2003z Posted December 28, 2006 Share Posted December 28, 2006 Will I need to shim the cam towers if I use it? Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted December 28, 2006 Share Posted December 28, 2006 Why don't you use an earlier head to allow you to easily get more compression? Your P90 would probably need to have the towers shimmed with a change from a 1.2mm stock gasket. I have that late E88 I would let go away for cheap... but you don't want that do you? Quote Link to comment Share on other sites More sharing options...
2003z Posted December 28, 2006 Author Share Posted December 28, 2006 I already spent $400 in labor plus the new cam getting this head redone for the motorsports pistons I intended to run. Quote Link to comment Share on other sites More sharing options...
2003z Posted December 28, 2006 Author Share Posted December 28, 2006 If this Idea won't fly, I have a friend who is dying for me to take his old 260 engine off of his hands, and I will just have it bored for my 86mm motorsport pistons. Then I just have to sell the set of .5mm flat tops I just bought, but that should be easier. Quote Link to comment Share on other sites More sharing options...
2003z Posted December 28, 2006 Author Share Posted December 28, 2006 I know I started out all bass-ackwards in my planning and prep, but this motor will go back together correctly! Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted December 28, 2006 Share Posted December 28, 2006 I see... Isn't a 3mm overbore a little risky on a L24/L26 block? You would want to have it sonic tested for sure and run a medium-light compression as not to push too hard on the thinner cylinder walls... low compression on a N/A motor isn't too much fun either as you have experienced. What about shaving the deck of your engine block? Of course that would mean completely undoing your motor's bottom end... Quote Link to comment Share on other sites More sharing options...
2003z Posted December 28, 2006 Author Share Posted December 28, 2006 since its the same physical dimensions as an L28, and basically the same block, I don't see how a 3mm overbore could be a problem, especially since an L28 has room to go to 89mm. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted December 28, 2006 Share Posted December 28, 2006 ah...but the L26/L24 block has an 83mm bore to start out with. The cylinder walls are thinner than the L28 block walls... The "how to modify your Nissan L series engine" book only lists being able to go 2mm over on the L24/L26 block. This is why I am looking for an L28 block so that I can go bigtime overbore for more cubes... Just some thoughts... And I have felt the thickness of the bores through the water jackets and it is not so thick anyways... Quote Link to comment Share on other sites More sharing options...
2003z Posted December 28, 2006 Author Share Posted December 28, 2006 ah...but the L26/L24 block has an 83mm bore to start out with. The cylinder walls are thinner than the L28 block walls... The "how to modify your Nissan L series engine" book only lists being able to go 2mm over on the L24/L26 block. This is why I am looking for an L28 block so that I can go bigtime overbore for more cubes... Just some thoughts... And I have felt the thickness of the bores through the water jackets and it is not so thick anyways... but if the block is the exact same outside dimension, and the center of the bores are in the exact same spot, how can the walls be thinner if you bore it to the same specs as an L28? The book also says they have the same bore spacing, so why can't I? btw, if I can, my block will be available, real cheap, so don't talk me out of it!!!!! Unless you have a good reason Quote Link to comment Share on other sites More sharing options...
evildky Posted December 28, 2006 Share Posted December 28, 2006 remember not all L28 blocks are cast the same internally, why would the L24 and L26 be the same? the N42 blocks have completely siameased cylinder walls, on the F54 block only every other cylinder is siameased, and with L28 blocks being so readilly available why not start with one and know the you have enough meat to handle the overbore also the LD28 has a higher deck height and I'm willing to wager different internal casting as well Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted December 28, 2006 Share Posted December 28, 2006 evildky: The L24 is the P30 block with the 73mm stroke and 83mm bore. The L26 is the same P30 block with a 79mm stroke and 83mm bore. The L26 is just a L24 stroked with the L28 crank and rods. HMM...well I just looking the how to modify yout L engine book and it only lists 1mm overbores available for the P30 block. I know that Forrest is using a P30 on his turbo motor and he has at least a 2mm overbore to make his 2.7 liter w/ the L28 crank. I think Mike/2003z wants to use an 86mm bore because of the Nissan Motorsports pistons he has already. Mike! I want to talk you into using your L28 block! I'l take a set of calipers out and try to measure the cylinder wall thickness on my P30 block sometime today. It may prove difficult to do though with the way the water passages are. If you want some help pulling your motor apart let me know...I have don't work mornings but I work almost all nights from 5pm. My L26 is already stripped down to the block and crank pretty much and I need one socket to be able to pull the L28 crank out. Quote Link to comment Share on other sites More sharing options...
2003z Posted December 28, 2006 Author Share Posted December 28, 2006 I think Mike/2003z wants to use an 86mm bore because of the Nissan Motorsports pistons he has already. Exactly, they were a nice score! Mike! I want to talk you into using your L28 block! I'l take a set of calipers out and try to measure the cylinder wall thickness on my P30 block sometime today. It may prove difficult to do though with the way the water passages are. If you want some help pulling your motor apart let me know...I have don't work mornings but I work almost all nights from 5pm. Mine is already completely disassembled, just trying to figure out what to do with it. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted December 28, 2006 Share Posted December 28, 2006 What would your compression ratio be with an HKS 1mm head gasket? I don't think you have to shim the towers for it since it is so close to the stock 1.2mm. I am guessing you want something in the 8.5-9:1 range right? Quote Link to comment Share on other sites More sharing options...
2003z Posted December 29, 2006 Author Share Posted December 29, 2006 it would be 8.8, up from 8.6 with the standard one. I was looking at about 10:1 with the other pistons though, and more of what I wanted. Either way though, it will be better than the 7.3:1 of the old setup. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted December 29, 2006 Share Posted December 29, 2006 My L26 was setup with flattops (I think they had dished pistons stock?) so it was around 8.8:1 which was way fun! Stock was like 8.3:1 for the L26. Quote Link to comment Share on other sites More sharing options...
Guest d3c0y z3d Posted December 29, 2006 Share Posted December 29, 2006 Hang on here... We are talking like .6mm difference here.. Just make sure you have your cam gear set on #3 and have a good chain that should be fine. You can plain 1mm off the head and not have to shimm i thought. And if you are after compression why not run an F54 Block, flat top pistons and an N42 head - that will give you way more compression! I realise that you have already had that work done to your head... Quote Link to comment Share on other sites More sharing options...
X64v Posted January 2, 2007 Share Posted January 2, 2007 My L26 was setup with flattops (I think they had dished pistons stock?) so it was around 8.8:1 which was way fun! Stock was like 8.3:1 for the L26. They did. I'm on a quest for some l26 dished pistons for my l24 turbo project. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted January 2, 2007 Share Posted January 2, 2007 never mind...not 8.8:1 "9.2:1" is correct... L26 pistons should be pretty cheap to come by since L26 motors have basically a bad motor setup...L24 block, L28 crank/rods, block was clearanced for bigger L28-ish valves (you can't o-ring it), and you can only bore it like 2mm...so no hot turbo on a L26 block...L24 is another story but not on a L26 over 5psi... My L26 with decent mods sure sounded good though!!! Quote Link to comment Share on other sites More sharing options...
X64v Posted January 2, 2007 Share Posted January 2, 2007 That does sound good. Yeah, l26 pistons shouldn't be hard to find at all, considering no body wants them. They won't be as strong as stock 86mm dished turbo pistons, but I would think they would be as strong as the 86mm n42 dished pistons, and with my 9mm rods (it's a 73) and running 7.8:1 comp ratio, I see no reason why this bottom end couldn't take somewhere in the teens for psi. [/thread jack] Quote Link to comment Share on other sites More sharing options...
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