L

lyosha

Active Member
Hi Folks,

I think I've settled that I want to put an EFII system32 in the RV10 that I am building. My decision point is down to whether I get a Thunderbolt engine or get one from Barrett. I've talked to both recently at SnF. Rhonda was more knowledgeable about Lycoming's engines than Lycoming's folks. But Vans does have a deal on Thunderbolts through the end of the month and they seem like they're built to slightly tighter tolerances?

Wondering if anyone would be willing to share pireps. I've searched previous threads already and figured the question is worth it's own thread.

Thanks!
 
Barrett

+1 for Barrett. Runs great and always someone to talk to on the phone. Customer service is phenomenal.

I am running a Barrett 540, CAI, System 32 EFII
 
lyosha said:
Hi Folks,

....But Vans does have a deal on Thunderbolts through the end of the month and they seem like they're built to slightly tighter tolerances?

Thanks!
Click to expand...

Why do you believe this; or, get me smarter here please.

New Limits, Service limits, etc. should mean the same thing to anyone.
 
difference

Besides $4000+ more for the thunderbolt, it can be customized with CAI, higher compression, and EFII.

Also, from their website:

"...All Thunderbolt cylinders are ported and polished to increase efficiency, and pistons and connecting rods are balanced to within a half gram for smoothness. Lycoming says there’s no empirical data to prove Thunderbolts are more reliable than the company’s stock piston engines..."
 
Freemasm said:
Why do you believe this; or, get me smarter here please.

New Limits, Service limits, etc. should mean the same thing to anyone.
Click to expand...

Well, the way I understand it Thunderbolt engines are balanced to within half a gram. Barrett's piece of paper at SnF said "dynamically balanced rotating assembly within one gram inch".
 
lyosha said:
Well, the way I understand it Thunderbolt engines are balanced to within half a gram. Barrett's piece of paper at SnF said "dynamically balanced rotating assembly within one gram inch".
Click to expand...

Kind of an apples/oranges comparison.

No one will argue that getting everything to the same basis is usually better; but, the dynamics change once things get wet with oil, once a spinner/prop/backplate are part of the rotating assembly, etc. The only problem would be if things were so far out of balance that they couldn't be dynamically balanced later.

On a similar note, porting and polishing are fine but if the set isn't flow balanced/matched you're trading problems. You'll continue to get a lot of opinions. Consider them all and then make a decision i.e. one may offer the EFI/EI you're looking for versus having to retrofit later.

Enjoy this part of the journey
 
To answer your question; my opinion, which counts for nothing, would be the assumption that DB to one gram-inch versus a SB to 1/2g is somehow better here. What if it were stated in gram-cm's or ounce-inches instead? Would be more appropriate it would seem to keep it all in common unit reference. Dynamic on its own would generally be better than static but the static "sounds" tighter, etc. etc. When would the benefits lines of each cross? Either way, it won't matter. It just has to be good enough to make later dynamic balancing of the entire rotating mass achievable.

In the end, you have two very good, reputable options. Google "Superior" here and you just might get some contrarian opinions.

Will either company build your PP with the desired EFI/EI system? Think of the time/money that will save you.

As mentioned, enjoy this part of the journey. People like to defend their choices as being the best but keep you ears open to all the the opinions and options.
 
Options

Either one is ok in my opinion. What you MIGHT want to consider if you are going with EFII or SDS Barrett will install and test with the injector and fuel parts needed from either company. Lycoming will not. For a parallel valve engine, it's not a big deal to install the parts after the fact but one more thing to do. It is more difficult getting factory new parts from a non-Lycoming engine builder. I went with a factory new engine from Lycoming (both times), but I've made many mistakes along the way. Good luck with the build.
 
Thunderbolt Balance

I have the Thunderbolt engine with the Hartzell c/s prop. and about 120 hours on them since new. I flew down to Pasco, WA to have Jackie Velasco balance it. He pull the analyzer on it and measured less than .1. Said it didn’t need any balancing! Here’s one happy camper!
 
This is always a tough decision. I ended up going with the Thunderbolt, forward facing sump, and a EFII ignition with mechanical fuel injection. I had a good experience with Barrett when making that decision, but for me and the timeframe when I made that decision, I could not find a core that I was comfortable with. I have about 200 hours on the engine now and no regrets. It's powerful and smooth. In the end, if I end up needing to rebuild it, Barrett is always there.

To the couple comments about who do you call... Thunderbolt has always answered any email or phone call immediately.

https://youtu.be/DzNs5iDGGKY
 
Coming late to the thread, but +1 for Barrett - they've been awesome to me when I did have an issue with the engine.

