rb26dett cyl walls

[gtrhybrid]

I just pulled my rb26dett head and gave it the port and polish job. I was looking at the cylonder walls and noticed that rather than seeing the cross hatch from the hone all the way around Im seeing mild scores on the exhaust side going vertical. I examined them and they dont seem to be bad enough to cause power loss but I was wondering if this is normal to find in a r32 motor. Thanks.

[Nameless EJ6]

That's never good...

If you were to scratch over with your fingernail, would it catch on them?

[gtrhybrid]

Fingernail wont catch but I can just slightly feel the texture difference. It doesnt seem like it will leak compression to me.

[hungry6]

if u can see scoring , get it redone while the motor is out otherwise u be compromising performance and additional cost at a later date

[wrxhoon]

thats the marks from the rings ( compression ) as the piston goes up and down .

if u can feel them when u run u r nail across them u should hone the bore out and put new rings . usualy the bore on rb26 's lasts a long time if the engine is fairly stock ( like 200-300 k k's ) .the other thing to look for is the lip on top of cilinder if there is a lip its a good idea to do the bottom end now rather than have to pull it apart again . the only problem is u cant pull the sump off the rb26 off while the engine is in the car u have to remove it from the car to do it . the front diff housing is part of the sump .

unless u have an rb 26 in some car other than a gtr and u se a different sump ( rb 25 sump for instance )

[gtrhybrid]

Im running the rb25 oil pan and there isnt a lip at the top of the piston track. Im wondering what caused the scroes and if its going to happen again. If the rings caused it my guess is that its gonna happen again.

[wrxhoon]

if u dont have any lip at all that means the bore is ok . with time the rings will mark the bore again of course it all depends how deep they are and we are talking about 1 or 2/100 of a mm here .u shouldnt loose compession though unless its like 5/100 of a mm deep cause the engine oil takes that up . are they all the same ? any piston slap ? try moving the pistons left to right when they are at the top of the cil and see how much they move .

as u have an rb 25 sump its very easy to take it off pull the pistons out , hone the bore out and put new rings in ( rings are only $200 a set or even less ) and while the head is off its ony a few more hours work .