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To: flyrotary@lancaironline.net
Date: Sun, 5 Feb 2006 07:14:36 -0800
Subject: Re: [FlyRotary] Re: NPG Coolant Temperature vs 50/50
Message-ID: <20060205.071505.324.0.alwick@juno.com>
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From: al p wick <alwick@juno.com>

<Cavitation theory:
Don't forget, I operate same engine as EGG, totally stock. With none of
the cooling issues. I think that eliminates cavitation as explanation.

Here's what I think it's all about....

Problem: You'd like better cooling, but are unsure about what's causing
marginal cooling. 
Test: Compare to my performance to prove that it's air flow thru
radiator.
Method:
a) Measure your radiator fin area in Cubic Inches. If more than 408 C.I.
proceed.
b) Operate engine, place hand all over radiator to verify no trapped air
pockets. 
c) Determine 7.4 gph throttle setting. This makes your power output same
as mine. 
d) Warm up engine (heat soak it, don't just get it warm). 
e) perform climb test with throttle at 7.4 gph setting. Take off at sea
level, climb to 12k ft.

If coolant temp raises during the climb, you clearly have air flow
problem thru radiator. Test different air flow concepts.

Notes: 
-My testing found trapped air in cooling system is 10 times more
significant than any other factor. Install dynamic air bleed to make sure
you are free of air.
-I have no oil cooler, so if your temp rises during climb, you have very
significant air flow problem.
-I have no rad air exit ducting. I found it aggravated my cooling. Even
though all the articles you read say the opposite. So don't make
assumptions.

I suspect this test can really help. 


-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html


On Sat, 04 Feb 2006 21:05:11 -0500 Chad Robinson <crj@lucubration.com>
writes:
> Ed Anderson wrote:
> > Delta T = Q/cM, now if the combined effects of c and m  provide 
> 13% less 
> > heat transfer capability than the 50/50 mixture that would 
> indicated 
> > that to carry away the same Q at the same flow rate, the delta T 
> of NPG+ 
> > would need to increase by 13%.  So if I were getting 180F with the 
> 50/50 
> > for the same Q load (and flow rate) then with NPG+,  I would 
> expect 180 
> > *1.13 = 203F.  Yet, if I understood correct we have reports  that 
> lesser 
> > temperatures results noted by users of NPG - this leaves me a bit 
> puzzled.
> 
> I don't have the answer, but how about a hypothesis? Suppose they 
> have a 
> cavitation problem. A more viscous fluid tends to reduce the onset 
> of 
> cavitation, no? And is there any data on what pressure their system 
> is being 
> run at?
> 
> Regards,
> Chad
>