Also, if you really want tighter tolerances, you can probably just tell Barrett and they may be able get you what you want.
 
lyosha said:
Can you educate me - in which way is it an apples/oranges comparison?
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getting piston weights to 1/2 a g is nice but not that critical, especially if the rods are not balanced. I would argue that balancing the rods will have a bigger impact than matched piston weights and my guess is that the tolerances are bigger here. The overall weight of the rotating mass is pretty significant and a gram of two difference is likely to be imperceptible. Dynamic balancing is a whole different thing. Here they are spinning the crank on a balancing machine, similar to balancing your tires. This can make a big difference in perceptible vibration, as we are talking 50 lbs of rotating mass. I had ASI do this on my 540 crank and it is quite smooth.

The piston pin weighs more than the piston by a good margin and if those are not also matched (highly doubt they are and have no weight range in the specs), what is the point of getting the pistons that close.

The piston weight thing is marketing. Sounds like blueprinting, but isn't. Also easy for them to sort pistons from the pile and achieve a perceived benefit. Barret OTOH strikes me as a real engine shop and suspect they are doing MUCH more blueprinting than Lyc is. Port and polish is an art and I suspect Barret is doing a better job of it and also is likely using a flow machine to match flow rates across all cylinders. I suspect that Lyc is not even putting the cylinders on a flow machine after the porting. Equal flow rates will have a significant impact on engine smoothness.

Not suggesting that you not match piston weights, only that you must consider the whole package.

Larry
 
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Hi Larry,

Just to let you know, I really appreciate you sharing your expertise on this VAF forum!

Mostly over my head, but I have learned a lot from reading your posts......
 
lr172 said:
getting piston weights to 1/2 a g is nice but not that critical, especially if the rods are not balanced. I would argue that balancing the rods will have a bigger impact than matched piston weights and my guess is that the tolerances are bigger here. The overall weight of the rotating mass is pretty significant and a gram of two difference is likely to be imperceptible. Dynamic balancing is a whole different thing. Here they are spinning the crank on a balancing machine, similar to balancing your tires. This can make a big difference in perceptible vibration, as we are talking 50 lbs of rotating mass. I had ASI do this on my 540 crank and it is quite smooth.

The piston pin weighs more than the piston by a good margin and if those are not also matched (highly doubt they are and have no weight range in the specs), what is the point of getting the pistons that close.

The piston weight thing is marketing. Sounds like blueprinting, but isn't. Also easy for them to sort pistons from the pile and achieve a perceived benefit. Barret OTOH strikes me as a real engine shop and suspect they are doing MUCH more blueprinting than Lyc is. Port and polish is an art and I suspect Barret is doing a better job of it and also is likely using a flow machine to match flow rates across all cylinders. I suspect that Lyc is not even putting the cylinders on a flow machine after the porting. Equal flow rates will have a significant impact on engine smoothness.

Not suggesting that you not match piston weights, only that you must consider the whole package.

Larry
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Sorry for resurrecting an old thread but I'm bored lol. I just wanted to get a better understanding of the "static" vs "dynamic" balancing on these engines. In the performance automotive world the guy on a tight budget weight the rods and pistons then combines light with heavy to get close. then a little material can be removed from the heavier combos to get the assemblies within a gram or less. Sounds a lot like the "static" balancing done to Thunderbolt engines.

If the hotrod builder has a few extra hundred dollars he pays the machine shop for "dynamic" balancing. That procedure looks like this; Balance the pistons and wrist pins to less than a gram (usually already there with aftermarket forged pistons). Ballance the rods by matching all of the small ends and all of the big ends using a special fixture over the scale. Finally put the crank in a balancing machine with bob weights on the rod journals that match the piston/ rod assemblies'. The entire rotating assembly ends up balanced to within 1/2 a gram. I would assume this is what Barret does.

Am I thinking correctly or is the automotive version of dynamically balancing not typically done? If I get to a point where I can build a plane I intend to balance my engine this way. It's really not very expensive.
 
Jjackh10 said:
Sorry for resurrecting an old thread but I'm bored lol. I just wanted to get a better understanding of the "static" vs "dynamic" balancing on these engines. In the performance automotive world the guy on a tight budget weight the rods and pistons then combines light with heavy to get close. then a little material can be removed from the heavier combos to get the assemblies within a gram or less. Sounds a lot like the "static" balancing done to Thunderbolt engines.

