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You can Oxy weld aluminum too, but need a special (very toxic) flux and special goggles with cobalt lenses. I've seen it done in a demo at a metal shaping class I took. I posted some photos here. The other trick is to cut your fabrication metal into thin strips to use as the filler rod. You end up with a perfect match and can pretty much do what you want with the finished metal in terms of future working or re-working.

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

I wish brazing wasn't as subject to fatigue wear as it is. Propane brazing aluminum is fairly simple, and strong enough. Don't know if I would trust it to be airtight though, or to last any length of time through many thermal cycles.

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Tucker

Oops, I notice now you're missing all those diagonals. I didn't think you were done, but I wouldn't have mentioned if I looked more carefully. The one I mentioned is at the back of the upper rail and goes down to the back of the bottom rail.

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

Marcus,

do you mean tubes W1 and W2? or M1 and M2?

W1 and W2 are in there. M1 and M2 are not. I was/am debating whether or not to use the 1" RHS tube.. or find some 1x2" 14ga for a little bit extra strength on the chassis mounting br@ck3tz

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Tucker

See what I mean? He said it his-own-self...

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

My bad. Somehow, while reading the text and not looking at the photos, I got the image of a serpentine system with an auxiliary v belt driving the water pump. No, I've not been smoking anything.

Bill

Maybe that's the problem

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Tucker

So Now I'm doing some more mathing trying to figure out the ideal intake size for this pig. how small can I make it while keeping it happy type stuff.

Basically I'm using engine size, target RPM for peak torque, intake runner diameter, intake wave count and cam duration to try and find something that will fit and still work.

The best I've found so far:
209CID
6 Cylinders
3700RPM
5 Induction waves (1 & 2 are impractical, 3 is F1/nascar level)
260° intake duration

The stock engine makes peak torque between 3600-4200 rpm, its a pretty flat curve about those parts. Seeing as this will primarily be a street/autocross car.. and I'm addicted to torque.. I think a 3700 RPM peak torque number is a pretty solid goal.

that leaves me with a 1.5" runner diameter and a total length of 7.7" per runner. If I can squeeze an extra 2.2" into the runner length (9.8") I can bump it into the 4th induction wave, which would be ideal, Which I may be able to do with some curved tube magic.

Now the tricky part.. Calculating plenum size. The general rule of thumb on NA engines is 1.5x the displacement of the engine.

so 1.5x3.5 = 5.25L

Now this motor is lengthy. 28" or so, and the intake ports all fall within a ~25" length. So assuming I keep the intake runners extending straight from their respective ports, a 25" long by 3" diameter cylinder nets a volume of 707CI, or 11 liters. about twice what I would realistically need. Intake volume tends to hamper throttle response past the 2.5x displacement level.

If I can the plenum down to a 18 x 3" volume.. that's only 8 liters and puts me within the 2.5x rule.


Now where I get even more unsure -
Thinking of making the whole shebang out of 18-20 Ga sheet metal, with a 1/4" flange and a 1/4" or 3/8" flange for the throttle body. I'll be able to weld bungs for all the necessary crap to it.

It would be an equivalent weight of an 1/8" thick aluminum plate manifold at a fraction of the cost and much easier to work with. I run the risk of denting it if I drop it.. but once its on the car I don't see why it won't be sufficient.

Correct me if I'm wrong on any of this - please.

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Tucker

There is no way I can critique your design, but maybe I can offer an alternate solution to the problem.

I have made several intake manifold configurations for the Duratec I 4. The one that works the best is the one in which I surrendered and declared the stock manifold to be the best set of compromises for the engine as configured by Ford. I just could not use the Ford intake. So I used (as closely as possible) the Ford sized components and reconfigured them. For example, the runners are the same diameter and length, different shape. My manifold is the "same" as the stoker, just totally different shape.

Bill

Unfortunately, the BMW runners are ~1.26" ID.. The runners are almost 14" long by themselves. The head ports are 1.46" ID though.

Mathematically, ~1.26" ID with a 14" length is a volume of 72CI
1.5" ID with a 7.7" length is 54CI
1.5" ID with a 9.8" length is 69CI

If I can some how - some way - hit a 1.5" ID runner size with a manifold runner length of 12".. I can get down to the third induction wave.

there is a solid 1.5" in the head from the port to the valve, so I should be able to hit the 9.8" easier than I originally anticipated.

I'm going into this kind of expecting to lose a couple hp on the intake side. It will be the first NA fuel injection manifold I'm designing.. Hopefully I can keep it as close to stock as possible, save a couple lbs and make up whatever ponies I lose through going to long tube headers instead of the log manifolds.

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Tucker

What if...

Motorcycle ITB's, and velocity stacks hanging straight out the side?

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Bubba had an end goal, half a plan, and a Dremel.

Connecticut emissions requirements for initial inspection means I can't...

Have to have an IAC, recirculated PCV, charcoal canister system, EGR depending on the inspector

I guess there would be a way to make all of those things work.. but it would make for more work..

hmm. decisions, decisions.

I guess if I'm scrapping the stock intake manifold, I could always try cutting and brazing it upside down..

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Tucker

You may be able to package the runner length by having a continuous curve in your runners. It's how I made mine. The runners start horizontal and curve downwards with about a 6" radius bend, so a 90 degree turn results in about a 9" runner outside of the head, plus your flange to valve distance. The runners then enter the plenum vertically from the top.

To reduce your plenum volume you could use a 3" diameter tube cut in half, with a flat piece welded on the cut line to make a D shaped cross section. One advantage of that approach is that it's easier to drill the holes for the runners in a flat piece compared to the side of a large diameter tube.

I don't thin 18 ga sheet metal will dent very easily with all of the curves in it. Mine is made from materials that I had on hand so it ended up being 16 ga runners, 14 ga plenum tube with an 18 ga end cap, 1/4" motor flange and 1/8" throttle body flange.

Believe it or not - but that's what I meant by banana shaped runners LOL

I was thinking D shaped, but a different method of going about it. I was going to cut the holes and tack the runners to a flat piece of sheet steel, then bend the steel around a 2.5" piece of exhaust pipe. it would essentially leave me with a D shape, but with less joints. I'll have to buy a gas bottle and properly mig this. I'm actually looking forward to it. Just need to find someone to cut me a flange!

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Tucker

I don't think kit cars need to go to emissions in Ct. I have a R1 powered Locost and have never been there are no specs for motorcycles.