318 Exhaust Manifold Outlet Size.

Posted By: Grizzly

318 Exhaust Manifold Outlet Size. - 08/03/13 03:48 AM

Have an '84 LA 318 in a Ram in need of dual exhaust. It has 2" pipe off the manifold now and was wondering what the outlet size is at the manifold?

Hopefully, bigger than 2"

Thanks.

Posted By: burdar

Re: 318 Exhaust Manifold Outlet Size. - 08/03/13 04:14 AM

Just measured a 73 Challenger manifold. ID of the outlet is only 1 3/4".

Posted By: 340SHORTY

Re: 318 Exhaust Manifold Outlet Size. - 08/03/13 07:45 AM

If the pipe is 2" the outlet will be 2"... The 360 manifolds had 2 1/4 pipes and outlets..

Posted By: burdar

Re: 318 Exhaust Manifold Outlet Size. - 08/03/13 01:55 PM

Quote:

If the pipe is 2" the outlet will be 2"

Tell that to the manifold I just measured before posting. I was shocked it was only 1 3/4". Maybe a truck manifold is larger? My measurement was ID. Most exhaust pipes are measured OD.

Posted By: Grizzly

Re: 318 Exhaust Manifold Outlet Size. - 08/03/13 03:45 PM

Quote:

Quote:

If the pipe is 2" the outlet will be 2"

I suppose, but was hoping to hear 2 1/4 like the 360 mentioned.

Tell that to the manifold I just measured before posting. I was shocked it was only 1 3/4". Maybe a truck manifold is larger? My measurement was ID. Most exhaust pipes are measured OD.

Well, and I searched it out a bit and can't find anything except for Magnum engines. Must be a few variations of 318 manifolds?

So, would the stock pipes on a '73 318 be 1 3/4" too? I have a '74 'Cuda that's all original but I can't get at it to measure.

Thanks for checking Burdar.

Posted By: burdar

Re: 318 Exhaust Manifold Outlet Size. - 08/03/13 07:47 PM

I don't know what the stock size was off the manifold. It could have been 2".

Posted By: 451Mopar

Re: 318 Exhaust Manifold Outlet Size. - 08/03/13 08:21 PM

I made an exhaust system for my '86 Ram W150 when I was working at an exhaust shop. 2" flared to connect the the mainfold, then I welded 2-1/4" onto the 2" right after the flange area. The pipes basically came down a bit farther before bending towards the back so there was plenty of clearance around the oil filter. Both sides came back past the transfer case, then the drivers side crossed over to the passenger side and ran both 2-1/4" pipes into a dual inlet single 3" outlet Imco chambered muffler (I think installed backwards), with a 3" outlet that went over the rear axle and exited out the passenger side at about a 45 degree angle right before the end of the truck. The end of the pipe was cut parallel the the bed side so it had the angled looking exit. It sounded pretty good on a mild 318.