The 'E' Type Forum

Folks,
Anyone got experience of running one of AJ6 Engineering's TT Extractor Torque Booster Exhaust systems? Was torque 'increase' noticeable ?
AJ6 is not giving any diagramm about the torque increase. They say 11% more in the midrange. But is this true ? Can I trust these words or I blowing money ?
Thanks Wolfgang Gatza

No personal experience but I would be very circumspect about such claims. For example a x% increase in the mid range could mean an x% drop elsewhere!

11% more in a given range sounds like exactly the sort of modest and specific gain you'd expect a reputable guy like ex-Jag engine development engineer Roger Bywater to make.

I had one of those exhausts and although I sold the car before I could fit it, it was very well made (it was used but still excellent). He doesn't deal in BS and there is even more available from his sport system, but it's loud for street use. I've got a different set of his pipes sitting in the back of the Discovery right now if anyone has an X300.

The silencers of my original exhaust system are nearly empty and instead of the back silencer, I have two 60 mm pipes from the two silencers to the end of the car. The motor has a good torque between 2000 and 4000 rpm. My question is: are the tt-pipes producing 11% torque more than the original exhaust system or also 11% more than my system ?
I think I have to do a dyno-test, before I decide, to spend money for tt-pipes.
Regards Wolfgang Gatza

Ihr System ist ganz anders als in der AJ6 System. The difference is in the front part of the system. Putting stright pipes after the main silencers will just affect backpressure and sound rather than gas flow per se - certainly in terms of refelcted waves and pulses.

The TT system uses much longer pipes from the manifolds backwards, before they merge. This is where the extractor effect comes from. What you do after your main silencers on your standard car is almost totally irrelevant in terms of performance, though not noise. Almost, but not quite, so you might see a tiny improvement over stock at wide open throttle.

Even the silencers of the TT system are better than the main mufflers of the standard car. My only issue with the system is those silencers were a tiny bit large, although there is no alternative if you want a reasonably low noise level. Them ore potent Sports system exists for those who don't mind loud exhausts on long trips.

But yes, there is no substitute for before and after dyno figures for any modifcation that ostensibly affects performance.

Pete

Hello Pete !
I know the design of the TT-pieps very well from the site of AJ6.
I have a doubt , that from a single change from the short originale "TT-pipes" (the merge of two into one pipe on each side of the motor) to the long separated pipes of AJ6 there is a gain in torque of 11%. Before I spend, I would have less doubt, that this is true.
A friend has bought the TT super-sport system with the four small silencers from AJ6 for his EV12. This system was much too loud.
Regards Wolfgang Gatza

Fine. It comes down to trust or verify. If you doubt enough you will not buy. If you buy you can verify. You can't not trust AND verify, so you have to choose.

If AJ6 claimed 11% improvement over the entire rev range I would share your doubts that such a simple change could make that much difference but I don't think that is what they claim. It is, on the other hand, quite believable that there is such a gain in a useful part of the rev band by harnessing the gas column pulses for an extraction effect.

Frankly, unless you believe the standard and most quiet system is also the most powerful of all options at all points of the rev range, then the AJ6 system could be expected to increase power by nothing more than random chance. I'm sure even you don't believe it was designed by chance, so the odds are good that it does what they claim.

However, I never got round to fitting mine and I am not paid to sell AJ6 tuning parts, so I'm done. Wenn schon denn schon.

MfG
Pete

Pete

Pete and Wolfgang

Maybe you should read this: http://www.jagclub.ru/AJ6.html

Interesting read although obviously neither I nor the Forum associate ourselves with some of the comments but we do love empirical measurements along with a healthy dose of scepticism. Unfortunately there is no link or name to find out who wrote it but I think it originated in Germany. It goes on to talk about "our" system so it could be a rival manufacturer? Shame, because without the vitriolic comments it would have been valuable. Don't shoot the messenger!

On the other hand you can read a lot about the AJ6 Engineering philosophy here: http://www.jagweb.com/aj6eng/index.php

Article on the XK engine by Roger Bywater: http://www.classicjaguar.com/xkengine.html

Heuer wrote:Pete and Wolfgang

Maybe you should read this: http://www.jagclub.ru/AJ6.html

I did, years go. From memory I even corresponded with the guy briefly. Scepticism is healthy in my book, and that guy's diatribe merits a lot of it. I don't mind him taking a pop at anyone if he subjects his own stuff to the same standards, but I haven't got the energy (or the disinfectant) to pick out the non-sequiturs and missing info that are bobbing around in that sewage.

