M104 - SL320 vs 300-24 SL whats the difference ?
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Its a very different engine.. The 24 valve is actually a M104 although its basically a M103 with a head that has been re designed to allow for 12 more valves..
The 320 M104 is a quieter engine, some would say more refined.
Id say they are both very good but they both need the 5 speed auto to get the best out of them.
The 320 M104 is a quieter engine, some would say more refined.
Id say they are both very good but they both need the 5 speed auto to get the best out of them.
grober
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They also have different fuel injection and ignition systems. The 300-24 has a discrete distributor type HT ignition system and Mechanical type fuel injection [ + a little electronic mixture control] and the 320 an integrated engine management system controlling both injection and ignition.
ray_hennig
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The 320 is the smoother and more economical of the two, more suited to daily driving. It makes less horsepower but more tourqe than the 300, it has electronic engine managment, which helps make it's power at fairly low rpms. It has 3 ignition coils in the head to deliver the spark, insted of a distributor like the early engine.
The 300 is noisier that the later engine due to it having an extra idler gear on the timing chain, the engine makes it's power high in the rev range which is why mercedes allow it to rev higher than the later engine. It has a conventional distributor, has a more agressive camshaft profile, stronger valve springs, plus many were not fitted with a catalic converter or an air injection pump. It makes more horsepower that the later engine, but less tourqe due to it using mechanical fuel injection. This engine is more suited to people who like to "drive" the car as opposed to the later engine which is more for wafting along.
There is also a little known crossbreed between these the two engines, which looks like the early 300, but isnt. This engine is fitted with electronic fuel injection, but retains the distributor to control the ignition, and is a 3.2 litre. Only found in this country in the w140 300sel.
The 300 is noisier that the later engine due to it having an extra idler gear on the timing chain, the engine makes it's power high in the rev range which is why mercedes allow it to rev higher than the later engine. It has a conventional distributor, has a more agressive camshaft profile, stronger valve springs, plus many were not fitted with a catalic converter or an air injection pump. It makes more horsepower that the later engine, but less tourqe due to it using mechanical fuel injection. This engine is more suited to people who like to "drive" the car as opposed to the later engine which is more for wafting along.
There is also a little known crossbreed between these the two engines, which looks like the early 300, but isnt. This engine is fitted with electronic fuel injection, but retains the distributor to control the ignition, and is a 3.2 litre. Only found in this country in the w140 300sel.
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Never driven either myself but I thought the bhp figure from both was the same, with the 320 having a bit more torque 
Ian B Walker
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320 engine = 215 bhp
non cat 300-24 = 231 bhp
cat 300-24 = 220ish
non cat 300-24 = 231 bhp
cat 300-24 = 220ish
Apial
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The 300-24 has a reliable wiring system that came with long life insulation. The 320 had a wiring system.
My 1997 model year R129 UK price list says 231 bhp for the SL320
(193 bhp for the 280).
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My 1997 model year R129 UK price list says 231 bhp for the SL320
(193 bhp for the 280).
The 320 engine in the sl and s class, had a better exhaust system, and better mapping of the ecu. They give 228hp and 232 torque, as opposed to the w124 which had 217hp and 232 torque.
231ps =228bhp?
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BillyW124
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Good thread
My UK price list definitely says 231 hp for the I6 SL320. I don't think they are all ps figures by mistake ... this is what it says:
280 - 193 hp
320 - 231 hp
600 - 320 hp
600 - 394 hp
SL60 - 381 hp
But anyway to come back to the original question ... did the M104.991 in the 300SL-24 really give more power than the 320? From a quick Google most sites quote 234 PS / 231 hp
280 - 193 hp
320 - 231 hp
600 - 320 hp
600 - 394 hp
SL60 - 381 hp
But anyway to come back to the original question ... did the M104.991 in the 300SL-24 really give more power than the 320? From a quick Google most sites quote 234 PS / 231 hp
Perhaps the most significant difference is that the 320 , along with its 280 sibling , suffers from the well known biodegradable engine wiring loom problem , whereas the 300 with distributor does not .
In my 300TE-24 the original engine lasted to 380,000 miles and the car was on its second engine at 430,000 miles when written off by an uninsured driver .
Strangely , I thought that the 24 valve engine with its extra camshaft was actually smoother and quieter than the two M103 engined cars I have had .
300SL-24 = M104.980 3.0L using Bosch KE-Jetronic injection and producing about 231hp but at very high RPM and torque is about 270 Nm.
SL320 = M104.992/M104.995 the latter is upto 1996 version. 3.2L using Bosch HFM-Motronic injection like SL280/E280/S280 and producing about 217-220hp and more stronger torqe about 315-320 Nm.
SL320 = M104.992/M104.995 the latter is upto 1996 version. 3.2L using Bosch HFM-Motronic injection like SL280/E280/S280 and producing about 217-220hp and more stronger torqe about 315-320 Nm.
bolide
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The other difference is that the 300-24 suffers from failed ignition modules, and the 320 and 280 do not
In the real world I think the 320 is a better engine than the 300-24 and that, in some ways, the 280 is better than both
Nick Froome
ray_hennig
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In the sl, the 320 is the better car. In the w124, the 300 is the better car. IMHO
Why is that? I would have guessed that the more rorty sporty 300-24 would be more appropriate for the SL.
R
