Self contained intake air cooling system ideas... Any thoughts?

VonYinzer

VonYinzer

Over 10,000 Posts
Been chatting with some folks in regards to a possibly (read: probobly) rediculous thought. Were all aware that high operating temps are the bain of power generation and efficiency in internal combustion engines. So, the response is to find a way to lower internal combustion chamber temps during combustion while still allowing for proper air/fuel mix, lubrication and detonation.

People have gone about this in numerous ways, which I'm sure don't need mentioned here. One of them though is intriguing to me based on the relative simplicity. Nitrous oxide. The problem you have with nitrous in a small displacement, and relatively high compression engine like a motorcycle (and especially a two stroke in this instance) is that it creates such a volatile intake charge that it generally ends with engine parts crossing the finish line before the rest of the bike.

That said, nitrois oxide when added to air mix is still a very effective way of quickly reducing temperatures. So, my thought is that if anslow "bleed" of nitrous was added to the intake air BEFORE the fuel it would reduce intake temps, allow the air fuel mix to remain constant, and still allow the oiling system to work correctly by not cooling the incoming lubricant and changing its properties.

I've read in the past about intake "misting" or "bleeding" using number of gasses or nitrous being implimented by automotive racers in the past. The benefit of this type of system being that you get the cooling properties of the gasses without the volatile combustion and unruly high compression numbers. I'm still searching to find any info on these setups.

Basically I'm attempting to design and setup an intake cooling system that WON'T dramaticaly increase compressikn or create volatile mixtures opon combustion, that is seperate entirely from the oiling system on a Yamaha R5 motor. The motor WILL have been ported and "built" on the low end of full track specs so it can still be used on the street.

So, now that I've made nearly no sense... Let me have it. Ideas, experiences, thoughts? Again, keep in mind that I'm working with a "built" two stroke twin. Dual carbs. Mild expansion chambers. Mild track porting.

I've already spoken with one guy who is very well versed on two sroke engines having built and rafed them for yeara, and once ran a similar system on a carburated automotive engine so I know its possible. Whether or not its feasable is the real question...

Thanks in advance for any insight.

Mike
 
I'm having trouble picturing how that will work, exactly. What you're describing, I think, is what's known as a "dry inject" nitrous system. It only add nitrous and requires the fueling system to make up the difference. More common is the "wet inject" system, because it adds fuel at the same time as the nitrous, rather than relying upon the existing fueling implementation.

While it's true that a dry inject system will significantly lower intake charge temps, one of the downsides is that it also drastically increases combustion chamber temps due to the extra oxygen that is present (N2O degrades to 2N2 and O2 at around 500°F). The additional fuel must be added somehow or you're running very lean.

There are several more common ways to reduce intake temps and you'll find most in use in forced induction setups. They can also be used in combination, which is nice.

The most common is an intercooler. For a forced induction system, these are almost a necessity to get reliable power. You may think they'd be useless for a naturally aspirated engine, and you'd be mostly right, except for one thing; they can be setup to be sprayed with a liquid. When that liquid evaporates, it can lower intake temps to below ambient.

Of course, you can skip that all together and inject the liquid directly into your intake (though I'm not sure if this will play nice with a two stroke). A combination of methanol and water is very common, though some swear by just methanol or just water.

The downsides to any of these approaches on a bike is the added weight and space. More often than not, it's just not worth the gains.

What can be done is to try to be mindful of the materials used within the intake system and how the exhaust is routed. Clever use of heat shields can also play a role. A programmable ignition on a two stroke will make a world of difference, as well. Unlike four stroke engines, which require a steady increase in advance, the ideal advance curve for a two stroke is shaped more like a parabola. Start off with advance and as you get on the pipe, retard the advance. This curve is not usually something that can be accomplished by mechanical means and it will make a huge difference to your operating temps (not to mention your power output).
 
Hmmm... I get ya. I need to figure out a better way of describing this.

Basically, the nitrous wouldn't be used as an "additive" as much as a means to create a cold air vacuum in front of the intake. Sort of. Let me sit down and work out the idea a hair more and retry this...
 
VonYinzer said:
Hmmm... I get ya. I need to figure out a better way of describing this.

Basically, the nitrous wouldn't be used as an "additive" as much as a means to create a cold air vacuum in front of the intake. Sort of. Let me sit down and work out the idea a hair more and retry this...
Click to expand...

I think I understand. The problem I see is that it's probable that the amount of NO2 needed to significantly cool the charge would also result in a significant amount being ingested by the engine. You could always go with a long metal intake and spray the outside with a compressed gas (fire extinguisher?) prior to running. That should cause a pretty good ice up on the outside of the intake which will transfer (a bit, at least) to the intake.

A head exchanger inside the intake would be your best bet, but that's also likely to cause more pumping losses than you gain in cooling. Systems like these are very tricky to get working on a bike because little weight additions mean a lot more and you lack space, too.

If you're doing drag races, it's possible to treat the fuel and ice up the intake before each run, but on a circuit, I think it would be hard to get something like this to work.
 
In the land of high turbo boost imports, they'll cool the intercooler with either a water spray (or something like windshield wiper fluid, as it has methanol in it and evaporates more readily) or...wait for it...

Nitrous Oxide.

You could set up a small intercooler like Sonreir mentioned, and then NO2 over it to cool it, and therefore the air inside the intercooler. That would give you your cooling effect without any of the downsides. You could also use CO2 or nitrogen as your cryonic gas to cool the intercooler, doesn't have to the NO2. You'd still have to jet up to compensate for the denser air, and, in the end, the power gains might not be worth it.

Only one way to find out though...
 
