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Jeremy Jon

GM LS 4th Gen V12 ?

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Okay, so I was working on a scale front placement conversion of the 4th generation 'vette LS V8 drivetrain, and came across/inspired by this article about some guys making a LS V12 engine from couple of V8s ....it's even easier for us to do in plastic, and so I figured why not? :)

How cool would a V12 LS hot rod be!? :D going to work on the block next, but otherwise should use all the same ancillaries, only manifolds to construct otherwise

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Very interesting project.

Do you have a link to the article? I'd like to see how they've dealt with the uneven-fire problem encountered when building a V-12 on 90 degree V8 block architecture.

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Here's a couple links I found

http://www.enginelabs.com/news/the-ls12-inside-scoop-on-the-v12-ls-engine/

http://ls1tech.com/forums/conversions-hybrids/1643786-v12-ls1-build.html

Corvette of course had a C4 test mule with a Falconer V12 some time ago, and more recently the Cadillac V16 version of the LS engine was in their show car 'Sixteen'

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Very interesting project.

Do you have a link to the article? I'd like to see how they've dealt with the uneven-fire problem encountered when building a V-12 on 90 degree V8 block architecture.

I find this an interesting Question . IIRC in this Site some one posted about Gm V/12's . I do have copies of how GM had no problem sorting out the odd V/S even fire in the '60's as they made a V/12 using two GMC V/6's to make these on a small scale of limited use in a Limited Market . Through out thwe World all other Vehicle Makers had No problem making V 8 10 12 16 in the Thirties or V 6 8 10 12 16 recently . So here comes GM and the world renown Bean Counters netting 16 Generations of V/6's later this is (still) a problem . Yet , 6 Inline is the smoothest Powerplant ever devised .

I think a functioning V/12 GM would be something to see . The Escalade V/16 , was not a "Pushmobile Show Car" IIRC . It ran under it's Own Power . Thanx ..

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I find this an interesting Question . IIRC in this Site some one posted about Gm V/12's . I do have copies of how GM had no problem sorting out the odd V/S even fire in the '60's as they made a V/12 using two GMC V/6's to make these on a small scale of limited use in a Limited Market . Through out thwe World all other Vehicle Makers had No problem making V 8 10 12 16 in the Thirties or V 6 8 10 12 16 recently . So here comes GM and the world renown Bean Counters netting 16 Generations of V/6's later this is (still) a problem . Yet , 6 Inline is the smoothest Powerplant ever devised .

I think a functioning V/12 GM would be something to see . The Escalade V/16 , was not a "Pushmobile Show Car" IIRC . It ran under it's Own Power . Thanx ..

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The firing order has mostly to do with the crank and cam shaft design and not that much with how the engine layout is, a full revolution is 360º and 360 divided with 12 is 30, so you can fire one cylinder every 60º on a four stroke.

V12's are also among the smoothest running engines around and was widely used in old warbirds.

Edited by Force

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The firing order has mostly to do with the crank and cam shaft design and not that much with how the engine layout is, a full revolution is 360º and 360 divided with 12 is 30, so you can fire one cylinder every 30º.

V12's are also among the smoothest running engines around and was widely used in old warbirds.

Sorry fellas, but the angle between cylinder banks is a determining factor to firing order, and 60 degrees between banks is the typical angle for V6 and V12 engines, 90 degrees for V8 (and V4) engines and it has to do with dynamic balance issues, what's called "rocking couple", and being able to use common rod journals on opposed cylinders, thereby shortening the crankshaft, allowing a smaller engine and making it easier to manufacture. Unfortunately though, even 60 degree V6 engine designs do not allow sharing of crankpins by two rod journals. You can see that a typical 60 degree V12 (Lambo Espada in this case) does indeed have two con-rod journals sharing crankpins. 60 degree V12 engines like this are lovely and smooth, and are essentially two inline sixes sharing a common crank. A 90 degree V12 will have peculiar balance and roughness issues that have to be dealt with by using split crankpins to achieve even firing impulses.

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Yes, GM DID hack off two cylinders from a V8 to make a V6, and it ultimately got what is now referred to as an "even fire" crankshaft, where the rod journals are staggered to get smooth , evenly-spaced firing impulses. Some of the cranks were prone to cracking through the staggared journals, and the non-even-fire engines felt like they were running rough, all the time.

