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Thunderbolt vs. Barrett for EFII - any pireps?

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?
Click to expand...

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
 
Last edited:
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......
 
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