enginehistory.org

avasko · Joined: 13 Jul 2003 Posts: 37 Location: Ft Collins, CO USA

R-4360 Turbo-Supercharged vs Non-Turbo Problems
My opnly experience with this engine was during conversion of ex-UAL B.377 to then BOAC requirements. A tremendous effort for ALL the wiring looms were replaced, two new overwing exits cut in, and Curtiss Electric props to be replaced by Ham Standards.
The total wiring replacement meant removal of the turbo-superchargers extensive ducting in each nacelle. An impressive amount indeed.
I had conversations with other techies who had experience with the engine from their military dass.
The seemed to be a general consensus that the non-turbo engines in the C-124 had less problems than their turbo'ed cousins in the C-97. It was their opinion that the exhaust back pressure used to power the turbo had an effect on cylinder exhaust scavenging.
Any opinions out there by people with experience on tris?
I do seen to remember of serious incidents on the C-97 types but don't recall hearing of any on the C-124. There certainly were a lot of them and they regularly crossed the Pacific..

rwahlgren · Joined: 15 Aug 2003 Posts: 324

avasko · Joined: 13 Jul 2003 Posts: 37 Location: Ft Collins, CO USA

Lacking the maintenance or overhaul manuals for the types makes getting numbers hard.
Having had to do whole engine (18 cyl)valve clearance checks, I shudder to think of doing it on a corncob. Messy when removing lower rocker box covers, valve depressors, feelers, finding TDC on 28 cylinders? Reinstalling all those rocker covers?
Remember reading that Rolls came out with new valve clearance on some Merlins. It was a Service Bulletin to be accomplished on-line on in-service aircraft. Disaster.
It's not that line maintenance Techies aren't skilled enough. But doing that kind of repetitious job outside in weather is not as easy as on a shop engine in a stand, no cowling, good lighting. Probably Quality inspectors too. Rolls decided to limit future wholesale valve adjustments to the shops.
Still think turbos did not help the cylinders. Although they were supposed to control the back pressure, I read (and can't find again) some pretty horrific back pressue occuring on turb'ed engines.