talking about Grp44 XJS, found this old pic

 

I still think the group 44 XJS was "almost" the complete package, its just simply a shame that they developed the car with Webers not the injection system it came with, those blokes would have taken us to dizzy heights now if they went in that direction.
Just love the fact they took it to the larger ci US cars and beat them, imagine if they put some more cubes in the motor and started matching the hp the others were producing. Still that 5.3 (326) sounded amazing and went like a scolded cat, I just hope I can get mine to sound and move like that, I have simply one persons (Holden/Vaxhual/Pontiac, Monaro/GTO) depending on where you are from that I really want to bring down to reality.

 

I completely forgot about this system that I removed from my donor vehicle, and stashed behind the pool house several years ago. 3" pipes, H-pipe and Dynomax turbo mufflers going under the diff, to glasspacks and large oval tips. VERY throaty as I recall, but, I never heard them on the road. Maybe I'll put them on SpeedDemon for a while, and see how I like them.

 

FWIW, I have spent a lot of time (and certainly some money) on this very problem. I replaced the cats with European downpipes and from there tried about every combination, with and without crosspipe I could, using glass packs alone, chambered mufflers, both, chambered alone...nothing brought the joy I was seeking.


But, before I go further, I must state this for you to ponder: for my money, the hands down best sounding XJS I've ever heard on a sound clip is JagZilla's. And I have heard a lot of clips over the past dozen or so years I have had this car.


The resonances I had in the various systems I tried has made me very wary, now. One combination proved pretty impossible to live with, as the resonant drone happened in the vicinity of 1500-1800 rpm, and it made driving at a constant speed in this range very miserable. Again, I am in a rag top, and that top is down 99% of the time when it is driven. Noise is a big issue, then. If you have the luxury of a 5 or 6 speed manual, the resonance issue can be dealt with more forthrightly: you just select another gear and move the engine out of the drone point. If you have an auto, well, you really are kind of stuck and then the resonances must be dealt with.


If you want the kind of sound that the E type could produce, take a good close look at exactly how they did this. The crosspipe is way up front, just behind the flywheel. The pipes go straight back to the fan tail, where both banks issue in a space of about 8" in the center of the rear of the car. And the muffler choice and position I am sure also plays into this. But two things stand out to me: crosspipe location and bringing both banks to the same location for exit, so that the sound field that emerges is 12 cylinders and not two six cylinders.


The latest 'vettes use this center location and I have also seen this on the V10 Viper (although that is the saddest sounding supercar I think I have ever heard- really awful tone. I *almost* want to put one of those rice rocket coffee can mufflers on those cars- couldn't be worse, might even be better!).

What the E type V12 does exhaust-wise
is hard to do on an XJS, especially one with Marelli ignition, because that crosspipe would have to go quite close to where the speed sensor is on the bell housing. Then, you have to decide to bring the pipes down the middle and up at the rear bumper. Not really designed for this.


I pulled the Euro downpipes and I have been running the AJ6 TT extractors going through the rear OEM boxes alone, and this after a whole season or two of putting together and taking apart many, many setups.


The cage is out right now, for some maintenance and upgrades, and one of the changes will be to make one final attempt on the exhaust:


I have settled on this: a pair of Thrush turbos in the center box locations, pipes through the cage, but running between the half shafts and the lower swing arms (hate the heat transferred to the calipers of the OEM cage pipes), and then to either glasspacks or chambereds in the rear silencer locations; I have both, and will try both, keeping the one I like best. I don't know how close that will get me to the promised land, but I don't care; what I get I will live with. I am tired of trying more options! I am, in a word, exhausted.


You are warned, though: this is not easy to pull off, this getting the ripping canvas sound of a V12. At least not with the jag v12.


-M

 

Lots of great insight here

 

Where should I throw in a cross pipe on my catless system with mid res delete?

 

Mine is catless with mid mufflers deleted, I put an "H" pipe just aft of the trans.

 

This is the sound some of us aspire to--the sound I want to build into my car.
Excellent video footage from this year's Targa Tasmania

 

GREAT video! Love that sound! I want it too!!!!!!!!!

 

NICE! its great to see and hear an XJS V12 doing its thing!

damn that sounds good.

 

That is pretty much exactly what I am looking for in my build. Who needs a radio when you can have that!

 

Nice video!!

 

I'm trying to find out more about the car. I know that the driver/nav team is Mark Hammond, and, Gordon Lennox, both from New South Wales. The guy who posted the video, told me that they have $150,000 in the car.

It looks like all 12 cylinders exit just in front of the right rear tire (excellent location for those of you with RHD cars).
Here are some photos of the car:

2012 & 2013



Pay close attention to those intakes. They are specially cast Group A intakes, and the inside of the runners is HUGE. They flow 35.7% more CFM than stock


2014

I guess 35.7% over stock wasn't good enough, because look at the setup they ran this year. This is where a lot of that great V12 sound in the video is coming from


A couple shots of the boot area

 

Cool video. Makes me wanna buy another XJS

Cheers
DD

 

The video is filmed in HD, so the image will go quite large. You really need to watch the video on a good monitor & hear it through something other than laptop or computer speakers.

My desktop computer is an iMac with a 27" screen, with Boston Acoustics CR6 bookshelf speakers, powered by a Sony 100 watt per channel receiver. You wouldn't believe how great the video sounds on it.

Better yet, is a smart TV & a quality surround sound audio system that allows you to watch YouTube videos. Car 626 shakes my whole house coming through my Pioneer/Infinity system.

Give it a try on something that really brings the sound to life.

 

about the custom fabbed plenum, when in doubt about plenum sizes,(many formulas are available) it should be at least the equal internal volume as the engine bank displacement.

so for one bank Jag V12 5.3 volume should be 2.7 internal(6.0L 3L) on each bank.

being larger doesnt seem to any problem,except room to put it, internal trumpets good for N/A engines , tests say not so important for turbo-supercharged engines.

also most good plenums seem to be tapered toward the far end(some unusual science there)from the air inlet. he also went to 12 ITBs. lotsa money there,for the complete system!

and JagZ 1st pix must be AJ6 engineering stuff, couple more of close to same.

and a pic from Forward engineering inlet system. Roger Bywater.

 

Don't know about you people, but I've recorded the sound from that Targa Tasmania video to be an MP3 and play it in my C30... Not trying to fake the engine sound but that literaly IS music!

 

Any imput on what he did to that motor other thwn the intake and I'm assuming a set of headers

 

Not sure what he has for mufflers, if any. However, most of what makes it sound so good is the crisp throttle response coupled with the resonance generated by those huge intakes and the 12-into-1 exhaust.

Part of the crisp throttle response partly comes from the individual throttle bodies, but, my guess is he's also spent a lot of money on making the rotating mass lighter, both inside the motor, and with things like an aluminum flywheel, and aluminum drive shaft.

 

it has been said for many years, that an open exhaust on a V12 engine has a musical sound!

like 6 beats in one revolution of crank(4 stroke), were V8 has 4 beats per, and a six 3 beats and so on! not counting flat plane crankshafts.

i do know my V12 exhaust all out one outlet has a nice sound, and the higher the revs the better it sounds.