build a bigger engine the hard way

[ericjon262]

I've seen a couple of these done, and was thinking about one day, doing it myself. with two V6's for a 7-ish liter V12 the hard part I see, is welding the heads and blocks together lots of preheat and jigging, obviously you'll need cams ground and a crank made, engine management could also get a little tricky as there aren't many V12's out there, maybe aftermarket.

anyone done it before? got any pointers? here's a couple examples using V8's.

https://youtu.be/YAfoe5ncm9M

https://youtu.be/4ssA_O4GGhA

[DaveMcLain]

You could call Steve Demos at Demos' Cams and ask him because he ground the cam for a guy who made a V12 out of two Ford Windsor small block engines. I believe he said that it runs as two in line 6 cylinders offset 90 degrees from one another.

Or you could do it like my friend Wes did it with two 429's and just make a coupler:

https://www.youtube.com/watch?v=ciQzp8B8sLU

[PackardV8]

Been attempted many times over the history of the IC engine. Those trying to weld pairs of iron heads and blocks were problematic. Starting with aluminum heads and blocks makes it possible for an individual with some welding talent in a home shop to accomplish this.

But yes, it's definitely the hard way. The easy way is to begin with a very large CNC and a very large budget.

[ericjon262]

But yes, it's definitely the hard way. The easy way is to begin with a very large CNC and a very large budget.

Sure, but what's the fun in the easy way! BTW, I would bet money the cadillac 16 engine wasn't welded.

[MadBill]

I saw a head casting at PRI a number of years back; it wasn't welded. There was a sign at the (?) booth asking us to guess what it was from. The rep said I was the first to ID as being for the The Cadillac Sixteen.

[PackardV8]

BTW, I would bet money the cadillac 16 engine wasn't welded.

That was exactly the point. I said welding is the hard way and CNC and a lot of money is the easy way (and by far the most likely to succeed).

FWIW, one of the first attempts I ever saw to "build a bigger engine the hard way" was in the late 1950s and involved boring the cylinders out of a flathead Mercury V8 and welding in sleeves. It was going to be the ultimate cheater in the hobby stock class. A very experienced welder employed at US Steel spend weeks unsuccessfully chasing leaks. He had access to a commercial furnace and despite being known as the best iron welder anyone had ever seen, he couldn't make it work.

[ericjon262]

BTW, I would bet money the cadillac 16 engine wasn't welded.

That was exactly the point. I said welding is the hard way and CNC and a lot of money is the easy way (and by far the most likely to succeed).

FWIW, one of the first attempts I ever saw to "build a bigger engine the hard way" was in the late 1950s and involved boring the cylinders out of a flathead Mercury V8 and welding in sleeves. It was going to be the ultimate cheater in the hobby stock class. A very experienced welder employed at US Steel spend weeks unsuccessfully chasing leaks. He had access to a commercial furnace and despite being known as the best iron welder anyone had ever seen, he couldn't make it work.

Your results may vary, but if one has to ask "anyone done it before? got any pointers?" chances of success don't seem likely.

that's fair.

the cad 16 was all cast. this isn't something I'm planning on tackling anytime soon, just looking at ideas for a future build I would like to make happen.

I have a few ideas kicking around, carefully machined plates installed along flat surfaces, and installing shafts in the journals for the cams and crank, to facilitate alignment during the welding processes, very carefully machining off the ends of he heads and blocks to make as close to a perfect seam as possible.

[pamotorman]

But yes, it's definitely the hard way. The easy way is to begin with a very large CNC and a very large budget.

Sure, but what's the fun in the easy way! BTW, I would bet money the cadillac 16 engine wasn't welded.

that engine was built by Katech for GM

[PackardV8]

that engine was built by Katech for GM

http://katechengines.com/street_perform ... rtrait.pdf

I have a few ideas kicking around, carefully machined plates installed along flat surfaces, and installing shafts in the journals for the cams and crank, to facilitate alignment during the welding processes, very carefully machining off the ends of he heads and blocks to make as close to a perfect seam as possible.

You have the physical concept correct. The devil is in the details. The more successful attempts keep the crank mains, oiling, cooling, intake and ignition separate. It's trying to join those internal passages which make the welding difficult. If one were to try to machine off enough front/rear block and head material to result in an even bore spacing, all manner of difficulties present.

FWIW, most industrial modular engines keep the cylinder heads separate units of two, three or four as they expand the block and crank up from V6, V8, V12, V16.



Just for the sake of discussion which two V6's for a 7-ish liter V12?.

[psychomotors]

that engine was built by Katech for GM

http://katechengines.com/street_perform ... rtrait.pdf

I have a few ideas kicking around, carefully machined plates installed along flat surfaces, and installing shafts in the journals for the cams and crank, to facilitate alignment during the welding processes, very carefully machining off the ends of he heads and blocks to make as close to a perfect seam as possible.

You have the physical concept correct. The devil is in the details. The more successful attempts keep the crank mains, oiling, cooling, intake and ignition separate. It's trying to join those internal passages which make the welding difficult. If one were to try to machine off enough front/rear block and head material to result in an even bore spacing, all manner of difficulties present,

Just for the sake of discussion which two V6's for a 7-ish liter V12?.

Are you talking about the old GMC 305 v6?

[pdq67]

Jack,

I don't know if you can find the link, but years ago, a Father and Son welding team took two 350 SBC's and put them together to come up with something like a 705" engine.

Also look to the 702" GMC V-12 engine.


A Look Back at the 702ci GMC Twin-Six V12 Engine

http://www.enginelabs.com/news/...the-702ci-gmc-twin-...

Here’s a mythbuster: The GMC Twin-Six V12 is not two V6 engines welded together, although at first glance that’s the immediate reaction. “The block is one-piece ...

Might be easier to use two 215", BOP V-8's since they are all aluminum. A big man can pack one right off, they are that light.

I looked into doing this and also B&S'ing them at the same time to max out the displacement. At that time I had both, an Olds and a Buick so had 1/2 the battle won.

I figure David Ray, (aka, Ignitionman) can help you with these little light weight jewels..

pdq67

[psychomotors]

Oops, sorry. I meant the old 351 v6. I had a 305 v6 and that was stuck in my head. Like pdq67 said, it's not really two engines put together .

[ericjon262]

I was planning on using two GM high feature V6's. stock bore/stroke puts you at about 435 (7.1 L) cubic inches, up to about 600 ish hp at the crank depending on varient used, assuming no other changes ignition would be coil per cylinder, possibly direct injection. cooling and oiling get complicated pretty quick though, that's a long way to send coolant, and I could see the back cylinders running quite a bit hotter than the front.

[ericjon262]

the GMC V12 is a cool engine, but very archaic, and heavy as hell!

[midnightbluS10]

Didn't Steve Morris recently do a V16?


For the Devel Sixteen


http://www.enginelabs.com/engine-tech/e ... 16-engine/