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Help with Snowmobile Catalytic Converter

Help with Snowmobile Catalytic Converter

Help with Snowmobile Catalytic Converter

The ASME chapter at our school is trying to retrofit a pickup catalytic converter to a snowmobile chassis.  Can anyone direct me to a good resource for learning more about catalytic converters (i.e. airflow ratios, acceptable temperatures, warm up periods, etc).  


Joe Friday

RE: Help with Snowmobile Catalytic Converter

Here's a contact for a potential industrial partner for your project:


RE: Help with Snowmobile Catalytic Converter

You may need a 2 way catylst instead of the normal 3 way to have a decent life span.  Is longevity an issue?  I see California chainsaw 2-strokes use cat.'s now, I wonder what type they use.

RE: Help with Snowmobile Catalytic Converter

It'll be a 4 stroke chassis.  660 cc's probably turbocharged.  Right now, longevity is only required for an endurance race (100 miles) and sprints.  If you know of any way to estimate mass airflow for a turbocharged engine too, I'd appreciate help on that.  We'd probably be running 8 psi.   


RE: Help with Snowmobile Catalytic Converter

Wouldn't you look at target horsepower, take a stab at efficiency numbers, and that info determines 'target' mass airflow. Engine breathing and RPMs would give you an idea what manifold pressure you need, then the turbo can be sized. The desired horsepower (and efficiency) pretty much determines mass airflow, right?
(Will this be crankcase scavenged? oil injected? Metering oil and accounting for that in the air/fuel mix should be interesting...)

Jay Maechtlen

RE: Help with Snowmobile Catalytic Converter

It's a 4 stroke, so it should behave similarly to a car as far as exhaust, fuel requirements etc.  We were planning on doing a "piggy back" fuel chip which monitors boost and adjusts fuel accordingly.  We'd also have to put larger fuel injectors in.  

I ended up taking a magazine that did some turbo compressor map sizing calculations and figured out what I needed to know: the turbo's too big.  Heh, so we have to go find a turbo for a 4 stroke snowcat somewhere cheap (we're all college students).  Anybody want to donate?  You pick a boost you want to run at, then calculate air density based on estimates of air temperatures, then calculate mass airflow based on engine size at various RPM's.  Then you plot those points based on pressure ratio (pressure of air entering engine/absolute pressure) and a mass flow rate for your turbo's performance data.  Turns out, anything under 3000 rpm would put the turbo in the "surge" region.  

Thanks for the replies.

RE: Help with Snowmobile Catalytic Converter

how about a turbo from a motorcycle?
What's the smallest car engine that was sold (in your country) with a turbo? I guess that's not entirely valid, 'cause the turbo needs to be sized for the right pressure ratio as well as flowrate...

Contact turbo distributors, manufacturers, and repair shops. Tell them about the project, and see if they might help you out.

good luck!
(of course, 'good luck' usually entails lots of planning and effort!)

Jay Maechtlen

RE: Help with Snowmobile Catalytic Converter

Yah, motorcycle turbo is exactly what we're pursuing right now.  About the smallest engine over here is like a 1.8L, which is still 3 times the size of our engine...  Thanks for the well wishes.  heh,


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