30 replies to this topic

[luna_s]

Right, almost got my head sorted (both one on top of my shoulders and the one on top of the block ) looks like i've also managed to get a block sorted too (block,crank,rebore,new shells, fitting pistons and rods (eagle rods and wiseco pistons +0.20). So its going to be like a whole new engine, Question is, is it worth removing the balance shafts ? What benefits would it acheive, i understand they are there to stop vibrations with counter rotation, but do sap some power from the engine, coupled with a lightened flywheel, i would expect the engine to rev a lot more freely? Vocky created some nice idler gears for the bottom chain assembly, so thats not a problem, - what would be the best way to block the oilways ? Also coming up with plans to design myself an whole new inlet manifold after seeing the plastic monstrosity...

[JawZ]

can't answer your question but glad to hear about the progress of your engine rebuild... seems to come along nicely Keep up the good work

[coopa]

They don't 'sap' power, they just add to the inertia that the engine has to accelerate. Steady state power output is unaffected. The danger is that the engine could rattle like a rattley thing if you take them out. 4 pots are inherently unbalanced. Ask yourself if you are building a race car or not

[luna_s]

engines didnt need them before, so why now ? are the engines that wobbly now that they need them ? are they just there for driver comfort ? if theres absolutely no or little gain i'll just leave them as is

Edited by luna_s, 26 January 2007 - 01:49 PM.

[coopa]

Suggested reading:

wikipedia

[luna_s]

yeah, i've been reading about, general concensus is that theres no harm removing them at all, also itll remove 4kg of weight from the engine, so it cant be all that bad! just adds a bit of vibration to the cabin, and in our cars not like you would notice

[Arno]

engines didnt need them before, so why now ? are the engines that wobbly now that they need them ?
are they just there for driver comfort ?
if theres absolutely no or little gain i'll just leave them as is

If you stretch a 4 pot to 2.5L or more you start to get relatively more vibrations, so engines bigger than this start to use balance shafts. They work well as Porsche showed with the 3.0L 4-pot in the 968..

The Z22SE is a bit 'early' with using these capcity-wise, but I guess it's a leftover from the type of car the engine is normally used in where smooth running is more important than throttle response.

With a lightened flywheel and balance shaft removal the engine should become a lot more 'lively' and pick up a lot crisper than the stock setup.

As you are having the underblock done as well I would suggest you contact these guys and have them balance your crank, connrods, pistons and flywheel for you:

http://www.vibrationfree.co.uk/

Should not cost a lot, but makes the engine rev veeeerrry smoothly and is a big positive influence on the lifespan of the engine (reduce vibrations == reduce flexing == less wear)

Bye, Arno.

[chris]

IMO these balancing shafts installed on Z20LET engine are useless ...

Fisrt version of Z20LET engine has not these balancing shafts and Z20LEH engine has not too ...

If you remove them, you save 4,76 kg and about 4 bhp @ 6000 rpm, bearing rubbing eat power and not only saving of rotating inertia should be considered ...

You could see justification of saved weight and photos of these devices to this link :

http://www.garage111....php?id=105&p=2

[vocky]

cheers for the link.........link

just down the road for me

I will have to get them to sort my crank/flywheel/pistons etc


back to the thread......bin them and fit a machined collet to block the oil ways

Edited by vocky, 26 January 2007 - 04:17 PM.

[coopa]

If you remove them, you save 4,76 kg and about 4 bhp @ 6000 rpm, bearing rubbing eat power and not only saving of rotating inertia should be considered ...

Depends what you fill the holes with. Some systems use deletion shafts and others use idlers for the chain, so bearing friction is still present

[luna_s]

Just drift out the bearings and rotate them i guess,

[vocky]

an update to blank off the rear bearings you can simply push the bearing a further 7 - 8 mm into the block, this blocks off the oilway or you can remove the bearings and fit some new items with the oilways soldered up. my engine is now running without balancer shafts, tickover is steady - even with piper cams fitted, there is no noticeable difference in vibration the only difference I can tell is the engine revs easily, my vx certainly goes well

[Steve Crisp]

If the balance-shaft chain-gear is still there, together with the idler-gears, is it really of benefit to remove these balance-shafts? I need to make a decision soon and I haven't seen any conclusion either way! Steve

[luna_s]

well the chain gear isn't having to rotate those heavy balance shafts, its only there to drive the water pump, I was considering moving to an electric pump, but reliability put me off. Wait for an answer off vocky, he's running without now

[vocky]

I would certainly remove them if I rebuilt another z22se apart from the weight, my engine has a better tickover without them maybe the balancer shafts are fitted to create a smooth tickover certainly the tickover is quite low on the z22se engines. so fitting cams might disturb the balance and removing them stabilises the engine once again I kept the chain driven water pump for reliability My engine does rev lightning fast, but I do also have a lightened flywheel

Edited by vocky, 17 April 2007 - 01:42 AM.

[speedster]

vocky, where did you get your flywheel?

[vocky]

courtenay were doing a special offer on flywheels, £199 seemed a good deal, so I bought one TBH they are all probably very similar

[Steve Crisp]

Keith, Did you think about removing the idler-gears and shortening the chain? What would be the possible issues with doing that? Rgds, Steve

[luna_s]

theres no links like a bike chain, its machined - so unless you get a machine shop to do it you can't shorten it, oh and my names not keith

[Steve Crisp]

A pin-punch will generally allow chains to be shortened without a split-link. I must look at the old chain I have in the garage. I thought Vocky was Keith? I thought he'd be the one to answer! No offence intended... Steve