How balanced is a stock engine?????

[dude]

Rather shockingly the latest one I have balanced is not at all, 3.5 grams diff lightest to heaviest con rod big end (not the whole rod just the big end and 5.1 gram between pistons, I only just managed to take enough out of the heaviest piston to get it the same as the lightest, maybe this is just a friday afternoon special but would you want to rev that to 7500 like we are told is fine!!!!!!:blink:

[hodge]

Total off topic John but how do you go about balancing an engine as in pistons and rods.

Just interested really.

[Chris Wilson]

The 2JZ-GTE seems a lot better balanced, on average, from the factory, than a Nissan RB25 or 26 engine, but neither seem very good. I only have a relatively small sample base of course. If you compare with pre 1998 Volvo engines a Volvo balance factor is like a Swiss watch.

[CanisLupus]

Got to love the T5 Volvo Engines

 

I'm a little Shocked that the 2JZ is balanced so bad :\

[j_jza80]

If you compare with pre 1998 Volvo engines a Volvo balance factor is like a Swiss watch.

 

I guess that explains the galactic mileages these things can cover?

[CanisLupus]

Yep also the rest of the Engine is built very durable. Mostly small things that fail on the Volvo Engines(experience from the German Volvo Forum I'm at and my own S40 ).

[Tricky-Ricky]

The 2JZ-GTE seems a lot better balanced, on average, from the factory, than a Nissan RB25 or 26 engine, but neither seem very good. I only have a relatively small sample base of course. If you compare with pre 1998 Volvo engines a Volvo balance factor is like a Swiss watch.

 

I shudder to think what the VQ35DE is like then, with a red line at 6,600RPM:scared:

[dude]

Total off topic John but how do you go about balancing an engine as in pistons and rods.

Just interested really.

 

Weigh the pistons and find the lightest one, then get all the others to weigh the same, I do mine in a lathe. The rods are trickier, first weigh all the big ends, find the lightest and get all the other big ends to weigh the same then weigh all the rods, find the lightest and take material off the little end till they all weigh the same, don't forget to weigh the gudgeon pins to make sure they all weigh the same, I'll try and get some pics up tommorrow.

[dude]

Got to love the T5 Volvo Engines

 

I'm a little Shocked that the 2JZ is balanced so bad :\

 

This is the worst Ive seen by a long way, most customers go forged and CP's will all be very close to each other, the rods are normally within a gram and a half at the big end, its almost like these are not matched sets as the rods for example vary a lot engine to engine but normally as a set of 6 they are fairly close.

[hodge]

Where abouts on the piston do you take the material off. Just scum the top?

[dude]

Where abouts on the piston do you take the material off. Just scum the top?

 

No dude FFS don't take anything off the top, you will end up with about 6:1 compression!!!! Inside the piston on the inside of the skirt, I'll post some pics.

[hodge]

I'm not about to do it lol. Just interested how really.

[dude]

A little vid and a couple of pics

 

http://www.youtube.com/my_videos_edit

[dude]

Just trying something

[sdistc]

Is the process similar to wheel balancing - in that, you use a machine to determine where to remove weight (i.e. from a specific part of the rod/piston/pin) in order to improve 3-dimensional balance?

[Wez]

Interesting.

[Swampy442]

Not really Andy, wheels rotatate so they need to be dynamically balanced and any small difference in weight gets magnified as speed increases, pistons reciprocate so static balancing is enough.

[dude]

Is the process similar to wheel balancing - in that, you use a machine to determine where to remove weight (i.e. from a specific part of the rod/piston/pin) in order to improve 3-dimensional balance?

 

Thats how we do the crank and flywheel, exactly like a wheel balancer, it tells me where to and how much weight to take off or add on if I choose to do it that way, but heavy metal is quite dear so if poss i always remove weight.

[dude]

Not really Andy, wheels rotatate so they need to be dynamically balanced and any small difference in weight gets magnified as speed increases, pistons reciprocate so static balancing is enough.

 

[sdistc]

Not really Andy, wheels rotatate so they need to be dynamically balanced and any small difference in weight gets magnified as speed increases, pistons reciprocate so static balancing is enough.

 

Thats how we do the crank and flywheel, exactly like a wheel balancer, it tells me where to and how much weight to take off or add on if I choose to do it that way, but heavy metal is quite dear so if poss i always remove weight.

 

Cheers, thanks boys. I thought that there may have been some component of elliptical motion (well, primarily with rods) in the cylinders which might need balancing.

[Guigsy]

No dude FFS don't take anything off the top, you will end up with about 6:1 compression!!!! Inside the piston on the inside of the skirt, I'll post some pics.

 

i can just picture him with a piston in a vice going at the top with a chisel and hammer then adding some weight with a soldering iron. Weighing it with a bathroom scale

[hodge]

i can just picture him with a piston in a vice going at the top with a chisel and hammer then adding some weight with a soldering iron. Weighing it with a bathroom scale

 

Give me some fecking credit will ya. I didn't know, that's why I asked.

[jagman]

What year was the engine?,I think I remember Reading somewhere there was an assembly plant change at some point in production , due a dramatic change in production numbers circa1996???

Or maybe someone had too much Saki the night before?