how large can you safely bore over a block? i am wondering this because i can get a great deal on a .3 over bore je piston aka 250 for piston and rings. also what color bearing would i use for a gsr crank in a b18a block? im assuming the usual green bearings are to be used but its always good to check. thanks

 

You'll be fine with that bore on stock sleeves... The most i ever go on stock sleeves is 0.50mm over... That's a hella good price for your JE slugs... what compression??? As for the bearings read the alpha stamp off the bottom of the block and match them to the numbers for your crankshaft.... On the bottom side of the towards the intake side of the block you find a letters that could look something like this.... DDDCD then read the numbers off the crank... 23323... again these don't mean anything I'm just giving an example... So for this you would need the bearings D2, D3, D3, C2, D3... It's pretty simple... NEVER go by just using green... Even after I assemble a motor with the correct bearings I still plastigauge to check clearance... Good Luck

 

sweet thanks. i thought it would be possible. the slugs are je 12.5:1 cr in a gsr. im building a "poor mans gsr" with a ported b16 head and utilizing a b18a block with the gsr crank and forged internals. i was definately going to use plastiguage to check the clearances and balance it all up too while its all torn down. definately going to do it right the first time around. can anyone help me calculate that compression. i tried on c-speed and wasnt too sure of my results. b16 head 12.5:1 on eagle gsr rods in a b18b block with a gsr crank. thanks guys

 

.3 overbore?
.3 what?

 

Best way to calculate your compression ratio is to cc the head and also cc your bottom end with a piston at tdc. Add the volumes together along with the bore X headgasket thickness (usually .029" for b-series). Take the volume and divide it into the same volume + your volume from bore/stroke and walla. There's your compression ratio. I'm not to sure about c-speeds calculator myself. I punched in my numbers and it gave me like 13.X:1 and what I measured came out to 11.4:1. Kinda makes me wonder. I always trust what I measure myself.

As far as the bottom-end is concerned. Plastigage is O.K. but a better way to do it is by torquing down the main caps and rod caps then use a dial-bore guage to measure them in several places. Then mic your journals and use that to get what bearing that you need to use. Plastigage only measures the clearance at one point.

 

Yea i guess you would want to know that... hahaha I assumed and am still hoping that you meant 0.3mm's not 0.3inches... If you're talking inches forget all that I said and sleeve.... hehe Peace
EDIT: Since your motor will be makin the same stroke as a GSR you'll compression will just drop due the to 1.1cc bigger PR3 combustion chamber (I would expect somewhere around 12.2-12.3:1, how come you aren't just using a B18C block tho?? internal oil feed and girdle are always nice...


[Modified by Kataku2K3, 1:40 PM 3/4/2003]

 

Well assuming they're the 6.7 dome JE slugs your static compression should come in right around 12.18:1 w/ the b16 head and stock gasket.

 

thanks for the help guys, ill ask the guy selling if its mm or inches...i hope its inches. the reason why im not is because no one is selling them for a reasonable price and i can get one right now for like 100-150 its a 95 with 50k on it and is only missing the pumps rods and slugs. unless someone knows of where one is at??? doesnt need to have any of the pumps (oil/water) or crank. thanks again

 

You say that you hope it's in inches well I would hope that it isn't... that's like a 7.8mm overbore piston bringing your total bore to 88.8mm's... Don't think that is possible, sorry... You sure it isn't 0.03 inches or .3mm??? Those are more resonable numbers for stock sleeves.... Peace

 

JE makes a +.02"(81.5mm) shelf piston. Perhaps this is what you're refering to. The part # is 179501. I've never seen a .03" or a .3mm overbore JE piston, but I'm sure they'd make one custom if you had the $$$s so it's certainly possible.

 

ok found out its in mm so im cool ill just bore over on the block...might as well its got 50k on it and for the price of the bore over and the pistons it wont even come close to what it would cost me just for the pistons and rings new. thanks for all your help.