I didn’t say or imply that it’s not internally balanced. Most engines we come into contact with are internally balanced. We even up the piston and rod weights and balance the crank and rods. Then the internal rotating assembly is balanced as a whole (if customer requests it). Then the damper and clutch/flywheel are individually balanced (not attached to internal assembly) if the customer requests it. They don’t need to be attached to the internal assembly during balancing because the internal assembly has already been balanced.
As you well know, when you balance the internal assembly and then bolt a damper or clutch/flywheel assembly on which is out of balance, the system becomes imbalanced and that’s what we all want to avoid.
At least on the SRT, balance shafts are dangerous to have after 400+ whp. So its good to get them out on some cars. But, you can’t just remove it, you have to plug oil holes etc… Or else you get no oil presure!
When a rotating assembly is balanced, yes you modify the rods and pistons to achieve equal weights, however you say if the customer requests… for having the rest of the assembly balanced as a whole,…You must do that regardless. This is the point of balancing otherwise all you are doing is getting the rods and pistons to equal weights…that doesn’t remove any imbalance in the engine, the imbalance is removed once the bob weight is calculated and the crank is spun then balanced.
There are two different types of balanced rotating assemblies. Internal and External. This is determined by the factory. The internal setup is all calculated off of it’s internal parts. An externally balanced engine is balanced using a bob weight and the flywheel as it is attached to the crank and spun as is the harmonic balancer. Weight is then added or subtracted to the flywheel to counter act the imbalance.
I do not know of a machine shop that will balance the rotating assembly and then perfectly balance a flywheel afterward and then give it to you and tell you to install it on a specific way because it is next to impossible as you are limited by the bolt pattern.
There seems to be alot of misunderstanding of how these processes work and I’m not trying to shit on your thread but I am hoping that people who are reading this might get the correct information and not incorrect information. This is all.
Don I know you’re trying to add more information, but these engines are internally balanced so I’m not getting into externally balanced engines. You can make a gen. auto or tech thread about them if you want. These internal assemblies get balanced without the damper or clutch/fly attached. As mentioned, our customers can have those parts balanced individually if they chose. In most cases we’re installing a new SFI approved clutch/flywheel package that the customer is willing to assume is balanced well enough for their needs. Again this is their choice. Most people aren’t building something extreme enough or have money to burn that they want to pay to have their brand new ACT flywheel (for example) rebalanced when it’s already come balanced from ACT. We’ve never had an issue with this, but sure it could bite them in the rear. Of course people play the odds just waking up in the morning so at a certain point you’re just getting carried away with it.
Obviously we use common sense and every build is different. The more aggressive the build the further we go in terms of balancing etc. If an engine has to rev to 13,000 rpm the balancing choices become requirements.
Yes of course. We tell everyone the internal rotating assembly should be balanced as a unit and all our customers have agreed to this on all builds thus far. None of them have even balked at the idea, but it’s still a choice that’s made.
nissans 2.5 liter motor comes with balance shafts that are dangerous past 6 k rpm…many people remove them or atleast cut the chain connecting them to the crank…there have is issues of the shaft breaking apart in the oil pan…anyone that has cut or removed the shafts have never had any issues…even the boosted ones
If you’re serious about a build, simply PM or e-mail me exactly what you want done so I can give you an estimate.
MKIV Supra engine:
This engine came in heavily damaged by another shop. The crank was damaged due to the shop throwing a rod, then replacing it with one that was not sized properly. The block was bored more than it should have been and couldn’t be bored over again, so a different block and crank were used.
The rods were all machined out in a way that Pauter engineers described as a crime against nature so they weren’t reused either. The pistons were worn from slapping around in the bores and the engine had bad compression.
Some of the parts used:
2JZ Block and Crank
CP Pistons and Rings
Eagle Rods w/ARP hardware
new bearings and freeze plugs
The pictures REALLY don’t do this one justice, but we tried…
