Balance Shafts in 5S

[RWDboy]

Well i've got myself a 5S motor out of a Holden Apollo in reasonable nick, I also have a 5S out of a 1990 ST184 Celica - i'm going to use most of the Apollo motor in my ST162 Celica except for that crappy FE head bollocks. As for which 3S-GE heads will fit onto a 5S block (1989-1994) I guess i'll find out soon enough.

The obvious difference between the 1st revision 5S-FE (without balance shafts) and the 2nd revision 5S-FE (with balance shafts) -> the block is slightly different at the sump as it needs mounting points for the twin balance shaft assembly, and also the crankshaft has a helical gear to drive the twin-balance shaft assembly.

So the downside of twin-balance shafts is, one thing, extra weight in the motor. I'll get an exactish figure as soon as I can. Secondly, they are 'driven' by the crankshaft and hence they consume some certain portion of power.

The up-side of the twin balance shaft is .... ??? I'm assuming that the better balance of forces means that, for one thing, engine mounts won't wear out as quick, but what about improving the ability of the engine to rev higher reliably? Would the fact that there are less undamped vibrations mean the engine block would be less likely to fatigue? I'm weighing up my options at the moment

Also if I change the weight of the piston/pin/conrod assembly will that mean that the balance shafts need to be modified as well?

[Enchanter]

I dont have experience with the shafts in this engine but in the Mistubishi 4g54 they sap a significant amount of power, they can be taken out and the only side effect apart from more power is a mild vibration at certain revs.

[RWDboy]

Well technically it should vibrate at all revs, however probably more noticeable at particular revs when there is constructive interference with other vibrations, or waves get set up between engine mounts maybe ?

Yeah older Mitsu motors had balance shafts as well, and sapped a bit of power, but then the 944 S2 (3.0 litre inline 4) couldn't have been made without balance shafts.

[cri_ag]

no actual experience with the motor in question but i helped in a rebuild of a (4g62?) mitsu cordia motor that had balance shafts, the shafts were removed and i couldent feel or hear any difference between the rebuilt motor (minus shafts) and the standard one (with shafts) and that was comparing them back to back (my mate had TWO cordia turbos )

[RWDboy]

How many cc's i the 4G62 again?

[Joshstix]

All the guys in the US using late model 5S's for 3SGTE strokers simply remove the balance shaft and leave the mount in as a kind of free girdle to keep bottom end strength up.

This is what I plan on doing when my bloody 3S throws in the towel again.

[RWDboy]

The mount isn't really that bulky, I guess every bit would help though. I would also imagine that most of them would be using much stronger/lighter conrod-piston combinations - and alot of them wouldn't care much about NVH

The 4G62 is only a 1800cc motor, and has a rod/stroke ratio that is favourable to *not* requiring the twin balance shafts (it's around about ~1.7) whereas the 5S motor has a rod/stroke ratio of ~1.5.

So from what I'm hearing/reading the balance shafts have *no* performance benefit whatsoever ???

[Joshstix]

Yep most people using the 5S block for 3S strokers are turning the crank down to 3S big end size and using forged pistons that are lighter than stock. A lot would also be using Eagle rods which are ~250 grams lighter than 3S rods, I don't know how heavy the 5S rods are.

I have to admit NVH isn't a big deal for me, I actually run a steel brace from the rear engine mount on the engine to the front mounting point on the chassis to stop the engine from torquing over and hitting the turbo on the firewall. Although it's not really noticably more vibey than without the brace.

[1UZFTTZZE]

those bloody balance boxes on the 5s always shit them selves y not go 3sgte?

[RWDboy]

Because a 3S-GTE doesn't really suit what I want. Turbochargers - for all their wonder - come with plenty of disadvantages as well. Heat, weight, added complexity to design and build of the rest of the engine and the car as a package - brings a whole new bunch of considerations to the table. Considerable torque means a standard open front diff will not really suffice, also you have to look at the extra heat in the engine bay and how it will affect starter motor, alternator and other electrics. Then you've got packaging and service issues to consider - working on the car and maintaining it becomes that much more expensive and time consuming.

