Ketchup
Epoxy member
- Local time
- 6:01 AM
- User ID
- 5594
- Joined
- Mar 12, 2018
- Messages
- 1,362
- Reaction score
- 3,752
- Location
- Colorado

I don’t totally understand back pressure in a can muffler. It doesn’t seem like a can is able to back-stuff the cylinder like a pipe.
My crude thinking is that a saw that blasts all the exhaust out should run the same, no matter how much raw charge makes it out after the exhaust. Have you guys tried tuning a saw with no can? I’m tempted to think it will make the same power if properly tuned.
I guess too little back pressure could inhibit scavenging. Especially if the transfers weren’t aimed well.
@Dieselshawn , have you put the 661 on the dyno after a carb reset with no muffler?
My crude thinking is that a saw that blasts all the exhaust out should run the same, no matter how much raw charge makes it out after the exhaust. Have you guys tried tuning a saw with no can? I’m tempted to think it will make the same power if properly tuned.
I guess too little back pressure could inhibit scavenging. Especially if the transfers weren’t aimed well.
@Dieselshawn , have you put the 661 on the dyno after a carb reset with no muffler?