we can get an L head to flow? 225ish being generous? With that in mind, it would be best to find a larger air horn, which is popular so you don't go poor. Something 50mm or higher. This 50mm will taper down to atleast 40mm, maybe smaller. Basically aiming for the maximum flow of the head so that there is no restriction. Just remember that your entrance diameter must be matched on the piston hole you drill. The bigger the entrance diameter, the large the piston diameter to accommodate a large hole, the larger the cylinder for the piston, etc. Makes everything bigger essentially. Perhaps its just me but I would imagine that its best for the tapered end to be after the cylinder and before the injector rather than it being on the air horn side. This way the velocity increase is closer to the fuel and the port. Also, to keep everything simple, use the adjustable rod in the linkage to adjust your idle, just thought I'd throw that out there. How to seal off the sliding piston? Like a motorcycle carb maybe, with a diaphragm... However if thats too difficult to do then why not just run a gasket around that top part and have a screw on lid. This is my top view of the cylinder: The dotted portion is an outline of the float and the center black part represents where the rod would go. Then maybe you're asking, how does the hole in the lid for the linkage rod seal off, I envision something like a valve stem seal. Then we have the flange to the head. I guess you guys call it a plenum? Or is that something totally different? The thickness of the flange should match the thickness of your exhaust flange so the ears on the shared studs/bolts actually do their job. Alright, so... if you actually read through all of that... who wants to paypal me some money so I can get started. Haha So now you may be asking, why are you wasting your time drawing and typing this ****? Well, I saw a video of a FIAT motor on a dyno, and the slide carb idea I liked, and I knew that some motorcycle carbs were slide carbs, and then I started thinking, and then my head exploded from the excitement! Yah thats about how it all worked out... Quote Link to comment Share on other sites More sharing options...
johnc Posted August 19, 2009 Share Posted August 19, 2009 Go for it. Quote Link to comment Share on other sites More sharing options...
Phlebmaster Posted August 19, 2009 Share Posted August 19, 2009 Cool idea...here is a good resource: http://www.totalvauxhall.co.uk/resources/totalvauxhall/TOV64.tech60697.pdf Quote Link to comment Share on other sites More sharing options...
Derek Posted August 19, 2009 Share Posted August 19, 2009 Start by downloading this http://sketchup.google.com/ And then send me your email and I'll send you a 3D model of the head and intake flanges from my manifold. By building it in 3D you will have worked out all the details before you ever begin to cut material. Less chance of building yourself in a corner as well. I haven't played with sketchup too much but people are doing some pretty cool stuff with it. Your drawing skills are about the same as mine. Crappy! That's what drove me to CAD 15 years ago! Derek Quote Link to comment Share on other sites More sharing options...
josh817 Posted August 19, 2009 Author Share Posted August 19, 2009 Thank you both! Phlebmaster, that write up is very very nice! Now really I have the best of both worlds, carbs or EFI. I hear that the mikuni/motocarbs are way easier to tune however I see they still have 4 jets or so just like a Weber would... I also see one main needle jet like an SU which would be lovely. A customer of ours went to the dyno just to see how much power his motor was making and they take an A/F reading from the tail pipe. He was runnning a triple SU setup and you can see the A/F was a nice and steady curve. Obviously this is due to only messing with a single needle of whatever size unlike a Weber or Mikuni where they are transitioning to different jets so to get a nice flat curve you have to take the time to tune. Easy if you're patient and have a good $1000 set of jets. >_< Although I HATE the wiring that comes with EFI, I'm sure it wouldn't be too bad once its in and taped. The ability to sit down with a laptop and tune (even though I don't understand half that ****) totally outweighs having to buy jets. Derek I will try out that Google tool! Freshman year at UTA starting next week. Maybe I'll be introduced to some cool hitech machines! I don't know if an AE department has that sort of stuff. I would assume ME and AE share a lot. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted August 19, 2009 Share Posted August 19, 2009 Why not just use motorcycle ITB's from a fuel injected motorcycle? seems it would be easier. Quote Link to comment Share on other sites More sharing options...
josh817 Posted August 19, 2009 Author Share Posted August 19, 2009 Why not just use motorcycle ITB's from a fuel injected motorcycle? seems it would be easier. Damnit, why not just buy Weber body ITB's and use the regular Cannon intake? Its cause I want to be one of those dudes that own something unique. And it would be majorly fun to build and work out all the kinks... until you hit a dead end and then you ditch the project. Quote Link to comment Share on other sites More sharing options...
h4nsm0l3m4n Posted August 19, 2009 Share Posted August 19, 2009 If youre in an engineering program at a university theres a good chance they have solidworks, pro-e, or catia in the labs on campus. Also, if youre school is anything like mine they will let you use a student copy on your home computer as long as you stay connected to the internet to refresh the license every 30 minutes or so. Google sketch up works fine, but might as well use (learn) the real thing if you have access... Interesting idea though Quote Link to comment Share on other sites More sharing options...
Derek Posted August 19, 2009 Share Posted August 19, 2009 If youre in an engineering program at a university theres a good chance they have solidworks, pro-e, or catia in the labs on campus. Also, if youre school is anything like mine they will let you use a student copy on your home computer as long as you stay connected to the internet to refresh the license every 30 minutes or so. Google sketch up works fine, but might as well use (learn) the real thing if you have access... Interesting idea though What he said! Quote Link to comment Share on other sites More sharing options...
naviathan Posted August 19, 2009 Share Posted August 19, 2009 Why not just use motorcycle ITB's from a fuel injected motorcycle? seems it would be easier. Probably because carbs are cheaper and easier to get your hands on. Not to mention, where's the fun in having half the work already done for you??? j/k Quote Link to comment Share on other sites More sharing options...
josh817 Posted August 20, 2009 Author Share Posted August 20, 2009 Guys, this google sketchup thing is busting my balls. 3D stuff on a presumably 2D screen just throws me off. Quote Link to comment Share on other sites More sharing options...
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