Engine fan air volume for a 280SL

[George Davis]

Tom,

On your hot days, with air at 104 degrees F, the absolutely lowest theoretical temperature you can get coming out of the radiator is 104 F, if said radiator is infinitely large or infinitely efficient.  Practically speaking, you can't actually get to 104, but the closer you get to 104 the more efficient your radiator is.  Since you're going to use an IR gun, one place to check is the radiator outlet temp.  If it's close to the air temp, it's a very effective radiator, and you probably need to increase the rate of coolant flow rather than increase the size of the radiator or the airflow through it.  If the outlet temp is fairly far from the air temp, this might tell you that you do indeed need a better radiator and/or more air flow.

It's usually airflow that is the issue with radiators, because that particular type of heat exchanger is more limited on the air side than the water side.  It's easy to transfer heat from water to metal, it's hard to transfer heat from metal to air.  I think you're on the right track with the electric fans, but checking rad outlet temp may help confirm or deny that.


George Davis
'69 280 SL Euro manual

[TR]

Mike -- Oh, man ... I gotta have it / try it!  Know where I can get one?  Is there anything else, related aspects, which one needs to be aware of with the addition of such an oil pan?

Thanks Mike.

Tom in Boise
'71 280SL 4-spd, signal red w/lt. tan interior, restored/enhanced

[norton]

Tom I think that it's the pan you would get now, if you ordered a new pan, but we should get Joe in on this. Have you tried a smaller water pump pulley to speed up the water pump. And what about a non MB impeller for the pump, there may be one out there that flows better.

Mike Halleck
Chesterfield Mi
71 280SL
68 250SL (parts car)
94 E320 Coupe

[TR]

George -- Ah, all those physics classes are coming back to us now, are they not?  Good thoughts those.  I hope we have enough hot weather left to continue chasing this down...

I'm really excited about all the additional inputs. Positive and good mojo.

I'm especially anxious to learn more about this newer replacement oil pan Mike has described, and as shown by Joe at the Tech Session.  Obviously I can't be certain, but it sounds like that is perhaps a simple bolt-on improvement, of the type that might deliver improved results here & now.

Tom in Boise
'71 280SL 4-spd, signal red w/lt. tan interior, restored/enhanced

[A Dalton]

This help ??


 http://www.sl113.org/forums/uploaded/cees%20klumper/2005621181316_airco1.jpg

[TR]

Dalton -- Now that's one potential solution which I think would be way, way down the list in terms of our back-up/contingency planning.



Tom in Boise
'71 280SL 4-spd, signal red w/lt. tan interior, restored/enhanced

[norton]

Tom here's a link to info about a mod to the clutch fan
http://pages.prodigy.net/jforgione/MB_vfc.html

Mike Halleck
Chesterfield Mi
71 280SL
68 250SL (parts car)
94 E320 Coupe

[TR]

Thanks Mike.  No word back yet from my guys on what the max CFM delivery would be from a 280SL's std. fan with the viscous clutch.  Over the years we've tried new VFCs, a new fan, a new shroud, 2 or 3, multiple new water pumps, new thermostats (of course), new radiators, by-passing the heater core, replacing the heater core, checking the accuracy of the temp. gauage against and IR gun ... the list could go on & on.  Hell, we even put in a new engine from Metric, whom I'm certain delivers an excellent product.  But none of that standard stuff seemed to do the trick. (at least not to my freely-admitted very high goals on those hottest of days).  

It's interesting where this fellow says the VFC doesn't engage until the temp hits the red (and in his words, "much too late").

That "replacement oil pan" you mentioned earlier; was it your understanding that it's something which is readily available, or is it a specialty item?  I'd sure like to investigate the possibility of that further.

Tom in Boise
'71 280SL 4-spd, signal red w/lt. tan interior, restored/enhanced