# GM 3.6L variants FYI

Discussion in 'General Auto Conversion Discussion' started by maticulus, Aug 11, 2019.

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1. Aug 17, 2019

### Marc Zeitlin

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I won't address the question of whether an auto conversion is cheaper/more reliable/safer (or the converse) than an aircraft engine, but I will address a couple of issues with your other claims.
While SB's are not mandatory, AD's are (for TC'd aircraft, and for EAB's specifically listed in the AD), and at least for Lycoming engines, there is at least one AD (2004-10-14) that requires an engine inspection in the case of a prop strike. Lycoming's definition of a prop strike is VERY broad.

HOWEVER....

This is NOT correct. AD's ONLY apply to E-AB aircraft if the aircraft in question is specifically called out in the AD. And since an engine is not certified unless it's using a certified engine/prop combination, there are very few E-AB aircraft that will have engines that are subject to AD's.

Now, I tell all my customers that if an AD is issued on a certified engine, and if their engine is a derivative of a certified engine and uses the same component that is discussed in the AD, they should seriously consider complying with the AD, but it's not mandatory.

So, with respect to prop strikes, if your engine meets the criteria for a prop strike that Lycoming calls out, even if you're not subject to the AD due to your non-certified O-360 (or whatever) engine being in an E-AB aircraft without a certified engine/prop combination, you should seriously consider a tear down.

I don't see an auto engine/PSRU being different in this regard - if the prop touches the ground, you're going to need to tear down the PSRU and MAYBE the engine, depending upon the PSRU type.

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2. Aug 17, 2019

### pfarber

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In a study of the 1999 LS1 BSFC is graphed multiple times. Its in mg/J, have no idea how to convert to Lb/Hp-hr

But in superiorairparts.com/downloads/vantageengine/SVIOM01.pdf BSFC varies from .54Lb/Hp-Hr to .61Lb/Hp-Hr from 2100 to 2700RPM at for a 180hp motor.

The LS1 is (on page 10 of the above report) a constant ~ .035 mg/J over all RPM ranges.

3. Aug 17, 2019

### pfarber

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It all depends on the magic words. See #2 below. #1 is obvious, its specifically stated. #2 is the kicker that sucks up E/AB into AD compliance. This could be any part.. the magic phrase is "This AD applies to any aircraft..." Note that while #1 specifically states an AC by name, it also states "This AD applies to any aircraft with the listed APU models installed." so if my BD-4B has an Auxiliary Power Unit (APU) models GTCP36-150(R) installed, I just won the AD compliance lottery!

b. Non-TC’d Aircraft and Products Installed Thereon. Non-TC’d aircraft (e.g., amateur-built aircraft, experimental exhibition) are aircraft for which the FAA has not issued a TC under part 21. The AD applicability statement will identify if the AD applies to non-TC’d aircraft or engines, propellers, and appliances installed thereon. The following are examples of applicability statements for ADs related to non-TC’d aircraft:

(1) “This AD applies to Honeywell International Inc. Auxiliary Power Unit (APU) models GTCP36-150(R) and GTCP36-150(RR). These APUs are installed on, but not limited to, Fokker Services B.V. Model F.28 Mark 0100 and F.28 Mark 0070 airplanes, and Mustang Aeronautics, Inc. Model Mustang II experimental airplanes. This AD applies to any aircraft with the listed APU models installed.” This statement makes the AD applicable to the listed auxiliary power unit (APU) models installed on TC’d aircraft, as well as non-TC’d aircraft.

(2) “This AD applies to Lycoming Engines Models AEIO-360-A1A and IO-360-A1A. This AD applies to any aircraft with the listed engine models installed.” This statement makes the AD applicable to the listed engine models installed on TC’d and non-TC’d aircraft.

4. Aug 17, 2019

### rv7charlie

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Not debating the (lack of) wisdom required to completely ignore an AD, but EAA's long-held position has been that ADs don't *legally* apply to experimentals; they are not 'airworthy' to begin with, because they have no type certificate to comply with (FAA hairsplitting). (Evidence: language in a homebuilt's annual inspection signoff; it's radically different from a type-cert a/c, and the fact that any a&p can sign off an experimental because we don't need an IA to verify *airworthiness*, meaning compliance with a type cert.) In the example given, FAA seems to be addressing a particular a/c without actually including the N number. How many Mustang Aeronautics INC Model Mustang IIs do you think are flying with either of those two turbine APUs? And what about a *Bushby* M-II (kit purchased from Bob Bushby before he retired), or a Builder-X M-II that was scratch built? They are obviously exempt (legally), because MA didn't supply the kit. And assuming that the APU has a problem, why didn't the AD just say 'any a/c, type cert or not, with that APU' ?

