New Header Dyno Results

[KBabcock]

As for the port sizes I measured each port at 0, 45, 90 degrees across the port opening then averaged the numbers. Measurements made about 10mm in with a digital caliper. Intake and exit ports measured the same way. Here are the results. From left to right looking into the intake ports as shown in picture 2:

Intake Ports:
Port 1: 27.8mm
Port 2: 27.9mm
Port 3: 27.6mm
Port 4: 27.7mm

Exhaust ports:
Inside Port: 33.5
Outside Port: 32.2

This is definitive for the manifold I have.

 

[rx1900]

Just to add to the confusion....and choices......

The other day local member Neil stopped by with a very interesting exhaust manifold.

It was from a North American spec EFI Yugo.

A bit difficult to measure accurately.......and the dimensions did vary a bit from port to port.......but I measured the intakes on it to be about 28-29mm on average...and the outlets about 33-34mm

For sure the outlet was "left-of-center". and appeared to be at about the same angle in both directions from the '74 USA X1/9 manifold I had here. Of course I DONT know if the Yugo left-of-center outlet was in the same exact position as the 7691660 or 4392487 manifolds. But visually appeared to be pretty close from all the pics......

The interesting thing about this manifold is that it has provision for an oxygen sensor right in it. Which of course would be needed for a EFI X1/9. so that would be handy...and avoid having to weld in a fitting after a new collector !!

The Yugo casting looked quite nicely made. And the inlets and outlet seem to be at least as large as the other options out there.

Neil is going to use this manifold along with a modified genuine Yugo 2 into 1 downpipe. We did notice there was a slight mis-match between the outlet port of the manifold and the inlet ports of the downpipe. He was going to match the ports by grinding the manifold a bit. My big-port gasket would allow for that. He cut off the rear flange of the yugo downpipe and welded on a couple of 90 or so degree bends, then a flex and a flange that bolted on to his stock muffler. Beautifully made - perhaps he will post a pic of it. A nice solution !!

And yes......I still find it amusing that.......installing parts from a Yugo is considered an upgrade

 

[AnthonyG]

Where's the O2 port? Is that it on the lower left side?

Does it allow the O2 sensor to pick up exhaust from both out ports? If not, seems like you'd want the O2 a little further down at the final collector merge to get an accurate read from all ports combined. But I also read that too far down might be problematic in giving an accurate reading due to exhaust cooling. Not sure if that's a legit concern.

Seems quite close in size/specs to the 7691660 or 4392487. From photo, number looks to read: 1612182.

And it appears different (larger?) from this Yugo exhaust manifold on MWB:

Exhaust Manifold 4-2 with Downpipe 2-1 (Yugo SOHC + X1/9 w/4-2 Manifold) - U8.5 - MODIFIED

Exhaust Manifold 4-2 with Downpipe 2-1 (Yugo SOHC + X1/9 w/4-2 Manifold) - U8.5 - MODIFIED

www.midwest-bayless.com

Part numbers listed for this one are: 46620089 and 46620662.

Just to add to the confusion....and choices......

The other day local member Neil stopped by with a very interesting exhaust manifold.

It was from a North American spec EFI Yugo.

A bit difficult to measure accurately.......and the dimensions did vary a bit from port to port.......but I measured the intakes on it to be about 28-29mm on average...and the outlets about 33-34mm

For sure the outlet was "left-of-center". and appeared to be at about the same angle in both directions from the '74 USA X1/9 manifold I had here. Of course I DONT know if the Yugo left-of-center outlet was in the same exact position as the 7691660 or 4392487 manifolds. But visually appeared to be pretty close from all the pics......

The interesting thing about this manifold is that it has provision for an oxygen sensor right in it. Which of course would be needed for a EFI X1/9. so that would be handy...and avoid having to weld in a fitting after a new collector !!

The Yugo casting looked quite nicely made. And the inlets and outlet seem to be at least as large as the other options out there.

Neil is going to use this manifold along with a genuine Yugo 2 into 1 downpipe. We did notice there was a slight mis-match between the outlet port of the manifold and the inlet ports of the downpipe. He was going to match the ports by grinding the manifold a bit. My big-port gasket would allow for that. He cut off the rear flange of the yugo downpipe and welded on a couple of 90 or so degree bends, then a flex and a flange that bolted on to his stock muffler. Beautifully made - perhaps he will post a pic of it. A nice solution !!

