my plan is to take the 318 in my '00 ram and make it into a 340, is the crank the only difference? which crank do i need? it will be getting heads and cam and a pile of other stuff on top of all the good stuff i already have. not shooting for the ridiculous, just a healthy 340 efi magnum r/t :rck:
littleredwagon
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You can't bore a 318 out that far, cylinder walls are way to thin. If you went .060 over that would net you 328CI. Why are you trying for a 340 specs? Get a junkyard 360 and rebuild that.
how does boring out a 360 make a 340? that seems kind of not possible. im afraid yall lost me here haha
yep, to get up to 340 with a 318 you'll need a stroker kit. around 1500$ or more for a kit with everything you need, including the crank, bearings, pistons, rings, and connecting rods.
Get a 360! It's not wort spending that kind of cash just to bring up the displacement of a 318. 318-360 they are just about identical except for the bore and stroke.
Mopar LA small block progression:
First there was 273, it was bored out more and became the 318 (3.91"bore). Both have 3.31" stroke.
In '71, the 360 was a redesign with larger bore (4.00") and stroke (3.58")
In '72, the 340 came out (4.04" bore), and 3.31" stroke of the 318, however it used heavy duty rods which is why 318 and 340 cranks are different in balance. Early (71-74) 360 blocks used the same internal coring, allowing the block to be over-bored to 4.10", 75-up 360 blocks are thin-wall and this can't be done.
The 360 4bbl and some early 318's use the heavy 340 rods, unfortunately all these are all pressed in piston pins. Full-floating pins went away in '73. Only the '72 340 and 318l 4bbl engine used full-floating HD rods. All LA rods are 6.123", with the same pin and rod size, making interchange easy.
Changing from HD to LD or vice-versa requires rebalancing the engine.
All of this info is in the book: "How to rebuild your small-block mopar engine".
Additional:
The TA 340 uses the large bore of the street 340 (4.04"), was utilized in Trans-Am racing, were displacement limit was 5 liters (302C.I.). A special short stroke crank was used. These engines had special heads with offset rocker, allowing the intake ports to be opened up for better breathing needed at high revs. They competed with the Boss 302 in the Mustang and rare 302 used in the Camaro, and won many races.
First there was 273, it was bored out more and became the 318 (3.91"bore). Both have 3.31" stroke.
In '71, the 360 was a redesign with larger bore (4.00") and stroke (3.58")
In '72, the 340 came out (4.04" bore), and 3.31" stroke of the 318, however it used heavy duty rods which is why 318 and 340 cranks are different in balance. Early (71-74) 360 blocks used the same internal coring, allowing the block to be over-bored to 4.10", 75-up 360 blocks are thin-wall and this can't be done.
The 360 4bbl and some early 318's use the heavy 340 rods, unfortunately all these are all pressed in piston pins. Full-floating pins went away in '73. Only the '72 340 and 318l 4bbl engine used full-floating HD rods. All LA rods are 6.123", with the same pin and rod size, making interchange easy.
Changing from HD to LD or vice-versa requires rebalancing the engine.
All of this info is in the book: "How to rebuild your small-block mopar engine".
Additional:
The TA 340 uses the large bore of the street 340 (4.04"), was utilized in Trans-Am racing, were displacement limit was 5 liters (302C.I.). A special short stroke crank was used. These engines had special heads with offset rocker, allowing the intake ports to be opened up for better breathing needed at high revs. They competed with the Boss 302 in the Mustang and rare 302 used in the Camaro, and won many races.
i want a 340 for a variety of reasons. one, i have a truck with an extremely healthy 360 r/t in it now, and it sucks gas like a hog, however my 318 truck is nearly as quick with the work thats already into it, except it gets exceptional fuel economy. i want a little more pony, im definantly shooting for a muscle car themed build, even going to run body color matched stock steelies minus the nasty trim rings, but more importantly i want to find that fine line between the decent gas mileage and enough horsepower to have some fun once in a while, plus it would be pretty cool to have a 340 powered muscle truck, so the 340 has been my plan for quite some time, definantly going that route. if i was going for all out no messin around brute horsepower full bore performance i would drop a 440 in the thing and be done with it, 360/390/410 wouldnt even be a prospect. after all its not always about as much horsepower as is physically possible, sometimes its just what you like.
not sure if you'll match a 340......like turn the 318 into a 340. stroker kits go over 340 and boring out a 318 only goes to 328 (i think). maybe you should go look for a 340 instead?
