18hp vanguard exhaust questions on smaller pipe

[SCMay]

I had a new exhaust made for my max which uses 1.5'' pipe in to a car muffler on its side centered on the side where the pull start is.
question is it sound is ok but if I put a small lawnmower muffler at the end it really quites it down, but will that choke the engine to much?
The small muffler is a screw type that screws in to a lawnmower its a 7/8'' id intake and 1'' id output pipe which looks the same as what comes out of each header.
so again will that work?

[thebuggyman1]

1.5" ID? Thats huge for the amount of exhaust gas an 18 can put out......is the entire header 1.5"? You are going to lose low end. with little gain on the hi end. R13 can probably explain this better than I can due to his racing background, but....When the exhaust gasses leave the cyl it creates a vacuum behind them pulling in fresh air/fuel mixture.
The smaller and longer the header tubes, the more low end you get at the expense of hi end. Too much restriction. So a comprimse has to be made. This is the reason header tubes are supposed to be equal length for each cyl. Unless you have eliminated the governor and bumped the HP....what you have is bad.
Is your muffler inside the tub? If so, this could create too much heat.....it should have air blown over it venting outside the tub. Plus the hot air going into the carb reduces HP.
My stock exhaust header tube is approx 1" OD. I would reconsider your whole exhaust.

[SCMay]

The header is the one that came on my max 1'' but they both flow in to the same pipe. The muffler is in the tub centered in the open side oppsite of the clutch side, I plan to wrap the pipe with exhaust wrap and I plan to make ducting like what is on the exhaust side to direct some air flow toward the muffler, and put some heat sheild around the area, but if I choke it down at the end back to 1'' that should add some back pressure to the whole system correct?

[thebuggyman1]

Back pressure is not a term I've ever liked......let's face it, it is RESTRICTION. Think of your engine as a pump, restriction in the exhaust or intake = less HP.
Go ahead and try the muffler.....Go on a test run without it then with it and see how it performs.
I'm still more concerned with the muffler inside your tub. Wrap it up good and see how much it heats up the area.....You can always change it.

[SCMay]

Ok this is what I ended up doing as the car muffler was hitting the body when I shut it.
so the muffler I took of was not in that bad of shape, so I cleaned it up and welded it on.

[Mike]

You will want to do a couple of things differently. First, you will want to move the muffler to the other side of the motor. The side you have it on is the fresh/cool air intake for the motor. The muffler will be feeding warm air into the motor which will cause it to run hot. Second, you will want to extend the exhaust out of the Max completely so that it exits the vehicle. Third, if you put the muffler inside the vehicle, you will have to duct it properly to get the heat away from it. Again, fresh air is coming in the motor on the right hand side of the picture and exiting on the left so you will want your duct work to take advantage of that so that your muffler is encased on the left side of the picture.

Edit: Here is a photo of the motor in my Max II. Look at the muffler. Below it is heat shielding and there are two other pieces of heat shielding on the upper body that close around the muffler when the body comes down. You will want to do something similar.


Here is another photo from the other side. I got this from Recreatives Industries website:

[SCMay]

I plan to use heat wrap on the hole system and exit out the back.
As of right now it doesn't get things that hot, after seeing your other air duct I plan make one that way, if I shield the muffler from the carb and top, and the duct will flow in fresh air to the motor to keep it cool.

[SCMay]

do you have any other pictures of your Bandolero box? How does it come in contact with the lid? on mine there is not that much room to vent it to the side because of the storage area next to the motor cover.