edited- sorry mate had this reply open for some time. as you can see bleow the posrsche rad is much smaller but still big enough.
Found a radiator size formula.
http://www.super7thheaven.co.uk/blog/what-size-car-radiator-for-my-car-a120.html
Gotta convert mm cubed to inches cubed and cc also but came up with this
Porsche centre radiator is 4562800 mm sq based on core dimensions. 610x170x44mm. Subaru 1781 EA81 engine is 108 sq ".
Formula stipulates the following-
Start with 2 cubic inches of core for every cubic inch of engine. Increase or decrease that value by the following factors:
ADD
0.1 for a vertical flow radiator core
0.1 for an in-line engine
0.1 for a small trailer towing
0.1 for a 2 row radiator
0.1 for double evaporators
0.2 for outside temperatures of 105°F (40.5°C)
0.2 for a medium trailer towing
0.2 for a small engine fitted to a heavy car
0.2 for a radiator fan with diameter less than 90% of smallest dimension
0.3 for air conditioning
0.3 for no fan shroud
0.3 for an antique car with small engine compartment
0.4 for large trailer towing
0.6 for a diesel engine
SUBTRACT
0.1 for remote transmission cooler (not within radiator)
0.1 for standard in-line transmission
0.1 for a single row radiator
0.1 for a V6 / V8 engine
0.2 for a spacious pickup truck engine compartment
0.2 for outside temperatures less than 90°F (32.2°C)
0.2 for a full fan shroud
02 for a horizontal flow radiator core
0.3 for a large engine in a small car
In my trikes case-
Add- - 0.1 for small trailer towing, 0.2 for outside temp over 40 deg, 0.3 for no fan shroud, = 3.19
Subtract - 0.1 for single row radiator, 0.2 outside temp less than 32 degrees, 0.2 for horizontal flow radiator, = 0.5 = 2.69
2.0+0.6-0.5= 2.1
2.1x108= 226.8 area of radiator is 278 sq". Conclusion- radiator is 19% larger than required.
As a safeguard I can also add a small motorcycle radiator off the heater hoses if required.
Now for a Kombi. Lets say its for a 2 litre EJ engine. 2.0 litres = 122 sq"
We know the cubic inches of the Porsche radiator is 278sq ".
Lets say the outside temp stuff cancels itself out. Add - 0.2 for small engine in large car, 0.3 for no fan shroud, 0.4 for large trailer towing (this for it being a transporter load carrying vehicle etc) = 0.9 total added. Subtract- 0.1 for single row radiator, 0.2 for horizontal flow radiator... = 0.3
2.0 + 0.6 = 2.6.
2.6x 122 = 317. With the radiator being 278 sq" it is too small by 13%
What about a kombi with an eA81?
the 2.6 factor remains the same.
2.6x108 = 280. Radiator is 278. likely is ok for this engine.
www.youtube.com/watch?v=HXwh4z8d66o
SUBARU ea81, VW auto, Detour camper
My ex girlfriend said "its me or a trike". Her big mistake.