View attachment 53533View attachment 53534View attachment 53535

And yes......I still find it amusing that.......installing parts from a Yugo is considered an upgrade

 

[NeilMc]

Doug is local and a fountain of knowledge about the X. I’ve been out to his shop several times to buy parts, get advice, and borrow tools. Attached is a picture of down pipe I fabricated with inspiration from SteveC.

The manifold was purchased from MWB as used/refinished. The 2-1 pipe is a new part from Yugoparts. The mandrel bends and flex coupling are from Vibrant, 1.75 in diameter. The exhaust flange is from Mandrelbends. The flange connects to the stock 1975 muffler where the test pipe would connect. I made a mockup from cardboard gift wrap tubes and then cut the sections with a bandsaw. A friend tack welded the parts. The finish welding was done at a Toronto shop named Kreater Custom Motorcycles that does beautiful work. The cost of this all-in is about $250 CAD, of which more than half was the welding. I’ll post more pics as complete my build.

 

[NeilMc]

Where's the O2 port? Is that it on the lower left side?

Does it allow the O2 sensor to pick up exhaust from both out ports? If not, seems like you'd want the O2 a little further down at the final collector merge to get an accurate read from all ports combined. But I also read that too far down might be problematic in giving an accurate reading due to exhaust cooling. Not sure if that's a legit concern.

Seems quite close in size/specs to the 7691660 or 4392487. From photo, number looks to read: 1812182.

And it appears different (larger?) from this Yugo exhaust manifold on MWB:

Exhaust Manifold 4-2 with Downpipe 2-1 (Yugo SOHC + X1/9 w/4-2 Manifold) - U8.5 - MODIFIED

Exhaust Manifold 4-2 with Downpipe 2-1 (Yugo SOHC + X1/9 w/4-2 Manifold) - U8.5 - MODIFIED

www.midwest-bayless.com

Part numbers listed for this one are: 46620089 and 46620662.

@AnthonyG: The manifold from MWB is this one: https://www.midwest-bayless.com/p-2...st-manifold-sohc-4-2-yugo-fi-128-x19-u85.aspx
The O2 port is on the left side just above the flange and does connect the two sides so that a single sensor can be used. I will eventually install a wideband sensor so that I can tune the jets of an upgraded carb. I couldn't find any definitive guidance on what is too close for a sensor but the original sensor happily lived there so I'll give it a try.
I can't make out the part number on it and I think the 1812182 is a casting number. The MWB listing does not have a PN either.

 

[rx1900]

Where's the O2 port? Is that it on the lower left side?

Yes. sorry for the poor pic. But you can just see it if you look close...

Does it allow the O2 sensor to pick up exhaust from both out ports? If not, seems like you'd want the O2 a little further down at the final collector merge to get an accurate read from all ports combined. But I also read that too far down might be problematic in giving an accurate reading due to exhaust cooling. Not sure if that's a legit concern.

Good questions. I did not notice if the O2 port picked up all cylinders. Perhaps Neil could take a look. But in any case...if it was good enough for Yugo........

Seems quite close in size/specs to the 7691660 or 4392487. From photo, number looks to read: 1812182.

And it appears different (larger?) from this Yugo exhaust manifold on MWB:

Exhaust Manifold 4-2 with Downpipe 2-1 (Yugo SOHC + X1/9 w/4-2 Manifold) - U8.5 - MODIFIED

Exhaust Manifold 4-2 with Downpipe 2-1 (Yugo SOHC + X1/9 w/4-2 Manifold) - U8.5 - MODIFIED

www.midwest-bayless.com

Part numbers listed for this one are: 46620089 and 46620662.

I think the # read 1612182. Yes...it is different from the MWB one you linked to.....that is for a carbed USA Yugo. Quite different as the carbed one has messy air injection or EGR tubes cast into it. None of that on the EFI one that Neil has.

and yes....appears to have at least as big ports as the 7691880 or 4392487. And a very similar spec. And note the strengthening rib built in along the long runners where the 4392487 failed . And the bonus of the O2 fitting. Looks like a winner to me. The very pinnacle of modern Slavic technology

 

[AnthonyG]

Good stuff! Thanks for the useful info about the process.

