<VV> Engine Bay Air temperature experiment

RoboMan91324 at aol.com RoboMan91324 at aol.com
Fri May 22 22:02:04 EDT 2015

Thanks for performing the experiment and for sharing.  I  have a few 
questions and comments.  Please don't think of this as "looking  a gift horse in 
the mouth."
Is it possible for you to perform the same experiment once the  seal is 
installed?  Hot air and exhaust exits the engine from beneath and  the fan will 
suck that hot air/exhaust into the engine compartment along with  outside 
air from above.
It doesn't appear so but I don't want to "read between the  lines" of your 
description.  Did you by any chance read temperatures or  have someone read 
temperatures, remotely while driving?  If not, can you do  so with your 
equipment?  If you had to stop, get out and access your  engine compartment to 
read the temperatures, you may have irrelevant  data.  If you stop for a 
while with the engine off, heat from a hot engine  will rise up into the engine 
compartment and heat the air significantly.   Starting the engine will suck 
the hot air through the fan and out the bottom but  I am not sure how 
quickly that will happen.  Just opening the engine  compartment lid will change 
readings quickly.
Real temperatures taken while driving under a number of  scenarios would be 
best.  The engine generates more heat while loaded  and at higher RPMs but 
the fan also sucks more air (CFM) into and through  the engine compartment 
at higher RPMs as well.  Even with a hotter engine,  I suspect the air in the 
engine compartment will be relatively cool while  driving at speed.
Your unshielded turbo and exhaust tubes in the engine  compartment will 
skew your data too.
Again, thanks.
In a message dated 5/22/2015 4:20:22 P.M. Pacific Daylight  Time, 
virtualvairs-request at corvair.org writes:

Message:  7
Date: Fri, 22 May 2015 16:20:08 -0700
From: kevin nash  <wrokit at hotmail.com>
To: "virtualvairs at corvair.org"  <virtualvairs at corvair.org>
Subject: <VV> Engine Bay Air  temperature experiment
Message-ID:  <BAY177-W46596E336F548C48BE4215D3C00 at phx.gbl>
Content-Type:  text/plain; charset="iso-8859-1"

I've been fine tuning my EFI set-up  recently and was curious as to how hot 
the engine compartment air was getting  while the engine was running during 
normal cruising. The engine compartment  air temperature was a particular 
concern to me as I don't have a heat shield  on the turbo (yet) and, until 
very recently hadn't bothered to put on the rear  engine compartment seal 
either. Anyways, I thought I remembered someone on  this board had asked about 
engine compartment air temps  sometime ago and  I just got done doing the 
test, I thought I would share my results. Since I  was concerned about the air 
temp just before it enters the air cleaner, I put  a digital thermometer 
probe on top of the throttle body's, not touching any  metal, approximately 1" 
away from the air cleaner. 

Morning before  starting engine and driving to work: T= 53F, 10 miles 
later, T=67F, head  temperature was well below 300. Afternoon before starting 
engine and driving  home: T=83F. stopped at gas station to get gas after 2 or 3 
minutes of  running- right after re-starting the car, T=97F. Continue on 
home, head  temperature gets to 300 degrees, and the digital thermometer 
reads....  82F.  I've done this same test 2 days in a row now, and have gotten 
the  same results each day, and I also verified that the digital thermometer 
agrees  well (within 1 degree) at 52F and 70F with our outdoor  thermometer.
For curiosity's sake only!!
Kevin Nash
63 Turbo,  EFI daily driver

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