making a tube type intake manifold

[allessence]

I have been looking for information on tube type intake manifolds for about a month now. Not independent throttle bodies, but more like and equal length tube exhaust manifold.

All I can find is information on standard design protocol.

Flange, runner, plenum. Plenum usually connected at 90degrees to runners.

Engine 2.0L inline 4 SAAB.

I have found that with flow patterns the cylinder closest to the throttle body usually doesn't have as good as flow as the cylinders further down the line.

The design I am in the process of building and prototyping is actually a tube design with throttle body, plenum, then straight into the 4 runners. The plenum will be about 5" round and 8" long, going into 2" round bell mouthed runners they roughly 17-20" to flange.

Has anyone else seen such designs? Any books on the subject of straight flow intake manifolds. This is not independent throttle bodies.

Thanks. I'll post pictures as things pan out.

 

[Cargeke]

http://www.cliffordperformance.net/

http://www.hogansracingmanifolds.com/

Here are two places I know of that could be of help.

Clifford makes a lot of pieces for inline six engines. Equalizing the fuel mixture between cylinders is a challenge with inlines, so their stuff should give you some ideas. Increasing the runner length so the differences between cylinders is small compared to the overall length is a start. The trick is keeping up the charge velocity.

Hogan makes some pretty trick sheet metal intakes.

 

[patprimmer]

A bigger dia plenum would help.

2 throttle bodies, each one directly over the mid point of 2 runners would help. Look at old fashioned high performanc multi carb set ups for ideas.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[Lou Scannon]

"2 throttle bodies, each one directly over the mid point of 2 runners would help. Look at old fashioned high performanc multi carb set ups for ideas." True...true, this stuff is simple physics and common sense.
(by common sense I mean a two carb setup for a 4-stroke inline 6 split 1-2-3 and 4-5-6 makes way more sense than a triple carb setup split 1-2, 3,4 and 5-6).

 

[IceStationZebra]

The original Oldsmobile Quad4 manifold was designed like an exhaust header. After a couple years they released a log-style manifold, and at the same time upped the torque rating. Coincidence?

This manifold design should be very similar to a log-style manifold except that the cylinder pulses will be trying to steal air from each other, making for many pulses, direction changes, etc. in the plenum. My guess is that you may find one RPM were this creates a flat spot.

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I also ran across this thread that may help.

http://www.honda-tech.com/showthread.php?t=2250786

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ISZ

 

[allessence]

The plenum design from what I understand needs to be at around/at least 1/2 the engine displacement.

What size/length of plenum would you suggest? Since this is in design stage and production of a prototype won't begin for a few weeks. I'm open just to about anything.

This is to assure plenty of air from being robbed from other runners.

One point I must bring into focus is this is a turbo charged engine. With boost coming on at 2200 rpms.

So, I have looked into seperate throttle bodies and the likes. And the complexness (cost) of such a system would prohibit mass production even on a limited basis.

Really the information I need is single throttle body and 4 runners, between 17-23" long. The design at this point is really about changing air flow to achieve max to all cylinders instead of one having less and the end having more.

The flow patterns on a stock manifold show that cylinder Number 4 which is right after the throttle body doesn't receive as much flow as #1 which is at the other end of the plenum.

Thanks to all who have replied.

 

[IceStationZebra]

Maybe you should post a sketch so we can get a better sense of your design.

ISZ