The FAA's position for decades was (and may still be) that any *engine* installed in an experimental was no longer certified because it wasn't installed in compliance with a type certificate. Many FSDOs, including the one here in MS, went so far as to confiscate the engine's data plate when they inspected a homebuilt and issued its paperwork. Happened to my neighbor on a couple of occasions.

Closest thing to an AD generally applicable to homebuilts that I can think of, is the recent NavWorx ADSB debacle, and FAA were quite specific about applicability. You an use them; you just can't *transmit* with them, in 'stock' form.

Again, not debating the wisdom of ignoring an AD; just addressing the rules aspect.

Charlie

5. Aug 17, 2019

### rv6ejguy

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Wiki doesn't differentiate between ROP and LOP which results in a 20-25% increase in MPG on aircraft engines. Only a source for general information in this case, not specific information.

The R3350 turbo compound radial engines from the early '50s were turning in .37 BSFC figures running LOP with sub 7 to 1 CRs.

Now if you could run a modern auto engine at 17 AFR at cruise power settings and have the pistons last, I'm pretty sure you could match or even exceed these figures. Nobody has proven that can be done yet.

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6. Aug 17, 2019

### rv7charlie

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Hmmm. Didn't the R3350 have boost, in addition to the turbo compounding (feeding energy back into the crankshaft)? Does 7-1 static compression have any real meaning, when we're talking about a boosted engine? What was the effective compression ratio after boost? And the compounding feature changes the achievable BSFC by quite a bit.

Just trying to point out that we should at least try to stay in the same food group.

Ross, how were the mid-.30's numbers obtained on that 12-1 IO360? Raw dyno numbers, same engine before/after mods? Or interpolated from airspeed?

Charlie

7. Aug 17, 2019

### Winginitt

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I think the idea that a homebuilder "needs to comply" with ADs is more a matter of common sense than legality. The thing here is that many homebuilders won't necessarily need to comply with some ADs depending on what they are.....but they do need to be aware of them when new ones are issued, and insure compliance with previously issued ones. If someone buys an engine thats been sitting unused in the corner of a hangar, it most likely hasn't been made compliant with even existing ADs. (We'll assume it was pickled and is still in usable condition) Some homebuilders actually build hybyrd engines from their certified core engine, but they still need to be aware of any AD that might have relevance to that core. Things like the Lycoming crankshaft fiasco some of the more recent Superior engine issues are serious examples. The problem is that most homebuilders who use these cores may not follow up by monitoring ADs or any requirement that their certified brethren must adhere to.

Then there is the problem of "prop strikes". While an inspection may be required when a prop strike is documented, they often may go undocumented. It may be intentional on the part of a seller, or it may be unintentional. I always harken back to the idea " Why did someone remove a "perfectly good engine" from a "perfectly good airplane"? The answer is that 99% (?) of the time the engine was removed because either the engine or the airplane suffered trauma. Many times people try to sell engines which have "lost" logbooks. While that actually happens, and sometimes legitimately....a buyer should still be wondering "why was this engine removed" from its airplane? Unless the buyer has personal knowledge of the history of an engine, they are rolling the dice. Personally I think every used engine that comes on the market should be inspected by disassembly and magnetic inspection of the crankshaft before bolting it into a homebuilt simply because "there had to be some reason for removing this engine".

The idea that a certified engine is available super cheaply and you can just bolt it into a homebuilt with no worries isn't true. A reasonably conscientious builder needs to verify why the engine became available, where its been since removed, are previous ADs complied with, and could a prop strike have been involved in the reason for removal. Even an airplane tossed by a hurricane while sitting in a hangar can have crankshaft damage. Ask to see the propellor that came from the engine.

Additionally the builder will need to research any recent ADs and future ADs that might have relevance. Further, there needs to be a physical condition inspection of the engine which will probably require the services and special tools of a professional aviation mechanic. While none of this may be "required" by law, common sense dictates that it be done. Unfortunately many builders buy into the idea that not treating the engine like it was still certified and generally following and keeping up with maintainance and ADs is a form of "cost savings" now that its in an EAB.

