The 'E' Type Forum

Hi all, my S1 4.2 has just come out of an engine rebuild and now has lightly modified heads and fast road cams. The Jaguar specialist who rebuilt the motor advised me that I have non standard front mufflers which are very restrictive, and suggested changing these.

Has anyone fitted a big bore exhaust system to an S1 FHC, and could you advise on the noise situation? I don't mind a nice rasp but I would like to avoid a drone when cruising. Other option is just to replace the front mufflers given the rest of the system is fine.

Many thanks!

Mike, there are quite a lot of comments/opinions about exhaust systems and the best I can suggest is to read what our illustrious leader (Heuer) has to say by searching for the word "exhaust" with 'Heuer' as author, eg
:viewtopic.php?f=4&t=19059&p=154519&hili ... st#p154519

I hope that'll help as he really does explain well in that topic alone how Jaguar designed the system and in other comments how to achieve a good but not deafening sound for such an engine as yours.

Geof

Hi,
I fitted large bore exhaust with the 6 branch manifold to match many years ago (20+) as I was also advised that the standard exhaust system was too restricting.
Also advised to get the rear pipes of the big bore refabricated where they go under the rear Diff cradle as they are slightly pinched to increase ground clearance.

I think my set up was made by Bell.

I find it is only a little bit noisier (even after all this time) but not obtrusive - it just sounds powerful rather than loud.

Cheers,

Richard

There's another option - have a look down the "inlet" side of the front mufflers as you call them. If the inlet tube terminates in a flat wall, use an appropriate diameter drill to drill out the plate at the end of the inlet tube.

You'll end up with a much less restrictive muffler and a more robust sound. If you like the result, good, you've saved yourself the cost of another new exhaust. If you don't, then consider buying a big bore exhaust. I did it to my standard Jaguar supplied front exhaust boxes and was very pleased with the outcome.

I have very limited technical knowledge. However, I know that exhaust design is a very important and technical matter, so "drilling holes" in a carefully designed product would concern me. I know people may argue that the design wasn't that robust in the first place, but personal modification would be unlikely to improve it in my view unless the individual was very knowledgeable

I had Hayward and Scott make me a mild steel sports system which has smaller silencers. I originally ran with big bore straight through rear pipes but sounded like a Messerschmitt. Now replaced rear pipes with big bore cherries like original design

Malcolm

It’s also worth noting that 2+2 has a different exhaust system from others

If you look up part’s schematics in (for example) SNG catalogue you’ll see the longer system is different

I fitted a SS slightly larger bore exhaust to my 3.8 coupe and it’s quite loud

I have just finished my 3.8 OTS and it has a Jaguar classic mild steel (with chromed rear resonators). …it sounds perfect. Deep but smooth and not too loud

Would definitely recommend

I fitted the Classic Fabs system this year and it is amazing. Transformed the sound of the car in the best way possible. Exact fit. Can't recmmend it highly enough.

I have had several exhaust iterations on my OTS which has a powerful modified engine. Best solution is cast manifolds as tubular ones reduce mid range torque, likely will cause the paint of your frames/bonnet to bubble and produce an annoying tinkling sound at very low revs.

Do not go with any system larger than 1.75" bore but specify straight through silencers (the resonators are already straight through) if you want something less restrictive but still fun to drive.

Seriously consider the Jaguar mild steel system as it sounds fantastic, the way the cars sounded in period. Alternatively use a s/s system with mild steel resonators as they define the sound.

Frankly the whole "big bore" concept is ridiculous in theory and practice unless you are going racing and then you will fail the noise test at most tracks. The XK engine needs a restrictive exhaust to maintain that beautiful torque curve. Go loud, go slow!

I would agree with the “drill through the first baffle” approach, as that’s exactly what I did over 10 years ago.

I even wrote about it here.

All it requires is a tube-type drill sleeve of a suitable diameter, it needs to be a proper professional one.

You just need to perforate one thickness, and out pops your washer.

I would hasard that the exhausts were made like that precisely so you can choose.

Mine was a standard, but stainless, system made, I think, by Bell.

There was no drop in performance that I could notice, just a slightly raspier note upon harder acceleration that I (sadly) found rather nice, but the car is absolutely not a nuisance for other road users, and there is no change to the comfort of touring.

I did try straight-through pipes instead of the middle boxes, and the result was dreadful, for daily use.

I am nowadays horrified by the volume of sound made by the motorcycles that I used to race and/or ride on the road, but the Jag is absolutely not in that category now it’s had its washers “popped”.

Came across this video might be of some help.