Miata Mailing List: June 1997, Message #157
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From: 	"Fletcher Blades" <fblades@fanshawe.newzealand.ncr.com>

Subject: Air intake temp measurements.

Date: 	Mon, 2 Jun 1997 17:46:16 -0500



Well, this past weekend, I borrowed the temperature probe with remote   

read-out from work again and took some temperature readings, with some   

interesting reslts...



All with an ambient temperature of a cool 14C (57F),



With the probe about four inches into the standard intake snorkel....



			at 60 kmh  (37 mph)	at 100 kmh (62 mph)



Lights down		40 C   	  (104 F)	30 C	  (86 F)



Lights up		30 C	  (86 F)		23 C	  (73 F)





As you can see, a definite improvement with the lights up.



Now for the interesting results, with the temperature probe above and   

slightly forward of the radiator, ie. where the JR CAI gets its air   

from...  (I have a '90 so there is no blanking plate to block this   

airflow)



			at 60 kmh  (37 mph)	at 100 kmh (62 mph)



Lights down		14.5 C	  (58 F)		16 C	  (61 F)



Lights up		15 C	  (59 F)		18 C	  (64 F)





Obviously, much lower temps all round, but ;



1) the temp is higher with the lights up, opposite of what you would   

expect.



2) the temperature rises with speed, where-as with the standard intake,   

temp falls with speed



I am guessing that #1 happens because of swirling under the hood,   

changing the air flow, possibly slow ing it, or blowing hot underhood air   

forwards.  This of course woudn't affect the CAI, as the ducting would   

separate the airflow in from the underhood air, and so they wouldn't   

affect eachother.



But #2 is counter-intuitive  (well at least to me).  Anyone got any   

ideas?  is it just the same effect as #1? or is something else going on?



Just thought you'd like to know...



Fletch.