Fuel additives and H2O injection

H

huntnfish08

New Member
I asked these questions on my first post under introduce yourself but I think they will get more response in the GD Forum.

Can these engines use higher octane fuel for increases power? What does 100 octane do to these motors? Blow them up from knock? I'm guessing that the octane boost doesn't do much for a naturally aspirated motor? Zylene is a good additive for raising octane but I've only used it in a turbo V6 application.

Has anyone tried either alcohol or water injection? Here's a link if someone can relate their experience or expertise to the subject. H20 injection can produce more HP at cooler temps and increase fuel mileage, believe it or not!

Mother Earth Alcohol Fuel: Ron Novak's Do-It-Yourself Water Injection System

Will the h2o injection system above work with the carbs used on these tiny 2-strokes?
 
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Higher octane would REDUCE knock, which these engines don't have due to already low compression. High octane fuel, or any kind of fuel additives is pretty much a waste of time and money with a 40's technology piston ported two stroke.
 
The beauty of these engines is that they are cheap, simple and easy to experiment with. I would suggest you try the water/alcohol injection and let us know how it goes....I think the carbs that come with these bicycle motors are open to modifications of any type- being that they are the crudest carb I have ever seen.
 
I don't have a kit yet so haven't seen the carb up close. Is there a vaccuum port on the carb? If not would it be easier to plumb the h2o/alki into the intake runner or into the carb itself. Pros and cons to either?

What about the walbro carb option some people are using? Is it worth replacing the stock carb with a walbro? Would this carb make a h2o injection project easier? Is it easier to tune/keep in tune? In relation to the "80cc" that is.

Thanks,
Adam
 
The thing with MW50 injection - as it used to be known if you were buzzing around in a DB605 powered fighter was this - it was supposed to provide Oxygen (from the water) and provide extra fuel as well (methanol + a side order of hydrogen.

This worked fine in a 6.5:1 compression engine of something in the region of 65L displacement - but only for short bursts as even with such low compression you could mince an engine in short order. I think on DB605 engines you have 5 minutes and thats it - generally it was used as, to quote the monty python crew 'run away!!' mode..

The merlin engine as fitted to spitfires had a similar system - referred to by pilots as 'going through the gate' as you had to literally jam the throttle through a wire top-stop to engage this extra power (if the wire was broken the ack-emma or engineer would know he'd have to strip the engine and most likely do a rebuild as well, and if you kept it doing woe betide you). Six hours of pulling, rebuilding and replacing an engine for no good reason while having the living cr*p bombed out of you does not a happy mechanic make...

Now its not to say that this wouldnt work with the chengines but there is a problem.. and that is of delivery of water or whatever else you want to use. Considering that a large V8 only needs a mist of water that would be provided by the feed of a small bore surgical needle to give an effect - I have no idea what you could use to provide a feed. The water needs to be vapourised and fed into the engine with the fuel. So far so good. But too much and you will end up, in short order, with a 67cc swimming pool and not enough - no effect. Worse is an uneven delivery which would also cause problems.

Given the vibration of the engine - anything too flimsy would break and even a small bit of metal up the works at full power isnt gonna help matters any...

Jemma xx
 
Thanks Joe.

However I missed the most important point - ALL engines fitted with an MW50 or similar system were 4-strokes.

I have very little confidence that a 2 stroke will work with this - at least not for very long as the water (which will leave residue) will likely trash a 2 Stroke...

Jemma xx
 
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