Keep the thread going. I am also interested for all the same reasons. One more to add. Turbos require extra vigilance when flown. Those who do not pay attention end up buying new cylinders/turbos, etc.

I own a turbo now. I just do not use its capabilities much. I do really like the turbo when I need it though. Opens up a whole other dimension to your flying.

FWIW Back in the 70s I flew a corporate 310 Navajo for 2200 hrs. In the first 1800 to overhaul I changed just 2 cylinders, 1 turb and 1 transition unscheduled. Averaged 36 GPH It carried ice real nice (hot windshield, props and boots) the potty seat was used rarely, the "galley" was used all the time. Great airplane in my mind. It was traded for a 421C by the company.

Just imagine Cliff if you were riding in it tonight, you could go to the galley, or better yet, have "your stewardess" pour a glass of champagne for you!

The compressions vary by model and upgrades. The 602Ps have AA1 A5s that are low compression boosted to 37". Everything prior to the 602Ps (600, 600A, 601, 601A, 601B, 601P) are high compression. The 700s are low compression U2As boosted to 42", 700hp. I believe all of the Machen upgrades are also low compression upgrades to the high compression originals and boosted to 42" 700 hp.. There are a lot of variations and it can get confusing.The nice thing about the low compression engines is that they are less prone to detonation than the high compression. The bad thing is they burn more fuel. The proverbial tradeoff.
I think what I said is correct. If not, someone please correct any inaccuracies.

The compressions vary by model and upgrades. The 602Ps have AA1 A5s that are low compression boosted to 37". Everything prior to the 602Ps (600, 600A, 601, 601A, 601B, 601P) are high compression. The 700s are low compression U2As boosted to 42", 700hp. I believe all of the Machen upgrades are also low compression upgrades to the high compression originals and boosted to 42" 700 hp.. There are a lot of variations and it can get confusing.The nice thing about the low compression engines is that they are less prone to detonation than the high compression. The bad thing is they burn more fuel. The proverbial tradeoff.
I think what I said is correct. If not, someone please correct any inaccuracies.

Okay Tom and Jgreen,
37 or 42 inches of MP puts these engines in the "turbocharged territory", turbo normalized producing sea level power to higher altitudes, about 29.5" of MP or so, depending on how efficient a particular induction is.
Here is a link, I haven't read the whole article yet, but looks like it explains the difference.
http://www.taturbo.com/tnvtc.html

Tom,

I think your statements are correct. On the high compression engines of the 601P, temperatures and detonation were a problem that had to be managed properly. The solution was the Machen intercoolers which completely alleviated both vices. My engines have the intercoolers, and I have absolutely no issues with operating temps or detonation. Hot and high operations pose no challenge either. I have never seen over 380 degrees CHT even on climb outs on a summer day. My "personal" opinion is that the turbo normalized, high compression engines with intercoolers is the optimum set up.
Jgreen[/quote]

I would agree with that. More power at altitude when needed, less prone to detonation, less fuel burn.

The 601, 601A, 601B and 601P were all high compression turbo normalized models.
The 602Ps and 700s were all low compression turbo charged. (Piper)
I believe all Machen upgrades were low compression turbocharged.

On descents I'd pull back 1 to 2 inches max every few minutes to avoid cooling to rapidly.
Decent planning is paramount. Don't be surprised the first night you fly and you see the exhaust stacks bright orange through the cooling louvers on the side of the cowls. Hads many passengers "interested" in the phenomenon.

Interesting. I wonder if a normally aspirated IO-540 glows like that as well? I guess the throttles should come back slowly on all piston engines and especially the turbocharged and turbo normalized ones.

Long time ago I flew in a Chieftain for about 30 hours or so and don't remember too much about it, but read and heard that the Chieftain and Navajo don't have any bad traits, and handle ice like an icebreaker, like what you are saying Cliff.