To my way of thinking its not about the legality but about doing the logical thing even if it costs more money.

8. Aug 17, 2019

### BJC

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I’ve never met a homebuilders or even a want-to-be homebuilder who thought that.

BJC

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9. Aug 17, 2019

### rv7charlie

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Not an exact quote, but Van (Van's Aircraft) used to tell builders that the best conversion engine was to convert the money they would have spent on an alternative engine into a used Lyc. So....

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10. Aug 17, 2019

### pfarber

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Wow I'm not sure how to explain this more clearly. If an AD is put out for an engine, by model/sn, and your data plate has that engine model/sn you must comply. Bolting it to an E/AB does NOT make AD's go away. Ever. I posted the FAA AC that clearly states it.

I'll post it again without my highlights:

b. Non-TC’d Aircraft and Products Installed Thereon. Non-TC’d aircraft (e.g., amateur-built aircraft, experimental exhibition) are aircraft for which the FAA has not issued a TC under part 21. The AD applicability statement will identify if the AD applies to non-TC’d aircraft or engines, propellers, and appliances installed thereon. The following are examples of applicability statements for ADs related to non-TC’d aircraft:

(1) “This AD applies to Honeywell International Inc. Auxiliary Power Unit (APU) models GTCP36-150(R) and GTCP36-150(RR). These APUs are installed on, but not limited to, Fokker Services B.V. Model F.28 Mark 0100 and F.28 Mark 0070 airplanes, and Mustang Aeronautics, Inc. Model Mustang II experimental airplanes. This AD applies to any aircraft with the listed APU models installed.” This statement makes the AD applicable to the listed auxiliary power unit (APU) models installed on TC’d aircraft, as well as non-TC’d aircraft.

(2) “This AD applies to Lycoming Engines Models AEIO-360-A1A and IO-360-A1A. This AD applies to any aircraft with the listed engine models installed.” This statement makes the AD applicable to the listed engine models installed on TC’d and non-TC’d aircraft.

I can't believe (well, its the Internet) how the black letter statements like:

This statement makes the AD applicable to the listed auxiliary power unit (APU) models installed on TC’d aircraft, as well as non-TC’d aircraft.
This statement makes the AD applicable to the listed engine models installed on TC’d and non-TC’d aircraft.

And I'll end with this:

10. AD COMPLIANCE. ADs are regulations issued under part 39. Therefore, no person may operate a product to which an AD applies, except in accordance with the requirements of that AD.

Unless I am missing something (my secret internet IQ lowering decoder ring is at home) where is the 'don't apply to muh 'spirimental' part?

11. Aug 17, 2019

### pfarber

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Yeah, certified engines never has mass mandatory crankshaft replacement, or camshaft ADs, or just recently, con-rods:

AD 2017-16-11 just cost 778 Lycoming engine owners about $4k-$8k

(g) Required Actions

(1) For all affected engines, within 10 operating hours after the effective date of this AD, inspect all affected connecting rods as specified in Lycoming Engines MSB No. 632B, dated August 4, 2017, except for the instruction to complete the online survey and the instruction to review your inventory.

(2) Replace all connecting rods that fail the inspection required by paragraph (g)(1) of this AD with parts eligible for installation.

Since this AD is by engine SN, being in a TC'd or E/AB is of no matter. If your motor is listed, by SN, time to write a check.

12. Aug 17, 2019

### rv7charlie

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Suggest you go back and read what I was responding to, and what my response actually said. Please don't twist another's words in an effort to make your point.

13. Aug 17, 2019

### TFF

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Most component ADs will have a statement saying the AD applies to all parts no matter application or modification. So if you use a crankshaft for a landing gear spindle, you technically are supposed to do the AD. Per homebuilt airframes the FAA would have to issue one to each individual one by name which they are not going to, but their big weapon is revoke the airworthiness of all like. Vans keeps up with problems like a certified company. Keeps FAA happy with 10,000 out there. The other side is most FAA are clueless in the field. I heard one talking about an investigation on an engine that had the data tag removed. He could not do an AD search. He definitely could not id it on experience. He was stopped in his tracks.

14. Aug 18, 2019

### Winginitt

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Those were two good posts pointing out the need to comply with specific ADs, but the overall importance is that certified engines maintain a sterling reliability record because they are inspected and maintained regularly. To hope for a used engine to be just as reliable requires pretty much the same thorough oversight.....even if there aren't any ADs issued.

