Tighter; quieter

[enochbell]

My car is definately tighter, quieter, smoother (at idle) and more refined in cold weather.  Is this my imagination?

My apologies if "quieter" is not really a word, but I drove my 230sl yesterday in 45F weather and it just felt great.  Tight, quiet, powerful and responsive.  Not that it is not a pleasure driving it in the Atlanta summer, but there is a notable difference in winter driving.  I can understand the feel of the gear shift: it is a bit "notchy" in second and,overall, heavier when cold, even in the summer.  But the rest of the car feels just great in colder weather.  No valve noise, bumps seem dampened, is this my imagination?  Has any one else had a similar experience?  (No, I did not have the hard top on :-))

g

'64 230sl, fully sorted out...ooops, spoke too soon

[JPMOSE]

Greg,

I live in Atlanta too and honestly can't tell a difference between hot and cold days. BUT...with other cars I could.  Late July '06, I drove the 250SL for two weeks, as the other two cars were in the shop at the same time.  As you may recall, the weather was near 100F during that period.  I was surprised that car started instantly when hot (hearing all the complaints of hard starting a Pagoda when hot). Also, the temp. gauge never climbed...the radiator hasn't been touched since 1976!  I was real proud of the car (and was grateful it never rained during those two weeks).

I must say I enjoy driving the car much more between Oct. and May!  I drove her this morning on the 285 and had her up to 90 MPH (giving her the Italian tune-up).  I figured I better get my high speed driving in before Sonny Purdue raises the fines for excess of 85MPH!

Best Regards,

J. P. Mose
1968 250SL
1987 560SL

[Tom]

I notice this as well.  I think what happens in cooler weather is that the engine is performing at its best-cold intake air improves combustion.  The engine operates more efficiently, less vibration, smoother acceleration.  Just my 2cents.



1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
1970 280sl Beach Driver with a touch of rust

[Raymond]

You aren't imagining it. Cold air is more dense than hot air.  That's why racing set-ups have cold air intakes.  An engine is nothing more than a complex air pump.  The more air molecules you can pump through the engine the more power it can develop. The more dense air provides a better mixture for combustion and expands more when ignited.  

Pilots are familiar with Density Altitude.  That is where the performance of the airfoil is affected by the temperature.  Hot air is thinner, like higher altitude.  It can take an additional 20% of runway to get off the ground on a 100F degree day over a 50F day.

Ray
'68 280SL 4-spd Coupe

[Naj ✝︎]

quote:cooler weather is that the engine is performing at its best-cold intake air improves combustion.

 

quote:Cold air is more dense than hot air. That's why racing set-ups have cold air intakes.

So why did MB engineers have to 'spoil it' by adding a heat chamber to the throttle valve body (Early 230s excepted)?

naj

68 280SL

[Abbas]

Actually having densier air in the engine is the main principle behind Supercharging a car. Supercharging increases the power of an engine by compressing air entering into it - in other words increasing the amount of available oxygen for combustion.

All the Mercedes Kompressor car series do that - I think "Kompressor" is the word for 'supercharger' in German.

I also had a similar quieter car - but it was due to using higher octane fuel than the one I usually use - which improved gas combustion in my car and the engine's overall performance.

I guess higher octane burns well, on time and completely; thus the cylinders & valves make less sound - where as lower octane may burn pre-maturely and less complete.

Abbas

280SL W113 1969 Ivory
E280 W124 1995 Silver

[mulrik]

Just a little science. Your horsepower output raises by 1% (only) for each 14 degrees celsius the temperature drops. So if some of you notice a calmer idle at cooler temperature I'd say you are very sensitive people....;-)
BR,
Ulrik

'67 250 SL Papyrus White 113043-10-000023

[J. Huber]

Since lately, "it never rains in Northern California.." I have been driving my car a lot in the clear cooler weather.

I'd say it seems to idle a bit faster at start up. Hard to say if it is running better than other recent seasons -- its been doing wonderful though. Part of the intrigue of winter driving for me is the alter ego of the hard-top. I really enjoy the look and it seems like the car is heavier and balanced (which of course it is)... I hear much less exhaust -- but more rattles. In fact, today on the way to work, I had to pull over and squash a rattle coming from the kick panel... (a wad of duck tape works wonders). Also, some of the window noise (wind) is more annoying because it should be quiet instead of whistlin' dixie.

James
63 230SL

[enochbell]

James,

I wasn't even going to mention driving with the hard top.  In the past 7 years I have only done that twice, both times to get the hard top from one storage location to another.  I can't say I really enjoyed either ride, like you I HATE rattles and they seem to bounce around with the top on.  And I don't hear any drive train noise with the top off, maybe it is masked by the wind and exhaust note, or maybe the hard top gives the whine a place to reverberate.  Either way, it is topless for me (unless I need to move the top again ;-)

g

'64 230sl, fully sorted out...ooops, spoke too soon

[Cees Klumper]

To Mulrik's point, 14 degrees Celsius will equate to roughly double that in Fahrenheit - so 1% extra HP for every 30 F degrees drop in temperature. Now I was taught once that the human senses can detect a change in -anything sensory- when it exceeds approximately 10%, so that would mean it would have to get 300 degrees colder before we would notice increased HP).

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[J. Huber]

Hey Greg. I know what you mean about moving tops around. For lots of years, my hardtop just sat leaning up against the wall. Only time I put it on (grudgingly) was when I was moving to a new residence... In recent years though -- and in the last couple with the help of a hoist, I put it on for a couple months just to enjoy the contrast. I like the fact that it is a dark blue (on a white car) -- looks very "mod" and 60's-ish to me...

James
63 230SL

[Raymond]

The "Density Altitude" I refered to is also affected by barometric pressure and humidity.  Cool, dry, air on a high pressure day is more dense than a hot day with low pressure.  The fuel is cooler as well until the FI punp warms up fully.  (When I raced my Dodge, I had a fuel cooler feeding the carburetor.)  I believe the car is happier all around on a brisk day near 0 Celsius than it is near 30 C.

To Cees' point, human senses probably SEEM sharper in cold than hot.

Naj, as you saw, I removed my intake heater coil.  My guess is the Mercedes engineers were worried about intake icing.  Not usually a problem for us here in Florida.  


Ray
'68 280SL 4-spd Coupe

[Ed Cave]

I'm a firm believer that 'colder' fuel seems to make any of my cars, particularly the older ones, run stronger and smoother. I've believed that for years. Take one out on a really cold day, let the oil temp warm and let her rip. I absolutlely believe it.



Ed Cave
Atlanta, GA


1971 280SL
1973 911S
2006 GS430
2007 328i Coupe

[Mike Hughes]

quote:Originally posted by Ed Cave

I'm a firm believer that 'colder' fuel seems to make any of my cars, particularly the older ones, run stronger and smoother.

The Series III Jaguar XJ6 deals with this in a rather unique way:  Regardless of season or setting, if the automatic climate control is on the A/C compressor is cycling.  There is a manifold on the "cold" compressor line through which the fuel line from the tank to the injector loop runs.  This refrigerates the fuel and is really helpful in the summer as the underhood temps can get up there a bit (the XK 6 cylinder is a hot running engine anyway!) So the injectors are always supplied with nice cold fuel, except right at a hot start-up, or if the climate control is turned off.  The intake gets a cold air from forward of the radiator as well.

- Mike Hughes  -ô¿ô-
  1966 230SL Auto P/S
  Havanna Brown (408)
  Light Beige (181)
  Cream M-B Tex (121)