Altered Lurch's exhaust system

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heinkeljb
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Altered Lurch's exhaust system

Post by heinkeljb »

Following a mishap where I basically ripped part of Lurch's exhaust pipes and silencer off whilst doing a punch hunt the other weekend. I looked into replacing the pipes and silencer with original style parts. Unfortunately, as a lot of the other parts of the exhaust system would also have needed changing it was going to cost more than I can afford right at the moment. So I looked at other methods of repair / replacement.
In the end I opted for buying some pre-bent bits of tubing and some flexible heating / exhaust pipe. I already had a small "cherry bomb" silencer I had purchased last time I broke the exhaust at a Haflinger offroad event a couple of years ago.

Started off by measuring how far down the pipes come from the heat exchanger mainfold (I only had the good nearside pipe to measure from), then I cut off the manifold mounting plate. Held another section of pre-bent pipe in correct position whilst my friend Stephen made some quick tack welds to hold the bits together.
Same happened for the offside bit of pipe. Now I had two bits of tubing coming up next the gearbox as I thought if I was going to the trouble of putting this all together, I might as well get the silencer really up and out of the way.
There are atleast a couple of other Haflingers out there with similar setups - why the original designers put the exhaust system below the sump guard on an offroad vehicle we will never know!

Another off the shelf exhaust pipe reducer made a bit oval allowed me to do some measuring and then tack weld it two join the two pipes into one.
Another off the shelf exhaust pipe joiner allowed me to put a length of flexible hose in the other end and bend it so I could fit the "cherry bomb" to the side of the footwell box.

Once it was all tack welded in place, took it off and TIG welded and brazed the bits together.

Pictures below show it all fitted.
Exhaust pipes under the engine
Exhaust pipes under the engine
Joining two pipe togther
Joining two pipe togther
Flexible hose and exit
Flexible hose and exit
It's a bit noisier than I had intended, so I might have to stick something down it's throat!

Atleast the only bits of exhaust system that are still vulnerable are the two bits which come down from the heat exchangers.
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !

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jhon
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Re: Altered Lurch's exhaust system

Post by jhon »

Hi John - that looks like a tidy job; was it mild-steel that you used? If it was you might want to get some paint or coating on them to prevent them rusting out.

I don't have heat exchangers so my system is quite different - fortunately it was fitted with a vertical stainless silencer when I bought the vehicle so has given no trouble.

Re the higher level of noise - because you have the cherrybomb bolted directly to the bed box it may serve to amplify the sound (like a drum) - you could try isolating it a bit to see if that helps.

Have you tried fitting the sump-guard back on to see if it clears the link pipe? Clearance can be tight there, however the guard should prevent further damage.

Anyway - well done! (always nice to see a bit of innovation).
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heinkeljb
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Re: Altered Lurch's exhaust system

Post by heinkeljb »

Those pictures were taken having just bolted it all in place to make sure it fits. I put the sump guard back on as well, just after and yes, it all clears there as well. Pictures wouldn't show very much with the sump guard in the way!

It will all have to come off again in order to put some paint on it - don't have any high temperature paint at the moment.

I'll also try your suggestion of some thing to insulate the cherry bomb from the footwell box, not that the noise seems to be from the chassis! Still it can't do any harm and as said, it all has to come off to be painted - unless I just leave it there to go rusty!

The guard didn't manage to save the previous system from damage as there was a modern vehicles back box on the end and it had an edge below the guard.... Now it's just a couple of short lengths of pipe that might get caught.

Shame there is not more ground clearance - but then it would have bigger wheels and would need more power - where does that stop ? Tara 8x8?

John
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !

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AustHaflinger
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Re: Altered Lurch's exhaust system

Post by AustHaflinger »

Your Cherry Bomb muffler is our Hot Dog Muffler :lol:
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StuartR
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Re: Altered Lurch's exhaust system

Post by StuartR »

Nice and neat solution.
Best Regards

Stuart

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Czechsix
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Re: Altered Lurch's exhaust system

Post by Czechsix »

Looks fine to me, good job.
Swiss 1963 700AP, Weber 32ICS carb, electric fuel pump, Black Diamond XTR 25x8x12 tires, Pertronix, civilian ignition and regulator system conversion, extra fuel filters, 4 point belts, NATO 3 color camouflage, Cobra CB radio, battery cut off switch
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heinkeljb
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Re: Altered Lurch's exhaust system

Post by heinkeljb »

Biggest problem with my home made exhaust solution? I guessed at the pipe diameter! Bought bits of 1" tubing when I should have bought 1.25"!

So I might remake it later in the year with the bigger diameter pipe and see if it works any better - it still feels like it is lacking power, but the original system has a very tiny outlet from the pancake silencer, so I am not sure why this one would not work at least as well.

Lurch went for an MOT today and passed (mainly because the MOT tester had never seen one before and didn't know what to check!!). One advisory, slight exhaust leak! - Only because he could see a soot trail! Hole must be all of 2 square mm at most....

John
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !

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AustHaflinger
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Re: Altered Lurch's exhaust system

Post by AustHaflinger »

If you used piping the same size as the original then it should be Ok - but like you I noticed the tailpipe diameter is a lot smaller than the exhaust from the engine so maybe the Haffie engines need the smaller tail pipe to provide the correct back pressure. I thought that the big oval units you have are both muffler and heat exchanger for the cabin heating, if this is correct why do you need the Cheery Bomb? or is the big oval unit just a heat exchanger?

As I have mentioned my engine is 762cc but I still have the standard cylindrical Haflinger muffler. The tail pipe end is much smaller (1" outside diameter - 7/8" inside diameter) than the inlet side so about the same size as yours - I think this is a bit too small and will also look at putting in a larger system - and putting in some sort of heat system as well.

Before you go enlarging you plumbing I think you need to check with somebody in the know if even larger piping will enhance or be detrimental to engine performance - however for most car engines making the exhaust a bit bigger so it exhausts easier does bring performance improvements.

Garry
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heinkeljb
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Re: Altered Lurch's exhaust system

Post by heinkeljb »

The heating system on a Haflinger which uses factory heat exchangers is just that- heat exchangers. Exhaust gas runs through cast iron sections with fins and has an oval sheet metal cover with an in from the air blown over the cylinders and an out which goes via an insulated pipe to the cabin. I don't think a Haflinger engine is as critical on back pressure as a two stroke engine is but it still might need a restriction at its outlet rather than in the length of the system. So as I say, I might remake it with larger diameter pipe up as far as the silencer and then put a restriction there if it still feels sluggish with the current cherry bomb silencer.

Something for later in the year (maybe)!!!

John
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !

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heinkeljb
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Re: Altered Lurch's exhaust system

Post by heinkeljb »

Had to change the engine from the "big bore" one I have, to the original crankcase engine which had the broken crankshaft. This is still standard (643cc). The "big bore" engine started leaking oil all over the place as I returned home last year from our national Treffen. It think it might have broken a ring or something because I pushed it a bit too hard on the way to the Treffen(!) Anyway, in order to check for a broken ring, you have to dismantle a fair amount of the engine ancillaries and tin ware. Therefore it made sense to take the engine out to do so as the really isn't much room to do that amount of dissassembly with it in place. Whilst it is out, I could just put the original engine in and have Lurch running again giving me time to do the dissassembly on the big bore engine at some tme in the furture (Famous last words)!! Engine swap happened quite easily, but the exhaust system did not like being taken apart. The new bits I put in, see earlier posts, where reasonable, but all the other stuff was now very rusty and thin. Holes appeared in pipes as things came apart.
This resulted in a rethink of the system and a decision that I didn't really like the routing of the original exhaust or the unequal length of pipes from one cylinder compared tothe other.
Now in fitting the "big bore" engine, we had removed the two "trumpets" that divert some of the cylinder cooling air towards the heat exchangers and then on to the cabin, so ALL the cooling air from the Dynastart now goes over the cylinders. This meant I could remove the heat exchangers completely now I was going to re-route the exhaust system. (I have got a cheap Chinese Diesel hot air heater which can provide cabin heat instead of the heat exchanger system).
In my head I had route for the pipes from each cyclinder going forward and then up and over the transmission, meeting in the middle of the Haflinger and then exiting out the side in a similar fasion to the version in the previous posts.
Require me to make a few joints in the exhaust to allow it to be fitted, but I think they work and the exhaust follows the route I had thought of.
New exhaust tacked togerther.jpg
Picture of the tack welded together exhaust - final welding do on all the various joints, Painted black with High temperature paint. We will see how long that lasts.

Following pictures show exhaust in place, bit difficult to show the everything nicely as there is not very much room to get a goood camera angle.
Righthand pipe.jpg
Righthand pipe.
Lefthand pipe.jpg
Lefthand pipe.
Going over to meet in the middle and exiting stage right..jpg
Going up and over to meet in the middle and exit stage left!

Having made the exhaust, put the final things back on the original engine and went to start - Nothing but coughs, pops and bangs! Now what's wrong!!
See new thread.
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !

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AustHaflinger
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Re: Altered Lurch's exhaust system

Post by AustHaflinger »

heinkeljb wrote: Sun Apr 09, 2023 10:23 pm
This resulted in a rethink of the system and a decision that I didn't really like the routing of the original exhaust or the unequal length of pipes from one cylinder compared tothe other.
I think you will find that the lengths of the exhaust pipe from each exhaust port to where they join into one is "tuned" so that they reinforce each other - like extractors on a normal engine so the lengths should be maintained. As I said back in 2017 I think that standard exhaust on my 763cc engine is a bit small as it runs out of puff at the top end but I still have not done anything about it.

Garry
Haflinger 700AP (73)
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Landrover Series 1 SWB Station Wagon (57)
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heinkeljb
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Re: Altered Lurch's exhaust system

Post by heinkeljb »

Considering I don't have Styer Puch's resources to work out the optinal engine speed to start making pieces of tuned pipe to put together. Easieat way is just to make the two pipe the same lenght. As you want an engine to have quite a wide rev range, I doubt it is too critical to the last mm to get the pipe the same length. I think my pipes are close enough in length to each other to cover the range.

We will see if it works or not now I have the engine running and can actually go for a drive.

John
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !

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