r31 ECCS Red top RB20 To s13 chassis questions.

[Lockdun1]

Well I’ve been out of the import game for a very long time. Bout’ 12 years I’d say. Well I ended up with a clean title Coupe that has what I figured out is a red top rb in it. Has an RB20DET-R sticker on the intake plenum but I’m pretty sure it’s just an eccs with a sticker on being that it’s doesn’t have that turbo sweet manifold it’s supposed to have. Anyways the guy I got it from is the third owner of the car with the rb, they claimed it to be running at some point when he got it. I don’t think they ever did once they realized it wasn’t a silver top they just gave up.

I have been reading for about 24 hours straight lol so this is what I’ve got.
From what I understand if I used a silver top swap harness the eccs red top parts that will work with the silver top harness/ecm are coils, igniter and injectors for sure. The cas is different but a silver top cas will be a direct bolt on and can be used.

Other sensors like knock water temp alternator all That jazz I still don’t know and can’t seem to find answers.

I read I can bolt up an after market plenum for a silver top to a red top lower being the gasket is the same but I could be wrong.

Replacement parts like water pump timing belt/idlers are interchangeable so that is good but are top end gaskets still available for it?


Intake port layout is different so lower intake are not the same at all but do Exhaust manifolds differ from the silver to red top?

Thank you all for any help or I info you can provide I’m very much wanting to try and use the red top since it does have good compression.




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[TheRealSy90]

Sounds like going to a standalone ecu would solve many issues as you could run any combination of sensors.

[Lockdun1]

Thanks for the response sy90.I mean I get that completely but having not been around the 240 platform in so long and never having any experience with an rb the learning curve is gonna be steep getting a tune dialed in on a motor and software I’m not familiar with.I was really hoping to use a pre made complete silver top swap harness, silver top sensors and r32 eccs ecu to get me down the road. If it’s a pipe dream then hell im just gonna get down and study but I’m hoping someone can chime and tell me for sure one way of the other.


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[Lockdun1]

Those are pics I’m not home at the moment so the quality will have to do. It’s got an RB20DET-R sticker. Fake I’m sure with that log turbo manifold and eccs intake.the finned covers are what makes me pretty sure it’s a red top.




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[JrDarknes]

I have a preupdate RB20 (silvetop rb20 with redtop rb20 plugs [SQUARE PLUGS for the CAS, IGNITER, COOLANT TEMP, IACV & Plug I cant remeber near throttle body]) so I might be able to help.

If you need a harness for your redtop just ask wiring specilties for a early model RB20 harness to S13. However this depends on how your ECU looks so I may be wrong. You have a picture of it??
I'm assuming you have the square type plugs for yoru cas and igniter? If so then this harness should work as long as your ECU is similar to the silvertop ones.

I had ordered a silvtertop rb20 harness for mine and realized 5 of the plugs (which I just mentioned ) did not fit. Everything else did. I did some research and realized some silvertop RB20s came with Red top accessories. I've been told you can use a silvertop rb20 harness but need to adapt those 5 plugs I mentioned using your original harness plugs (redtop harness connectors).

If you go ahead and buy the early model harness from them and want to replace some parts.

If your trying to replace your O2 Sensor. Type this in your search bar.
APW INTERNATIONAL INC. AP3-10 OE Style

If Youre trying to replace your Ignitor
Type this (22020-58s01 nissan) in google. You should find some websites still selling these new.
OR
Just go to autozone website and register vehicle as 1990 Nissan 300ZX turbo [ I havent verified this yet but they look exactly the same].

If your trying to replace your coolant temp.
Add 1990 300ZX as your vehicle in Autozone (or anythign similar) and the coolant temp sensor should be square plug.

All I know so far. It sucks there is not alot of info on these engines man.

[Lockdun1]

You sir are the king that is defiantly what I’ll do! I had no idea they offered that harness! I’ll get the pre update harness with the ls coil set up and I’ll be golden I think.


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[Lockdun1]

Thanks that’s exactly what Ima do. So when you talked to them they actually offer the “early type harness” with the square plugs?


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[Lockdun1]

Really are a life saver Jrdarkness


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[JrDarknes]

Originally Posted by Lockdun1

Thanks that’s exactly what Ima do. So when you talked to them they actually offer the “early type harness” with the square plugs?


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Before anything upload a picture of your ECU just so I can make sure your okay.

If your ECU is fine.
Email Yuri (Wiring Specialties) and ask them to sell you an early updated RB20 Harness.

Also tell him you will be sending out your coilpack harness so he can match the pinout to their harness so you will need to ship them the coilpack harness as well. I had to do the same thing.

[Lockdun1]

Ima just get a r32 ecu I think that will be best and I’ll also just be doing the ls2 coil conversion I have a lot of em just around that way I’ll just use their jumper harness and ls coil harness.


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[JrDarknes]

Originally Posted by Lockdun1

Ima just get a r32 ecu I think that will be best

Oh yea thats smart loll.

Originally Posted by Lockdun1

I’ll also just be doing the ls2 coil conversion I have a lot of em just around that way I’ll just use their jumper harness and ls coil harness.

Alright nice! I think you should be set then haha. If you run into any more problems just PM me and I might be able to help.

[Lockdun1]

Originally Posted by JrDarknes

Oh yea thats smart loll.







Alright nice! I think you should be set then haha. If you run into any more problems just PM me and I might be able to help.

Man thanks again so much this is gonna help a ton.


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