This is basically what I'm trying to do on my 86 FI X, but I have to fit a cat to pass smog.

I bought the 7691660 with the intention to fabricate the dual down pipes, but already having them certainly seems a bit easier if you have the room to spare.

Doug is local and a fountain of knowledge about the X. I’ve been out to his shop several times to buy parts, get advice, and borrow tools. Attached is a picture of down pipe I fabricated with inspiration from SteveC.
View attachment 53538
The manifold was purchased from MWB as used/refinished. The 2-1 pipe is a new part from Yugoparts. The mandrel bends and flex coupling are from Vibrant, 1.75 in diameter. The exhaust flange is from Mandrelbends. The flange connects to the stock 1975 muffler where the test pipe would connect. I made a mockup from cardboard gift wrap tubes and then cut the sections with a bandsaw. A friend tack welded the parts. The finish welding was done at a Toronto shop named Kreater Custom Motorcycles that does beautiful work. The cost of this all-in is about $250 CAD, of which more than half was the welding. I’ll post more pics as complete my build.

 

[AnthonyG]

@AnthonyG: The manifold from MWB is this one: https://www.midwest-bayless.com/p-2...st-manifold-sohc-4-2-yugo-fi-128-x19-u85.aspx

Ah yes.. it's currently out of stock, and therefore doesn't show up on search. Seems larger and preferable to the other he still has in stock. Would be great if he finds more of them. Lists for $190.

I just got my 7691660 from Bilstein in Germany for $130 shipped. New and looks legit. Will photo, measure, and post within the next couple of days. Good price, but without the convenience of bolt on Yugo downpipes and an O2 port.

The O2 port is on the left side just above the flange and does connect the two sides so that a single sensor can be used. I will eventually install a wideband sensor so that I can tune the jets of an upgraded carb. I couldn't find any definitive guidance on what is too close for a sensor but the original sensor happily lived there so I'll give it a try.

Seems like it might work fine.

I can't make out the part number on it and I think the 1812182 is a casting number. The MWB listing does not have a PN either.

The part number is indeed listed at the top right of the MWB page: 1612182.

 

[rx1900]

Oh....in case I did not mention it.....I did confirm from Neil's manifold that you could certainly use a Yugo downpipe with a Fiat manifold. The bolt pattern there is identical. And the yugo downpipe (well at least on the one Neil has ) has a generous ID of 33-34mm. So at least starting with a Yugo downpipe would give you the required correct flange and 2-1 collector......They are cheap to buy so even if you chopped it up it would be a good starting point....

 

[AnthonyG]

Good to know! I just might do that if I can find one.

It looks like part # 46629053 here:

Exhaust

The FI front pipes, and NOT the carb front pipes (46620662), which I gather are smaller?

Oh....in case I did not mention it.....I did confirm from Neil's manifold that you could certainly use a Yugo downpipe with a Fiat manifold. The bolt pattern there is identical. And the yugo downpipe has a generous ID of 33-34mm. So at least starting with a Yugo downpipe would give you the required correct flange and 2-1 collector......They are cheap to buy so even if you chopped it up it would be a good starting point....

 

[NeilMc]

Good to know! I just might do that if I can find one.

It looks like part # 46629053 here:

Exhaust

The FI front pipes, and NOT the carb front pipes (46620662), which I gather are smaller?

@AnthonyG: the part I ordered was the 46620662, pictured here: https://www.midwest-bayless.com/p-7...npipe-2-1-yugo-sohc-x19-w4-2-manifold-oe.aspx
MWB was out of stock so I ordered from Yugoparts. I don't know how the 46629053 is different.

 

[Dr.Jeff]

There were a couple of different Yugo exhaust manifolds. The one discussed here is the later FI version, which was not very common in North America. The vast majority of the ones you will find here were from the carburetor models with a big AIR injection log cast into it, plus some various flanges and ports for other smog equipment. It has also been measured as smaller ports compared to most of the others we've been discussing. That one is not a good candidate for the X in my opinion. If a Yugo manifold is to be used this later FI version (discussed above) is a much better choice, if you can find one. However for $130 delivered I think it is much wiser to get the new Fiat item that @AnthonyG posted.

