er27, it has two exhaust ports on each head, and three cylinders feed exh out those two holes, i figured the center combustion chamber would be split between the front and rear exh port. instead the rear one has its own bigass hole and the front and middle one share the same size port. this seems crazy to me. i think im gonna hog out the one that is shared, to try and get em even. that explains the compression readings i got. the engine doesnt wear evenly on all cylinders.

SOP for many non-inline 6s.

 

Can't see how port size would affect either compression or wear. Miniscule thing compared to the violence of the cylinder. 02 cents.

Yeah, that arrangement does seem a bit odd.

Just to be clear... Its 2 cylinders on one port and 1 cylinder with a port all to its self? Or do all 3 connect internally, like a "log" style manifold, 3 in and 2 out? Seems the later might make more since?

I'm not sure you would see uneven back pressure (or wear) due to this design though. If the engineers did it right the port that exhausts two cylinders would have the firing sequence of those two cylinders timed in such a way that only one cylinder is using the port at a time, and enough dwell time between them to dissipate and local high pressure. None of the stock exhaust systems use tuned lengths so the length (time) from valve to convergent point is of little importance.

Gary

If the engineers did it right the port that exhausts two cylinders would have the firing sequence of those two cylinders timed in such a way that only one cylinder is using the port at a time, and enough dwell time between them to dissipate and local high pressure.

Gary

never thought about that.

one has its own port, and the other two share one port.

if you just tacked on 2 extra cylinders on an ea82 , wouldn't it be easiest to just give it it's own port......

 

It works tho.

if you just tacked on 2 extra cylinders on an ea82 , wouldn't it be easiest to just give it it's own port......

 

guess i shoulda thought about that first. it was the easiest, cheapest way to do it.

if you just tacked on 2 extra cylinders on an ea82 , wouldn't it be easiest to just give it it's own port......

 

"Engineered" on 2 extra cylinders...

Right.

 

The ER27 engine is basically an MPFI EA82 with two more cylinders tacked on the end. That's why the pistons, connecting rods, hydraulic valve lash adjusters, etc. are the same. The front looks very similar too, but some of the running gear has been beefed up.