Anyone have any experience with AJ6 Engineering? It looks like they make a "shorty" style exhaust manifold. Though probably not inexpensive if it solves the cracked manifold ordeal I would be interested.

And for me even better if I can keep the rest of my stock exhaust (Cats) in place.

HIGH QUALITY XJ40/X300 EXHAUST SYSTEMS from AJ6 ENGINEERING / AJ6 Engineering

 

I offer flanges or dxf files from which they can be profile cut. Please email me directly if you want more details andystodart@Metronet.co.uk

 

Fabricated AJ6 exhaust manifolds won't fit an AJ16 engine because the bolt pattern is different.

 

We, the AJ16 community, should petition them to build them. I understand to be financially lucrative there would have to be enough of a demand but, the AJ6 look pretty similar. And a log design is much simpler than an equal length long tube design.

 

If you visit the site mentioned they do a system for the AJ16 engine. I have no personal experience of them, but I have heard of them, and no harsh words.

 

If I recall, Roger Bywater (of AJ6) said demand had shrunk to basically zero and it wasn't financially viable to make them anymore.

 

Too bad, I would be in for a set.

 

I tried that route before, and that was why I started a thread here in March 2014 to gauge interest in custom-made exhaust-manifolds, ending in lukewarm response that lacked sufficient incentive for any exhaust workshop to produce them. I went it alone and, frankly speaking, it wasn't a great success, particularly when the exhaust manifolds were modified into equal length 2 x 3 assembly made in the UK for a car physically in Hong Kong. I therefore shared my experience with folks here by this latest thread (read Post #1). Stainless steel means higher material cost and more time needed in hand-making them (whereas factory originals are mass-produced by cast iron) so the sums have to make sense before any professional workshop taking orders. X300 was quickly replaced by the X308 model after production of 3-4 years, and was out of production for some 20 years. Indeed it is too small a market to maintain business interest in continuing making OEM parts for it. Unless and until its surviving population stabilizes like the X40, in the interim it has to be an individual's effort to keep them on the road.

 

Anything can be done with enough perseverance and cash. I have been down this road before with people saying things couldn't be done designing and building an exhaust manifold for a Toyota Landcruiser 1FZ-FE that I wanted to turbo charge. I would not attempt equal length long tube headers but, a log style like AJ6 Engineering may be possible.

I would be interested how the AJ6 Engineering manifolds tie in the individual exhaust ports into the "LOG".

 

Would certainly wish you every success in exploring this further. The log style is easier to make and install, and certainly the bolt pattern can be changed. Specifications, accuracy in engineering and quality control are of paramount importance. Not being physically present hence relying solely on remote communication can be a hurdle - I had my lessons with Hayward & Scott before, even though it is a reputable professional workshop.

 

This is what I was thinking design wise for a log style exhaust manifold. The one pictured was for a custom turbo set-up on a Landcruiser I-6 but, the same principle would apply other than the Jag version being a 3 into 1 into 2 style versus the Landcruiser 6 into 1 into 2 design.


The elbows are made out of T304 stainless and can be had in any size, 90's, T's, reducer T', etc...


https://stainlessandalloy.com/stainl...weld-fittings/


The other route would be a more custom built design.




Thoughts???

 

I suppose a professional workshop should take a look at the actual manifolds and the engine room with the car present and have a feel of the constrains and possibilities for modifications. Left and drive and right hand drive have different clearance requirements due to proximity to the steering column, upper cats and downpipes, AC pipes, EGR, air injection pump, power steering hoses, heat shield..... Log style manifolds resembling the factory originals would be best, but some trade off is also possible. In my case, I have removed original heat shield, shortened the pre-cats, removed air-injection pipe and pump. Keep modifications to the minimum if volume and cost are the priority factors.

 

The original manifolds on my '95 XJR cracked and both welds and brazing did not hold so my Dad made me these log manifolds. They are made of handrail tubing separate the ports a bit better and have cuts in the flange to allow for expansion. Had them at least eight years now including a few trackdays and no issues.
At the time I did not know if I could remove the downpipe cats without issue as they are upstream of the oxygen sensors, so they are a direct replacement fro the originals. I have since knocked out the downpipe cats without any issues (UK car 2 o2 sensors + no EGR) and recently modified and replaced the front exhaust section.

 

Looks like this is the way to go, i.e. log style keeping modifications to the minimal; just doing away with the original heat shield. Certainly a new heat shield is easier to fabricate to protect the aircon pipe from extreme heat. Surely pals would like to know more about the material used, exact measurements and the magic behind to prevent future cracks.

 

Hi Qvhk. For more information my dad made a jig by bolting plates to each flange of the original manifolds and welding them together. He then cut the flanges based on the original gaskets using (I think) 3/8" mils steel plate. The ports are oval so he formed the pipe by heating with a cutting torch and knocking a round bar against the inside / hammering the outside. The downpipe flanges have a taper inside, so he machined that at work. The flanges were joined up using handrail tubing which is heavy wall mild steel and standard 90 degree elbows are available. Once assembled the flanges were cut between each runner to allow for expansion of the longitudinal section, otherwise it would try to bend the flange away from the head. I use the standard steel gaskets and plenty of copper grease on them. It is important to make sure that you will be able to get a spanner on each nut, and also that you can get them on and off the head studs. In my case the rear one only just fits on and off! As per the originals, the middle hole has a smaller clearance on the stud for location, the other studs have a very large clearance.
It is not an easy job, lucky for me my Dad is an experienced fabricator and engineer.

 

Hopefully someone would be able to repeat your Dad's success, and share the formula to help other build their own manifolds. This is no easy task, and may involve many trial and error to get it right.

 

I have found a local shop that does a lot of custom turbo manifolds for the tuner crowd turbo charging BMWs. Maybe a future project. Of course the exhaust ports are oval. They couldn't be round like nearly all other exhaust ports could they?

I am sure buying pre cut flanges would be a huge help to them. One less thing they would have to design where it has already been done.

 

XJRengineer, Andy, has the specifications for the flanges if you need them.

 

I got a message from someone in Australia that makes headers but now I can't find it. Who makes theses? He said they weren't cheap but, expense is relative to one's budget.

As a side note I just bought a stock style downpipe/converters from Premier Performance auto parts based out of Ottawa, Ontario, Canada. My rear two O2 sensors snapped off while trying to remove them and decided it was just time for a new downpipe.

 

https://www.facebook.com/groups/XJR6...2930706664004/

There is now a stainless steel solution developed by a professional shop called “Simply Performance” in the UK. Heard that it it costs below GBP900 which is, in my view, good value.