Is an Intercooler Worth It for Naturally Aspirated Engines?

[Mech_Engineer]

Would this be against the rules? Although it's not in the tank, methanol would probably count as fuel.

Could be, I didn't bother taking a look at the rules. Still, he might be able to run pure distilled water to cool the intake charge and possibly get a little more "oomph" out of the engine by running more advanced timing. Water injection usually functions as an intercooler application for roots-type blowers, but it does have the advantage of increasing heat absorption in the fuel mixture.

 

[Camron201]

Mounting the injectors at the top of the intake bell uses the vapourization of the fuel to cool the incoming air and increase the density.

The bike uses a throttle body with the injector built in. We can move the whole throttle body slightly, but because of rules we can't change the injector type.

 

[Camron201]

Would this be against the rules? Although it's not in the tank, methanol would probably count as fuel.

I will talk to the next racing event dean and see if it's illegal or not.

There is nothing in the regs about using cooled fuel though. You can also use aftermarket fuel tanks so long as they are heavier. Looking to integrate the cool can idea into the tank may be worth it (hides it from the competition). You could have the fuel pick up directly into the cool can then the cool outlet can to take the fuel to the carb/injectors.

We already use an aftermarket aluminium tank to have enough fuel to make it through the race. With a good design it could be done, but the fuel tank area is pretty cramped.

 

[Camron201]

If we did run a water/methanol injector. How much fluid do they normally consume?

 

[jack action]

If we did run a water/methanol injector. How much fluid do they normally consume?

There's a lot of info on http://www.rbracing-rsr.com/waterinjection.html" and a calculator at the bottom. They say that the coolant to Fuel Ratio (Based on mass not volume) should be in the 12.5% to 25% range.

You can use water alone if methanol is illegal. IIRC, it's less efficient than the 50/50 mix but it still does the job.

To make best use of space and weight, why not use ice to cool the fuel and recuperate the water once it has melted?

 

[mender]

They also say:

"Water or water/alcohol/methanol does not make power...superchargers and turbochargers make power. The cooling effect of the water injection only allows you to run higher boost pressures and leaner mixtures without engine damage. The increased density or higher pressure ratio is what makes the power, not the water."

Unless the compression ratio is too high for the fuel, I don't see this helping much. Any advantage to be gained from water vapourization could be realized by using more fuel, which is legal and already on the bike.

 

[jack action]

They also say:

"Water or water/alcohol/methanol does not make power...superchargers and turbochargers make power. The cooling effect of the water injection only allows you to run higher boost pressures and leaner mixtures without engine damage. The increased density or higher pressure ratio is what makes the power, not the water."

Unless the compression ratio is too high for the fuel, I don't see this helping much. Any advantage to be gained from water vapourization could be realized by using more fuel, which is legal and already on the bike.

Of course, using water alone, at ambient temperature will have little or no effect on power. If the water is colder than ambient temperature, it will cool the air and increase its density. But the real cooling effect is inside the cylinder, when the water changes phase under compression. To get the most out the water injection on NA engines, you have to increase the CR or advance the timing which, just like higher boost, makes more power.

 

[mender]

... advance the timing which, just like higher boost, makes more power.

If the fuel is compatible with the compression ratio, timing should already be optimized. Advancing or retarding it from MBT will reduce power.

 

[Camron201]

Thanks for your Ideas and info. I will experiment with a few of these Ideas. If any thing seems to work well I will get some Dyno runs and pics up on here.

 

[FAlonso]

The power gain from cooler air alone isn't that much (due to temperature), the majority gains come from the increased density of cooler air allowing you to burn more fuel.

The reason why intercoolers are used on forced induction motors is becuse the compressing process increases the temperature of the air (decreasing density) the intercooler then brings this temerature down (increasing density).

There wouldn't really be any gains from an intercooler on a naturally aspirated engine because the air doesn't really heat up that much between inlet and inlet manifold. For a N/A engine a ducted cold air intake would do more.

You nailed it. This can probably only help with super/turbo charged engines