Balancing 1UZ Rotating Assembly

[bmech211]

I posted this over at Club Lexus, but to no avail. So, hopefully I'll get some feedback here:

I've got a set of forged NASCAR Lentz rods, and will be placing an order for a set of JE custom pistons once I get all the correct measurements down. I will also have to offset grind the rod journals to accept the smaller 1.888 rod bearings.

My main concern, which I didn't give much thought about until now, is that the weight of my rods are 537 grams while most aftermarket off-the-shelf rods are in the 600 range. Coupled with lighter forged pistons and the total weight of material removed from the crank rod journals, how much more difficult would it be to balance the whole rotating assembly?

Is there usually a limit as to how much material can be removed from the bob weights during balancing? (Is this correct terminology??)

Also, would the fact that the 1UZ cranks being steel, as opposed to cast iron, add to or take away from any difficulty in balancing? Attached Images

 

[gloverman]

A good engine balancer should be able to sort it as at the end of the day and engine is an engine and the principles of balancing are the same. Cheers

 

[bmech211]

Thanks for the response. Decided to go with an LSx swap instead.

 

[gloverman]

We are doing an LS conversion as well. Easy way to make power and torque. Cheers

 

[Clayton Carlyle]

A bit off topic but how much piston to bore clearance would you guys run for forged CP pistons at std bore size in a twin turbo application??
The standard bores before honing are already .004" clearance with no real sign of bore wear,(no lips).

 

[XR8tt]

.005 in mine.. ring gap .025 top / .028 lower comp rings..
Expect 800+ h.p..

 

[ash]

I posted this over at Club Lexus, but to no avail. So, hopefully I'll get some feedback here:

I've got a set of forged NASCAR Lentz rods, and will be placing an order for a set of JE custom pistons once I get all the correct measurements down. I will also have to offset grind the rod journals to accept the smaller 1.888 rod bearings.

My main concern, which I didn't give much thought about until now, is that the weight of my rods are 537 grams while most aftermarket off-the-shelf rods are in the 600 range. Coupled with lighter forged pistons and the total weight of material removed from the crank rod journals, how much more difficult would it be to balance the whole rotating assembly?

Is there usually a limit as to how much material can be removed from the bob weights during balancing? (Is this correct terminology??)

Also, would the fact that the 1UZ cranks being steel, as opposed to cast iron, add to or take away from any difficulty in balancing? Attached Images

No,
Alittle off counter weights is ok.
They can add heavy metal easy as if required .
Cranks are fine..
Block will fail before crank

 

[ash]

.005 in mine.. ring gap .025 top / .028 lower comp rings..
Expect 800+ h.p..

What rpm?
What fuel?
Is a difference ....

 

[Clayton Carlyle]

Xr8tt does yours have any piston slap when cold?
I think the limit will be .006 which is probably where mine is going to end up. I can't find out the final bore clearance till tomorrow when the machine shop opens again.
Also did you have your engine balanced? Is it worth it?

I'm also using std size ACL main bearings & haven't worked out all the different sizes that apparently match up numbers from the main caps with more numbers or letters on the block. Do you think just standard size woul do the trick or should I take the time and work out the variations?

Only got ARP 2000 rod bolts also, should I go L19?

Any help would be appreciated?

 

[Clayton Carlyle]

Engine details:

Standard forged & coated CP pistons: 9.5:1 comp.
Eagle rods w ARP 2000 bolts
Standard size ARP head studs
ACL main & big end bearings
MLS head gaskets
11,000rpm valve springs. Limit will be 7200rpm
Twin Gt3082r garret turbos
Twin 38mm external gates
Custom turbo manifolds
Wolf V500 ecu
T56 tremec 6 speed manual.
ATM only 550cc injectors rx7

 

[XR8tt]

Xr8tt does yours have any piston slap when cold?
I think the limit will be .006 which is probably where mine is going to end up. I can't find out the final bore clearance till tomorrow when the machine shop opens again.
Also did you have your engine balanced? Is it worth it?

I'm also using std size ACL main bearings & haven't worked out all the different sizes that apparently match up numbers from the main caps with more numbers or letters on the block. Do you think just standard size would do the trick or should I take the time and work out the variations?

Only got ARP 2000 rod bolts also, should I go L19?

Any help would be appreciated?

Was intended to run C16 but I think E85 will be used..
Yep all balanced up fine.. Friends do my engine work and leave
things up to them.. I think E85 runs much cooler..
My 1UZ engine is all out race engine. It won't see any open road..
I went .020 overbore.. The thing you consider is going over bore and chance weakening cylinders or running the extra clearance..
I find the C.P's to be a quiet piston in engines we've fitted them to..

Turbo's SEEM to be easier on rod bolts due the theory of having some pressure on piston on exhaust stroke. The rod bolts are not tensioned quite the same as blown / N/A engines...
You shouldn't have issues with balancing..
What does your machinist / balancer say ??
Later models have lighter rotating assembly also..

 

[Clayton Carlyle]

Xr8tt do you have a build thread?
Thankyou for the ring gap measurements, I have used the same top of .025 but the second comp ring is already .029-.030 without any filing. I hope I don't get blowby.

 

[XR8tt]

P.M sent...
Pressure build up between rings causes ring flutter and blow-by..
As in early Gen lll's..
Strange as it may seem letting build up between top and second helps rings seal..
Gas ported pistons helps cylinder pressure push rings against bore
from behind ring..assisting in good sealing...

 

[ash]

P.M sent...
Pressure build up between rings causes ring flutter and blow-by..
As in early Gen lll's..
Strange as it may seem letting build up between top and second helps rings seal..
Gas ported pistons helps cylinder pressure push rings against bore
from behind ring..assisting in good sealing...

In one sentence , you say pressure build you is bad, then 2 sentances later you says it's ok...
You want to pick a direction Or belief And stick with it....?

 

[XR8tt]

I one sentence , you say pressure build you is bad, then 2 sentences later you says it's ok...
You want to pick a direction Or belief And stick with it....?

Yep pressure behind the ring as the ring tension is not enough to seal cylinder pressures on it's own..

The ring GAP prevents any build up between rings which can hold
rings away from cylinder walls..

Which is why a larger gap is on "second" ring is recommended..

Especially when used with anti detonation groove, lateral gas ports etc..

http://www.cp-carrillo.com/Tech/PistonTech/tabid/74/Default.aspx

 

[ash]

Yep pressure behind the ring as the ring tension is not enough to seal cylinder pressures on it's own..

The ring GAP prevents any build up between rings which can hold
rings away from cylinder walls..

Which is why a larger gap is on "second" ring is recommended..

Especially when used with anti detonation groove, lateral gas ports etc..

http://www.cp-carrillo.com/Tech/PistonTech/tabid/74/Default.aspx

Yer, I know
Just put in in your statement to help others that may not under stand....

U still left other information out, like ring groove types,
Like key stone grooves
Stepped rings, step on the top, or bottom...
Barrel ground rings, square rings , gapless rings

Ring material type,
Moly, cast iron, chrome plated...

Half a statement is miss leading...

 

[XR8tt]

Yer, I know
Just put in in your statement to help others that may not under stand....

U still left other information out, like ring groove types,
Like key stone grooves
Stepped rings, step on the top, or bottom...
Barrel ground rings, square rings , gap less rings

Ring material type,
Moly, cast iron, chrome plated...

Half a statement is miss leading...

All good info... Thanks for contributing ..