Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

[mitchcarley]

Dear smart-AAFO'ers...for us that have pulled and overhauled L-Head / F-Head / Small Block Chevy's / FoMoCo / AMC family of V8s and on...(basic understanding of names-of-parts / reasons / (auto) mods). What is the simple definition of: "Tube Motor(s)?" I have read this term again recently re: Hisey / MissA. Re: MissA / Hisey, I understand the basic assumed and or known mods being mentioned - yet - I do not know what this 'Tube Motor term' means. I assume this is a common go-fast mod. for RR/Packard Merlins...can other water cooled engines have this done to them, GM Allison's? For me - please 3RD Grader terms, super-simple, if you will? Thank you and thanks for the Ramp updates it helps all of us who cannot attend. Go Wayner Go! : )

[RAD2LTR]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

A tube Merlin is one that has had the air to water (coolant) aftercooler removed, and replaced with a big tube running directly from the supercharger exit to the intake. Now, how does one cool the intake charge after it leaves the supercharger? ADI. ADI is Anti Detonation Injection. Its a 50/50 mix of distilled water and methanol alcohol. The alcohol evaporates rapidly causing a drastic drop in localized temperature. ADI fluid is also used for the engine/radiator spray bars. The ADI is injected into the intake charge just after it leaves the supercharger (I believe) through a metered nozzle. This is what allows the crazy high manifold pressure required to go 500 mph.

Its mostly done for Merlins, I'm not sure if its been done for a Griffon or Allison.

Here is a normal Merlin with the aftercooler assembly.


Here is a Tube Merlin.



Will

[Bigger Al]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

That tube engine is so, so sexy.

[Lon Moer]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

From a Bruce Lockwood article on Tube Merlins.

[mitchcarley]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

RAD2LTR & Lon, fantastic - 100% understood. Wow - I am sure that is a lot of weight removed as well - yet - with the ADI liquid - maybe not far off in LBS...at least at takeoff. Also, it seems the CG would be maybe a wash as elements of removal are both in front-of and behind-of the CG point...I assume. RAD2LTR, that perfect set of photos that really make it easy to understand the weight advantages alone. Lon - where is that article that Lockwood did - that is awesome deep-dive for the guy-on-the-street consumer-type reading...can that be bought in a book? Who invented this (was this the stuff of Dago & Strega or was it earlier)? Will be interesting if Doc went to this level of 'tweek'...man! Thank you guys.

[Race5]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

RAD2LTR & Lon, fantastic - 100% understood. Wow - I am sure that is a lot of weight removed as well - yet - with the ADI liquid - maybe not far off in LBS...at least at takeoff. Also, it seems the CG would be maybe a wash as elements of removal are both in front-of and behind-of the CG point...I assume. RAD2LTR, that perfect set of photos that really make it easy to understand the weight advantages alone. Lon - where is that article that Lockwood did - that is awesome deep-dive for the guy-on-the-street consumer-type reading...can that be bought in a book? Who invented this (was this the stuff of Dago & Strega or was it earlier)? Will be interesting if Doc went to this level of 'tweek'...man! Thank you guys.

Doc is the one that pioneered the tube motor back in the 1960s. It was used on unlimited hydroplanes as well. I believe the first Mustang raced with a tube motor was Chuck Lyford's Bardahl Special. Later, both Mike Nixon and Mike Barrow adopted the technology as well. Rick Shanholtzer, who builds the motors for Miss America, does not build tube motors. All of his race motors still utilize the aftercooler.

[GRNDP51]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

Rick Shanholtzer, who builds the motors for Miss America, does not build tube motors. All of his race motors still utilize the aftercooler.

Haha …..

[PowerByPackard]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

Haha ?..

I'm hoping this means he has something pretty slick under the hood. We'll all learn soon. Heading out on Tuesday! Can't wait!!!

[Lon Moer]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

Was an article called "It's Quicker by Tube", by Bruce Lockwood from The Aviation Historian magazine in 2020.

[Sparrow]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

I worked for Dwight for a number of years, I just carried on....

[Lon Moer]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

I worked for Dwight for a number of years, I just carried on....

Do you use the Allison connecting rods on race motors?

[RichH]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

Wow - I am sure that is a lot of weight removed as well

Removing the aftercooler has nothing to do with weight savings... the aftercooler cannot withstand nor facilitate higher manifold pressures. The radiator vanes tend to crack. BTW, the earlier versions of the Merlin engine are also "tube" motors, as the aftercooler was a later addition...

[Sparrow]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

Removing the aftercooler has nothing to do with weight savings... the aftercooler cannot withstand nor facilitate higher manifold pressures. The radiator vanes tend to crack. BTW, the earlier versions of the Merlin engine are also "tube" motors, as the aftercooler was a later addition...

Lon Moer--yes.

In regards to the aftercooler you are correct in the fact the core cannot take the high MAP, they can start getting unhappy going past 115", however it is also closer to 100 LBS than not. Only thing is, putting all the bracing and such in and on the crankcase makes it a wash for weight savings. It does however somewhat change the CG of the engine itself. Also, the other Merlin's that were "tube" engines were also single stage. If you look at the pic of the RR engine at the beginning of this thread it is a Merlin 61 which is an early 2 stage engine with a beer cooler.

[L.E.D.]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

Here's a couple newer examples of tube motors (circa 2010)

Strega:



Voodoo:



And Miss A with an aftercooler:



Interesting how the arrangement of other accessories varies, like the..well, what is that thing in front of Miss A's oil tank?


And by the way . .what was "up" with those exhaust stacks in RAD2LTRs post? Was that a boat motor? And what airplane was that?

[MRE]

Re: Tube Motor? ...please explain in 3RD Grader terms...Merlin / Allison?

That thing in front of the oil tank on Miss A is the battery. The Mustang in those pictures is Roto Finish Race 5, probably 1971. The boat stacks were just used on the test stand,just not changed out yet.