Pre Turbo Methanol injection.

[keithmac]

I`ve been reading up on pre turbo methanol injection and was wondering if anyone on here had tried it?, the theory is you can get more air through the turbos for a given amount of "work" because the methanol/water offsets the heating of the air as it is compressed (there`s a lot more to it than that though).

Some people have seen good gains with it and other`s haven`t. I`m making a pair of jet holders to sit directly in front of the turbo air intakes and mist vapor into the compressor (you have to have a very fine fog in order not to damage the compressor blades). Should be able to allow the tubos to build more boost to redline hopefully.

It`ll cost peanuts and some time to do this with my setup so I`m going to give it a go and see what happens.

Would be interesed to here if anyone else has ever set up a similar system?, not just 3/s specific.

[DoctorDex]

I don't know much about this, but to me it seems like you'd do damage to your turbos no matter how fine of a spray you put it in. The centrifugal force created by the compressor would cause the fluid to come out of suspension and you'd essentially be trying to force large water droplets through your turbos that are spinning at very high rpm. To make things worse, you'd think the extra weight of the water would cause the turbos not to spin smoothly and/or vibrate, causing premature wear and/or shaft play. Scary if you ask me.

[glimerman]

It's like discharging shotgun into turbine wheel...spinning at 120K
Most popular way is to place injector before TB.

[glimerman]

Compressor wheel,not turbine

[Deathsled]

Originally Posted by GTOPWZ

So how does a carby turbo setup work?

most people build a box around a carb and pressurize it, so the turbos are before the carb. I've seen carb'ed turbo setups in draw-through however.

[keithmac]

I`ve seen plenty of draw through turbo setups and that`s a good point, they`ll be flowing more "liquid" trough the turbo than my setup.

I`ll be using Aquamist jets (very good atomisation), aimed at the centre nut of the turbo.

Will let you all know how I get on..

[Deathsled]

Another thing to consider is that the methanol (or whatever mix you're running) is going to be displacing air/oxygen going into the turbo.

[magapaka]

Originally Posted by keithmac

I`ve seen plenty of draw through turbo setups and that`s a good point, they`ll be flowing more "liquid" trough the turbo than my setup.

I`ll be using Aquamist jets (very good atomisation), aimed at the centre nut of the turbo.

Will let you all know how I get on..

Not really a good comparison, sorry. Water is noncompressible and has a very high surface tension compared to gasoline or other hydrocarbons. The water droplets which will be sucked into the compressor wheel have both weight and density which will not yield or dissipate easily on contact with the compressor vanes - and will erode it over time.

Squirting water before the turbo has been done many times - the best data I ever found on it was way back on either Gus Mahon's tech tips or on the TurboBuick forums, and had a few pages of pictures of various setups and carnage that resulted alog with charts. I can't find it now - may no longer be out there but I'm sure part of it is out there somewhere.

It CAN be done and will work, but you have a few issues that have to be accepted. One, water WILL come out of suspension when it meets the compressor vanes. How much damage it does depends on a lot of factors, but generally the finer the mist your nozzle can make,. the less damage is done for a given amount of use. When you get off the throttle, water WILL pool in either your pipes or intercoolers - as soon as the throttle closes and the air velocity in the pipes drops, it will come out of suspension and condense then drain to the lowest point. That leaves you open to sucking droplets - non=atomized - into the engine next time you rev it up. There is more to think about but those from what I remember were the main points about water being sprayed prior to the turbo.

Compared to water, hydrocarbons have a very low surface tension and very little molecular bond - they dissipate easily and carry very little mass per particle when suspended as vapor, and will not abrade the compressor vanes on impact. That's why the old draw-through carbs don't usually wind up with compressor vanes that look like they tried to eat their way through a prison wall.

[Highboosted]

Think about this, then make your own decision:

We wash jet engines to remove deposits (mostly after a birdstrike, and the guts stink really bad). Every engine has a written limit to how much water and for how long because it erodes the compressor blades. Modern turbofan engines are designed so that the water from heavy rainfall is directed by the slow moving fan away from entering the fast moving "power section" compressors, otherwise they'd fail in short order. Same limits apply to spraying deicing fluid in the engines before takeoff in bad weather.

And for the rest, I agree with magapaka