Re: Mods, Upgrades, Thoughts

["sidney raper" <spl310@hotmail.com>]

I too have to disagree with John.  If you look at old race cars from the 
60's (ie. the first racing cobra) louvers on the hood were a standard way to 
increase cooling.  Usually the air coming in through the radiator is limited 
by the exit path - under the car .  The big problem as I recall was that if 
you increased the grill opening, you just increased the up force on the car 
making it less stable.  That is one reason why the Cobra Daytona had the 
radiator exhaust through the hood.  That alone actually decreased engine 
compartment temperatures.  The side louvers could be done to help, but you 
would have to eliminate the inner fenders (not a real good idea on a street 
car) or make ducts for the air (lots of work for little gain).  To improve 
the cooling, the best thing that you can do is to duct the grill opening to 
the exact size of the radiator - that increases the flow and reduces the 
turbulance.  Remove the backing off of your grill for a little more help in 
cooling.  Little gains, but it helps.

Daniel is right on in his note (in my opinion - based on my observations and 
readings on racers of the period.)



>From: Daniel Neuman <dneuman@quark.sfsu.edu>
>Reply-To: Daniel Neuman <dneuman@quark.sfsu.edu>
>To: sandhoff@csus.edu
>CC: datsun-roadsters@autox.team.net
>Subject: Re: Mods, Upgrades, Thoughts
>Date: Wed, 10 Apr 2002 10:48:12 -0700 (PDT)
>
>John wrote,
> > Just IMHO, but chopping holes in the hood can lead to spot overheating!
> >
> > The hood helps direct air flow around the engine and down the back. If
> > that airflow is interrupted, you may not get the expected flow around 
>the
> > sides and back of the engine.
> >
> > -- John
> >      John F Sandhoff   sandhoff@csus.edu   Sacramento, CA
>       I don't believe that there is a significant amount of cooling done
>by the air that flows around the engine.  If the rad is sealed to the sides
>of the car at the front high pressure area you will force most of the air 
>thru
>the rad.  This hot air then flows over the engine and out thru the bottom 
>of
>the engine bay.  If you put louvers in the low pressure-high velocity zone
>on the hood this will help to suck the hot air out of the engine 
>compartment
>and also to pull more air thru the rad.  So I think louvers can be a good 
>thing
>whether or not they look good is another thing.
>       just my .02 cents
>               Daniel 69 2000
>               Oakland CA
>
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