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Geronimo332


Joined: Jan 24, 2010
Points: 16

How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Original Message   Jan 25, 2010 5:42 am
Is there a low cost and easy way to convert my B&S 15.5 Snow Series Max engine to a 16.5?

Since both engines are 342cc it can`t be to much different. Does anyone now?

It isn`t very important since my engine is powerful , but if it don`t cost to much it vould sure be nice to have the extra tourqe.

Replies: 2 - 11 of 13Next page of topicsPreviousNextNext page of topicsAllView as Outline
mech12


Joined: Feb 20, 2006
Points: 273

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #2   Jan 25, 2010 5:07 pm
ya  buy a decal that says  16.5.     same engine different marketing strategies
snowmachine


Location: Washington State
Joined: Nov 12, 2008
Points: 267

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #3   Jan 25, 2010 5:25 pm
+1 on Borat's response. All parts in same series & CC seem to match when I compared them as well.
mml4


Snow is good,
Deep snow is better!


Joined: Dec 31, 2003
Points: 544

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #4   Jan 30, 2010 9:30 am
If you have some time pop open a cold one and try to get through this thread from 2005. It is a long read but  very enlightening.

http://www.abbysguide.com/ope/discussions/7869-A-1.html

Marc

This message was modified Jan 31, 2010 by mml4


SnapperV210P,Toro22177,TroyBilt42010Snowthrower,Craftsman Shredder,American Turbo Pressure Washer HondaGX200,Stihl011Saw,EchoPas260Trimmer Edger,EchoPB602Blower,EchoHCR150Hedge Clipper
Geronimo332


Joined: Jan 24, 2010
Points: 16

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #5   Jan 30, 2010 4:50 pm
I didn`t pop a cold one, but got pretty "loaded" of all the reading.

Thank`s for the link.

Geronimo332


Joined: Jan 24, 2010
Points: 16

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #6   Feb 23, 2010 1:32 pm
I think i found out what B&S do to restrict torque in their engines.

They simply restrict AIRFLOW into the engine.

This picture shows a "intake manifold" that  sits between the carburator and the engine head. As you can see it has a smaler diameter in the end.

This view is the way air og fuel is flowing into the head.

I didn`t mesure the diameter, but a guess is that the carburator is 30mm and this part has 30mm diameter at the begining and then mayby 20mm at the end.

This is the end that sits against the head, as you can see it has a different shape that match the intake opening of the head.

This will restrict the engine from breathing especially at higer RPM`s.

I found this out after i startet taking down my new (2hour run) engine for some tuning. I have opened up this diameter so it is a straight tube

.

As you can see in this picture.

I also milled down the head, did a valve seat job, porting of the intake and exhoust and tuned the ignition spark

     

I can`t say you what difference it will make to open up this "plastic manifold" since i did all the above modifications at once, but i can say that it did a huge impact on

the power of this engine. I`m impressed of  how i handles heavy snow now!

It also have a deeper tone now ( under heavy load) and you can hear that it flows alot better and have bigger "throat".

The snow thrower just takes every thing you throws at it, and newer bogs down.

This message was modified Feb 23, 2010 by Geronimo332
Catt


Location: Minnesota
Joined: Oct 16, 2009
Points: 196

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #7   Feb 23, 2010 1:42 pm
Kind of like NASCAR and a restrictor plate.
This message was modified Feb 23, 2010 by Catt
Catt


Location: Minnesota
Joined: Oct 16, 2009
Points: 196

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #8   Feb 23, 2010 4:37 pm
How much did you take off the head and will you now be using premium?
Geronimo332


Joined: Jan 24, 2010
Points: 16

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #9   Feb 23, 2010 5:43 pm
I took of 3 millimeter and i now only use 98octane (Norway)
Catt


Location: Minnesota
Joined: Oct 16, 2009
Points: 196

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #10   Feb 23, 2010 9:19 pm
I like it!  A high compression high performance snowblower engine.  I have no doubt that you have way more horsepower than the average 15.5 or 16.5.  What changes did you make to the spark?  Did you advance the timing?
This message was modified Feb 23, 2010 by Catt
Geronimo332


Joined: Jan 24, 2010
Points: 16

Re: How to make my 15.5 B&S Snow Max engine a 16.5 engine?
Reply #11   Feb 26, 2010 10:51 am
It`s no way of advancing the timing as the coil is fixed.

The only adjustment i was able to do, was to minimize the distance between the coil and the flywheel,

in order to create the strongest spark possible. The smaler the gap, the stronger the spark!

I did that by losning the bolts holding the coil and then put a piece of paper between the coil and flywheel and then

fastening the bolts again. Then remove the paper and rotate the flywheel in order to check that it run freely.

As my flywheel was not 100% round i had to do this a couple of times.

I`m gonna make a custom bracket to hold the coil that makes me able to adjust the timing.

I just didn`t have the time at this moment. I read somewhere that the optimal timing was 26 degree`s.

I don`t know what the original timing is, but from what i understand it will mayby give me 1-2 HP more.

Also here are som more pictures of where this "plastic manifold" sits on the engine!

   

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