If I understand correctly, the LTx engines are externally balanced. So, does it hurt or help for the internal components to be balanced on a rebuild?

I'm thinking about going with a forged crank and rods - worth the extra $$$? The car is a daily driver in the summer, stored winters, never been to the track but may do that sometime. I don't mind spending a little extra money if good components will help make the engine outlive me.

All SBC are neutral balance at front EXCEPT 400ci
2 pce seal engines are internal balance at rear EXCEPT 400ci

1 pce seal engines (late L98 /LTX ) are external balance at rear; they have a counterweight on the flexplate.This was required because the round crank flange on the 1 pce seal crank didn't allow for the conterweight to be placed there

When you rebuild you get the rotating assembly with flexplate and balancer balanced as a complete assembly , preferibly to stock balance configuration.That way you can buy a off the shelf flywheel / flexplate anytime in the future.

Forged is nice but the better quality cast steel cranks (SCAT / EAGLE) are supposed to be good for 450Hp.

Get the internals balanced. It's the best thing you can ever do.

A properly balanced engine will not put out any more power, but it will do it seriously more reliably.

Forged is always the better part, no question. However, if you are not abusing the engine, I don't see the benefit. Then again, if you plan on holding on to this car for a long time, forged is a good investment.

Think of it this way, balanced, forged components, then driven as a stock type car, the engine should almost last forever.

Then again, the build has a lot to do with it. This is where "blueprinting" comes into play.

I don't know how GM builds engines. However, room temperature, part temperature and such are very important to meeting tolerances. Blueprinting is when an engine is built as close to all mfg tolerances as posible. This, again, won't result in a lot of power, but it will result in a ton of duribility.

One other point to add after seeing VetteOz's post.

The flywheel. You see, the DMFW your car uses IS the external balance. That piece is EXPENSIVE. If you get the engine internally balanced, you can now buy a cheaper steel SMFW, get it neutral (or zero) balanced and be on your merry way.

The DMFW is about $700, no matter how you cut it.

I will most likely stick with the DM flywheel - I have read too many negatives about the noise of the lighter weight ones.

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Don't neutral balance the engine. Balance it to a OE flywheel like vetteoz says.

There is no argument of cheaper flywheel, since OE replacement flywheels are the same price as neutral balance flywheels and it's a lot easier to say "I need a flywheel for a 19xx Corvette" when your on the phone with mcleod, RAM, and so on.

-- Joe

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The same is true of the less expensive cast parts. Cast parts don't wear more quickly than forged parts, they just aren't as strong. If your "driven as a stock type car" isn't built to produce a lot more power than stock and it is "driven as a stock type car" the cast parts will last just as long as the forged counterparts. My poor old 1984, with 165,000+ miles on it, is worn out. It has probably in excess of 800 quarter mile passes on it and my cast iron crank shaft hasn't broken yet, even under the strain of slightly more than stock horse power. What ever wear that crank has, wouldn't be any less if it were forged. Forged is stronger, but no more wear resistant.

When an engine is balanced, all the components of the rotating assembly are made to be equal weight. The piston weights are equalized, the big ends of the rods, the small end of the rods, piston pins, etc. are made equal weight within a small tolerance. A bob weight is made up for each crank throw, based on the total weights of the rotating and replicating components. Then the crank is spun up and balanced. The balance is achieved by removing weight from the crankshaft in the proper places. If there isn't enough weight in the crank at the right place, it can be added to the flywheel (flex plate) at the rear or the damper at the front as the factory does in some cases. To a point, the more accurate the balance, the smoother the engine will feel and the less the strain on parts as it spins up. The higher you rev it the greater the forces of imbalance and the greater the importance of the balance accuracy. Confused yet?

RACE ON!!!

Yea, what CFI said. The forged stuff will live longer at high RPM. Fogred would be better if you're going to redline the car all the time, but your's is a street driver.
Forged components would not have prevented tha spun bearing you have.

Balancing (per above) is definately worth the cost since the motor's at a machineshop anwway.

Blueprinting is a different deal. It is building to specs but it's more for the next time you pull the motor apart. You blueprint the motor and do a build sheet so you know exactly what parts wore and by how much. It's not something you normally do on a street motor.

I'm gonna print all this on one of those yellow sticky things and paste it on my forehead :-P

Thanks, all!

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Depends. I used to be cheap, but considering the cost is usually only a few hundred dollars (ok maybe $500) to balance a rotating assembly, mock it up and deck the block to be within my typical quench spec of .044", I build everything that way no.

Besides, even on the street, if you can get away with a little more advance to build power at the same octane, why not? It's free horsepower.

-- Joe

This is an interesting tidbit:

http://forums.corvetteforum.com/c4-te ... s-dual-mass-flywheel.html

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I totally agree, Joe. Especially on the balancing, the deck heigth/quench probably depends on what the budget is and what Brad wants out of the build.
The extra money to do a full blueprint, recording cyl. bores, piston dia., ring gaps, spring pressures, etc. usually isn't done.

Speaking of budget, what kind of ballpark do y'all think I should be looking at spending? Assuming my block is in good shape, using decent quality components, getting it balanced properly, etc.? Maybe also some moderate port work on the heads and intake. Again, it's a driver, not a track car, so durability is my highest priority.

Does engine need full build; as in rebore?
If so make a 383.
$300 extra for a stroker crank ; zero if you were planning on upgrading crank.You have to buy new pistons anyway to suit rebore

For what you are describing, I don't think the forged parts are necessary. If you were to go that route, I would do forged pistons first, then the rods, and finally the crank. It doesn't sound like you plan to make power, use a power adder, spin it, or really abuse it; so I don't see the benefit of the forged parts.

If it were me, I would do forged pistons, cast rods, and a cast crank. Maybe some budget forged rods if I had a good week at work. The only reason I would do that is because I know that eventually I'll put nitrous on the car. The added insurance of the forged parts is great when using a power adder like nitrous.

I'm not a metallurgist or anything, but I've been told that the forged parts change size more than a cast part as the engine warms up/cools down. That size change would be wear inducing; so if the rumor about forged parts growing/shrinking is true a forged set up could actually wear faster than its cast counter part.

I agree with building it to OE balance as opposed to neutral balance.

I had my 383 LTX stroker internally balanced (see the heavy metal slugs put in the counterweights) it's going to be much easier on the bearings.



BTW the counterweight on my dual disk flywheel simply unbolts.