I think we're saying the same thing.

Each EGT probe is sitting in relatively cool air most of the time, because the exhaust valve is closed. If the EGT probe reads 1500, that value is an average of the typical, say 1400 degree environment with occasional blasts of, say, 1700 degree exhaust gas.

The TIT probe is getting six time more blasts of the 1700 degree exhaust gasses, hence, it reads hotter.

Doug,

Not precisely sure where the TIT probe is on the RAM set up.

There are several factors involved.

Example: On the Navajo engine, the turbo is a couple of feet behind the engine. The exhaust system plumbing is VERY long compared to almost all other systems.

The TIT on those installations normally runs about 50 degrees cooler than the average EGT measured at a point 2" below the cylinder exhaust flange.

Why? Because that LONG exhaust system gives off a LOT of infra-red energy and the exhaust stream tends to cool off substantially.

With short exhaust systems, the "real" TIT measured at the inlet to the turbo (where it should be measured) tends to be higher than the individual EGT values - - for the reasons already given: ie, the individual EGT probe is only exposed to about 1/6th of the short duration high temperature exhaust pulses as the real TIT.

In your case, your one-sided "pseudo" TIT probe sees primarily only 3 of the 6 short blasts of high temperature exhaust gas.

But seeing 3 of those means that its "average" (there is some small thermal mass to the tip of the EGT & TIT probes) temperature is typically higher than the three cylinder EGTs.

The Cessna turbo is, like the Navajo, located a long ways from the engine. So the "real" TIT gets some benefit from some thermal heat outflows before the exhaust plumbing gets to the turbo.

On the TN Bonanza, the TIT will normally run 50 to 100d hotter than the average EGT.

Does that help ?

George

Hi Doug, nice looking 340. I don't have the STOL kit or any RAM mods on mine but I have had some success running higher power settings when LOP for improved speeds. I have the AA intercoolers on stock engines and have been using 2450-2500 RPM and 35-36'MP at altitude (rarely much above 18,000) for speeds of around 200KTAS. FF 64-66lph (17gph-ish for about 60 deg LOP). It would be worth a try and see how your machine goes. I had to do a bit of baffle work (try a rolled up piece of baffle seal between the rear of #2 and the oil cooler to improve cooling of that cylinder if you haven't already) and optimising ignition timing to get it to run smoothly, but it seems quite happy at higher power settings. With a bit of perseverance in getting everything set up right, they can be reasonably efficient for the type of aircraft they are. Unfortunately we don't have the benefit of nice modern baffle STC kits so we are stuck with 45year old designs that don't cool very efficiently but lots of old shirts, skinny wrists and RTV sealant are your friends. Fly it hard!

Bob Thompson has informed me that my plane has been chosen to be the cover story for the December issue of Twin Cessna Flyers! Keep a look out for the story!

Cool...did you try out the relief tube? How does that work in a pressurized plane?

Cool...did you try out the relief tube? How does that work in a pressurized plane?

Nice Doug!

But did you show that Black Jack table who's boss?