You could, of course, machine an even-fire, staggered-journal crank to work in a 90 degree V12. That's what I was wondering about...what it looked like, and if they even bothered.

Edited by Ace-Garageguy

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I did some searching a few days ago. The newest posts/discussions were a year and a half old. I wonder if the project stalled.

It's an interesting idea, but what would be really cool is an American V-12 that us mere mortals could afford to buy. The. Falconer V-12 is cool, but you won't see many in street rods. Nelson Racing Engines have an aluminum block DOHC V-8 with up to 500ci displacement, but it has a billet block. I don't even want to know what that costs.

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Found on the Interweb.

A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft.

Since each cylinder bank is essentially a straight-6 which is by itself in both primary and secondary balance, a V12 is automatically in primary and secondary balance no matter which V angle is used, and therefore it needs no balance shafts.

A four-stroke 12 cylinder engine has an even firing order if cylinders fire every 60° of crankshaft rotation, so a V12 with cylinder banks at a multiples of 60° (60°, 120° or 180°) will have even firing intervals without using split crankpins.

By using split crankpins or just ignoring minor vibrations, any V angle is possible. The 180° configuration is usually referred to as a flat-12 or even a boxer although it is in reality a 180° V since the pistons can and normally do use shared crankpins.

Edited by Force

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Found on the Interweb.

A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft.

Since each cylinder bank is essentially a straight-6 which is by itself in both primary and secondary balance, a V12 is automatically in primary and secondary balance no matter which V angle is used, and therefore it needs no balance shafts.

A four-stroke 12 cylinder engine has an even firing order if cylinders fire every 60° of crankshaft rotation, so a V12 with cylinder banks at a multiples of 60° (60°, 120° or 180°) will have even firing intervals without using split crankpins.

By using split crankpins or just ignoring minor vibrations, any V angle is possible. The 180° configuration is usually referred to as a flat-12 or even a boxer although it is in reality a 180° V since the pistons can and normally do use shared crankpins.

Like I said...

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Yes, but it also says by using split crank pins or ignoring minor vibrations you can do a V12 any angle you want...and that's what I meant with my first reply in this thread.

Edited by Force

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Yes, but it also says by using split crank pins or ignoring minor vibrations you can do a V12 any angle you want...and that's what I meant with my first reply in this thread.

You are correct, and I also mentioned split or offset crankpins in my post. The 60 degree (or multiples thereof) V-angle between banks is still the preferred layout. All you have to do is look at the beautiful symmetry of the Lambo crank, and you know why.

Split crankpins and "ignoring minor vibrations" just aren't parts of my particular definition of good engineering.

Your opinion may differ. B)

Edited by Ace-Garageguy

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You are correct, and I also mentioned split or offset crankpins in my post. The 60 degree (or multiples thereof) V-angle between banks is still the preferred layout. All you have to do is look at the beautiful symmetry of the Lambo crank, and you know why.

Split crankpins and "ignoring minor vibrations" just aren't parts of my particular definition of good engineering.

Your opinion may differ. B)

To build on what you've said, Bill, in my opinion there are no "minor vibrations" in high performance engines. Odd vibrations are an engine's way of telling you it is slowly (or not so slowly) killing itself.

Now, the beauty is that in the model car world, none of these inconvenient realities matter. Our "Hot Rod Shops" have unlimited budget and the best talent that unlimited budget can buy. They can accomplish anything we can imagine.

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You are correct, and I also mentioned split or offset crankpins in my post. The 60 degree (or multiples thereof) V-angle between banks is still the preferred layout. All you have to do is look at the beautiful symmetry of the Lambo crank, and you know why.

Split crankpins and "ignoring minor vibrations" just aren't parts of my particular definition of good engineering.

Your opinion may differ. B)

No it doesn't and I agree with you fully.

I never said it was a good idea to do a V12 in the 90º angle, I just said it was possible to do it if one want's to... the 60º angle is of course a better design for a V12, otherwise most of the manufacturers wouldn't use it...or multiples thereof.

Edited by Force

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They all run smooth and get 35 MPG in plastic. :)

Exactly. And they sound bloody awesome.

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