Exhausts, previous owners , straight through or not?

[malcolm]

Thanks again, although perhaps worth bearing in mind that I don't have a straight through system, and I've only changed the manifold/front pipe arrangement. The sound is thus the same as before, and I'm pretty confident from the plugs and the way it runs that the mixture is about right.

Steve, I got the system from Hayward and Scott in Essex (www.haywardandscott.com) on the recommendation of the engineers who look after my E Type (members of E type club). They manufacture their own pipes, and they fit! They know what size fits a 2+2, although my rear silencers had previously been changed so they had to cut two inches off their standard fit for me. The system I got was the "long manifold", where the manifold and front pipes are all in one down to the first box, rather than having a join in the engine bay without the single pipe strangulation section - it is reported to add about 10 bhp compared to the standard set up, but I can't of course testify to that. Looks good as well!

[mgcjag]

Thanks Malcolm......didnt realise that u had changed the complete manifold. I like the look of the original cast manifolds and was thinking u had just put in a section to replace the 2 into 1 piece...thanks Steve

[christopher storey]

Woolfi . I do apologise. How foolish I am to rely on the specifications which jaguar used. I should have realised that you know best on all occasions

[Woolfi]

Like I wrote before: if the back-pressure of the different original Jaguar exhaust systems is similar, the needle can be the same.
Have you ever measured the exact lambda of such a motor at different loads, after the exhaust or air-filter system has been changed ? Like 99,5 % of all people, who talk about this, not. Too much believe, too less exact measurement.
Maybe (?) this helps for understanding.
http://www.patmanracing.com/klrdyno.htm

Regards Wolfgang Gatza

[42south]

Im with Woolfi regarding new needles.
I modified my S3 to straight thru center muffler and no rear resonators.
It ran terribly and no local guys could get it to run right.
Finally I took it to a guy who fitted sensors in the exhaust and ran it through all rev ranges.
The answer was new needles.
It now runs like a dream through all rev ranges and plugs look excellent.

[christopher storey]

Mark : we are talking in reality about the 6 cylinder cars with SUs , which I don't think Wolfgang has realised. I have no idea what V12s require, but of course the Strombergs are completely different from the Sus except that they share the fact of being constant depression instruments

As far as Vizard is concerned, it must be recognised that the bulk of his experience, and certainly the bulk of what he wrote about, was on the BMC A and B series siamesed port engines, which are a completely different animal from the Jaguar, having 2 siamesed inlet ports ,and a siamesed exhaust port for cylinders 2 and 3 .

[mystery type]

and get straight through silencers

I have searched and cant seem to find any for a 2+2, only complete systems.
anyone have a link?

[malcolm]

Mystery type - I got mine from here:
http://www.haywardandscott.com/
Mine aren't straight through, but they make these to order, and will provide whatever you want. Part or full systems, straight through/silenced, - and they are very familiar with the 2+2. They make everything on site, and have been doing this for many years.
Might be worth a ring?

[Woolfi]

"Mark : we are talking in reality about the 6 cylinder cars with SUs , which I don't think Wolfgang has realised. I have no idea what V12s require, but of course the Strombergs are completely different from the Sus except that they share the fact of being constant depression instruments."

The main funktion is the same like the Strombergs, constant depression. Therefore the needles MUST alswo be "reshaped", if silencer system or air filter syster are changed. There is a book about SU-cabrs from Des Hamill, in which very exantly is described, how the change the needle profile of a SU for "power-tuning". of the motor.

"As far as Vizard is concerned, it must be recognised that the bulk of his experience, and certainly the bulk of what he wrote about, was on the BMC A and B series siamesed port engines, which are a completely different animal from the Jaguar, having 2 siamesed inlet ports ,and a siamesed exhaust port for cylinders 2 and 3."
The bulk of his experience are more than 10000 hours at the dyno with different motors. Also he was working as a university teacher. He has written some books about power-tuning motors from the tiny Mini motor up to big US V8.
I know nobody, who knows more about power-tuning and who is able to write very clear about this. His big book abot "Tuning the A-Series engine" is a very big can of knowledge, good to use for tuning or power-tuning of all motors.
Regards Wolfgang Gatza