If the hotrod builder has a few extra hundred dollars he pays the machine shop for "dynamic" balancing. That procedure looks like this; Balance the pistons and wrist pins to less than a gram (usually already there with aftermarket forged pistons). Ballance the rods by matching all of the small ends and all of the big ends using a special fixture over the scale. Finally put the crank in a balancing machine with bob weights on the rod journals that match the piston/ rod assemblies'. The entire rotating assembly ends up balanced to within 1/2 a gram. I would assume this is what Barret does.

Am I thinking correctly or is the automotive version of dynamically balancing not typically done? If I get to a point where I can build a plane I intend to balance my engine this way. It's really not very expensive.
Click to expand...
Balancing of an automotive crank is typically done by the manfucturer of said crank. THe machine shops/engine builders tend to limit their balancing to the big end and small end of rods and matching pistons by hogging out excess weight. They may statically balance a crank but quite rare for these shops to have dynamic crank balancers. I doubt barret has a dynamic crank balancer. I suspect ASI is the only shop with enough volume to justify such an expensive machine. In fact, I would expect that barret sends their cranks to ASI. They are by far the largest machine shop doing this kind of work for aviation engines. referring to classic machining as opposed to case overhauls or cyl overhauls.
 
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Jjackh10 said:
Sorry for resurrecting an old thread but I'm bored lol. I just wanted to get a better understanding of the "static" vs "dynamic" balancing on these engines. In the performance automotive world the guy on a tight budget weight the rods and pistons then combines light with heavy to get close. then a little material can be removed from the heavier combos to get the assemblies within a gram or less. Sounds a lot like the "static" balancing done to Thunderbolt engines.

If the hotrod builder has a few extra hundred dollars he pays the machine shop for "dynamic" balancing. That procedure looks like this; Balance the pistons and wrist pins to less than a gram (usually already there with aftermarket forged pistons). Ballance the rods by matching all of the small ends and all of the big ends using a special fixture over the scale. Finally put the crank in a balancing machine with bob weights on the rod journals that match the piston/ rod assemblies'. The entire rotating assembly ends up balanced to within 1/2 a gram. I would assume this is what Barret does.

Am I thinking correctly or is the automotive version of dynamically balancing not typically done? If I get to a point where I can build a plane I intend to balance my engine this way. It's really not very expensive.
Click to expand...
Next = add a prop, spinner. and rotating mass is oil wet through normal ops. Now the original static balance and related rotating moments have moved. This may or may not erase any advantage from the extra SB'ing.

In a simplified view, the static balancing should be done to a point where the dynamic balancing can fine tune it. DB is relatively cheap and saves PP, airframe, and instrument wear. It's extremely rare that it cannot improve the DB of the system (PP and prop).

Enjoy
 
lr172 said:
Balancing of an automotive crank is typically done by the manfucturer of said crank. THe machine shops/engine builders tend to limit their balancing to the big end and small end of rods and matching pistons by hogging out excess weight. They may statically balance a crank but quite rare for these shops to have dynamic crank balancers. I doubt barret has a dynamic crank balancer. I suspect ASI is the only shop with enough volume to justify such an expensive machine. In fact, I would expect that barret sends their cranks to ASI. They are by far the largest machine shop doing this kind of work for aviation engines. referring to classic machining as opposed to case overhauls or cyl overhauls.
Click to expand...
Not true, most performance machine shops have the equipment. I've balanced the rotating assembly many times at a friends shop. Sometimes you remove a bit of material from the counterweight, sometimes you drill and add heavy metal.
 
Freemasm said:
Why do you believe this; or, get me smarter here please.

New Limits, Service limits, etc. should mean the same thing to anyone.
Click to expand...
New limits tolerances are quite a bit tighter than "service limits". A new limit crank shaft journal (rods or mains) would mean the OD of the journal would not have any material removed from the factory. A "servicable limit" for a rod or main journal would be M10 or .010 ground off the main to remove any defects that occurred during usage, corrosion or the overhaul process. This would apply to any new part versus an overhauled part. You can remove only so much material before that part falls out of limits and becomes "Red Tagged". So an engine built up with all brand new parts would have tighter tolerances than an engine built from all overhauled parts. Lycoming allows you to reassembled engines following their service limits guideline so you can run an engine to TBO without issues. Gear lashes, con rod side play, and some other limits need to be adhered to very carefully or you can have some severe issues after running them for some time. Other items like journal bearing dimensions are not super critical because as you remove material from the journal and the bearing INCREASES in size to make up the difference so you maintain the "fitment". Same goes for Pistons, you take material out of the cylinder bore and add back in piston size with a P10 (plus .010) in size. There are several areas where Lycoming makes P sizes for holes like valve guides, valve seats where they know that in order to maintain tight fitments of parts into other parts, they upsize the OD's of the component part to fit into the receiving part so you can keep the fitment in the correct tolerances.
 