Charlie, I wouldn't exactly consider Van to be an unbiased source since his business is selling airplanes designed to use aero engines and he probably gets some financial consideration for the discounted engines Vans ties to kit purchases.I have a lot of respect for DV and what he has accomplished but I find it a little jaded for him to feel it's ok to provide "alternative" airplanes yet feel that developers of alternative powerplants shouldn't be doing the same kind of innovating. Just as Vans developed a very successful fleet of airplane kits, someday someone may actually find a way to provide alternative engine kits cheaply. You never know what the future might bring.

15. Aug 18, 2019

### Marc Zeitlin

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So certainly, _IF_ the AD explicitly calls out non-TC'd aircraft (and more do these days) then the AD obviously applies, and I thought I said that in my original response. However, many AD's do NOT explicitly call that out, and per the EAA's interpretation of the latest version of the AC from 2012:

they don't apply to non-TC'd aircraft unless specifically noted. I don't think we're disagreeing here, except possibly on the frequency of when they are specifically noted.

16. Aug 18, 2019

### rv7charlie

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We're kinda getting into the weeds, but my statement was in response to someone saying that 'no one' recommended just hanging a used a/c engine on their homebuilt. Van has repeatedly stated that a used Lyc is a better plan than the generic 'conversion' engine. In this statement, he had nothing to gain, because he doesn't sell used engines. In a more general sense, I'm sure that he considered it better for his kit company if builders stuck to Lycs, since chances of success are undeniably higher (I say this with a Mazda rotary on my -7 project's motor mount). The fewer RVs that have accidents/incidents, the better the product looks to potential purchasers.

It's undeniable that alternative engines, *as a group*, provide a far lower chance of project completion, and a far greater risk of failure after completion. There are various reasons for this, most of which are *not* the engine itself. But it is reality, and that's what Van was saying.

17. Aug 18, 2019

### TFF

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Vans very much sell a certified style designed plane where every engineering need is addressed; if they learn something they address it. With their output of kits, they have kept up on their infrastructure making easier and easier kits to put together because of their tooling. I know of one certified aircraft company that uses 90% of their engineering staff to fix inconsistencies from aircraft to aircraft. Some of the tooling is ancient. Vans has a lot to protect in their position.

To the people who think auto engines are easy, why don’t we all have one? To the ones really doing it, a big thumbs up.
When I learned about kitplanes in the late 80s I wondered why everything did not have an aluminum V8 and wondered why there were not a stack of P-51s with Ranger V-12s. The why is hard? Homebuilt helicopters, how hard could it be? Very hard. To dream it up is easy. Today someone talented in cad can make a model that may have merit. Making it; all bits and pieces is hard. Dreams don’t fly. Hardware does. CNC should make this cheap as water;yet it looks like the hand drafters and machinists built more stuff. It’s hard.

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18. Aug 18, 2019

### BJC

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If you are referring to my comment,
note that I was referring
I do know several builders who, expecting to save money, installed auto conversion FWF packages on kitplanes originally developed around Lycomings, and ended up spending more for the auto conversion FWF than the cost of a good used / rebuilt certificated engine. They all eventually ended up with either a Lycoming or a Continental. Also consider that most homebuilders do not fly enough for the cost of an overhaul to be relevant.

I understand why a designer, Van or anyone else, would not approve of the installation of an auto conversion or a certificated engine different from what the designer used.

A good FWF auto conversion package in the 160 - 300 HP range, that weighed no more than a certificated engine, would be good for sport aviation. Some of the newer ones may turn out to do that.

BJC

19. Aug 18, 2019

### mm4440

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CNC is not magic nor inexpensive for one offs or small runs. The machines are very expensive. Programing and set up are not cheap. Those costs spread out over a 100 and up parts may be affordable. There is a FWF Aeromomentum engine package for the RV-12 at Oshkosh that looks like a less costly alternative to the recommended Rotax. More flight time will tell.

20. Aug 18, 2019

### TFF

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My point was no one was doing anything. Everyone has to make a buck or no. The crusty old guys who started hacking into a chunk of aluminum with hand tools got it done. Today you can email your file or build something homemade, and it falls short of leaving the computer screen. What, it all costs. I doubt percentage of income to build is not different. No one have friends with fancy tools? People just want it given to them their way.

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