TNIO-520 or IO-550?

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Jbublik

Filing Flight Plan
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May 8, 2014
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Jbublik
my centurion is 400 h past TBO still strong engine, but time for OH is near. Currently there is IO-520L. Running LOP - it is slow especially with my radar pod. I love the ability to go above the weather and fast, but my primary flying is within 200 NM range. Should I put IO-550 in it (with new prop) or TNIO-520 with new prop? If you have personal experience please share.
Thanks
 
Flown 206s, 207s and even a 182 with the 550 and have nothing but great stuff to say about it. Also not a fan of a turbo unless high altitude ops are mandatory.
 
For a 200 nm normal trip, you won't get much of a block time difference with either. Probably about the difference of about as much time to shut down and open the door. The 550 will help you a bit more because you can go faster lower. That means less time in the climb and normally better ground speed with headwinds.

If I was going to upgrade, I would go for the 550. Turbos add complexity, weight, and failure modes, three things that aren't good to add if avoidable. But I would only upgrade in your position if I needed better takeoff and climb, the cruise speed won't make a huge difference for your trips.

We have 520s on the 310 and debated putting 550s on at overhaul. For the $30k upgrade cost for about 5 kts that we might be able to get increased cruise speed (on a 187 kt plane), it just didn't make much sense.
 
The take-off distance is not that big of a deal for me as much as being able to go farther faster. I agree with 550 would give me approximately 5-7 ktas more and it doesn't seem to be worth the extra $$ and 3gph.
TN-520 is appealing because I can go to upper teens and take an advantage of winds (and over weather) on long trips. However these trips we're doing probably only 3-4x/year. Hard to decide. Thank you for your thoughts.
 
??????
What is a TNIO-xxx engine?
Are you sure you don't mean TSIO-xxxx
(Continental says they never heard of a TNIO-)
 
Yes, The main difference between TSIO (Turbo Supercharged) and TNIO (TurboNormalized) is compression ratio (TNIO is just like IO - 8.5:1 and TSIO is 7.4:1 - 550s and 520s) and Manifold pressure for TN is never above 32 (sea level pressure), TSIO 36-42 and more depending on model.
 
is a turbo normalizing setup cheaper and more reliable than a turbo charged setup, based on these differences? My intuition says since the normalizing kit is less aggressive on the cylinders and turbine on the pressure and temperature front, thus it would be cheaper to maintain, but I've never owned a turbo.

My only experience with a turbo was my exwife's vw beetle. And it was a piece of junk. the top end blew, literally, timing chain went bye bye, all the valves got bent. It was insane. 3200 to replace the top end, back in a time when 3.2 AMUs represented the majority of my life savings. Which is why I don't own turbo cars either. Blinky lighted little maintenance time bombs, car turbos are. /bias
 
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