I solved that problem by using a section of wire from a clothes hanger (about 6 inches per filter housing), bending it in a radius slightly larger than the arc of the butterfly, and welding it vertically across the TB opening of the inside of the air filter housing. This holds the filters away from the path of the butterfly. Works well with K&N filters, or AJ6 foam filters. You would likely need to weld it diagonally across the openings in order to keep it out of the creases of the stock paper filters.

 

The Jag V12 manifold was designed very poorly. Each runner is a different length and many have a different shape. The air flow to the front cylinders basically has to make a u turn. The Group A V12 sales flow test shows a 9% difference between the best and poorest flowing runners. How can you properly fuel and engine with up to 9% difference in air amongst the cylinders? You'll need a 9% difference in fuel too. That's hard to do so at any one time you will have some cylinders too rich and some too lean by up to 9%...that's nuts and a recipe for power loss. I guess you could run different injector sizes on each port according to the flow but that's a bit imprecise. Can your ECU trim each injector? So in practice you'll have to run a 24lb injector on the poor flowing ports and a 26lb injector on the good flowing ports. I believe the hi performance Jag v12 needs a log manifold with much longer & straighter equal length runners like the BMW v12 manifold. Fabing one of those would be a monumental task for even the best welder but it's probably worth 50hp based on proper fueling alone. Its not unheard of...a proper designed intake can be the difference between a engine that makes 400hp or 500hp.

 

funny that you mention it ICS, my engine system allows me to individually tune each injector to make the mixture in each cylinder burn correctly

 

I was looking into.this, what unit should I use exactly? a 3.6? or a 4.0

 

Have you got O2 sensors on the exhaust of each cylinder? if not how can you tune each pot, it can only average what exhaust monitoring.

You could use 4 O2's 1 for each set of 3 cylinders then the ECU could fuel 3 cylinders.

 

Thats great because its going to be real useful for getting the most from your project. Doing and getting it right is another matter. I guess you can start with the known CFM differences and work from there but the only way to really get it right is to use 12 wide band 02's and data logging. You could probable do it in groups of 3 or simply one at a time and after awhile work it out. Your exhaust manifold will look like Swiss chees but it could be worth the effort if the flow is as disparate as advertised. If your heads weren't CNC port matched precisely there will be flow anomalies there too.

flow in (cc) / Fuel amount in(cc) = AF Ratio & Result

196 / 16 = 12.25 ok

182 / 16 = 11.375 NG

173 / 16 = 10.8125 NG ( way to rich may misfire)

179 / 16 = 11.1875 NG

187 / 16 = 11.6875 NG
196 / 16 = 12.25 ok

The table above illustrates the importance of tuning each cylinder. It shows that if you tuned your best flowing cylinder to an AFR of 12.25 to quell detonation you would have 8 cylinders with an AFR that would not be ideal and therefore not make the most power.

 

I was eventually going to get headers and install wideband sensors in each port to tune with.

 

Doesn't this all come back to using ITP's with the same length trumpets on each pot, will solve all the dramas.

 

read this....
https://www.jaguarforums.com/forum/x...22/#post876452

 

so I have a set of extra intakes at my house, what would you guys say to me cutting them open ans welding bell mouths like.the AJ6 one? since I'll be getting my ac TIG machine in a couple weeks.

 

i still think for a street XJS this is a good compromise, large plenum, long runners, good flow angle into port, and large single TB(90mm),at front of each plenum! with room for K&Ns

if flow is important with 12 itb's contrary to most think the port angle is not vertical, and long runners would contact at the cross over area.( splitting hairs now).

 

IN effect, make one of these with the intake runners with rolled edges, AJ6 says it works:

5. Our Ram Plenum tuned length induction system kit for the V12 produced during 1986-92. This beefed up a standard engine by nearly 70 b.h.p. but was too expensive to manufacture. Close to 600 b.h.p. was possible from a race engine. We first started producing our large throttles for this application.

6. The Ram Plenum induction installed in an XJ-S. All ancillaries could be retained even including the valve block for Teves ABS brakes.

 

With a TIG why don't you make new manifolds a good place to start is by looking at the BMW and Mercedes V12 intake manifolds. Granted these long X manifolds are too long to go in the XJS bay and unless you move the dissy you can not cross the manifolds over.

