Topic: oppy exhaust

[PJG56]

New to this forum,Ithink it's awsome,Now to my question,I,m building 42" oppy for ice racing wondering if i need the short stubs behind exhaust flanges that fit in exhaust ports.I read somwhere in here where it was a must on single cyl. flatties. thanks paul

[The Tank]

I have a 2 into 1 header for an opposed with those on it if you are interested.

[PJG56]

Thanks fot the input Tank,but that doesnt answer my question

[BIG AL 202]

Not on the oppys, most do NOT run them. You can however cut out the tube and use the flanges, or use them as patterns. Hope this helps. Most don't use them on singles.

[The Tank]

I was still half asleep and some how didnt see the question. The truth to that is the exhaust port is actually too big on the flatties. The best fix is to get a pipe nipple and screw into the post then grind it down flush without grinding the head. I left the pipe on behind the flange on my oppie when I use to run one. The port needs to be reduced one way or the other from what Ive learned.

[Jeff McKelroy]

A 2 into 1 header? I'll take it! Have a pic?

Jeff

[Rooster]

I was still half asleep and some how didnt see the question. The truth to that is the exhaust port is actually too big on the flatties. The best fix is to get a pipe nipple and screw into the post then grind it down flush without grinding the head. I left the pipe on behind the flange on my oppie when I use to run one. The port needs to be reduced one way or the other from what Ive learned.

Tank, that may be true on the singles, but you do very much work on the Opposed your going to need all that exhaust port and then some.

New to this forum,Ithink it's awsome,Now to my question,I,m building 42" oppy for ice racing wondering if i need the short stubs behind exhaust flanges that fit in exhaust ports.I read somwhere in here where it was a must on single cyl. flatties. thanks paul

The smallest you want to go on the exhaust will be 1 1/8", it all depends on how much work is into it. I run even bigger yet.
Lose the flanges!

[more4les]

Tank, that may be true on the singles, but you do very much work on the Opposed your going to need all that exhaust port and then some.
The smallest you want to go on the exhaust will be 1 1/8", it all depends on how much work is into it. I run even bigger yet.
Lose the flanges!

Sums it all up!!!!

Lester

[The Tank]

Tank, that may be true on the singles, but you do very much work on the Opposed your going to need all that exhaust port and then some.
The smallest you want to go on the exhaust will be 1 1/8", it all depends on how much work is into it. I run even bigger yet.
Lose the flanges!

There you have it folks from Rooster AKA Mr. Oppy 

Lol, in all honestly take roosters advice as he is the oppy specialist.

[THawley08]

Try to go equal length also with a two into one. We picked up a ton of extra torque.

[BIG AL 202]

Try to go equal length also with a two into one. We picked up a ton of extra torque.

and here is the other one!

[flatlanderfornow]

I use 14" primaries shaped like the old Chev ram's horn exhaust into a 1 1/2" collector (90 deg
sweep conduit), cut off where the paint burns off.  Engine is stock, ports
just cleaned up a little, and timing advanced.  Very strong engine.  I went from this to
a Kohler Magnum 18 and had to drop 1 tooth in the transmission.  Going back to Briggs
power for next year. The Briggs is a 42 by the way.  No dyno to prove anything,
but the engine runs real smooth and pulls harder with this than it did with
any other setup.