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Hello guys this is my first post on your forum. I come here seeking info and I think I know what I want. i just cant quite seem to find a post on here already with the exact info I am seeking

I have played with 5.9's in the past so I have a basic idea what is going on. The project is a 1964 British Abbot-105. (AKA a british TANK with a 105mm gun) They have a 6 Cly. 12 piston engine from the factory. Two pistons in each hole that meet top to top (dome to dome) with 2 crank shafts. They are 2 stroke 240 [email protected] I am repowering it with a 5.9. At least working with a 5.9. It requres me to cut into the Turret area and give up ammo storage, not that I need it but its alot of extra cutting.

We have been working with a 5.9 CPL 1551. It is 190hp and 445 TQ. We want to use the allison AT 545. We put it in just enough to test drive to see the power compared to the 240 HP 2 stroke. It had PLENTY of power. Just right and maybe just a little extra. SO the big question is.....I have read around and am fairly sure I can get the power and it will live but what combos will do it and what do I look for in a motor to buy? It is a 30,000 LB rig and is geared for 16MPH at 2800 RPM just to give you an idea. The vehicle will be used to let people drive it so I cant be watching the pyro all the time.

A 4BT over a 6BT would help make motor swaps MUCH simpler and better in the long run.

If any one might be interested in pictures check out www.driveatank.com
Thanks in advance and happy hot rodding
-Tony
 

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this is one of those posts where you dont have any good info to give except just to say how cool of a project you have! :beer:
 

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In the images Tanksgiving is it 5, 6, 7 or 1 & 14 or another unit?

Anyway, my donor van was huge and rated at 17,500 GVW. It had highway gears and a toasted 3 speed automatic transmission. I only drove it empty so no idea how it performed at full load. Empty it had lots of power.

In your swap due to the heavy weight I'd say gears, gears, gears. But I say that about any swap :) Still, even at that weight, and with such a low top speed, I think you'd be okay with a 4BT. Nobody is going to sue for acceleration induced whiplash, but it should move it okay?

Also it seems nobody is going to have much idea what it's full power characteristics should be, nothing to compare to. Seems the big thrill would be getting to drive it and snap a few pics to pass around at work.
 

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Excuse me, WELCOME! I guess I got a little whacked by the whole thing myself haha! Yes, one heck of a unique idea, probably the only of its kind in the history of the world! Have fun!

Another thing: far as I know 2 strokes aren't the torque monster that a 4 stroke is? That 4 stroke cycle itself might make up for some losses....
 

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Discussion Starter #6
JimmieD, Check out the "tanks" page. It is the 433 Abbot.

yes, the 2 stroke thing kinda sucks. Like I said we chopped the hole and stuck the 5.9 in and just hung a gas can on it, cobbled the coolers, and ran an elbow onthe exhaust to see how it would perform.

The Two stroke is a bigger dog than I thought. The stock allison had a 7:1 and the 545 is only like 3:1. That is why I was not quite sure about power, well the 5.9 was truely "neck snapping". It makes the front of the vehicle lift about 8 inches during full power from a dead stop. I found it truely crazy, and even have been considering moving the fuel plate in the SLOW direction to save wear and tare on the parts down the line.

15 MPH might seem slow on the interestate with a truck but let me tell you on our path with a tank it feels like you are going 50 through town in a truck. Thats why If I had the same power as my 1551 it has more power than it did stock and with a little less it would seem like it was stock.
 

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I'm glad to see that you got things worked out with the city/county. I personally would go with a 4BT even if it is lacking in power. I don't think that the drivers are going to notice the difference in power and if it keeps operating costs down while saving room on the installation, why not? I will have to stop in anf say hello sometime. Good luck with your swap!
 

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You can always hop the 4bt up to the stock 6bt specs if the stock 4bt in not enough. In this day and age you don't want to short yourself on ammo. Your awful close to the invaders from the north.
 

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Discussion Starter #9
Screamin Seeman, Your welcome to stop in any time, there is usualy some one around here. Not ALL is well with the county, the neighbors are still sure that my 30,000 pound vehicle will DESTROY the whole county and some one will steel it then go destroy the city with the gun that does not work.

None the less I still press forward!

Kaptar, Do you think that a 105 BTA would go to 190hp 445Tq. and work well? That is what my idea was but some times getting HP is one thing and getting enough air through the ports to cool it when you can work the snot out of it is a whole new ball game.
 

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just my 2 cents, but it has been my experience that a bigger engine not working very hard will last much longer than a higher stressed little one.
 

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I agree with you 100% its a give and take. The angle I am taking is that it will probably only go to full power 2 times a day for less than a minute each time. Thats why I'm not sure that it pays to carry a whole 6BT around just to use a couple times a day. Thats where I figured it would be better to just give up a little motor life than carry around a bigger hunk of iron. At least thats the ange I was thinkin, just looking for some one elses thoughts.
 

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My experience is upto about (guestimation) 160hp and about 400 ft/lbs 4BTs are pretty good and still quiet. This takes more turbo, injectors, and fuel.. After than, especially with too much fuel at idle, they are bone jarringly loud... Cranks your bones a little, changes the pitch of them from OK to almost like an incredibly loud 24 valve Dodge when they first came out... A little food for thought, but you could quiet down by retarding. The 4BTs are like 6bts with two cyls cut off as you know. My guess is the added torque versus your incredibly odd dual piston engine (the British!)... Common stock ratings for are 105 hp 265 ft/lbs and 120/305 ft lbs. Your 190hp is probably more in the 465 ft/lbs range which is why it has so much power off the line...
 

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What kind of setup is required to get 160hp 400 ft lbs? That sounds like right where I want to be, about the same rating as a first generation 5.9. I'm getting 2 4bts delivered this weekend bounce . One will be going into a 93 cc 4x4 dakota on 33's and the other will be going into an S-10 with jeep axles and 33's.
 
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