 

[AnthonyG]

@AnthonyG: the part I ordered was the 46620662, pictured here: https://www.midwest-bayless.com/p-7...npipe-2-1-yugo-sohc-x19-w4-2-manifold-oe.aspx
MWB was out of stock so I ordered from Yugoparts. I don't know how the 46629053 is different.

Neil, if you look at the diagram on the YugoParts exhaust parts page here..

Exhaust

.. you will see both listed.

The 46620662 is labeled as the carb front pipe, which worked for you. The 46629053 is labeled a the FI front pipe.

I wonder what the difference is between them? I might have to call them to see if they can offer any insight.

 

[rx1900]

I wonder what the difference is between them? I might have to call them to see if they can offer any insight.

Yes...please do that.....

 

[Dr.Jeff]

It would be nice if the later FI version has a bit larger diameter pipes. I would cut one of these off at the red line (below) and start the custom fabrication from there down:

That way the secondary section could be made longer before it merges into one pipe, for more low to mid range torque.

But at $84 plus shipping I'm not sure just how much that top portion is really worth. Since more of the pipe needs to be made anyway, it might be just as well to make all of it? However I realize it is different for those that can do such work ourselves vs paying someone else to do it. So the answer will be different for everyone.

 

[NeilMc]

It would be nice if the later FI version has a bit larger diameter pipes. I would cut one of these off at the red line (below) and start the custom fabrication from there down:

View attachment 53559

That way the secondary section could be made longer before it merges into one pipe, for more low to mid range torque.

But at $84 plus shipping I'm not sure just how much that top portion is really worth. Since more of the pipe needs to be made anyway, it might be just as well to make all of it? However I realize it is different for those that can do such work ourselves vs paying someone else to do it. So the answer will be different for everyone.

@Dr.Jeff that was my thinking originally before I got scared of the scope of work. In preparation, I purchased two top sections of euro downpipe from @Dino66. I think the shorter is from a later car and has a 34mm ID at the flange, $15 USD plus shipping will take it. The longer is from an earlier car and has a thick weld bead that prevents accurate measurement, $5 USD plus shipping will take it since it needs a bit of cleaning up. I no longer need them so if anyone is interested, PM me for details.

[edit: shorter one sold]

 

[Dr.Jeff]

@Dr.Jeff that was my thinking originally before I got scared of the scope of work. In preparation, I purchased two top sections of euro downpipe from @Dino66. I think the shorter is from a later car and has a 34mm ID at the flange, $15 USD plus shipping will take it. The longer is from an earlier car and has a thick weld bead that prevents accurate measurement, $5 USD plus shipping will take it since it needs a bit of cleaning up. I no longer need them so if anyone is interested, PM me for details.
View attachment 53578

We are on the same page. Nice work on your final product. I especially like that you included a flex section. Particularly on a short exhaust system like the mid-engined X has, there needs to be either a very strong reinforcement to support the entire system (if it is solid) or a flexible section to allow movement. For the most part the factory used the solid approach with the support arm extending out from the lower trans mount. But I prefer the flex approach (like you did) to prevent cracking and excess vibration.

 

[Alain - The Red Scorpion]

I deleted the catalytic converter and installed this header (made in UK). I has no provision for an O2 sensor. Do I need to provide one? My X is 1980 with Fuel Injection and performance head by MWB. It started fine yesterday and seems to idle smoothly.

 

[carl]

If you have fuel injection you will need an O2 sensor. The stock injection system does not use the O2 sensor info for idle or full throttle so that's probably why it idles nice.

 

[kmead]

If you have fuel injection you will need an O2 sensor. The stock injection system does not use the O2 sensor info for idle or full throttle so that's probably why it idles nice.

Carl is correct. The Lambda circuit in an FI car fiddles with the mixture in a narrow range, if it is non functional the computer defaults to the richer side so your economy will suffer and the car will always run rich.

I would run an O2 sensor and if you convert to the three wire heated one it could go down in the collector elbow. This could also set you up for the future with a programmable injection system to replace the Bosch system.

That is a nice shiny bit of kit. Very nice Indeed.