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We need a big V-12

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We need a big V-12

OliverHevvy OliverHevvy
New User | Posts: 9 | Joined: 05/14
Posted: 05/29/14
01:58 PM

So, we keep making V-8 aftermarket blocks and cranks that push displacement up. 600+ CID is doable now, more in some cases.

Puny. What we need is something around, say, 1710 cubes. Which, coincidentally, is the size of an Allison V-12.  ;-)

I'm serious. I'd like to see Dart, Edelbrock, Crane, and the other vendors create the blocks, cranks, heads, and other things we'd need to build build V-12s.

The computer guys call this "open source" - we'd settle on some basic dimensions, such as bore spacing and deck height, and let the designer at the major vendors pool key CAD drawings for bolt holt placement and such, so that all vendors can participate.

I'm not suggesting an _exact_ copy of an Allison, just something in that size range. With bore and stroke of about six inches each you are in the 1700-1800 cubic inch range for a V-12. And, incidentally, a 1200 CID V-8. Or a 900 CID inliner, for the old skool crowd.

Yes, the engine would be expensive to buy. But so is a modern 1000 HP V-8. A truly big motor will make that kinda power, and more, without any fancy parts. And a heck of a lot more with a little work.

Also, you wouldn't have to design every part from scratch. Big truck diesels have dimensions in this range. If you build a four-valve head, like the Allison had, the valve sizes you need are about the same as current big automotive V-8s.

So, let's get thousands of enthusiasts to start pestering the vendors to get started on this!  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 05/29/14
03:06 PM

BIG allison V12s needed all that cubic inches as they needed to keep the RPMS LOW to stop the propeller tips from going supersonic..

read this article for reference and a good loud laugh..

what would be the application??? aftermarket already supports oil field production with complete aftermarket big block chevy motors..  as gm ended the big block production..

is this going to be for cars??? pickup trucks??? at higher RPMs.. there is the torsional issue with V10 and V12 and V16 cranks.. they tend to have more rotational deflection that you have to damp with ever larger harmonic dampers.. so you don't reach the harmonic frequency and  shatter the crank..

a motor that large would need extra large crank main journals .. so you could have a nice wide connection between the  main and rod throw...  some have a small cross section of material between the main and rod journals..  and that's a weak point..

with the advent of 3D printers..  you could actually draw the various components up in CAD.. use CFM to calculate coolant flow and heating needs..  then instead of printing a prototype... Print the  sand casting tooling. either in positive or negative.. hint..   create a negative to produce high strength concrete  sand molds.  from there its only assembling the sand cores and the external dies.. and look back at the saturn engine production.. they did expanded poly styrene positives. glued together.. packed the sand in and around them.  hardened the casting sand ... then bottom fed the complete sand casting .. the molten aluminum instantly vaporized the expanded poly styrene and  perfect cast aluminum blocks and heads were made

there are already ENLARGED versions of big block chevy motors available..  not just bored and stroked.. but actually enlarged in all dimensions..  i think it was around 30%. might have been 40% increase in all dimensions..

money will get you anything you need if you ask the proper person..  

OliverHevvy OliverHevvy
New User | Posts: 9 | Joined: 05/14
Posted: 05/30/14
03:19 PM

Well, "need" is of course a relative term. We don't _need_ blowers, nitrous, 600 cubic inches, etc.

But we like them!   ;-)

I'm aware of at least one shop that has, in effect, scaled up a BBC to around 1000 cubes. Good for him! But asking one small shop to take on all the engineering involved is asking a lot, in both manpower and money,

I think a BIG V-12 would find a substantial market, in power boats and in serious custom hot rod cars and trucks. Wouldn't it be cool to see a roadster with a nice polished V-12 up front, under its long louvered nose?

It's certainly true that you cannot spin a long-stroke motor as fast as a shorter-stroke motor, but a six inch stroke is still good to well over 4000 RPM.

And think of the sound!

Allison V-12s, and especially its close cousin, the Merlin V-12, gave long and reliable service in both warplanes and later in commercial service. I doubt there are any design challenges that modern engine designers, with the better materials and design tools at their disposal, cannot do better than the original. But if that's not the case, let's start by just copying the original, and then developing from there.

I've never been able to find an ad for a used Allison for sale. They do change hands now and again; you see them turn up in tractor pulls and such. I've heard rumors that even a well-used one sells for well over $100K, so if the industry can create new ones, there is clearly a profitable, if small, market.  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 05/31/14
10:06 AM

in boat racing.. i can see the need..  but as i don't follow that  very much.. and i see turbines in many boats.. i have one major comment. on turbine boats..

when boat builder design the Hull.. add a long duct thru multiple bulk heads with the openings at the top.. so airflow for the engines. goes around the long way and thru different size chambers to allow any water to drop out of the airflow.. saving the turbines from salt water damage... saving the race and perhaps winning a few more.. at least finishing the races  proper planning would create a duct structure that would increase hull strength.. increase side impact resistance into the cockpit from collisions with other boats.. as rare as that is..  yes.. i am talking about a pair of horseshoe shaped ducts that wrap around  the cockpit..

i have also wanted for Drag boats and hydroplanes to have a very strong wheelie bar structure mounted to the transom with additional structure inside.. that if the bow of the boat pitches up.. the end of these wheelie bars has a shovel scoop on it that will catch in the water and drag the hull back down before it can become air born.. it does not need a big scoop to perform this. it would be above the water while underway..