Aden Rich said:
New limits tolerances are quite a bit tighter than "service limits". A new limit crank shaft journal (rods or mains) would mean the OD of the journal would not have any material removed from the factory. A "servicable limit" for a rod or main journal would be M10 or .010 ground off the main to remove any defects that occurred during usage, corrosion or the overhaul process. This would apply to any new part versus an overhauled part. You can remove only so much material before that part falls out of limits and becomes "Red Tagged". So an engine built up with all brand new parts would have tighter tolerances than an engine built from all overhauled parts. Lycoming allows you to reassembled engines following their service limits guideline so you can run an engine to TBO without issues. Gear lashes, con rod side play, and some other limits need to be adhered to very carefully or you can have some severe issues after running them for some time. Other items like journal bearing dimensions are not super critical because as you remove material from the journal and the bearing INCREASES in size to make up the difference so you maintain the "fitment". Same goes for Pistons, you take material out of the cylinder bore and add back in piston size with a P10 (plus .010) in size. There are several areas where Lycoming makes P sizes for holes like valve guides, valve seats where they know that in order to maintain tight fitments of parts into other parts, they upsize the OD's of the component part to fit into the receiving part so you can keep the fitment in the correct tolerances.
Click to expand...
I believe you missed my point, Sir. I was trying to say that the definition of "new limits" doesn't change between engine builders. Same goes for service limits. I was trying to point out to the OP that an engine assembler's claims of a building a new PP to tighter limits is dubious at best.

Not uncommon in the industrial gas turbine world for OH'ers to claim similar. Sometimes a performance gain can even be demonstrated in a recommissioning test. Then, the first blade tip rub that occurs due to these "tighter" tolerances during a load transient erases those gains and then some. The customer is then left with an underperforming turbine for the next 50K hours. That or the expense and lengthy generation/revenue loss of a repair. Loosing efficiency hurts. Not getting dispatched because said efficiency loss lowers your dispatch ranking can force said owners out of business.

To reiterate, I don't believe there to be a measurable difference in performance or service life between two PPs when each is built to new service limits.; all other things being equal. If anyone has real proof (not anecdotal) to the contrary, I'd be interested to learn.
 
Another Barrett VS Thunderbolt comment: May 2023 I ordered an engine. Really wanted an EXP-119 from Thunderbolt through vans. Ended up purchasing through Barrett because the cowl and accessory install was going to be easier. Barrett had the engine crated and ready for delivery within the quoted time (December 2023) and a little under the quoted price. In hindsight with the Vans re-negotiating Lycoming prices and the multi year delivery times, I'm very glad we went this route.

The -390 has over 50 hours on it and everything is working well.
 
Freemasm said:
I believe you missed my point, Sir. I was trying to say that the definition of "new limits" doesn't change between engine builders. Same goes for service limits. I was trying to point out to the OP that an engine assembler's claims of a building a new PP to tighter limits is dubious at best.

Not uncommon in the industrial gas turbine world for OH'ers to claim similar. Sometimes a performance gain can even be demonstrated in a recommissioning test. Then, the first blade tip rub that occurs due to these "tighter" tolerances during a load transient erases those gains and then some. The customer is then left with an underperforming turbine for the next 50K hours. That or the expense and lengthy generation/revenue loss of a repair. Loosing efficiency hurts. Not getting dispatched because said efficiency loss lowers your dispatch ranking can force said owners out of business.

To reiterate, I don't believe there to be a measurable difference in performance or service life between two PPs when each is built to new service limits.; all other things being equal. If anyone has real proof (not anecdotal) to the contrary, I'd be interested to learn.
Click to expand...
I think it depends on who is building the engine. A Ly-Con or Barret built up to new limits isn't the same as a Lycoming built engine. One has "ways" to eek out more performance and the other is going to stick to pre-scribed build approved by the top people at Lycoming. Those two engines are not the same.
 
Aden Rich said:
I think it depends on who is building the engine. A Ly-Con or Barret built up to new limits isn't the same as a Lycoming built engine. One has "ways" to eke out more performance and the other is going to stick to pre-scribed build approved by the top people at Lycoming. Those two engines are not the same.
Click to expand...
Freemasm said:
…….. all other things being equal..,,,,,
Click to expand...
As previously stated.
 
