PDA

View Full Version : intake manifold design for a 200X



oldred95
04-19-2008, 10:18 PM
So I'm upgrading to a 29mm mikuni carb that came off an XR200 and although its an aftermarket carb it worked quite well. On the XR it used a rubber intake boot that was bolted directly to the head and the carb was clamped into the boot at an upward angle. That being said here is where my idea come in. I'm big into early 90s Chevy EFI stuff and the Tune Port Injection 305 and 350's used extremely long intake runners, lets say 10 inches or so of runner before entering the cylinder head and they make tremendous torque throughout the entire rpm range because of the intake velocity developed by the long runners. The stock intake manifold on the 200x is about 2 inches or so in length and I don't know how much it contributes to the relatively good torque the 200X makes. I am going to need to make an intake manifold for this carb to fit and I'm debating whether or not a longer intake runner would help promote better velocity and torque overall or not. Has anyone ever experimented with anything like this on an ATC engine?

turbostang
04-20-2008, 12:09 AM
the reason the efi cars can use this long runner system is that the intake is 'dry' with the fuel being introduced at the cylinder head instead of early in the intake stream. carb intakes prevent this, and generally cause fuel puddling in long intake runners. chrysler tried this years ago with the 426 cross ram and it did not work very well. if you do try it I would guess it will take alot of tuning to figure it out.

let us know how it works if you do it though, my 350x could use some more torque:)

oldred95
04-20-2008, 12:26 AM
I know it works on the tunnel ram style intakes because they are pretty well verticle. I was wondering how a carb might react mounted horizontally like that. I'll have to play around with it and see what I can come up with. I'm wanting to retain the stock air cleaner setup and the mikuni is about a half inch longer then the stock carb and its going to need a rubber boot intake on top of that. I'll just have to get things mocked up and scratch my head a while.

Billy Golightly
04-20-2008, 01:20 AM
I'd be interested to see how this turns out. There have been extra long tuned length intakes on 2 strokes done before (Theory being to time and harness the pulses from the intake pretty much exactly like the exhausts) but it was sort of a fringe idea. I think Eric Gorr is the one that filed the patent on that.

Not sure how well it'd work on a 4 stroke but I'd worry about the mixture not staying suspended well because of the length like turbostang said. Thats the main downfall with draw through turbo/carb setups.