Swapping Intake and Exhaust -Opinions???

[smokyjoe]

I've been trying to work out a reasonably straightforward exhaust for my Hatz E79 powered Suzuki, and it seems impossible to do without a gazillion 90 degree bends to bring the exhaust from the "rear" of the engine to the muffler, and over and around the jackshaft without burning my ankle. What is desired is a smooth, sweeping exhaust from the "front" of the engine like a "proper motorbike". During a fit of late night insomnia I had a crazy idea that may work.

The Hatz E79 (and other Hatz engines of this venerable family) use a unique valve/camshaft/pushrod arrangement. They have a somewhat conventional single camshaft arrangement (but running at 1/4 crank speed with 2 lobes per cam) but the weirdness lies in that they have the intake at the "front" of the engine, the exhaust at the "rear", both actuated from their respective cam lobes by side-by-side long rocker arms with a pushrod arrangement like a pair of crossed fingers. (sorry, I can't get a good picture of this without removing the pushrod tube, hence no photos) If the pushrods are crossed the other way, the exhaust cam drives the "intake" valve and the intake cam drives the "exhaust" valve, with absolutely no fuss I've swapped intake and exhaust! This is a direct injection Diesel, and from what I can see it has a symmetrical combustion chamber with the injector squirting down on the piston crown. The intake runner is identical to the exhaust other than a threaded hole in the intake used to add oil for cold weather starting. For this I could make a fitting for either an exhaust gas temperature gauge (pyrometer) or a plug with a stud for a head temperature gauge.

The valves, valve seats, etc. etc. are the same part numbers for both valves, but the compression release originally works on the exhaust valve by pushing up on an adjusting screw threaded into a boss on the exhaust rocker arm. With the swap the release would be blowing through the intake, but I see no problem with that as I will be using a "conventional" motorcycle metal gauze oiled filter element (not the original oil bath). Maybe I'll have to clean the filter element more often, but that isn't a problem.

I've seen a thread on swapping intakes for exhaust here before (maybe a couple of years ago), but couldn't find it. Any opinions on my crazy idea? I'm sure it's been done before, and the only drawback I can see is the compression release working on the intake. Here's a pic of a similar engine (scoffed off the 'net), notice the valve arrangement and single pushrod tube feeding the rocker arms under the funny-shaped rocker cover:

Note: This doesn't have the original crank in the picture, it looks homemade, and the crank is removed after starting. This engine also appears to be a bit smaller than the one I have

[balboa_71]

Smokey,
I don't know, think I'd leave it alone and let the exhaust exit in the rear. There are many good looking diesel bikes built by the experts in Europe that have figured a way to get the exhaust out. Look at the bright side, you can put a velocity stack on the front of the engine and get some ram induction

Cris

[Curtis in Texas]

So have you tried swapping the intake/ exhaust?
Be an interesting experiment to try.
I have never let conventional wisdom dictate logic before.
No sense of adventure in being normal.
I'd try it. Course I'l try almost anything as long as I thought it was worth the trouble.

Post up some pictures if you havn't given up on it yet.


Curtis

[balboa_71]

Smokey,
On the other hand from what I said before, having the exhaust on the front of the bike would allow for better cooling. Thing about the valve diameter is intakes are usually larger as it takes more to suck in fresh air than it takes to exhaust inert hot gas that is under pressure. So try it both ways and see which way the engine runs better

Cris