So what about water injection, AFTER the turbine?

[GS70350]

After all, turbochargers rely on both pressure and heat to operate.

Pressure and temperature drop across the turbine is the ultimate driving force.

In the quest for increased turbine efficiency, most people follow set rules.
The mainstream aproach is to install a larger downpipe or an open dump after the turbine to create a low pressure zone and allow for a greater pressure drop across the turbine. Of course as pressure drops temperature will drop as well, also causing a greater temperature drop across the turbine which again adds energy to the wheel.

A side effect of this is also a decrease in spool up time thanks to the extra temp/pressure drop as the exhaust gases pass through the turbine.

Im going to test out a new idea of mine that may or may not work. Ive yet to see this used, so there must be a inherent flaw in the idea. If so, please let me know.

Idea:

Inject a fine mist of water just after the turbine outlet on the turbocharger to absorb heat and reduce the temperature of the exhaust gases as they exit. This should create a larger pressure drop across the turbine and therefore aid in decreasing spool up time and add HP/TQ.

A few problems i can see would be the fact that water changes to steam and causes a large amount of expansion in doing so. This could increase pressure after the turbine and reduce the benefits of the temperature drop.

Adjusting the amount of water injected could change this, as more water would absorb more heat while reducing the amount of steam produced after a certain point, however this would take a lot of water.

What else can be done to reduce the temperature at the turbine outlet? This is an area that i have never seen testing done or even mentioned. If anyone is interested or wants to discuss such things please speak up. Im probably going to do some testing of my own for ****s and giggles.

Later

 

[bruce]

A few problems i can see would be the fact that water changes to steam and causes a large amount of expansion in doing so.

That's what I've heard as being the downside to it.

Thou, MSD sells a water injection kit for use in 2 stroke expansion chambered engines. A goggle should yeild more info on what they're doing.

 

[denn454]

intresting idea. it all sounds like it SHOULD work. i'm no chemist but there has to be some liquid or other gas that has a evoporation point higher than whatever the exhaust temp's are.

maybe using co2 would work, it starts out at a very cold temp, so it would take longer to get to the point where it would expand. by that time most of the heat would be gone and it wouldn't be much of an issue. (just my thoughts here, not fact)

 

[Drac0nic]

This makes sense actually, I was doing some reading a day or two ago about exhaust systems that the cooling allows you to use a 1/4-1/2 inch less diameter pipe for the muffler exit then the entrance. The things I'd be afraid of are A)puddling B)corrosion C)thermal shock. all in all I'm a big fan of giving it a shot, innovation comes from trying something not talking bullsh!t like a lot of people do.