318's get better mileage because:
1. Unlike 360's, they have higher compression ratio. This because the heads have smaller chamber, and the pistons don't sit below the deck so far. This increases turbulence and mixes the fuel air mixture so it burns more completely.
2. The surface to volume ratio is better too, because of the smaller bore.
(All Modern engines are have all of these features.)
The larger bore of the 340 is the wrong way to go for best efficiency. It has been proven that cylinder bore over 4" hurts efficiency, and emissions too.
1. Unlike 360's, they have higher compression ratio. This because the heads have smaller chamber, and the pistons don't sit below the deck so far. This increases turbulence and mixes the fuel air mixture so it burns more completely.
2. The surface to volume ratio is better too, because of the smaller bore.
(All Modern engines are have all of these features.)
The larger bore of the 340 is the wrong way to go for best efficiency. It has been proven that cylinder bore over 4" hurts efficiency, and emissions too.
well if i understand correctly, to make the 318 into 340 you increase stroke, not bore, so this might be right on what i want. either way its what i want, i mean yes a 390 is great for people with unlimited money, tho its probably not that much more expensive, paying for gas sure will be! and 410 kits are awesome if you dont wanna drive the thing EVER AGAIN unless its perfect conditions and you got two spare back tires, but i have a plan set in mind and im not asking everyone here what motor i SHOULD run. i know what motor i WILL run, i was simply asking the best way to acheive that. take note folks, the thread title does not say "what engine should i put in my truck please im an idiot everyone tell me how to live my life" does it? lol. anyways SOME of you were quite helpful, thanks!
Still. You want to turn a 318 into a 340. Its not possible. Stroker kits will bring it above 340 status no matter what you do.
And boring it out brings it below 340 ci. So your stuck. No reason to hate on everyone here trying to help you. Dick.
lol im not hating on the people who are trying to actually help me, im not hating on anyone to be honest. i just hate it when i ask someone a simple quesiton and i get bombarded by stuff i didnt ask for. like if you went to a dodge dealerhip and said i want a new ram with a hemi and the salesman went "oh you mean cummins those are over here, buy this cummins its a cummins its better you should buy this cummins forget the hemi thats stupid buy the cummins." i mean, hes just trying to help, right?
its like when you go out to some gearhead event and everyones telling you dump that dodge crap and get a chevy. do you find that helpful? i dont.
is it possible to take the 318 ci 3:31 stroke crank out and swap in a 360 ci 3:58 stroke crank? use the 360 crank in the 318, custom height pistons and what KNOWT? what would that bring the compression and the volume up to? iirc the 340 ci had a 3:41 stroke.
reinventing the wheel here.
reinventing the wheel here.
may want to read here.
http://www.forabodiesonly.com/mopar/showthread.php?t=91733
i know its old stuff.
http://www.forabodiesonly.com/mopar/showthread.php?t=91733
i know its old stuff.
^ if he's bent on a 340 would probably be easier (and cheaper) to go find one, build it, and switch to carb.
To the OP: I don't think you are going to realize your fuel efficiency goals running a 'in-between' (318 vs 360) displacement engine.
If you want power and performance forced induction would be the best way to achieve that...but that isn't an option since you want a 340.
The LA 340 was designed for upper rpm HP, not torque (big bore short stroke) so I don't know how that would work out in a truck.
To the OP: I don't think you are going to realize your fuel efficiency goals running a 'in-between' (318 vs 360) displacement engine.
If you want power and performance forced induction would be the best way to achieve that...but that isn't an option since you want a 340.
The LA 340 was designed for upper rpm HP, not torque (big bore short stroke) so I don't know how that would work out in a truck.
Well you were givin the choices here by some smart people, seems your between a rock and a hard place, bore it and you come to 328ci and stroke it your over 340ci so thats your answer, good luck let us know how it tunes out!
I was wrong. how bout that. the 318 had the same stroke. the 340 just a huge bore. bigger than the 360 bore. I do remember about the 340 blocks being real thick! now the problems are: cant bore out the 318 to 4.04. all the rotary mass will be one-off design and it will all need to be blue printed and calculated for displacement and compression. what crank to use? this could be huge expensive painstaking project. really the hp could be more easily achieved.
a 3:91 bore at a 3:58 stroke. what would that displacement be?
a 3:91 bore at a 3:58 stroke. what would that displacement be?
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