I'm not actually expecting it to do anything beneficial in terms of power since it's a balanced engine anyways, but does the sound noticeably change for the better or good? I've read Kirby Palm's book and he mentions you get more of a 12 cylinder sound instead of 2 individual inline 6's. Do the pulses not have any negative interference even with so many?

I'm very curious. I'd like to try different iterations (converge to a single exhaust, x pipe, h pipe, etc) to hear the differences.

 

Lots of thoughts and theories out there, much like the infamous "oil threads".

I looked at this on mine back in 1995, and lack of room under there for "normal" access, had me thinking seriously about it.

I eventually went with new front mufflers of a "thru flow" style, and 2" pipes hand made to go thru the cradle (easier than most will have you believe), and "Hotdog" resonators at the rear, with a fancy twin pipe tip on each, just coz I could.

The sound suited me to a "T", basically barely audible in the cab and at highway speeds, but when stood on, that growl sent shivers up the spine.

There were many other enhancements to go with "upgrade"\\BIG throttle bodies
NO balance pipe
NO overrun valves
NO emissions junk at all
NO AAV
XJ40 TPS.
PreHE distributor base, and an 18deg vac advace capsule.
Real cold air intakes
Home made foam air filter elements.
Electric fans, with the front V of the crank pulley machined off (less weight, more grunt)
Tappets set at 0.013 and 0.015 inches respecfully.
Timing set by "drive timing", and since I ditched the timing plate, no idea what advance it had, it went like stink, that is all I know.
Adjustable, compact trans vac modulator fitted, and set to what I wanted.

Then when I refreshed the engine internals, I balanced rhe beast, and was quite amazed how far out the internals were.

Sooooooo, in answer to your question, I have NO "scientific anything" as to +/- of the exhaust changes I made alone, but it did sound better, and seemed to "breath" better.

 

On the V12 a X or H pipe will have ZERO effect on power. Jaguar did have this on the eType V12 to tune the exhaust note.

Unlike a V8 (90° crank only) that fires 2 cylinder on the same bank in sequence and benefits from a H/X pipe the V12 fires each bank alternately.

Having said that the benefits of a free flowing exhaust and cold air intake were not lost on TWR XJS road cars.

My car has a dual 2.5" from the down pipes with 2 straight through mufflers and 2 straight through resonators. Sound is great and with my 4 speed auto doing 2000rpm at 100km/h (62mph) its not overly noisy on the open road.

 

All I want to know is, how do you make it sound like this???

 

Others have reported that an H-pipe/X-pipe/balance tube of some sort does give the exhaust a more V12-ish tone. When I have the exhaust done on my current V12 project I plan on going that route.

Years ago, when I was a V12 XJS owner, I had low restriction mufflers without a balance tube and the sound was a bit odd.

Cheers
DD

 

Thanks guys for your input!

This is mostly what I'm interested in. I expected for there to be no power gains due to the nature of the V12 like you explained.

Do you know what they were aiming to achieve in terms of exhaust tuning on the E-Type? Do you get a higher pitch/smoother sound/anything due to the interaction of all the pulses?

EDIT: I dream of this sound all the time.

 

That Tasmania v-12 is pretty extreme in its intake runners and other mods. I've done extensive work on my exhaust, complete muffler removal, empty cats, empty down pipes, "H" pipe. All that's left is the rear resonators. I've even got open K&N air intakes (Growlers) and I have to report.....meh, not much different or likable then stock. IMHO the Jaguar V-12 is not easy or cheap to make sound "aggressive" in a pleasing manner.

 

That Targa XJS has tubular headers and the TRW race car had 3 into 1 cast headers this is what gives them their distinct sound. The E Type is a wonderful sounding V12 so you could add a H pipe behind the mufflers.

 

I've messed around with "pipes" from way back. Fours, sixes ands eights. But, so far and not likely a 12. That would be real fun...


Pipes from afar. The Tucson Speed Sport Special of the late 50's. A drag racer. 27 T roadster body. Rear mounted 331 Chrysler Hemi V8. 8 Flex pipes out the back. It didn't bellow, it screamed!!!


Present:


Ram horn manifolds on the Cadillac sourced LT1 in my 83 XJ wuzza 6. Real dual pipes. Sun Coast sourced down pipes One cat on each pipe, just aft of the transmission . Heat concerns. Then an "H" pipe. Thence in to the original Jaguar mufflers. Through the cage in to PO installed glass packs, and then the classic "S"
ends.


No irritating bark or even worse, a drone. No back "wrap". A nice burble at idle.


Not going to mess with it, for sure.


Carl

 

I know Marko in his videos has tubular headers, a cam, and eventually ITB's, not sure if he has the headers and cam when he did this video. I would be very, very happy with this sound.

 

Not in that video, as the individual TBs were done somewhere this year - if I remember correctly.

Most of the louder cars simply dithc the entire exhaust and have a sidepipe coming out around the rear wheel. No mufflers, resonators etc. All with a larger pipe diameter...

After playing wirh my XJ8, I noticed larger tailpipes already give it a louder, deeper grunt.

 

this vid really doesnt do justus, i'm barely at 3500rpm, now at 7000revs it screams/whistles.

but it makes the muscle head car guys notice ,Corvettes, Camaro, Mustangs,etc.

 

No video, just a picture...

 

.


yeah iknow some reason at 95%, it cancels vid saying its to long, so thats a still.

darn computers

 

I had you in mind when I started this topic, because I don't remember anyone else having all their runners merge into one.

Looking forward to the video if you can get it working

 

Maybe try youtube?

 

i know most the guys here think i'm working out of a different tool box,LOL.

 

How much of a difference to tubular headers vs stock cast ones sound? Anyone know that for sure?

Man, so many different variables. We haven't even talked about runner lengths, diameters, and stuff yet.

 

Assuming we are talking about the V12, it depends upon the rev range. In effect each bank of the V forms two separate 3 cylinder units as far as the exhaust manifold is concerned. According to Roger Bywater's book, this gives pretty good exhaust pulse effects and is far better than it looks to the untutored eye. AJ6 Engineering offer a special exhaust system that enhances mid range torque, but still uses the OEM manifolds.
There are firms that offer really lovely looking long branch stainless manifolds and I contacted two of them about whether they had done any before and after measurements. Answer no, and they had no figures of any sort at all about the difference they would make.
My belief is that at anything below 5000 to 5500 rpm the OEM exhaust does not restrict engine power at all. Above this RPM figure all sorts of other factors come into play, most notably cylinder filling (ie breathing on the intake stroke). TWR in their racing ETCC XJSs were prevented by the rules from using tubular manifolds, and from what Allan Scott wrote in his book, they would have helped considerably at high revs (as in well above 5000). TWR sliced open the OEM cast iron manifolds and removed any casting restrictions they found, cleaned up the passages and smoothed out the way they ran together from 3 into 1. But again, I suspect this had effects at well above road rev ranges. Also, the heads they used were pre-HE flatheads with the biggest valves they could get in there. etc etc.
Maybe Warrjon has some points and ideas about the exhaust manifolds he will install on his new engine?
Greg

 

I am using stock cast manifolds on my 6.7L. They have been cleaned up de-burred and the outlets opened up to remove the lip. Downpipes will be 2" not sure what length I will be using yet.

I tend to agree with Greg, that tubular headers will have no effect at mid and low RPM as there is not the room to make them long enough. The stock cast manifolds are good for 500hp with enough work.