If you don't want to make new manifolds, The stock manifolds with the larger capacity you have will work better and adding trumpets of varying lengths is a good place to start.

 

I was Googling BMW V12 intakes just now, and came across this unusual application for a Pre-HE. It has an interesting intake manifold design, and a Vortex supercharger. I also see that it is running a TEC3.

Martin Jansen's Austin-Healey 100 with Jaguar V12 Engine

 

i just saw that aswell, and i was wondering, what would be the advantages or disadvantages of having a central intake manifold? similar to a dodge viper?

this was my oridnal idea, use a plenum for a RB26 intake, and make long qual length runners simiar to the bmw intake.

how long should i make these runners?

 

Love the intake style calvin I have been thinking of make one much like the v10 one you posted. Make it a two piece hide the injectors inside and sit the coils in back by the fire wall.I must go dig up the schematiilc I made awhile back for my old Iroc z . I think if you where too put three xjs throttle bodys on top too one solid linkage the car would breathe quite well.

 

which one did you like????

 

Bottom right , thats the way too go

 

Each cylinder will see equal amounts of air provided the air drops in from the top instead of a tpi style.

 

Went down the intake root 25+ years ago. At that time the Group A manifolds where unobtainable and indeed TWR / Jaguar denied their very existence. Got ali tubing bent up to do a cross ram system and replaced the dissy with the latest valley cover and coil packs. found that tigging in the pipes to flanges caused distortion to the angle and that it was very hard to get all around the flanges. Not just that the diameter of the pipes and their angle meant that the A and B bank would be inseparable, the finger of one side going though the fingers ofg the other. The piping was so very tight that when the warping occurred, even if small, the whole thing was a mess with different part interfering with others, I gave up. but do believe a good welder could do it (but you better not be paying him an hourly rate!
Yet this wouldnt be the total answer! You will still have unbalanced flow leading to inablilty to match all cylinders, always happens. Even Scott and TWR never got it all right with the Group A / std manifolds.
Jaguar say the idea of different length runners is to widen the power band, seems reasonable , as in a reasonable fudge. The truth is likely to be because it was easier, as simple as that. It was sill a reasonable effort for the time though and remember that ECU development had only just started and was totally incapable of running different cylinder advance or fueling. Sequential was rare and complicated, there were no after market ECU's and the biggest problem was getting enough sparks through a coil for a V12. Ferrari gave up and used 2 x 6 cylinder systems which works unless you link them, then they fight for control, literally.
Now you all have it easy.
If you want/ desire equal flow then get a manifold and flow it. Hog it out with die grinders and flap wheels but work on the poorer flowing ports 1st and only bring the others upto what the worst flow. Lots of time needed and lots of regular checks on a flow bench. But it can be done. Different sized washers on a stick give you the clue as to where the meat has to be removed. If you go through a std manifold on the underside you can tig a plate over the hole or use ceramic sealer. If you do a few of these manifolds you will get better and wont go through again.
So yes it can be done, and this will allow you to maximize the package.
AJ6 sent me their prototype long runner manifold, It was heavy (steel) and looked a bit ugly all tigged up. it flowed well but was crude, They made maybe 12 sets later and they were tidied up a lot. Not cheap but they did the job. Importantly for me they were not factory and got banned for my form of racing.
Better was the Broadspeed manifolds, but you will be lucky to find these nowadays. Made the inlet stubbs from ali thick wall tube and had a massive reamer cut to open the tubes at 2 or 3 degrees over their length The tubes were highly polished and oiled s that the wonderful trumpets were a push fit on top with a viton seal. All the cast and machined trumpets fitted internally to the twin throttle plenums with 4 10/32 screws so that you could line everything up perfectly. The plenum had a top and bottom joined on a flange with loads of 10/32 screws. The 2 x throttle bodies were std. I ran this on a metering unit to start with but ended up welding 'blimps' into the inlet stubs and using pre HE green injectors in the end. You could simply pull the top off the system if you needed access and I found a need to retain the top under racing as you could pop it off (and thereby end your race) on backfire on the over run going into paddock bend.
So now you know how to do it go forth and lets see who actually does it. I wont be holding my breath.