Cooled intake manifold

[Frogster]

Hey there everyone. So I ordered my flying horse motor from bike berry and its currently in shipping to me. I tried to order the short billet intake manifold to compliment the upgraded NT speed carb i got with it, however bike berry didnt have any in stock when i ordered.

Im not about to order one from somewhere else and pay the added shipping, as ive already spent enough money on the parts to do this build.

So I got to thinking... What if instead of focusing on making the path of the air to fuel mixture from the carb to the cylinder shorter, how about focus on making it cooler, and therefore a denser charge to begin with. I was thinking what i would do is port and polish the stock intake manifold, make the flow passage as clean and resistance free as possible, then weld on cooling fins to the outside of the intake manifold with the intention of significantly adding to the cooling surface area.

Im thinking along the lines of the way an air to air intercooler would work, minus the forced induction part.

My question is has anyone ever done this before? Does my idea make sense?

 

[2door]

My feeling is that the amount of work would not pay off in any discernable power increase. The run is so short and the exposure time to whatever cooling effect you'd create would have little effect on the density of the incoming fuel/air charge.

I'll say that it would look very cool but unless you have a steel intake manifold you'd have to be an accomplished aluminum welder to achieve what I think you're looking for.

I think you'd be surprised at the temperature of the intake manifold under normal running conditions as it is. Try an experiment. Run your bike down the street a block or two and before it has a chance to sit and idle, reach down and touch the manifold. You'll see it is much cooler than any other part of the engine.
What little the cooling fins would lower the temperature would be negligible at best.

But I repeat. It would look very neat. Try it and let us know. Good luck.

Tom

 

[maniac57]

A longer intake tract can improve power a bit, but your idea will not make enough difference to notice, other than looking very neat. If you want to experiment, try making longer manifolds and testing how it impacts your engine. (after the engine is well broken in)

 

[Frogster]

Well, I am not an acomplished welder, however I am currently co-oping for the next 4 months or so at a welding and fabricating shop. I am in a shop with about 6 or 7 very experienced welders in mig, tig, stick, and flux core. The owner is so old, he originally started welding back when oxy-acetylene gas welding was the primary form of welding. Ive also improved my welding a fair bit in my opinion over the past two weeks imo. Anyways it was just a thought, ill take ur advice 2 door and maniac. Might end up doing it to make my manifold not look stock lol.

Also, maniac, if a longer intake manifold improces power, then why are short billet intakes a performance part? Care to explain the science behind the impact of intake length?

 

[maniac57]

I'm a backyard experiment kind of guy. No idea why some engines respond but they do. Others not so much. Most two strokes seem to like a bigger intake tract for low end response.

 

[scotto-]

All I can tell you is this. With 4-strokes, the longer the intake tract, the colder the the air/fuel mixture will become. The longer the intake on the 4-strokes does infact add more hp to the engine. The intake on my 212cc Slant race bike almost ices up because it gets so cold and it is made out of radiator hose.

I'm sure this would have similar effect with the 2-strokes.......experiment a bit and see what ya find. It can't hurt.

 

[BigBlue]

Here's some experimentation done with extended intake length on a Happy Time 48cc engine:
http://www.motoredbikes.com/showthr...or-more-low-end-power&highlight=intake+length



Good luck,

Chris
AKA: BigBlue

 

[MEASURE TWICE]

I know this is an old post, but I thought maybe with the additional length of intake due to the elbow I have on my 4 stroke 3.5 Briggs I could enhance the charge even more by packing some snow around it while out on the forest service routes. Free for the taking I'd suppose. I paid my OHV Reg.

 

[bairdco]

The intake on my minarelli bike will ice up on the outside if the temps fall below 60°.

Which is bad, as too cold will freeze the atomized mixture.

 

[MEASURE TWICE]

OK, sort of not liking crystals of ice in beer. I don't want to damage anything inside the cylinder either. By default though I have a longer intake as the elbow was needed for elbow room. The engine just barely fit and the carb was never going to. If you use nitrous oxide then that too could from decompression out of it's bottle also freeze up the mixture. Need a fuel that won't freeze.I guess there was not enough alcohol in the beer.

 

[Tony01]

My intake manifold gets ice cold and collects condensation in any temperature.

Instead of cooling the intake, you can make a gas line cooling can that you fill with ice. This would be very cool and you can run a bit leaner.

 

[MEASURE TWICE]

I was told the best time to by gasoline is in the early am before sunrise as the gas tanks even under the ground would be cooler. How much savings over a life time would that account for? Since gas is sold in volume you get more in your tank when it warms up. Denser colder gasoline? Be sure not to bend the needle on the gas gunge when it heats up. HaHa!