docaam Posted April 4, 2013 Share Posted April 4, 2013 (edited) Hey guys, As some of you might have seen I sold my current setup as was planning for NA RB setup preferably 26 head with ITBs. I found a way around it to work but yesterday got another option and need some help in working out the compression on it. My friend is selling a new RB26 N1 block, N1 crank, Nitto forged piston, Rods, Crank studs, bearing etc. In short a nice new block ready to be used. I also have a stock RB26 head with intake manifold and stock ITBs but without turbos. Details of pistons are they are 8.5 : 1 (picture attached) Now my question is is there any way, I can shave the head to get the compression to around 10.5 to 11 and run this engine just on ITBs, really want to have a NA RB26 running on ITBs. I am not good in calculating compression but have seen people working it out. First preference is just to shave head and which gasket size should be used and if compression cant be achieved only by head shaving then how much should the block should be shaved (though will prefer not to shave the block) I would like to do that for a while then when have more funds (or doesn't like NA setup) change the head and install a single turbo. Edited April 4, 2013 by docaam Quote Link to comment Share on other sites More sharing options...
Careless Posted April 4, 2013 Share Posted April 4, 2013 Post the spec sheet with the pistons that I see underneath your pistons there. RB26 specs: Bore: 86mm Stroke: 73.7mm Using the calculator shown below with the stock specs, and using the specs i found on nitto's website (15.3cc dome), you get the following with a 1.5mm headgasket. This is close, but not exact. using the same calculator, adjusting values to get your desired compression ratio, I got the following: you can weld the combustion chamber on the head to reduce combustion chamber volume, you WILL need to get new pistons, and there's not much else you can do (1mm gasket is the thinnest head gasket). Also, shaving the block and the head will cause other things to go out of whack. There are limits in the FSM to how much you can shave both. The pistons on the RB26 are proud of the deck by .260mm or so. a high compression RB26 would be probably done best by taking the head to endyne (theoldone.com) and having them CNC the head and then buying a set of their Rollerwave pistons to fill the entire combustion chamber. I don't think you'll get 10.5 or even close with your nitto pistons. 1 Quote Link to comment Share on other sites More sharing options...
ZT-R Posted April 8, 2013 Share Posted April 8, 2013 I have the endyne head, but without the roller waves and combustion chamber mods. Nice work. Get new pistons. Quote Link to comment Share on other sites More sharing options...
docaam Posted April 10, 2013 Author Share Posted April 10, 2013 Thanks guys for the help, with custom pistons I know it can be sorted out but not feeling spending so much money on just trying a NA setup. I have been told to get RB30DE and Rb25De Neo and use RB25 pistons and rods in 30 block then can use Rb26 or RB25 head over it with good compression. DE engines are cheaper here will look into that. Quote Link to comment Share on other sites More sharing options...
EF Ian Posted April 10, 2013 Share Posted April 10, 2013 IMO if you are going to go RB26 NA then you should either do it properly or not at all. For decent power you are going to want around 11:1 comp ratio, custom pistons and custom ground cams to suit an NA setup would be the best way. I definitly wouldn't skim the head or deck the block, best to leave as much there as possible imo. Quote Link to comment Share on other sites More sharing options...
ZT-R Posted April 11, 2013 Share Posted April 11, 2013 ^ Totally agree. Quote Link to comment Share on other sites More sharing options...
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