It just makes the car a whole lot messier than what I want.

Having said that, the 2.2 litre crank has brought a few considerations to the table too

You say the 'balance boxes' shit themselves often ? Is that due to poor maintenence or design? Obviously the drive gear, bearings, caps/mount and the condition of the balance shaft (straightness - balance of itself etc) should be checked during an engine rebuild much like any other rotating part in an engine. I don't see how they could fail if serviced properly?

[1UZFTTZZE]

Because a 3S-GTE doesn't really suit what I want. Turbochargers - for all their wonder - come with plenty of disadvantages as well. Heat, weight, added complexity to design and build of the rest of the engine and the car as a package - brings a whole new bunch of considerations to the table. Considerable torque means a standard open front diff will not really suffice, also you have to look at the extra heat in the engine bay and how it will affect starter motor, alternator and other electrics. Then you've got packaging and service issues to consider - working on the car and maintaining it becomes that much more expensive and time consuming.

?

Starter motors on the gt4 never seem to stuff up, heat increase is nothing to worrie about considering the gains, standard gearbox would be fine unless u are going to be doing 8 grand launches every day!, and if u do it right u will not have any more issues than with a 5s and u will get more k's out of a tank of fuel

the 5s balance shaft boxes just seem to die on them try to get 1 from the wreckors bet u cant and if u do it wont be under $200 thats y i put the 3sgte in instead of the 5s!
Just my 2 cents worth

[RWDboy]

I don't see any need to argue this - but I will anyway . You seem to refuse to accept that I simply don't want a turbocharger in my ST162 - but i shall elaborate anyway.

We are talking an ST162 here, and I have a ST165 in my garage and I'm aware of the lengths Toyota went to to ensure that, even with the basic - crappy - level of performance they got out of the gen 1 3S-GTE, the engine doesn't overheat. Even then, my ST165 was NEVER happy on a hot day.

Secondly, the standard gearbox might be fine in the dry, but around any corner on the wet - even the ST165 would struggle to get a fair percentage of the torque down to the ground without slipping the front inside wheel. And that is with all-wheel drive.

Thirdly, it is highly unlikely you will get more k's out of a tank of fuel with a turbo-charged motor than with a naturally aspirated motor of the same size and essential design. Simply because of tuning issues (intake charge temperatures, and high combustion chamber peak pressure).

Fourthly - it adds alot of weight to the car overall. Not only is there the turbo/compressor to consider, but the weight of the intercooler, piping, heatshielding (especially for the bonnet with the high-ish mount of the CT26 on the standard 3S-GTE), vents etc as well. To do it properly, you could easily end up gaining 80-100kgs, never mind the fact that your brakes may now be undersized, your springs may now be slightly too soft at the front and also you could be looking at a more involved engineer-certification process.

Now - i'm not saying turbochargers don't offer better performance for a track car, but for what I want out of MY car - it is not the best solution.

So back on to the topic at hand....balance shafts 'just seem to die' - well thanks for that useless bit of information I will look into it further, but it would've been nice if you could have been more specific (ie bearing failure, oil related issues, construction defect etc).

I bet the *real* reason you can't get 'em from some wreckers is because they don't want to part a good complete engine or long motor up ... they generally don't like selling motors in bits.

[1UZFTTZZE]

ok anyways balance shaft boxes fail due to oil problems which kill the bearing

[off-road]

When building a 3sgte stroker why do people use the whole 5sfe short motor rather than just the 5sfe crank? Is it to avoid end ing up with thin bores on the 3sgte block or to avoid boring at all by using 5sfe block?
Also can anyone verify the existance of a 8 12mm flywheel bolt 5sfe crank?

[RWDboy]

I dunno about 12mm but the bolt pattern on the 5S-FE crank (that came with an auto box attached) numbered 8 - i'll check the size tomorrow if i get time.

Cheers 1UZFTTZZE - i'll look into it for sure