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IO540 Lycoming Thunderbolt vs Reg Lycoming

Subwaybob

Well Known Member
Is the only difference that you can paint the Thunderbolt? They seem to have the same HP. The reg experimental is 260, so it the Thunderbolt. Both are IO540's. Is the any reason to get it or not to?
 
Differences

I am pretty sure you can customize the thunderbolt whereas buying the regular lycosaurus, you get what they built...
 
I have done 25 hours of test flying on a brand new RV10 with a thunderbolt and 3 blade carbon fibre Hartzell.

I normally fly behind a stock IO540 and two blade.

My observations;

Don't get it painted black!
No appreciable HP difference although there may be one or two.
Was very smooth and it may be partly the prop, but it was smoother than our engine by a small amount. And we dynamically balance ours, the test aircraft has not seen a balance yet so the engine and prop must have been good out of the box.
Lots more $$$, and even more so with the prop.

Would I do it, no not likely but each to their own.

YMMV
 
Balanced rotating assembly, pistons, rods, etc. Roller cam. Port and polish, volumetric balancing of the cylinders.

We went with dual slick mags, we will get a CPI2 in the near future. And a Airflow Performance fuel servo.


Vic Syracuse told me to get the Thunderbolt. I listened and I'm glad I did.
 
I asked the same question to the Lycoming representative who gave a presentation at our local airport. His reply was they both swing big heavy weights at the end. He recommended the prop. dynamic balance, to balance the system.

These are aircraft engines; the parts need to conform to design specs, thresholds, and tolerances. The thunderbolts may conform to tighter specs and weights, but do these improvements overcome the prop/system's imbalance.
 
Titan Option

For those looking for IO540, don't forget about Titan option. I recently had a Titan clone delivered. Working with James Ball and Titan team was very good. They worked with me to build\ship and IO 540 D4A5 clone minus the fuel ignition system so I can install SDS electronic ignition and fuel injection.

The engine was run 3 hours using slave ignition and injection system and then shipped to me.

Pricing was very competitive and they have worked with me to resolve minor issues. The one issue for those having an engine built to keep in mind is the Van's supplied governor requires longer case studs than those on std engine.
 
Why not black?

I have done 25 hours of test flying on a brand new RV10 with a thunderbolt and 3 blade carbon fibre Hartzell.

I normally fly behind a stock IO540 and two blade.

My observations;

Don't get it painted black!
No appreciable HP difference although there may be one or two.
Was very smooth and it may be partly the prop, but it was smoother than our engine by a small amount. And we dynamically balance ours, the test aircraft has not seen a balance yet so the engine and prop must have been good out of the box.
Lots more $$$, and even more so with the prop.

Would I do it, no not likely but each to their own.

YMMV

David, have to ask. Why not black? I was just looking at the 90th anniversary Thunderbolt at Sun ?n Dun and the matte black looks really cool.
 
David, have to ask. Why not black? I was just looking at the 90th anniversary Thunderbolt at Sun ?n Dun and the matte black looks really cool.

For me, i?d Imagine it would be harder to look at the engine and see places where oil was possibly leaking. I ordered mine. I?m getting it painted red :)
 
Sounds like they are doing what Aerosport Power have been doing to their engines for years ...............
 
Paid the extra for the Thunderbolt

I paid the extra for the Thunderbolt for all of the reasons mentioned above, plus one more. I was able to go to the Lycoming factory and watch the engine build. I was told that was a bit unusual, but everyone was very nice and supportive. I made a real effort to not be a pain to anyone. The result was a good schooling on the engine build and a very smooth running engine. I view it as one of the highlights of my build experience.

I was not allowed to pick up any tools (union shop) but ask any questions I had along the way. I was able to get a full tour of the factory as well. Jeff told me that the porting, polishing and balancing adds about 1 HP per cylinder, give or take.
 
A stock Lyc has set limits for rotating and recip balance. The T-bolt limits are a bit smaller. The difference is not huge, but like so much in aviation manufacturing these days, the exact numbers seem to be a state secret. See Henry VI, Part 2, Act IV, Scene 2.

The "port and polish" is balancing of a different kind. The ports are not enlarged or changed significantly. The idea is to put a set of cylinders on the flow bench, find the best flowing one, and then tweak the others so they flow the same. The end result is similar volumetric efficiency for all. If every cylinder gets the same air charge and the same fuel delivery (adjusting GAMI spread is your task), they make similar power.

Regarding smoothness, it's my opinion that the cylinder flow balance is more valuable than the rotating/recip tweak, in particular for a 540 with its long crank.
 
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