I don't know enough to have any input but it's an interesting conversation so I just want to follow along.
 
It's funny this was brought up because I've contemplated ways of getting cooler air into an engine many many times. To the point of sketching stuff out but no farther. I've thought of crazy things like ice boxes to mini air conditioners to just plumbing. It's a fun subject that I can get cought up in for hours. Following to see where this goes! I've even looked into crazy things like the vortec cold air gun. That was for a car though. You'd have to get really creative on a bike.
 
It's a valid approach and one that has been tried many times. In WW2 many high performance engines ran Water/Methanol injection to reduce intake temps and increase the mass of air ingested. They typically had 2 stage superchargers but the idea is the same.

Others have attempted to use reversed heads (ram air) to cram more, cool air in and leaving aside the pressurizing effect for a moment they are not the most effective techniques.

Reducing combustion temps can be achieved many ways:
Using a fuel or other liquid with high latent heat of vaporization
Lower compression ratio
More effective exhaust gas extraction
More complete combustion
Better intake flow
Revised head geometry to increase squish velocity or to reduce Surface area: Volume ratio
Water cooling
Programmable ignition
Better cooling air flow management

And so on

Just keep in mind that cooler air is denser air and will need more fuel which in turn generates more heat......
 
Honestly, I think the best route is to pursue a reverse port like Brother Joey is after on his 550. Please forgive any typos that occur. I am way too drunk right now. I've tried to remove the typos, but you can't ever be sure... Shit, have I spent five minutes on this reply already?!
 
teazer said:
It's a valid approach and one that has been tried many times. In WW2 many high performance engines ran Water/Methanol injection to reduce intake temps and increase the mass of air ingested. They typically had 2 stage superchargers but the idea is the same.

Others have attempted to use reversed heads (ram air) to cram more, cool air in and leaving aside the pressurizing effect for a moment they are not the most effective techniques.

Reducing combustion temps can be achieved many ways:
Using a fuel or other liquid with high latent heat of vaporization
Lower compression ratio
More effective exhaust gas extraction
More complete combustion
Better intake flow
Revised head geometry to increase squish velocity or to reduce Surface area: Volume ratio
Water cooling
Programmable ignition
Better cooling air flow management

And so on

Just keep in mind that cooler air is denser air and will need more fuel which in turn generates more heat......
Click to expand...

Also... bear in mind that WWII engines tended to derive from aircraft and they were meant to operate at 30,000 feet above sea level. A supercharger was almost a necessity.
 
And also, don't forget about expansion ratios. Everyone forgets expansion ratios. Google "Atkins Cycle". Fuckt it. I'm going to bed...
 
Hahaha... How's you're head feeling today Matt?


Ok... Running a reverse cylinder setup with a "ram air" type intake (remember, the bike in question will have a full fairing which allows for all kinds of neat intake routings) has most certainly been discussed. Its actually a relativly simple operation compared to a big four stroke like Joes bike.

Another option I've been pondering was to run intake "scoops" on the fairing that led to ram air style tubes (think 70s muscle cars). The tubes would be aluminum to save weight and for its ability to transfer/maintain cold temps. Around the aluminum intake runners I could coil copper line than wrap it all in thick plastic (shrink wrap?). The copper line would be a closed loop and tied into a small can of automotive AC coolant with a small valve on it.

Start the bike, open the valve and super cool the intake runners. Overall your looking at maybe three or four pounds of added weight.
 
The real issue is not how to cool the intake air, but where to put the equipment and the weight. The other small issue is making the engine reliable enough to handle the increased power.
Think of this- if you doubled the hp of the engine, what would break first?? The crank?? The heads? Holes. In the piston Would the connecting Rods hold up??

So not only do you need a cooling system, but the engine needs better parts. Even a turbo requires piston and rod changes, sometimes crankshafts.

The idea of cooling the intake is good, but the practicality of it is not so good, especially ona motorcycle.






Sent from planet Earth using mysterious electronic devices and Tapatalk
 
I'm feeling OK, but I can't remember why expansion ratios are important to this discussion. I'm pretty sure I felt it was extemely important last night...

Anyway... Metal intake is almost always a poor idea. Metal is one of the very best conductors of heat and so any cold temps would almost definitely get heated by the ambient heat of the engine; especially so once you come to a stop and heat soak starts to set in. Silicone tubing is your best for keeping temps cool in the intake tract. If you wanted to run copper tubing through it, you can do that, too, just check flows. Good air flow is more important than cool air flow.
 
Expansion ratios are important, but not relevant to an itsy bitsy 2 smoke motor at this time of the morning. Yes those engines were operating at high (for the time) altitude but the reason for intake cooling remains the same and it works when you need it to. It's also been used on some modern turbo applications and as long as it's tied into the overall electronics so that the advance or boost is controlled when you run out of cooling liquid, that's all fine.

Reversed heads bring more complications and issues than they fix. On a two stroke the primary advantage is straight exhausts. Ram air on two smokes ends in disaster - every time.

But why add all the weight and complication on a simple bike when it should be able to live with almost any reasonable state of tune.
 
teazer said:
But why add all the weight and complication on a simple bike when it should be able to live with almost any reasonable state of tune.
Click to expand...

A healthy mix of curiosity and stupidity and I havent seen it done before. The main hurdle I'm trying to jump is how to do it without adding any real substantial weight.
 
from years working on dirt latemodels. when we run alky the intake manifold actually would sweat from being cold after running the car, but the alky burns about 2-1 vs gas, and all the joys of it being corrosive to the aluminium if not drained/flushed at the end of the night

9cpgher-1.jpg


(pic added cause its cool..lol )
 
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