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I have a TB540 on order since Feb 22 and gave up on the wait after being told many times over the last 18 months how my engine was next inline and it would be in assembly next month, ect.....I called Rhonda and will get my 540 built the way I want it, not only what is offered by Lycoming and it will be here about the same time as the TB but after talking with a few friends of mine I will be going with the Barrett instead of the TB. The attention to build detail, customer service, and track record are the reasons for my decision. I have a friend that is the head of maintenance over 27 aircraft at a flight school. They have always used Lycoming for their engine rebuilds but after problems and lengthy wait times they are now using Barrett for their engine needs. Another plus: no sales tax on aircraft parts from Oklahoma.
 
lr172 said:
THe machine shops/engine builders tend to limit their balancing to the big end and small end of rods and matching pistons by hogging out excess weight. They may statically balance a crank but quite rare for these shops to have dynamic crank balancers. I doubt barret has a dynamic crank balancer.
Click to expand...

Oh ye of little faith....

Monty (Rhonda's dad, RIP) installed a Schenck crank balancer before some of our builders graduated from balsa. This a six in process, circa 2014:

Crank Balancing.jpg

Not done yet, but getting there.

Schenck Screen.jpg

Pistons get matched for weight. Rods go on a static fixture to weigh each end. They cut valve seats on a Serdi machine, superior to grinding seats in several ways, most notably concentricity with the guide and no embedded abrasive.

SERDI 60.jpgSERDI Cutters.jpg

I've been in both shops, T-Bolt and Barrett. Both can do a good job. Given both are sponsoring our Social in a few weeks, I'm not going to make a specific recommendation. I do think any differences have little to do with competence. Talk to them.

A half gram vs one gram? You can't tell the difference.
 
All of that is well and good, to be balancing everything possible. However, the moment you bolt your flywheel, prop and spinner to that, you are right back to balancing everything out again. Not saying it's something you shouldn't do because once it's done and inside the engine, you can't go back very easily to alter anything. But some folks forget that if you don't balance out the other spinning mass, a balanced engine really doesn't give you that much. Everyone should spend the few extra bucks to get the prop/spinner balanced when you start flying.
 
Aden Rich said:
All of that is well and good, to be balancing everything possible. However, the moment you bolt your flywheel, prop and spinner to that, you are right back to balancing everything out again. Not saying it's something you shouldn't do because once it's done and inside the engine, you can't go back very easily to alter anything. But some folks forget that if you don't balance out the other spinning mass, a balanced engine really doesn't give you that much. Everyone should spend the few extra bucks to get the prop/spinner balanced when you start flying.
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Rotating mass vs reciprocating mass ! Cranks rotate at a very small radius compared to flywheels and props. The the affect of imbalance varies by a square function I think.
Rod weight and both ends matching on all rods impact both rotating balance and horizontal shaking moments. Are bob weights matched to real rod weights as built ?
I have always spent the money to have ASI balance the crank and I personally match total rod weights and both ends. Does it really matter ?
I have been told it doesn’t matter because OUR RV engines turn so slow. Fuel injection or carb. Are injecters balanced , constant flow or Bosch electronic ?
How do you measre smooth ? Balancing the prop is seat of the pants noticable. Does the same equipment yield useful information on the abve discussed varibles, not for me to know 🤔
 
Back in the day when ECI had a shop at Troutdale airport, I took my box of IO-360 parts to them for OH. Tim at ECI had my crank, rod (matched) and flywheel all dynamically balanced together on their machine. Then Ken Tunnel at Ly-Con got me a set of matched pistons and pins for the cylinders. I bolted on my OH prop and we did a run for dynamic balancing and it was at .06 IPS. That's almost nothing and we could have left it alone. However, we hung an offset weight (to make it out of balance so we could hang another offsetting weight) and we got it down to .01 IPS. The engine ran like a turbine. Saves on cowling cracks, baffling cracking, exhaust cracks, alternator brushes, airframe fatigue, carb float failure and light bulb filaments. I've had the opposite with certed engines and props and got all those listed above due to high vibration (.55 IPS). It pays dividends to get everything balanced. Not to mention your body after a 3 hour flight in a buzz bird. Flying that -6 was a dream and it was soooooo silky smooth. Anyone overhauling an engine or having one overhauled should spend the extra money and get the balancing done. You are going to spend it later in other areas on your bird. Vibration is a silent killer
 
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