FI Plenum Design, MS'ing my 2270 Options

[Tom Perso]

Hey Guys,

I am designing a MS system for my 2270 (163.86b cam, 48x38 valves, future Triad header). I am looking at running stock intake runners and possibly making a new plenum to run my Ford TB (probably from a 4.0L Exploder/Ranger).

Are there any "design guidelines" that should be followed when making a new plenum, such as a certian volume required for engine displacement?

Looking at space requirements, I see running the TB on top of the plenum is the only way to go. That, of course - begs the question... Is the stock 914 2.0L plenum a good starting point to modify to allow for the Ford TB?

Here are some pics for reference... I had a Bus 2.0L intake system to borrow, so I am basing my measurements and ideas off of that.

http://www.qtm.net/~persot/MS/

Any ideas, suggestions, etc, are appreciated!

Thanks,
Tom

[jwalters]

(IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) Just to add a little--common practice with the rice tuners and crotch rocketeers is to use as large of a plenum as possible will fit--with actually a smaller inlet opening into the plenum than the throttle plate---it is shaped into a venturi--

What the goal is, is to use the small venturi ( velocity increases magnanomously, with no loss of flow) which rams the air into the large plenum, changing the velocity to pressure---hence, " Ram Effect "

This is the only way turbines will survive at high speeds--just extropolate this practice into automotive--the practice is the same--but different--with turbines, the air has to be slowed down, or the engine will stall and flame out--piston engines are spark dependant, and never get to this speed, and hence can use this effect to an advantage--much testing has shown that when you increase the velocity of the air into the plenum beyond supersonic--and then have a large plenum to extract the velocity and turn into pressure--truely significant HP gains are achieved!!! Sometimes on the order of 20%

I have read SAE papers, and bike mag tests ( when they actually did this kind of testing--this technology is actually very, very old ) on jap bikes that make as little as1.9 HP per liter-to as much as 3.5, normally aspirated--the key element that they always hit on was that the velocity of the air entering the carbs was over 900 MPH----and the areas in the tract after the carb were of much larger volume than the carb throat displacement itself.

God, I have sooo many ideas on plenum designs and exhaust design based on my experience with aviation that it kills me I am not in a position to actually design and test this shit!!! (IMG:http://www.914world.com/bbs2/html/emoticons/mad.gif)