spring loaded exhaust connection upgrade

[bonefish635]

My 710K exhaust has the original spring loaded (but otherwise fairly slack) connection pipes upstream of the heat exchanger. You can hear gas escaping readily through the gaps, and if you use an exhaust driven inflation bag when stuck you can't get much pressure built up. I have a suspicion that the occasional popping on the overrun either emanates from the oxygen rich air coming in through the gaps like some sort of venturi, or is at least worsened by their presence.

I assume the complex linkage is there because some movement is needed between the manifold and the heat exchanger, but I wondered whether anyone had tried perhaps a braided (unsprung) pipe link to bridge the gap?

Maybe there's a better idea out there than that?

All advice and wisdom gratefully received as always.

Tony

[edzz]

Look here http://www.pinzgauer.com/showdetails.ph ... no=SAV6894
Mine came from Expedition Imports I like Scott's better than SAV's however I don't see it pictured on EI's site, contact him or SAV. Yes the poping is coming from this air leak at least in part.

[Twin Pinzies]

The flex-pipe upgrade is worth every penny! Every pinzgauer should have it.

[NoahDL88]

The flex-pipe upgrade is worth every penny! Every pinzgauer should have it.

More HP, better fuel economy? Will it make me more attractive to the opposite sex?

[pcolette]

The flex-pipe upgrade is worth every penny! Every pinzgauer should have it.

More HP, better fuel economy? Will it make me more attractive to the opposite sex?

You have to get the gold-plated, diamond encrusted model for that!

[bonefish635]

...or a longer length of pipe?

[Twin Pinzies]

The flex-pipe upgrade is worth every penny! Every pinzgauer should have it.

More HP, better fuel economy? Will it make me more attractive to the opposite sex?

Tighter, smoother, quieter, no backfiring, less cabin fumes, and it makes it possible to inflate exhaust bag lifts, etc,..
And yes, all of those benefits should increase your power and fuel economy.

[bonefish635]

Ordered SAV's version this morning. Spoke to Scott at EI but they don't carry it anymore.

Thanks for the guidance again.

Tony

[pinzinator]

My 710 arrived from Switzerland with that modification already installed.

[bonefish635]

Upgrade installed. I could mention a few points should anyone else be embarking on this:

The exhaust manifold studs are hard to reach (more so for some cylinders than others). A 12"+ extension to a 1/4" drive socket works a treat. The stud heads are close in to the piping, and all manner of things gets in the way so my usual 1/2" drive socket wouldn't seat on some of them. None of them required the extra muscle of 1/2" drive to get moving.

After nearly forty years, getting the bolts out of the heat exchanger connection was a non starter. I had to grind them off, and then drill the remainder out since the heat exchanger is a close fit behind the nuts and the headless bolts couldn't be pushed through (at least in the centre pair of bolts of the six). I can't see an easy way around that.

The downstream end of each of the exhaust manifolds has a trio of floating rings, like piston rings, held in place on a circular channel welded into place. THe spartan instructions from SAV suggest grinding this flat. That's a fair amount of grinding. Instead if you grind down the continuous welds on the upstream face, and then the random spot welds on the downstream face, you can knock the whole lot off with a chisel and hammer.

SAV provide six bolts for the heat exchanger connection. they are all the same length. On mine I had to swap out the middle pair for shorter ones since there was nothing like enough clearance behind the plate for bolts that length. The corners four were fine.

Pay attention to the removable inserts that will come off the head with the old exhaust gaskets and in fact look like part of the gasket. You need to keep these and reinsert them into the heads before refitting, since they are hollow spigots that provide accuracy in the manifold re-location.

Lastly, REMEMBER TO FIT THE NEW CLAMPS BEFORE YOU REATTACH THE MANIFOLDS AND THE FLEXIBLE PIPE. That will remove the need for a lot of cursing of the type your six year old son shouldn't be hearing.

The whole thing took a bit less than three hours, including the swearing.

Thanks again for advice.

Tony

[bonefish635]

An update:

Does anyone find that the new flex pipe coupling has introduced a harmonic vibration into the body? I guess that's what the old spring loaded coupling was designed to avoid, given that the heat exchanger is bolted rigidly to the body. I notice it as the revs die back during a gear change. Very pronounced.

I'll be damned if I'm going to change back though. It seemed a lot of work to get everything back on correctly.

Tony

[spandit]

I need to get something fitted here that can take an O2 sensor. What I'm planning is taking the flange bit that bolts to the heat exchanger and fitting it onto the manifold pipes. This will leave me with two flat flanges (about 137mm apart) that I can just bolt a fitting into. I'll still have some movement with the piston ring arrangement but it should be easier to get it properly seated.

Interesting about the vibration, mind... although with my engine I'm not sure how you'd notice!

[pcolette]

An update:

Does anyone find that the new flex pipe coupling has introduced a harmonic vibration into the body? I guess that's what the old spring loaded coupling was designed to avoid, given that the heat exchanger is bolted rigidly to the body. I notice it as the revs die back during a gear change. Very pronounced.

I'll be damned if I'm going to change back though. It seemed a lot of work to get everything back on correctly.

Tony

I had the same thing happen on one of mine. After some careful searching with a friend we found that the heat exchanger/muffler assembly had shifted slightly during the upgrade and the heat shield above the muffler was now vibrating against the muffler and the parking brake cable. Some minor re-adjustment of the whole mess and the problem was gone.
Hope this works for you.

[bonefish635]

Thanks Paul, That fits exactly with the shape of the resonance. I'll have a look.

Tony