I've owned a 310 Navajo for 10 yrs now and absolutely love it. I am retired AF fighter pilot, retired airline, and currently fly corporate jets so I'm pretty serious about planes. I generally fly it at 60% power to increase longevity of my engines as well as saving fuel. The fuel distribution on these engines is so good that I can run lean of peak without GAMIS. Typically I fly between 5 and 10 thousand feet depending on winds though I have occasionally gone as high as 15. I don't like to wear canullas or masks so that's why I stay this low. Today on takeoff, tower warned me about many flocks of large birds near the departure end and suggested a steep climb. With 5 adults on board and 148 Gal of fuel I was climbing at 1800 fpm through 2000 feet. At 8000 feet I cruised at 175 KTAS on a total burn of just 26 GPH. We normally leave the outboard tanks half full to increase payload by 240 lbs. With that fuel load we can haul 1264 lbs of people and luggage 740NM with a 1 hrs reserve. With full tanks we can go 1050 NM with a 1hr reserve, but can only carry 1024lbs of payload. It was my wife's idea to get this specific airplane because as she said we could carry the kids and grandkids. We normally fly it with the 6 regular seats plus the potty seat, though we do keep the 8th seat in the hangar in case we ever need it. If you need to carry a lot of folks a long way safely this is a great machine for it.

I should have added that the 310 version only has one high pressure electric fuel pump per side and as you go higher (with them off) the fuel flows start to fluctuate giving the engines a surging with each fluctuation.
I crawled under a 350 model (because they have a low pressure pump AND a high pressure pump system) to see how it was mounted. Surprisingly the entire wing root system would fit in the 310 with just a couple of factory mounts riveted on and wires and switches installed. I got the parts and installed a Chieftain system in the 310 with a field approval only and from then on whenever I went high I could use the low pressure constant flow pumps to even out the fuel pressure to the injector. Worked like a champ.
A great airplane, a great engine package and one that won't (if maintained properly) nickle and dime you to death.

This conversion sounds astronomically expensive to get approved.

Take the money you save by not doing the conversion and use it to overhaul the existing turbocharged engines once or twice and still fly the thing down low for the rest of your life... Coming out ahead in the bank.

Jgreen,

I am an ATP, on the A320 for the last eight years, now also flying the A321's. Before that, Boeing 737's, and before that a whole bunch of other airplanes. This is my 40th year aloft. Long time ago, two and a half years as a CFIIME, and ground instructor out of Teterboro airport.
Turbos, by all means are about flexibility, but they can also be about speed. The -310 Turbo Navajo on 75% of power at 6500 feet will true out at 186 knots, and at the same power setting, and the same fuel flow of 38 gph, at 22000 feet will true out at 213 knots.
The normally aspirated Navajo very handsomely covers all my projected parameters of usage. It will take six people from NY to FLA, nonstop in about 4:45, in a huge cabin where you can move around, with a bar/galley in the seventh seat position, with food and drinks in it! and a toilet in the eight seat position, preventing those bladder bursting events, in air conditioned comfort. Additionally, it can be equipped with all the safety/emergency equipment such as a life raft, life vests, one or two fire extinguishers, crash axe, smoke goggles and built-in oxygen system with a mask at each station - not for high altitude flying but for possible emergency situations, such as cabin smoke. Being of Beechcraft quality, with all respect due, a Travel Air wouldn't get of the ground with this load. $40 per hour in higher operating cost is insignificant to me.
I intend on operating it below 10000 feet, at or near sea level airports. What is absolutely essential to me, is engine out performance. Here the Normally aspirated Navajo excels as well. At maximum gross weight of 6200 lbs, on a standard day, you can peel it off a runway, suck the gear up, feather the dead prop, and climb away at 315 fpm, all on one engine. If the temp goes up to a hot and sweltering 100 degrees Fahrenheit, it will still go uphill at respectable 220 fpm. That translates into safety. At lighter weights it will naturally climb even better or much better. Not many airplanes will give you this kind of performance. Some of the Aerostar models, all Baron models can do even better, and a Geronimo at the Diamond Aire claimed 750 fpm - on one mill! - is almost as good as an Airbus A320 at about 900 fpm.
I don't care for the flight levels, pressurization, and all that. If I did, I would just buy a Mojave. I get enough of it every time I work. It will be 98% low and slo East Coast tooling around. When I will fly for myself, I will also choose the time and day or night I fly. If it gets hellacious, I will have the option of not going. I want a color navigation, terrain, traffic, as well as weather displays. Full weather capability, good autopilot with a Flight Director, and an altitude/VS preselect.
A friend of mine, also an Airbus pilot is very happy pitt-putting, goggles and scarf, bugs on his teeth, and all! in his open cockpit Tiger Moth. Try to understand that, it's easy.

KW