signalpuke

Do you happen to know the lengths? I dont have the actual pieces on hand, I found the info from aftermarket conrod manufacturers on the internet. I cant imagine the rods are that different, other than the bearing width, as it would make sense from a production standpoint

I am trying to do as much research as possible on the RB motors, and being from the USA makes it a lil difficult as the motor is rare, and most information is in Japanese. I have an RB20DET, and the last thing I want is oil starvation, as the parts to repair it are expensive and hard to come by. I do have a few questions regarding this topic. -It seems this is an issue with all RB motors, is this true? -Will restricting the oil to the head cause any problems? -Has anyone considered having their crankshaft, connecting rods, and the underside of their pistons coated with an oil shedding material such as teflon? If this is an issue with all RB series motors why didnt Nissan address the issue by restricting oil to the head from the factory? Did they determine that reducing oil to the head would cause more harm? An oil shedding material coating the internals of the engine would allow the pan to fill faster, and create more horsepower as the RPMs climbed.

On another forum that I frequent quite regularly there is a discussion going on about rod/stroke angles, and there is a lot of good information that really applies to all motors. May be of some interest to some of you K20A.org Spoon Motor thread And here is a cool piston speed calculator

This is a handy calculator http://golenengineservice.com/calc/calcci.htm

RB20 - Std Rod Ratio 1.743 RB25 - Std Rod Ratio 1.694 RB26 - Std Rod Ratio 1.65 RB20DET - 78mm Bore/ 69.7 Stroke, RB25DET - 86mm Bore/ 71.7 Stroke RB26DETT-86mm Bore/ 73.7 Stroke 20 conrod length 121.5 rod journal bearing 45 25/26 conrod length 121.5 rod journal bearing 48 30 conrod length 152.7 rod journal bearing 50 Hope that helps, by swapping the 20 crank in the 25 you will destroke the motor, and have a smaller rod journal bearing, but the R/S ratio will improve to that of the RB20, you may need custom pistons though. Overall displacement will be 2055.651316787177cc

Max, I was looking into this idea a while back. This is why I chose NOT to go this route. I am also from the states (Texas, but currently in Iraq) and I have an RB20DET in an S14 chassis. RB20 parts are a pain in the ass to find stateside, I waited 3 months for a new valvetrain from Japan. So, keep in mind, if you blow something you may be sat back for a while waiting. With the last "fast and the furious" movie parts will start coming in faster, as the demand will grow, but expect the prices to go up as well. Ok, now on to some tech stuff. The RB20 has a great rod/stroke ratio, and piston speed is slow compared to other USDM engines. That is good. If you stroke the engine, you will end up increasing the piston speed and sidewall stress on the cylinders. Increased piston speed and friction reduce the reliability of the engine and will not allow you to rev as high As far as porting the head - CFMs only tell part of the story. Your head porter needs to calculate the size of the port relative to the CFM. Any machinest with real racing background will confirm that high CFM numbers mean nothing if the ports are bored out to the point that the velocity of the air is not changed. This is what I have planned for my RB are anti friction (teflon) coating of the underside of the pistons, the rods and crank. Rotational mass at high RPM is affected greatly by oil on your parts, it adds a lot of weight. With these coatings weight is reduced the higher RPM you go. This in turn will make more horsepower for your motor. And it does not sacrifice reliability or weaken the crank like knifing it does. I also plan on getting the pistons coated on the side and top with other coatings to reduce sidewall friction and to reflect heat from the combustion chamber. I need to do a lot of reseach for this engine still. The coatings are great for all motors, thats why I am starting there.