Engine Balancing

[Darryl Pritchett]

I'm getting ready to build a motor for my ITA Neon, question I have is worth the money to balance a engine? Can you expect more power out of it or just more life expenctancy?

[Ron Earp]

Absolutely. I'd expect a tiny bit more power but the big deal is longevity. Another thing you should do that will increase power a bit is have it bored with a torque plate and line bored on the crank center line to insure the cylinder bore and crank centerline are perfectly orthogonal. A lot of folks say tell you there is no power in the bottom end, so why open the motor. They are wrong.

Also, piston ring are free so investigate this for your engine....there will be builders who know how to get power using various rings. Select your pistons carefully, buy a batch and match the light ones. Degree the cams properly, the stock cams may or may not be properly ground and marked.

All those little bits of power add up to make a big deal in IT and seem to be common practice in the NE and SE.

[shwah]

Ron is right. Better life, better power with balancing and good machine work.

[Darryl Pritchett]

Thanks for the input. I should have been more specific. I actually got a great deal on a NEW Factory short block so there won't be any boring or anything. So on a new factory motor will you get the same results?

[GBugg]

Everything Ron said applies to a "factory" motor or a junk yard motor. If you want to build a competetive motor for IT, you need to do it.

[Ron Earp]

Thanks for the input. I should have been more specific. I actually got a great deal on a NEW Factory short block so there won't be any boring or anything. So on a new factory motor will you get the same results?

A new factory block should be checked for the parameters I listed. I'd be willing to bet with critical parameters of your new block are checked some issues will be found that need correcting. All the build ups I've read about with new castings generally have something that needs attention. A good builder will check to make sure your new bores are squared up, the deck is square and flat, and so on.

The boring with a torque plate is important because it creates the cylinder bore when the block is under stress and distorted. The bore might be round, centered, and perpendicular to the crank in it's normal state. But when the head is torqued on the force can change the bore shape. Boring the engine with the torque plate on means you're boring into a block under stress and you know the resulting bore will be straight and true when the head is clamped on. Having a motor built 0.010", 0.020", over is many times done on new castings so this boring process can be performed - the displacement increase isn't worth anything.

If you're going to be competitive you've got to cover all the bases. You live in FL and throughout the SE IT tough. You'll need to pay similar attention to all the details in your engine build.

And yes, even if you don't check your block like mentioned at least balance the assembly, preferably with the flywheel and pressure plate you are going to use.

[spnkzss]

Going one step further, is balancing really worth all that in a I4 motor? I completely understand when it comes to V motors, but in an I?

[quadzjr]

Like Ron said you want to balance the motor with all the accessories that you plan on bolting to the crank when it is in the motor.. (flywheel, balancer, crank pulley, etc..)

I am going to have to disagree with Ron on one point however. I don't believe that you need to line bore the motor reguardless. I believe that yourself or the machine shop will determine if the the motor needs to be line bored. Maybe they are close to perfect already? Maybe they need a light hone becasue they are too tight? In either case, I say it is worth the investigation to see if it needs to be line bored or not. Since you can only line bore your block a limited amount of times just like cylinder boring. IMHO.

[Z3_GoCar]

Thanks for the input. I should have been more specific. I actually got a great deal on a NEW Factory short block so there won't be any boring or anything. So on a new factory motor will you get the same results?

I'll provide the desent. Since it's a new short block, I'd run it for a season before I'd tear into it. Granted domestic manufacturers are noted for precison build, but they do a good job. If you blueprint now it'll move more, than if you let it go through some heat-cycles and hard use and then blueprint. In the world of Karting the best motors were those that were used first then blueprinted. Now, when you do blueprint have it ballanced too. I'm in the process of installing a stock flywheel and will definetly have my motor balanced with the new-old flywheel.

As for the cam timing, you should have picked a DOHC motor that comes with slotted cam sprockets... stock. Then the cam will be degree'ed in every time

[quadzjr]

As for the cam timing, you should have picked a DOHC motor that comes with slotted cam sprockets... stock. Then the cam will be degree'ed in every time

Some of us can't afford such luxury.. haha..