inlet size to outlet size cowling?

[Smilin' Jack]

I have just completed my 4 hour of my Phase one. I have a question regarding the above Title. inlet vs outlet.

I am using the horizontal induction system, I have only the 2 inlets on the engine cowling.
I also have a 4 pipe exhaust system and my drain tubes from the air/oil separater and a couple other drain tubes take up about 1 1/2 inch between the 4 pipes. that leaves about 5 to 6 square inches of space around the exit point of the cowling.

During taxi I notice the cylinder temperatures getting up to the 300 degree mark before the oil is getting up to the 120 and approaching 350 before the oil temp has reached the green arc.

Should I consider installing a louver on the bottom of the cowling to allow the low pressure air a more rapid to escape. During my takeoff, the temps are right up near 390 degrees and I have to really shallow up the climb to keep the temps below 390 even at a 130mph climb.

I would appreciate your thoughts on this. If I need to add a louver can you recommend a supplier for that.

Thanks for the input.

Smilin' Jack.

PS. I climbed up to 7500 feet yesterday over the airport and was indicating 176mph with a true of 196. Would you consider this average for an RV7 with
a 180hp engine and constant speed prop.

Thanks again.

[ColoRv]

Why does the 350 during taxi bother you? It's in the green right?

As a point of reference, I rented a 2005 C-172 G1000 this weekend and took it on a long cross country. Leaned according to the book it sat right at 390 from Denver to Nashville and back. I remember thinking that VAF's resident experts would have a meltdown over such numbers. It seems to me that 390 in climb during break in is far from concerning numbers. As I approach first flight, I asked my engine guru last night what numbers I should expect to see on breakin. He said over 435 would be grounds for concern and require action which is, I believe, exactly what lycoming says.

Remember to question the validity of advice from strangers far more than that from the manufacturer unless you have very good reason. If someone in here told me to make VnE on my airframe 150 knots because it's safer...they would be right in that it is safer...but does that mean Van's VnE is unsafe? I'm just saying, 400 isn't a drop dead number.

[Joe]

Originally Posted by Smilin' Jack

I have just completed my 4 hour of my Phase one. ...

During taxi I notice the cylinder temperatures getting up to the 300 degree mark before the oil is getting up to the 120 and approaching 350 before the oil temp has reached the green arc.

Should I consider installing a louver on the bottom of the cowling ...

PS. I climbed up to 7500 feet yesterday over the airport and was indicating 176mph with a true of 196. Would you consider this average for an RV7 with
a 180hp engine and constant speed prop.

You're still in the break-in phase (assuming a new engine/cylinders). Within about another 10 hours the CHTs should drop dramatically. You will notice it like switching off a light.

Meanwhile, minimize ground operations as much as possible to avoid glazing the cylinders and continue to "shallow out the climb" like you have been doing. 130 KIAS is a good climb speed with a new engine.

Not sure what you're using for a minimum oil temperature for takeoff but I use 75F and don't feel the need to run on the ground just to increase it.

Don't install a louver. Why increase cooling drag on a proven cooling design?

Your 170 KTAS at 7500' is right in line with Vans' performance figures. Carry on!

--
Joe

[DanH]

Jack, as noted previously your temperatures are normal for a parallel valve motor, particularly when still in break-in. I'd even venture to say your baffling is quite good. Be happy.

A true airspeed of 196 knots is fast for a 180hp RV7. Although pleasant to accept as correct, it's probably time to do some three leg airspeed calibration runs using the NTPS method.

[BillL]

Originally Posted by DanH

Jack, as noted previously your temperatures are normal for a parallel valve motor, particularly when still in break-in. I'd even venture to say your baffling is quite good. Be happy.

A true airspeed of 196 knots is fast for a 180hp RV7. Although pleasant to accept as correct, it's probably time to do some three leg airspeed calibration runs using the NTPS method.

Dan, I am assuming he is saying MPH not Knots, wouldn't that be more in the ball park for 7500 ft?

[Smilin' Jack]

Bill your correct every thing is in mph. I just changed my oil again and everything looks good.
Dan, Bill, Joe and Colo RV, thanks for the input

Jack