questions about building a motor:

NYSpeed Automotive
1

well guys, im looking into the possibility of building up my motor, and im curious about a few things. for one, is it absolutely nessesary to have the crank balanced? could i just pull the old pistons/rods out and throw my new ones in, never touching the crank/bearings? if i want to put in billet main caps, do i need to replace the bearings, or can i re-use the existing ones? will i need the sleeves honed lightly before putting in new pistons, or does it depend on the shape of the walls?

thanks in advance, i though i would ask here because i trust you guys better then the focus community, they are all name brand and bolt on parts humpers

2

i wouldent reuse the bearings, hell no

3

even if i leave the whole crank assembly alone? just putting new rods/pistons in it?

4

dont be cheap on parts that are cheap… call it insurance.

5

bearings are so cheap anyways, you’d be crazy NOT to replace them while its out.

6

Technically speaking, the crank should be balanced from the factory. If it isn’t, you should burn the car.

When you buy pistons and rods, they should be weight balanced as a set.

If you have an accurate scale, you can always balance them even further by taking SMALL (VERY SMALL) amounts of material off in non-critical areas. But, you really shouldn’t have to because any good reputable manufacturer should send them to you weight balanced. (ie. each piece weighs the same, or very close.)

7

so basically, i could take out everything, put new bearings in, torque to specs, and be done with it all DIY?? no sending out for balancing?

im pricing it out because i can buy a fully built shortblock from Focus-power.com for roughly $2700, and if i can do it cheaper myself with my spare motor, i wont waste the money, although i can also get a fully built stroker shortblock for $4k.

8

it should cost me about $1400 for the pistons, rods, rings, wrist pins, and billet main caps. otherwise i would just need the ARP studs and ford replacement bearings.

how hard is it to actually do the build?

9

What are your power goals? That will dictate what you need to buy. If you have some mechanical ability assembling it shouldn’t be a problem. I rebuilt my engine having never done it before, and so far it has run like a dream. :knocksonwood: You probably need someone to put the piston and rod package together, but the rest you should be able to DIY.

10

if ur gion this far make the storker motor…you will decrease spool time and make some trq gains.

11

well, my power goals are up in the air, im just figuring out what i CAN do. i would love to do the stroker motor, as it is a 2.3 instead of 2.0, and i would need a larger turbo, meaning i could probably jump to the gt30r and make some seriously rediculous power. but its all about the $$$$ right now, and im looking at either having to go AWD if im putting that kind of power down, and unless i get sponsored thats not going to happen, especially since i would be the only AWD focus existing

12

you dont need awd for that power…you just need good tires and low boost through first.

13

Yes it is ABOLUTELY necessary to balance a crankshaft when you add new rods and pistons unless you are just replacing them with factory parts that weigh the same amount. So if you put in heavier forged pistons and rods then yes it will have to be balanced for a different bob weight.

Rods & Main bearings are very cheap in relative terms to other engine parts and it would be foolish not to replace them.

Billet Main cap - not sure on the Focus engines but most billet main caps require a line bore or at the very least a line hone to mate the caps to your engine. The caps some slightly undersize, egg shaped because of this.

If you intend on using new pistons and I will assume new rings then yes you MUST hone the cylinder walls to break the glaze and give the new rings a new surface. This is very critical in ring sealing and making good power. The finish of the walls will be determined by the material on the rings you use.

Anyone who tells you different…turn around and RUN

14

Exactly what I was about to post… don’t mess with engine parts… it will cost you 3-4X as much to do it over again, then it would to spend the time and $$ the first time and do it right.

15

Do it right or do it twice. Don’t skimp on machining and balancing, or even new bearings that could potentially cost you the engine down the line.

16

Wow 13 posts before that came up. That was the first thing I thought.

17

I would inspect the cylinder walls cross hatch. chances are if the motor is low miles the cross hatch will be fine and you will be able to get away with it. I agree with jnj about honing but isnt as necesary on small displacement motors. But im sure everyone will disagree with me and call me stupid even though ive built plenty of motors.

18

you should have started with the 2.3 liter block, idiot

19

YOU always rehone the block when u install new pistons, even if the crosshatch is still there, you need the new crosshatch to seat the new rings!!! alll the time no exceptions

yes you should use new bearings, they are cheap, and again always do it

as far as balancing…

balance each piston/rod combo to the lightest one, your crankshaft is balanced from the foctory, so unless u have the crank reground this would be fine

dont listen to JNJ… well he is JNJ and always likes to have a contradictory point to every thread…

20

BTW i built my motor myself, and i put almost 6k miles on it already @ 300whp and its still great… as long as u meaure and plastiguage, there is no special anything that needs to be done