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#2
06-21-2013, 12:45 PM
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Quote:
As far as cooling differences, I suspect that the limiting factors are not the compressor but rather capacity of the evaporator and condenser which are primary components that remove heat from the cabin and transfer it to the external air. Having excess capacity in the compressor would likely do nothing to increase cooling unless the condenser (and likely the evaporator) were replaced with larger units. Obviously other factors like debris blocking the condenser and evaporator, clogged expansion valve, leaking monovalve, bad aux fan, bad pods and so forth will affect cooling capacity and effectiveness. Another major factor that has been debated to death is the refrigerant. I won't get into that here other than to say that 134a is inferior to R12 or the other "alternative" refrigerants that are being used. Maybe someone else knows the actual relative displacements of the R4 vs the 5 cylinder Sandens that would indicate whether the compressor is under-sized for the application. My hunch is that the 7 cylinder units are designed for dual zone A/C as might be used in large vans that have larger condensers and evaporators. ...not speaking as an expert, just someone that has taken an interest in A/C systems and has done extensive informal research and installed a Sanden in his 617 powered 107.
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#3
06-21-2013, 04:26 PM
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Here's a bit more information.
The R-4 compressor's displacement is 10 cu-in. I couldn't find a chart, but it's power consumption is 9.4 hp at 2000rpm. The SD5H14 compressor displaces 8.4 cu in while the SD7H15 displaces 9.5 cu in. As you can see in the below chart, at the same 2000 rpm, the Sandens are consuming 3.75 and 4.0 hp respectively (1 kw = 1.34 hp) The Sanden's are quite efficient as shown by the C.O.P which is the coefficient of performance ( calculated as power in/power out )
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#4
06-21-2013, 08:33 PM
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Thats a great response! Thanks very much. I ran across those performance charts today. The (big) reason I asked is that I had a new R4 on the car for two days before it crapped out, and the drivability was terrible. If-thats-what- AC-is-like-I-won't-bother-with-it kind of terrible. Maybe there was something wrong with this compressor, as I had to use a wrench to turn it over. Fortunately, I was able to return it, so that money will now go into a Klima kit. They give you an option between the 5 and 7 cylinder, so I figured I'd ask what the difference is.
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#5
06-21-2013, 08:40 PM
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Klima is one option but be sure to check out Rollguy's bracket. That's the one I used on my conversion.
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#6
06-22-2013, 01:37 AM
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Look at mine and other's posts about the available rear heads. One guy installed one that let him use the factory hoses. I have a head that I think will work (with Rollguy's kit), but still waiting for my son to return that car. Of course the heads are different for SD5 and SD7 compressors (5 vs 6 bolts). I suggest a Sanden "shortie", i.e. the "13". That will give you ~1.5" less depth so easier to fit the hoses without bumping into the motor mount. I will be visiting my son next week, but am not going to try swapping compressors in a motel parking lot, though I will replace glow plugs and such. If worried about cooling capacity, don't use R-134A. I will use Duracool. A parallel flow condenser would help too.
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