Whatever happened to the light grey exhaust pipe.

[vpr]

You always knew if your mixture was right when you had a light grey exhaust pipe.

I’ve noticed old cars just emit a horrid smelling soot which stinks and leaves you needing a shower. Exhaust pipes are only black now. Surely this means there’s modern fuel doesn’t burn as cleanly?

[friederich]

Grey deposits were lead compounds. When the mixture was lean you could see the lead. When it was too rich it would be black.
Modern cars running unleaded without GPF only show black for the periods where they run rich.

[Allan L]

vpr said:

You always knew if your mixture was right when you had a light grey exhaust pipe.

I’ve noticed old cars just emit a horrid smelling soot which stinks and leaves you needing a shower. Exhaust pipes are only black now. Surely this means there’s modern fuel doesn’t burn as cleanly?

No it simply means there is no longer lead in the fuel to provide the grey colour.
Full explanation available on request, courtesy of the articles written by John Rowland when we were first faced with unleaded fuel.
ETA snap!!!

[vpr]

Yeah it came to me in the night when I remembered the lead content went.

Still old cars don’t smell great now.

Followed a Testerossa yesterday and it stank.

I get comments re my old Aston chucking out smoke and also my Ratsun Z which is on itb’s. I’m told that it’s mapped perfectly and needs that level of fuelling

[Yertis]

If you put in Tetraboost, will you get the grey-ness back?

[JxJ Jr.]

vpr said:

Still old cars don’t smell great now.

Followed a Testerossa yesterday and it stank.

I'm not sure they ever really did and suspect part of it is perception as we've become used to cars being pretty much odourless.

[Yertis]

Petrol used to smell much nicer.

[HealeyV8]

Use Castrol R for that great sweet smell

[Sardonicus]

Super unleaded does mid grey although not as obvious as leaded back in the day often seen after hard driving or after a motorway stint

[vpr]

HealeyV8 said:

Use Castrol R for that great sweet smell

I use it in the garden equipment. It’s the only thing that makes gardening mildly pleasant.

It does gunge up the carbs though

[Leveret]

[quote=vpr]Yeah it came to me in the night when I remembered the lead content went.

Still old cars don’t smell great now.

Followed a Testerossa yesterday and it stank.

Probably because its 15 litres of oil was old, never got fully warm and so contained moisture and lots of oil degrading bacteria which used to make following old unserviced cars so unpleasant. It's those bugs that make the appalling stink.

[a8hex]

JxJ Jr. said:

I'm not sure they ever really did and suspect part of it is perception as we've become used to cars being pretty much odourless.

Most of the time modern cars don't smell, but get behind some performance cars* when the driver has lead boots and you get a whiff of their combustion products. I remember thinking the other day that I thought they'd stopped selling fuel with sulphur in, but there was a definite sent of rotten eggs.

(* usually things like MB 6.3 models, M series BMWs and the like, can't think when I was last saw a Porsche/Ferrari/... put their toe down on the road)

[uk66fastback]

vpr said:

Still, don’t old cars smell great now.

Makes for a better sentence

[Yertis]

a8hex said:

Most of the time modern cars don't smell, but get behind some performance cars* when the driver has lead boots and you get a whiff of their combustion products. I remember thinking the other day that I thought they'd stopped selling fuel with sulphur in, but there was a definite sent of rotten eggs.

I think we might be talking about some different smells here. There's the old traditional smell of four- or five-star exhaust. I quite like that smell. Then from the mid-90s, that pongy H2S bad-egg smell, which I must admit I've not smelled for ages and as you say must be to do with reduced sulphur content. (I always associated this with catalytic converters but that's because that's what forced me to buy unleaded.) Then there's Castrol R smell...

Perversely I also like the smell of old fashioned diesel fumes, it reminds me of our old school coach that made big black clouds of the stuff.

[a8hex]

Yertis said:

a8hex said:

Most of the time modern cars don't smell, but get behind some performance cars* when the driver has lead boots and you get a whiff of their combustion products. I remember thinking the other day that I thought they'd stopped selling fuel with sulphur in, but there was a definite sent of rotten eggs.

I think we might be talking about some different smells here. There's the old traditional smell of four- or five-star exhaust. I quite like that smell. Then from the mid-90s, that pongy H2S bad-egg smell, which I must admit I've not smelled for ages and as you say must be to do with reduced sulphur content. (I always associated this with catalytic converters but that's because that's what forced me to buy unleaded.) Then there's Castrol R smell...

Perversely I also like the smell of old fashioned diesel fumes, it reminds me of our old school coach that made big black clouds of the stuff.

I know we're talking about different smells. Even unleaded burnt in a good classic engine had a certain aroma. A number of years back when we were having some building work done we'd let the builders store some of their stuff in the garage and I noticed they kept going in an out. Turned out that were just going into the garage to smell my old XK. Who can blame them. I didn't use Castrol R, although a previous own had done. The Valvoline racing oil didn't smell too bad though.
The H2S smell came from high sulphur fuels run through certain types of catalytic converts. I think it was German spec ones, that one of the catalysts can produce carcinogens under certain circumstances if now handled properly. The other problem with high sulphur fuels is that while the engine is warming up they produce H2SO4 (Sulfuric acid) as a combustion by-product and this eats Nikasil engine linings which caused Jaguar, BMW and Porsche so much grief.