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Angle Valve Cyl#1 Intake Pipe

DanH

Legacy Member
Mentor
Plenty of past debate about cold air intakes, but not much actual data.

I'd like to measure the intake air temperature just prior to arrival at the cylinder head. Doing so would require drilling a hole in the intake pipe, and possibly welding a bung or fitting. My 390 has a nice set of chromed pipes; I don't want to drill or weld on them.

So, anyone have a rusty old intake pipe gathering dust? Looking for cyl #1, angle valve with the tuned plenum sump, Lycoming # 78741, same as most IO360 angle valve models.

No1%20Intake%20Pipe.jpg


Temperature is also required for understanding intake pipe wave activity with this sump.

Example.jpg
 
Dan, why not use the primer port in the head? That's pretty close to the gasket interface where the intake tube mounts, and with the engine running should be plenty of gas flow to get reasonably close to the same temp as in the pipe.

You could use a Swagelok compression fitting in the port with a thermocouple inserted to whatever depth you want. You can find cheap TC readers on ebay.

Also, you could tap a hole (1/8 NPT) into the back of the plenum/sump and put a probe there. That's what I did years ago to tap off the manifold pressure for my panel gauge and electronic ignition. Could even do that while installed. Just remove the rear intake pipes so that you can clean out the chips from drilling/threading.

Heinrich
 
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Dan,

If you can slip an extra gasket in place you might be able to position a thermocouple across the diameter and centered in the airflow. The extra gasket would electrically insulate and provide a seal around the thermoouple wires. We have used this technique to measure temperatures of in fluid flows where we did not want to make permanent modifications to a system in the past.

- larosta
 
Dan, why not use the primer port in the head?

Good idea, but already have a pressure tap screwed into the primer port.

If you can slip an extra gasket in place you might be able to position a thermocouple across the diameter and centered in the airflow. The extra gasket would electrically insulate and provide a seal around the thermoouple wires.

Hey, there's a trick worth remembering!
 
I've always wondered if cold air intakes worked. It seems that the time the air spends in the hot part of the sump wouldn't be long enough for it to absorb much heat.
 
I've always wondered if cold air intakes worked. It seems that the time the air spends in the hot part of the sump wouldn't be long enough for it to absorb much heat.

Depends greatly on whether you are talking to someone from Engineering, or someone from Marketing.
 
Looking forward to seeing the numbers Dan measures! From what I have seen previously, the cold air sump is usually worth about 8hp. The angle-valve cylinders account for another 8hp on the 200HP variants (they usually make around 196Hp actual)

Also consider the IO-360M1B. It has a very similar "cold air/tuned length induction" sump as the 200HP engines. They usually produce closer to 188hp, as opposed to the normal vertical induction engines which are pretty spot on with 180hp actual.

I would wager a guess that the tuned length accounts for far more of the power gain, then the actual temperature difference between sumps!
 
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