Citroen SM V6 engine noise!

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Mandrake
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Citroen SM V6 engine noise!

Post by Mandrake »

There are lots of videos of the SM online that I've seen before of course, but this one really caught my fancy as it's the only one I've seen that really gives a good impression of how the car sounds to drive, recorded from within the car. :)



And boy does that old school V6 sound awesome! :twisted: Rich at the bottom end and rather raspy and throaty at the top end! Check out the clip starting at 2:40. (And again at 4:20) Best appreciated with good earphones or earbuds to get the low frequencies...

I'm not sure whether the exhaust raspiness above 4000 was standard or due to an aftermarket exhaust but I remember one of our GS's had a somewhat similar raspiness to the exhaust at high RPM whilst our others did not, so I'm going to put that down to the exhaust.

More modern 60 degree V6's like the Xantia are certainly quieter and much smoother at the top end (and a lot faster) but there is a certain appeal to that old school sound I have to say. :-D

Another thing I observe from the video is it seems like the SM has a really heavy flywheel ? It seems to be very slow to loose RPM during a gear change and it seems almost as if the flywheel inertia is pulling the car forward once the next gear is engaged... :lol:

Hell Razor5543
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Re: Citroen SM V6 engine noise!

Post by Hell Razor5543 »

I believe that the SM had an engine originally found in the Maserati of the time, but somewhat trimmed down. IIRC the Maserati engine was a V8, but for various French political reasons the SM had to have a V6, so two cylinders were lopped off.

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Mandrake
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Re: Citroen SM V6 engine noise!

Post by Mandrake »

Yep, I'm quite familiar with the design of the engine, but just haven't heard a good recording of one until now. :)

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white exec
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Re: Citroen SM V6 engine noise!

Post by white exec »

I'm no expert on the SM, but agree with Simon about maybe a very heavy flywheel. It positively lumbers between one gear and another! The exhaust (or lack of it) and its mounting are a disgrace - agricultural, in fact.

When I compare that with my Rover V8 manual, it's chalk and cheese. Rover was smooth, zippy, responsive, with a delicious exhaust note (very distinctive on automatics), and felt like an engine without cylinders.

An interesting and revealing video.

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Re: Citroen SM V6 engine noise!

Post by hattershaun »

Having had my SM for ten years now, I'd say the engine noise in the video clip is quite accurate.
In particular the tone as the engine approaches 4000rpm and onto 5000, which is just spine tinglingly wonderful.

My car has a full stainless steel exhaust, as do most of the cars I've seen in the UK.
An original Citroen mild steel exhaust gives a slightly softer noise, I believe, as my mechanic has been working in SMs since they were new.
My car had the flywheel lightened and balanced with a new clutch, which improves the responsiveness.

I'm always happy to take people for a drive, when I've got the car at a Citroen Car Club rally.

The SM is one of the World's most wonderful cars, if I had only one car to keep forever this would be it.

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Re: Citroen SM V6 engine noise!

Post by Mandrake »

white exec wrote:I'm no expert on the SM, but agree with Simon about maybe a very heavy flywheel. It positively lumbers between one gear and another! The exhaust (or lack of it) and its mounting are a disgrace - agricultural, in fact.
I think you miss the point of a 1970's "GT" car. It's supposed to be loud and have character when revved hard, not quiet and refined. :-D I would also point out that its pretty obvious from the wind noise that the windows are all wound down during the video as well so I doubt it's that noisy with the windows up.

If they thought they could have got away with a straight pipe with no muffler they probably would have gone for it... :twisted: but no doubt they added the minimum amount of muffler that they could get away with and still meet noise regulations, whilst still preserving the basic character of the engine sound rather than suppressing it, not to mention maximising performance - the specific power output of the SM engine is actually remarkably high compared to more modern engines - per litre its only a little bit short of the output of the ES9J4 for example, both in torque and horsepower. Not bad for an engine that's over 25 years older in design.
hattershaun wrote:Having had my SM for ten years now, I'd say the engine noise in the video clip is quite accurate.
In particular the tone as the engine approaches 4000rpm and onto 5000, which is just spine tinglingly wonderful.

My car has a full stainless steel exhaust, as do most of the cars I've seen in the UK.
An original Citroen mild steel exhaust gives a slightly softer noise, I believe, as my mechanic has been working in SMs since they were new.
One of our GS's (my Dad's) had a "custom" exhaust, custom in that in those days (especially in New Zealand) it wasn't feasible to buy the OEM exhaust/mufflers, and after market types weren't available so when they wore out the local indy exhaust guy would custom manufacture a new exhaust on the spot right from the Y joint all the way to the tail pipe - they'd copy the layout and configuration but inevitably the mufflers themselves would be quite different inside.

With that exhaust that 1220 had a delightful raucous cackle and raspiness to the exhaust above about 4000 that sounds quite similar to that SM video, it also had a more throaty sounding bottom end when pulling. In short it sounded a lot more impressive than its 1220cc would suggest. :twisted: And guess what ? It went like stink too, it out performed any of the other 1220 GS's that I'd driven at the time even though it was really high mileage and had worked hard all its life. The standard GS exhaust really does strangle the engine in the name of quietness.
My car had the flywheel lightened and balanced with a new clutch, which improves the responsiveness.
That's interesting - so it does have an unusually heavy flywheel then ? Is that a common modification among SM aficionados ? Does it make the engine any lumpier given that its a 90 degree V6 with the typical uneven 90/150 degree firing pattern ?
I'm always happy to take people for a drive, when I've got the car at a Citroen Car Club rally.

The SM is one of the World's most wonderful cars, if I had only one car to keep forever this would be it.
I'd love a ride in an SM one day - well, I have ridden in one when I was 7, but that was a long time ago, and I was too young to appreciate it... my Dad test drove one and almost bought it in 1983 (we had a GS 1220 at the time) but couldn't quite get the money together and convince the keeper of the purse strings the necessity of such a purchase when they had a perfectly good GS... :lol:

It would be wonderful to get a ride in one again to see it with grown up eyes and after decades of driving other models of Citroen. I can see I'm going to have to make an effort to go to some of the Citroen meetups despite the long distances involved! :)