Pete

Presumably that Russian site hosts the only copy left!

AJ6 is never showing a dyno-diagramm about horsepower gain of his tuning-parts. Because of this lack and my own experience I have doubts.
Beside this, I beleave that Roger Bywater is a lot of know how about Jag motors.
Regards Wolfgang Gatza

Yes Wolfgang - you said you had doubts in your first post and you still have doubts in your last post, so nothing has changed in between.

There is nothing wrong with requiring hard data before paying a lot of money for something, but if dyno charts are what it will take to persuade you then it would be better to just ask 'Has anyone got before and after dyno charts for the AJ6 system?'

If I had known that it would have saved me some time because I don't have any either. It's a pity nobody here has experience because i have seen a few systems on Series 3 cars.

Pete

From that article:

With AJ6 TT exhaust system:


Without AJ6 TT exhaust system


This is on a 6 cylinder but fitting the TT system seems to decrease power by 25bhp and there is nothing to suggest it is counterbalanced by a rise in torque. It would be interesting to hear of anyone who has fitted the AJ6 TT system on either a 6 or 12 cylinder car. That article, if you skip over the needless sniping, does have some valid points. It really annoys me when someone who has a great deal of experience and has access to test results feels the only way to get his point across is to insult everyone.

As I have found out tubular manifolds compromise performance in a road car compared to the cast manifolds unless you take action further back to modify flow.

Hello Pete !
I say thank you for the effort you had, to answer my question. My english is to poor to aks the questions very clear. But I hope, that at the end of such a discussion, I will have more infomation about the TT-system of AJ6, to make a better decision.
On his site and in his book R. Bywater is describing the theory of a extractor system. I believe in the theory, but I am asking not how big is the advantage over the "closed" original system.
I am asking, how big the advantage is over a original system with "cleaned"/openend silencers plus a big-bore end ? To "open" the two middle silencers is done in two hours and the cost are zero. The two big-bore 60mm pipes had cost of 80 pound plus 6 hours of work. The sound is great.
But I MUST reshape the profile of the 4 needles. Otherwise the mixture would have been much to lean. If I remeber well (? ? ?), R. Bywater wrote on his site, that this is not necessary, because of the technology of the constant depression carbs. In my experience of 10 years with this carbs, I had to change the shape of the needles every time, when I have done a major change to the exhaust system or the small inlet-trumpets of the airfilter box. These trumpets have 32 mm id at the front, a 1 Euro plastic water-pipe has 46 mm inner diameter. This is roundabout the doubble square and helps the breathing of the motor with cost of 2 Euro.
When I changed to 58 mm pipes of id, I had to reshape the needles again. I checked the result with a LC-1 Lambda-meter. The "red beast" is running very strong, but I have never done a dyno test. Soon I will do another real life test against an EV12 6,0 with a programmable modern injection system. I will report.
Pete C. wrote in his buyers guide for the EV12, about the "desirable AJ6 tt-extractor system". Yes it is desirable, but is it also "torqueadding" ?
Regards Wolfgang Gatza

Dear everyone,

Sadly, there is what we at work used to call a "spot the benchmark" problem here, in that anyone who has spent hundreds of pounds on an aftermarket exhaust or intake is extremely unlikely to speak badly of it, while an unsuccessful competitor will do nothing but speak badly of it.

It is indeed rare, and welcome, for someone to ask for some evidence before putting money down and I hope there is some hard data available to clarify what the effect of such an exhaust system really is.

kind regards
Marek

V12 2+2

I fitted one of these, largely because I considered the original too quiet. My observations would be as follows

First: According to CMC in Shropshire, it actually reduces performance. They have modified mine and the results speak for themselves... much livelier now.

Secondly: because of the fact it comes in sections and the clamps supplied to secure the sections are insufficient to maintain a good seal it develops annoying blows at the joints at the slightest provocation. Given how low these cars are provocation is not uncommon.

Thirdly: For the brief periods it has no blows it sounds nice.

Personally I consider it has been a complete waste of money and I wish I hadn't replaced the original.