Author Topic: twin engines and counter-rotating props (Read 818 times)

Bodhi · « **Reply #15 on:** July 08, 2005, 09:56:57 PM »

Quote

Originally posted by Ecliptik
This means almost twice the manufacturing overhead for the extra production lines. Maintenance is also worse as many parts cannot be interchanged between the two engines.

That statement is completely false. Listen to Virgil, Allisons's are just assembled differently, but use common parts.

Captain Virgil Hilts · « **Reply #16 on:** July 09, 2005, 12:18:20 AM »

Virgil misses working on Allisons terribly. I love those big sweethearts. When I heard both Glacier Girl and Porky II it brought back memories of working on those engines. About two years ago, I got lucky, and there was a killer Allison powered tractor on TV, and I cranked up the home theater. That one was direct injected with a custom intake and a BIG turbo. There was an Allison power unlimited hydro that actually won a race a year or so ago, it was the 1st piston engined boat to beat a turbine boat in about 12-15 years. Sounded great with the system cranked wide open.

bolillo_loco · « **Reply #17 on:** July 10, 2005, 05:10:58 PM »

I was under the impresion that the allison engines the P-38 used were identical. The gear boxes (which could be unbolted from the engines) were the only thing different. to make the left engine into the right engine or the other way around, the only thing needed to be changed was the gear box. I believe the crank shaft in the left and right engines spun in the same direction.

Tails · « **Reply #18 on:** July 10, 2005, 05:40:17 PM »

Nope. Like Virgil said, they just swapped the camshaft end for end, reset the mags, and likely redid the pumps and alternaters and such. But the engines litterally turned in opposite directions.

bolillo_loco · « **Reply #19 on:** July 10, 2005, 05:45:36 PM »

yep I see my error now.

Tails · « **Reply #20 on:** July 10, 2005, 05:54:37 PM »

Hey Virgil, you know if Allison even makes those engines any more? Seems like they would, what with racers and pullers wanting to get their hands on them.

Captain Virgil Hilts · « **Reply #21 on:** July 10, 2005, 07:23:45 PM »

Quote

Originally posted by Tails
Hey Virgil, you know if Allison even makes those engines any more? Seems like they would, what with racers and pullers wanting to get their hands on them.

No, they haven't been built in decades. Everyone has been running surplus and scavenged stuff for all this time.

Allison is now, and has been, the truck transmission division of GM for 30+ years.

As opposed to 25 years ago when I was working on them, there are practically no Allisons left in pulling or boat racing. The turbines took over unlimited hydroplane racing, and tractor pulling is mostly dominated by the big block Chevy in a confirugration similar to NHRA Top Alcohol Dragster engines.

Oddly enough, I think Oliver and Eagle make connecting rods, Ferrea makes valves, and a couple of the big name racing piston companies make pistons. Other than that, plus overhaul parts, nothing new is available for the most part. That's why an overhaul costs $25K.

Every once in a while, you'll see some NOS surplus engines creep into the market. They bring more money than you can dream of.

Tails · « **Reply #22 on:** July 10, 2005, 09:54:46 PM »

Well, I know some part of Allison still makes aviation engines, what with the A-250 on the turbine side, and the opposed type engines Piper likes to use. Maybe, at least, someone can get the castings off these guys (assuming they still exsist). Hate to see such a neat 'little' engine fade away once all the blocks wear out.

Captain Virgil Hilts · « **Reply #23 on:** July 10, 2005, 10:20:25 PM »

I think GM sold off the Allison aircraft section.

I seriously doubt any of the molds are left.

It was a very complex engine when you think about when it was designed.

Reproducing it today, even if you have all of the dies and molds, would cost about $500K a copy. That is to produce a complete new Allison V-1710, without any used parts. That would not buy you the turbocharger for the P-38.

Wolfala · « **Reply #24 on:** July 10, 2005, 11:01:23 PM »

The Allison that you knew and love is actually owned by Rolls Royce today. When we were restoring a P-39D, it had a V-1710-30, problem was of course finding the erection manuals and all that fun stuff. But I was in Champaign Illinois at the time and a very helpful RR rep based in Indianapolis was awesome enough to help go through the archives they had there and find everything needed.

The initial phone call went something to the effect of "I have a very strange request to ask, so don't fall out of your chair. (Ok) I need get some documentation on an engine that you guys havn't made in over 60 years." (extended silence)

Anyways, great engine all around - bulletproof compared to the Merlin.

Wolf

AmRaaM · « **Reply #25 on:** July 12, 2005, 07:07:11 PM »

thought they just injected the gas at BDC and it ran backwards? ..