B20 bottom end build and high cr cast pistons. help/advice needed


Stakis

Stakis

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Sep 6, 2010
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I need some advices on b20vtec bottom end build.

What about clearances for RS machine or YCP pistons cast pistons when overboring to 84,5? Keep them in oem ranges? or do alittle bit biggers?

I will use forged rods and everything else will stay in oem dimensions and specs, I will just renew with acl race bearrings, etc. No balancing or what so ever, because everything revs perfect from factory assignment and balancing (I reve everyday to 8500rpm, and sometimes to 9000rpm in drag runs and no problems for 2 years allready). I just want to rise cr.

I will weight rods and pistons that they would be all in exactly the same weight (rods and pistons), I weoghted oem parts and they all are the same also.

Thank you.
 
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If you mean piston-valve clearances then it shouldnt change with an overbore but as always when rebuilding u should clay the engine. If you mean piston-cyl wall clreances then stay oem if cast pistons but if forged then manufacturers recommendations.
 
Btw, are you revving that high with oe pistons? If you are and want ycp or rs machines then i wouldnt rev that high because these pistons are heavier and so your reciprocating assembly is out of balance and beleive me it will not last as long as it has already, get it balanced!
 
I will weight pistons, etc to be sure they all are the same weght. I believe if all 4 pistons are the same weight, so there is no disbalance here. I replace them and that's it. If 2 pistons will be heavier, than I believe there can be more problems later.

The same with rods. all 4 are the same weight and it doesn't matter lighter or heavier they are.

How you unerstand balancing everything? Please explain, maybe my understanding is wrong.

Thanks
 
Stakis said:
I will weight pistons, etc to be sure they all are the same weght. I believe if all 4 pistons are the same weight, so there is no disbalance here. I replace them and that's it. If 2 pistons will be heavier, than I believe there can be more problems later.

The same with rods. all 4 are the same weight and it doesn't matter lighter or heavier they are.

How you unerstand balancing everything? Please explain, maybe my understanding is wrong.

Thanks
Click to expand...

i just got my set of YCP high comp cast pistons 84.5mm tday and iv weighed all four and surprisingley they were all exactley the same weight of 345.2g, same with the wrist pins all the same 96.2g. i highley doubt that your oe b20 pistons weigh the same as these because:
1) they are a smaller diameter of 84mm or 84.25mm
2) the oe pistons have a smaller dome too which means less weight
3) the oe wrist pins will probabely be lighter because the oe pistons are lighter

so for example the oe pistons/rings and pins weigh 400g and your ycp or rs machines pistons are heavier then you would need more counterweight on your crank to cancel out the vibration and balance everything out. so where before you were revving to 8500 with oe setup and now your revving the same with a heavier piston set then the reciprocating assembley is out of balance. i hope you understand my explanation.

i may be wrong so if anybody knows more then correct me.
 
yeh, i understand what you are saying, but who can balance such a rotating assembly. i don't know such place in Lithuania :(

maybe some other ideas/inputs here?
 
Stakis said:
yeh, i understand what you are saying, but who can balance such a rotating assembly. i don't know such place in Lithuania :(

maybe some other ideas/inputs here?
Click to expand...

No need to balance... Everything will be "gerai", this setup is very popular here in Latvia, also I had such block with RS pistons. Engine is runing now for 5 years..
 
In england theres a place in doncaster called john sleatg race engines, he balances 4 cylinder engines for £120+vat, thats where im getting mine done from.
 
v1b20 said:
No need to balance... Everything will be "gerai", this setup is very popular here in Latvia, also I had such block with RS pistons. Engine is runing now for 5 years..
Click to expand...

What was your full setup including comp ratio amd rev limit and power?
 
qais_vtec said:
What was your full setup including comp ratio amd rev limit and power?
Click to expand...

RS pistons, skunk2 pro1, skunk2 intake manifold, supersprint race header 244 hp, 242 nm, same stup with rmf narrow style 247hp 220 nm at cosmic rpm...
 
When you balance your rngine do you mean getting your crank balanced ??
 
you used oem crank pulley? ar somekind of lightweight aluminium one? as i have only 1 belt left (alternator) I elieve there is no need to keep oem pulley with rubber inside. it is safe to go with ligtweight aluminium one. because in one side of the crankshaft is solid aluminium flywheel, in another end, aluminium pulley.




v1b20 said:
No need to balance... Everything will be "gerai", this setup is very popular here in Latvia, also I had such block with RS pistons. Engine is runing now for 5 years..
Click to expand...
 
v1b20 said:
RS pistons, skunk2 pro1, skunk2 intake manifold, supersprint race header 244 hp, 242 nm, same stup with rmf narrow style 247hp 220 nm at cosmic rpm...
Click to expand...

Good numbers there, is it remapped with cam gears tuned aswell?
 
Stakis said:
you used oem crank pulley? ar somekind of lightweight aluminium one? as i have only 1 belt left (alternator) I elieve there is no need to keep oem pulley with rubber inside. it is safe to go with ligtweight aluminium one. because in one side of the crankshaft is solid aluminium flywheel, in another end, aluminium pulley.
Click to expand...

I have an aluminium crank pulley that weighs 0.5kg and will surley release around 6-7hp to the wheels but have decided not to use it because of longevity issues, its ok for a race/track car where engines are rebuilt frequentley but im not planning on rebuilding every 10000miles, aparently it sends vibrations back into the bearings, crank and oil pump. Im will remove some weight from the oe crank pulley, alternator pulley and PS pulley and have them balanced aswell so it should release about 2-3hp depwnding on how much weight i can safely remove.
 
maybe some resources about such balancing? or maybe youtube video etc? thanks
 
ok guys i just spoke to a company and they said i would need to give them crank flywheel clutch plate crank pully and pistons and conrods and they would balance the lot for £200+vat

also asked them about if i need new valves and they said they could just re cut them £3 each valve + re seating or homing or sumert them but forgot how much they said for that is this right and resonable priced

also they youst to do work for paul at spd automotive so they are supossed to be good
 
so how they balance everything? they just weight all the parts and make them ideal? or they balance each part: flywheel, clutch? I don't understand this purpose of the job and how it is done.

My engine runs on stock b20z1 bottom end and simple fuel, and I am pushing 242bhp and 200nm with just head modifications.... So now I am planning to go with high cr rs machine pistons, that's why I have so much questions.
 
X2 stakis I have just bought a b20z1 bottom end so I want to know these answers also so how does it go compared to a b16b ??
 
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