In need of some wiring diagrams/help... Older RB20DET swap

[pumpiniron]

I purchased an RB20DET redtop. It's from a late 89 so it has the ECCS system (not the NICS). The only real difference in the motor is I BELIEVE (but can't be sure since I have never seen another RB20DET harness) that the wiring harness is a little different... For example, I can't find the 6 and 8 pin connectors that everyone speaks of. It seems I can find the 6 pin but definitely not the 8 pin, some of the wires on the 6 pin I found are different colors and don't match the ones in the wiring writeups on the main page by Skillzilla and Carl H. The motor is going into a 91 240SX and the lower harness seems to work just fine. I am just a little lost on this upper harness because I am not sure what exactly I need to be cutting and splicing and what wires are going where? I have alot of experience with soldering and wiring things but without some sort of wiring diagram I am lost... Can anyone point me in the right direction?

[pumpiniron]

To clarify for some people this motor either came from a Nissan Cefiro or a late model R31 Skyline. I'm not 100% sure which one it came from but my problem obviously lies with the fact that everyone knows how to wire a R32 RB20DET to an S13 but the wiring on my motor is just a tad bit different so my question is obviously where do I start or how do I go about wiring this thing!? It's killin me!

[Carl H]

honestly man dont waste your time with that motor, the only thing its good for is swapping out the intake cam from that motor into a silver top.the silver top goes into the s13 chassis much much easier than the redtop does, its wiring is closer to that of the s12 or z31.time to bust out a multimeter and wire trace my friend...

[pumpiniron]

Well you say don't waste my time with this motor but here is my question... If the motor has ECCS then what is the major difference? I mean I plan on replacing the turbo, manifolds, and everything with aftermarket parts which only really leaves the block and head which I am assuming is the same as the silvertop correct? I also plan on getting some stand alone engine management down the road so it's not like I am just bolting in the stock motor you know? What else is so different about this motor other than the wiring?

[Carl H]

the stock redtop rb20 is horrible man, very small ports and a general pain in the *** to work with, not to mention the ungodly 12 port intake manifold that the motor has so it makes fabbing a diffrent intake mani a complete nightmare.iirc the CAS the ignitior and all the sensors on the redtop are completly diffrent than anything on the silvertop or current rb motors.i believe you can bolt a silvertop head onto a redtop block but dont hold me to that, i could be mistaken.if the motor has eccs then its the very crude and early form of it, its not near as good as the silvertop setup.the redtop block is a more 'robust' block due to larger oil passageways and smaller coolant passageways, so they tend to run a bit hotter but make great rb24 canidates.in the end the silvertop pwnz the redtop; newer motor, less mechanical and electrical hassle, and more parts available for it.

[pumpiniron]

Guess I'll have to ditch this motor and get an RB25 then...

[pumpiniron]

Than again I am not even 100% sure what motor this is... I know it's an RB20DET obviously but upon further inspection you can tell the valve covers were removed at one point due to some aftermarket gasket seal and I'm almost wondering if someone couldn't have replaced the covers with red ones... Then again what would I know, this is my first RB engine ever so I have know way of knowing how to tell what motor this really is right?

[Yellow4g63]

If you look near where the injectors are on the intakemanifold you could see the diffrence. The RB20-25 intake manifold dosen't look like the Red top RB20. I thought I Took some pics of my old redtop I got for free, If I can find them I'll post them up.

[pumpiniron]

I'd love to see some pictures if you could find some... My RB20DET intake manifold on my redtop looks exactly like the silvertop intake manifold... exactly.

[Yellow4g63]

Sorry couldn't find them. But I found these old.