HELP, i need info about my cessna 170A

[LVFJY]

Im was installing a DYNON 10 EMS in my cessna 170A - O-300 2 continental and i need a little help with info for ex

1) what is the normal CHT temp in cruise speed, and what is the MAX admisible CHT TEMP in take off
what is the normal EGT temp in cruise speed, and what is the MAX admisible EGT TEMP in take off

2) what is the MAX OIL presure admisible ( 60 PSI ???) , what is the NORMAL presure in CRUISE ( 35 A 45 PSI? )... all in psi pls

3) NORMAL OIL TEMP IN CRUISE???? ( 175 F?)

4) CRUISE RPM 2200/2400 RPM ? MAX RPM 2700?


well thks so much, by the way... my normal air speed is 105 mph without wheel pants at 2300 rpm... tell me about u performance in cruise speed

[Bruce Fenstermacher]

Hello,

I'll address these one by one and give the book reading when available. Some of your questions however there is no book answer as each plane is different for many reasons.

Im was installing a DYNON 10 EMS in my cessna 170A - O-300 2 continental and i need a little help with info for ex

First it could have been a typo or translation. There is a C-145-2 or 2H or a 0-300-A (B,C,D,E) but no 0-300 2. Doesn't matter really for your questions because all the answers are the same no matter what C-145 or 0-300 you have.


1) what is the normal CHT temp in cruise speed, and what is the MAX admisible CHT TEMP in take off
what is the normal EGT temp in cruise speed, and what is the MAX admisible EGT TEMP in take off
Max allowable CHT any time is 525°F. There is no book value given for EGT. (From the C-145-0-300 operators manual X-30015)

2) what is the MAX OIL presure admisible ( 60 PSI ???) , what is the NORMAL presure in CRUISE ( 35 A 45 PSI? )... all in psi pls
C-145- 30-45 psi, 0-300- 30-60 psi. This is normal range cruise. (From the C-145-0-300 operators manual X-30015)

3) NORMAL OIL TEMP IN CRUISE???? ( 175 F?)
Minimum oil temp for takeoff- 75°F. Max oil temp 225°F **. There is no book value for cruise and you will find no two aircraft the same because of the difference in baffling. (From the C-145-0-300 operators manual) ** The Max oil temp can be 240°F if you are using a straight 50 weight oil. (This is from another Continental source I can't think of at the moment)

4) CRUISE RPM 2200/2400 RPM ? MAX RPM 2700?
Max RPM 2700
Recommended cruise RPM is 2450. (From the C-145-0-300 operators manual X-30015)

Your cruise at 2300 of 105mph is typical. Way to many variables to consider when comparing one 170 to another to say if yours is good or bad.

[GAHorn]

The increased allowance in oil temp to 240F using SAE 50 wt oil is found in the engine type certificate.

[Bruce Fenstermacher]

A little more time this AM. As stated cruise oil temperature range is wide on the 170 models and depends on cowl lip, baffling, blast tubes and the calibration of the gauge itself.

Your 170A should have a cowl lip of about 2-1/4" on an early style cowl with an internal pressure box. I have found many 170s from '48 to '51 tend to run cooler than '52 and later. My '49 A model runs about 140°-160° during cooler months here in PA and as high as 190° on the hotter days of July and August, specially running at higher RPM. My normal temperatures would be considered by many later 170B model pilots as low. They routinely see temps in the 180°-190° range and running at 220° most of the time is not unusual.

Oil pressure is effected by two major things. Engine bearing clearance and oil temperature. Your minimum normal oil pressure should be 30 psi and if not your bearing clearance is probably getting a bit sloppy. How much pressure over 30 psi your engine makes really doesn't matter to a point. 60 psi is always the max Continental specs but on the C-145 60 psi is the max and not in the normal range while on the 0-300, 60 psi is both the max and the high limit of the normal range. And in reality both the C-145 and the 0-300 are the same engine so we would only be guessing why the difference. The point is oil pressure greater than 30 does not lubricate your engine better. You aren't likely to see much higher than 60 psi because the bypass spring will be set off and limit it.

And while I'm talking about it, the bypass does NOT regulate the normal oil pressure range. It is a max pressure bypass. When your engine oil is at operation temps your bypass should be fully closed and remain that way. Oil pressure escapes out of the oil galleys past the main and rod bearings and cam.

I have found oil temperature to make a big difference in oil pressure. I've charted this closer in my Cub but I also see it on my 170. For example an engine might be making 35+ psi at 180°. If the oil temperature climbed to 200° you could easily see 5 psi less and even more at 220°.

[GAHorn]

I can't offer any specific source for this anecdote... but when I worked in the Precision Airmotive engine shops two engines which had been deliberately run at max-continuous for many hours at 5 psi in a research test had no more bearing wear than those run at normal pressures. It was a test performed for an NTSB (I believe) investigation by my employer in the test cell.
Other readings I've come across from time to time support that also.

And, if you were at the Benton Harbor convention, you might remember the humorous "ramp check" performed by out FSDO guest who tagged my oil pressure gauge for not having the req'd 5 psi red line on the face.

Continentals Operating Handbook specifies a minimum idling oil press of 10 psi, although the TCM Overhaul Manual states 5 psi.

The Overhaul Manual also specifies that normal operating oil pressures are taken at full throttle and oil temps between 175-185, and should be 35-50 psi. This is for test purposes however, and not "allowable" limits.

[LVFJY]

thks so much all for the info and specs...