R3VO 3VOM Posted May 9, 2011 Share Posted May 9, 2011 (edited) So I came into ownership of an RB20 for basically nothing. It's not bad, but I can get a crankshaft and connecting rods from an RB25 for $80 in mint condition. So I want to install these into my 20 and make it a stroker. I've done some research and they all say use the pistons from the 4AGE engine, 82mm. My question is do I have to use these pistons? What would happen if I just used the stock size pistons? From my knowledge, stroker kits are only supposed to touch the stroke, not the bore. Doesn't going from 78mm (RB20 bore) to 82mm defeat the purpose of a stroker? Edited May 9, 2011 by R3VO 3VOM Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted May 9, 2011 Share Posted May 9, 2011 Why wouldn't you do both? You might run into issues with piston clearance if you use stock pistons, which is why people use different pistons (KA24) when stroking the L28. I wouldn't know with an RB though. I feel like you could sell that motor to a S13 fanboy and use that to getting a real RB25. Quote Link to comment Share on other sites More sharing options...
stprasinz Posted May 9, 2011 Share Posted May 9, 2011 20's are fully counterbalanced, and 25's are not, its common for a rb25 to be destrocked with the 20 crank to gain revs.... Quote Link to comment Share on other sites More sharing options...
jakeoster Posted May 10, 2011 Share Posted May 10, 2011 Basically free engine? Drop that sucker in and use the money saved to do a few bolt on's! Quote Link to comment Share on other sites More sharing options...
70 Cam Guy Posted May 10, 2011 Share Posted May 10, 2011 Basically free engine? Drop that sucker in and use the money saved to do a few bolt on's! That is what I was thinking, the stock driveshaft will slide right into the RB20 5speed. Make, or buy a rear sump oil pan and bolt the thing in. My current build is an RB20 swap. I got the motor and trans for less than I could have built a stout L28 so I ran with it. I 'upgraded' to the stock RB25 turbo with rb20 actuator, freddy ebay intake, and ebay front mount. Budget turbo elbow, and Jet Hot coated shaved exhaust manifold. I resealed the engine with the Nissan gasket set and ARP head studs. Nissan timing belt, water pump, tensioner, and idler pulley. I didn't need to do most of that stuff but the install will look cleaner IMO than that cross over intake, and now I know what the inside of the engine looks like. But to answer your question about the pistons, the RB25 rods are probably longer, and so you would need a shorter piston height so it doesn't poke above the deck with the long stroke. The stock 4AG pistons are probably the correct height, but with a larger stock bore. They are also probably plentiful/cheap from all the Corolla guys Quote Link to comment Share on other sites More sharing options...
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