My engine is getting eagle rods and wiseco pistons and my engine builder tells me there is no one locally who can do a balance for me and with the new rods and pistons it will be unbalanced which can obviously potentially cause issues such as redeuced bearing life and engine shudder etc! Want to get advice on peoples experience with the VG and whether it is really necessary I get it balanced with this change of gear? I'm tight on cash so would prefer not to if I can get away with it but if it needs it then it needs it.. Thanks, Adam
There is no need to get it balanced if you plan on doing another rebuild in the short term. Because without one, you engine will rattle itself to death within a short time.
you dont have to get it balanced, its just nicer if you do. those pistons and rods are suprisingly close in weight
May sound like a stupid question but how exactly are these engines balanced? Are counterwieghts just added/removed on the harmonic balance at the front? Also is it done just on the block before heads and accessories go on?
Adam my engine was balanced by Barbagallo's in Ayr. Cost about $500 but did a fantastic job. My engine is smooth as silk at 8000RPM. The rotating assembly with clutch and crank pulley attached is required for it to be done properly.
Here are some engine balancing videos from youtube. This channel is run by a bloke in California who owns an automotive machine shop- walks thru a lot of the fundamentals and details of engine building. Crankshaft balancing http://www.youtube.com/watch?v=08ZR89xObl0&playnext_from=TL&videos=Y1nR5w9jw_E Conrod balancing http://www.youtube.com/watch?v=QLpiF0E0EJU&playnext_from=TL&videos=2EZC8vgczM0 Flywheel balancing http://www.youtube.com/watch?v=sl8F_ZtMhNk&playnext_from=TL&videos=dcpAzxRUicA
I am using the the same Piston/Rod combo ... they are way lighter than std eg. 170gms per cylinder ... I figured with that much of a difference the engine would die fairly quickly if it were not balanced.
I had ACL pistons fitted to mine a few years back, I'm not sure if the eng was balanced or not (I doubt it was judging from all the other stuff ups they made). My bottom end has only done about 15 - 25000Kms of sometimes extremely aggressive driving, there is a knock that is getting worse & finally evidence of metal in the oil. Fairly certain a big end bearing has given up - this should not have happened this early on. Most likely cause = engine not being balanced. Balance the engine or pay the price later on.
I used Je pistons and Eagle rods - my engine balancer said required a lot of material to be removed as the weights are quite different from stock. Engine still going strong 4+years later.
You should get it balanced if you want it to last. Depending on your goals you may want to get it overbalanced but the place doing the job for you will know what is best for your car, well, should know what's best! From memory my build had an overbalance of 47%.
Overbalance http://www.circletrack.com/enginetech/ctrp_0504_engine_balancing_tech_terminology/index.html ??????????????
This is pretty interesting. Makes me wonder what was done to the race car engine before I got it. ALSO makes me want to pull it apart and check if its right. Love these sorts of threads. I always learn stuff.
Great read, thanks Wayne. I think a recent Zoom had an article on balancing but the one you have posted is much more detailed.
Sorry for the delay, I rarely get on these days. I just read that article and it basically describes exactly what was explained to me at the time, with my rotating assembly mass and lightened crankshaft, it was nicely balanced so that at around 7500 or 8000 RPM there were no vibrations. The people who balanced my RA only worked on drag cars/high performance engines, mainly V8's. I hadn't heard of it until I got it done those many years ago
Don't forget they are talking V8s in that article, V8s can not be balanced perfectly apparently, V6s can be balanced fairly well & V12s can be balanced to perfection. I'm no expert on the subject but from my understanding V8s are inherently out of balance due to the design so "overbalancing" will be used (as the article says) to cancel out vibrations at high RPM. I am not sure if that actually applies to a V6 engine - anyone got any V6 specific articles etc? I actually just started working on my new bottom end today, I've removed the casting marks etc from the crank - 500 grams gone from that alone. I have removed a similar amount of material from the opposite side to try & keep the balance close at the stage, will have forged rods & pistons going in anyway so a balance is required regardless.
