Most of you know that I am in the process of building 1.625 primary heat exchangers for the 914-6 market.. Danny so kindly has lent me a pair of factory heat exchangers to use as a pattern.. The issue is that the heat exchangers when sitting flat as if they were mounted on and engine the exit flange is off of perpendicular square(word) by about 3/16" .. Both of them are.. So a better explanation would be if you are looking at that back of the car with the muffler off the muffler flange bolt holes do not look square across the back of the car..

We have been discussing this for a few weeks. It should be square imho and some ssis I just installed on a customer's car today do as well..


So the question is what is the general consensus? Either way is easy but square and level makes the most sense to me as all 911 mufflers are built that way..

I have stock heat exchangers on my car now. I don't know what you are referring too.

If you're talking about the flanges that mate up with the muffler inlets, I agree....level and square.

Put a straight across my muffler flanges and they are level and square.

Click to view attachment

This what I am referring to although this is with 911 heatexchanger s

I'm going to want to bolt on a m&k exhaust. So what ever is going to make that fit gets my vote.

Same here!

The exhaust flanges have to mate with the muffler flanges. So make them match up with the 911 muffler flanges. (The 914-6 muffler is hard to find, so chances are people will be using 911 mufflers.)

--DD

NOS M&K

Guys remember I am Mr m&k in a former life.. Just want to understand why the stock 914-6 exchangers are clocked off.

I think the key to your answer is 'as if they were mounted...'. If you are just laying the factory exchangers on a flat surface without actually bolting them to an engine, I don't think the orientation of the muffler flanges will be accurate.
Find an engine to bolt them up to, or make a solid jig that matches the 2 sets of cylinder head ports exactly and fabricate from there. If I recall, that was the problems with the first sets of Dansk heat exchangers that came out.

I'm almost certain that the muffler flanges/holes on my factory set line up horizontally.

I think I know what you're asking here....
Now if you look at the 911 engine the cylinder heads do not align from side to side.
They are off so that makes one header longer then the other...
Is that what you're asking?

I added a few pics so you can see what I'm talking about.

I have several engines to mount them to along with nice fixtures started.. I will make them the same as an ssi would be .. It will be correct.

I am specifically talking about flanges to head versus clocking of the exit flange.. They should be on the same plane but are not in the samples I have but that maybe because they are not new and could have warped over the years as they often do considering the way the muffler bracket design that would make the most sense as they get lazy on the outward hole on each exchanger.

No I am NOT talking offset of the cylinders but I can see how it would appear that way.

I guess to clarify. Look at the picture of the engine in my shop and see how the straight edge lines up with all the bolt holes. This does not happen with the exchangers I have for a 914-6. Sample.. They are rotated.

Ok, I see what you're saying now. It could be one of your test headers is bent or repaired in the past ?

I would need to mount my headers on the engine to see if things align. I can do that if you need another look at things. Let me know..

The flanges should be parallel like your picture, but also make sure they line up with the 914-6 trans muffler hanger.
Should be the same as a 911 muffler.

Ok that's what I assumed however that's not the story I was getting from my samples.