datsun-roadsters
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Re: Cooling

To: "datsunmike" <datsunmike@nyc.rr.com>,
Subject: Re: Cooling
From: Ronnie Day <ronday@home.com>
Date: Wed, 25 Apr 2001 11:39:45 -0500
>However now that I stroked/bored the engine do you think the cooling system
>will be taxed even more? I had it recored with a core that has many more
>fins per inch than my old radiator but both are the same number of rows.
>
>I also have a stock 7 plastic bladed fan that I can use or I can buy a
>Flex-a-lite fan.

An increase in engine size is going to increase the load on the cooling 
system in any case. The key to making a fan work is a good shroud so that 
the fan pulls air through the entire surface of the radiator, not just 
the area directly in front of the fan itself. The fan need to be centered 
on the shroud opening and allow just enough clearance so the fan doesn't 
hit the shroud when the engine torques over. With electric fans you don't 
have to deal with engine movement, but you still need a good shroud for 
maximum cooling efficiency. I don't remember if the roadsters have a 
shroud, but they probably should. It would take some work, but I'd think 
fabricating a workable home built version shouldn't be too difficult, and 
would yield measurable benefits.

If the OEM radiator still falls short, a popular radiator swap for the 
510, as well as being used in a lot of other modified cars, is the 
Scirocco (VW) unit. It's so popular that there are a number of versions 
available up to a very heavy duty all aluminum unit from Griffin. To 
compliment the design, you can get a dual electric fan/shroud combo that 
completely covers the back (engine) side of the radiator. This is the 
setup I plan to run in the 510s from now on, provided there's enough room 
between the Scirocco radiator and the water pump pulley for the fan 
assembly. Some that have used this radiator use one or two smaller fans 
offset to avoid the pulley. Most of the time this radiator has enough 
cooling capacity to work well without a shroud. In case anyone wants more 
info, Jegs and Summitt both sell an aluminum/ABS version for $110, the 
fan setup is around $180. The Griffin unit is $200 plus, but should 
handle just about any motor at any power level.

In any case the fan is really only needed when a car's not moving at all 
or in slow or stop and go traffic.

FWIW, Ron

Ronnie Day
ronday@home.com
Dallas/Ft. Worth
'71 510 2-dr (Prepared Class Autocrosser)
'73 510 2-dr (Street Toy)

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