inlet for the left evaporator core.  The right evaporator core was left
unmodified to  provide a safety net sufficient to do the pattern and land

take off temps exceeded expectations.  Fortunately, that was not

OAT on first take off was a humid 85 degrees.  No temperature increased
noted during ground run up, so launched and made max rate of climb, not
seeing any abnormal temp increase I left the pattern and continue Max rate
climb to 4500 MSL.  Max temp of coolant during climb was 210F (normal for
max rate climb at these OAT temps is 205F), Max oil temp was 200F nominal
for max power climb. Max temps were reached about 2/3 of the way through

climb.

In level flight, my coolant temperatures normally run 5 degrees colder

my oil temp.  Today my coolant and oil temps were the same.  So average
coolant temp was increased by 5 Degrees F.  Total radiator inlet duct area
was decreased from 48 square inches to 33 square inches.  24 Square inches
for the right inlet duct and 9 square inch inlet for the modified right
duct (See attached photo for comparision). Probably some drag benefit, but

aspect.

I flew to an airfield 50 miles away to have my transponder recertified and
when I launched out of it, the OAT (ground level) was 92F

After level off I ran at different power settings to see the effect.

 5800 rpm burning 11.9  GPH at 4500  MSL with OAT at 78F My oil and

were both 190F.

5400 rpm burning 9.6 GPH at 4500 MSL with OAT 80F My Oil and coolant were
both 185F

5200 (Around my normal cruise rpm)  burning 7.25 GPH at 4500 MSL with OAT

oil and coolant were both  180F

In summary, the 33 % reduction in total  radiator inlet area appeared to
have increased coolant temps by an average of 5 Deg above the normal (the
old duct).  It could be that both the remaining radiator and perhaps the

cooler are rejecting any additonal load with no problem.

It appears that smoothing out the path for the air from inlet to radiator
surface has benefited the cooling situation.  It could be that additional
heat may be rejected by the right (second in series) radiator as the

it received from the left radiator was probably now a bit hotter. I also
observed that the plate of the PSRU covers an area 3 " in from top to

of the rear of each radiator and the plate is only 2" from the rear of the
fins at its closest, so that is obviously not helping flow, the Ross Bell
housing did not, so a bell housing might improve flow conditions .

 I strongly suspect I would probably  find that a similar  reduction of

right radiator inlet duct to 9 square inches  would see my coolant (and
probably oil) temps increase considerable more than another 5 F.

type I normally prefer to fly in.

>From what I have seen so far, I think it worth pursuing a reduction with

right radiator duct.  I will probably not reduce it as much for the reason
mentioned above. With some other things to take care of, probably won't

to it until later part of Sept at the earliest.  But, I have no problem
flying with current asymmetrical ducts, so will leave it as is for the

being and collect some more data.

It it appears that some cooling benefit is derived from providing a

transition from duct to radiator (even if far from a perfect

of the K&M approach) than my old duct provided.  The volume of the duct

Oh, yes, as an aside, its been 25 hours since I replaced the spark plugs

right on schedule - on the way back, I got the first SAG (Sparkplug
Attention Getter)  indication.  So it appears 25 hours on 100LL about the
average time for replacing plugs in my case.  I finally got a spark plug
cleaner, so need to clean a set (as the electrods do not appear worn) and
see if getting the lead off the ceramic  cone helps any.

Best Regards

Ed Anderson