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TheSnail

The ease of an rb swap.

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Hello I just want to clarify some things on the rb swap. I was shocked as to how easy swapping the motor was into the z. Ive done a dozen rb swaps into 240sx but never in a Z until this past weekend. It is basically the same, but the 240sx you swap out the crossmember and the z you swap the oil pan. So here is a outline of what we had to do.

 

The car is my friends 280z and the motor is a rb20det out of a 93 skyline. So first we took the l28 out and cleaned up the engine bay a bit, then changed the oil pan to a rear sump. Then we grinded down the nipples on the stock rb20 mounts as they are on opposite sides. Then we put the engine in. We used the stock Z trans mount and bolted it up to the rb tranny. Then we bolted every thing up. Then zizwheeled the cover plate off the input shaft, and bolted up the drive shaft. That was it. It sits in there just like one in a 240sx with the shifter forward one inch. So after that it was just fluids, fuel pump, wiring and a throttle cable from a 240sx. It took about 10hrs from start to finish.

 

After seeing how simple it was, I have decided on getting an rb25 for my newly acquired 240z (hence Im a newbe). I will use a rb20 trans and mounts just out of simplicity and a weekend of down time. I would keep the rb25 tranny around just incase I keep braking the rb20/ca/ka/sr tranny’s. But I think it will hold up just fine at 400hp. Same goes with the rb26, but the main bitch part with those is the whole oil pickup part. I had a rb26 240sx where I used rb20 mounts and a rb25de trans which is the same thing as a rb20det trans, and it bolted up just the same as any other rb. The tranny held up even after 460rwhp so Im just going to go with that. Anyways, I don’t know if what I said has already been covered but I figured I would share. Hopefully I'm not just wasting bandwidth.

 

Snail

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Congrats on getting your swap up and going so quickly. Mine would have been together and running if I had stuck to the original RB20 plan. I agree the RB20DET / RB25DE swap can be done with relative ease. All it takes is a little enginuity and common car sense.

Unfortunetly I am suffering from the "As long as its apart, why not do this?" syndrome.

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Congrats on getting your swap up and going so quickly. Mine would have been together and running if I had stuck to the original RB20 plan. I agree the RB20DET / RB25DE swap can be done with relative ease. All it takes is a little enginuity and common car sense.

Unfortunetly I am suffering from the "As long as its apart' date=' why not do this?" syndrome.[/quote']

 

 

HAHAHA, I know just what you meen. Doing the rb26 swap I kept saying "I need this" or "might as well get this while I'm at it". 12k later the car was up and running about. lol

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hey if i can just hijack this thread for a second, ive got an rb20det sitting in my 280zx, i know its a different platform, but my problem should be a familiar one... basically what's the easiest way to do away with the old solid accelerator linkage and fit a throttle cable? everyone else who's done the swap must have done something at this point, but it doesnt seem to be a modification that anybody bothers to mention? cheers in advance

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ok, so you did away with the solid pivot on the firewall? just trying to work out what you've described, without looking at my car.. you made the slot in the top of the pedal itself, or somewhere on the mechanism? if it was on the pedal itself would that mean that the throttle cable looped back towards the driver before going through the firewall, to get leverage in the correct direction? cheers

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id really like to see some pics of the rb20 installed on the 280z cuz im really leaning towards this engine. also did you go with an aftermarket ecu.

 

into a z or a zx? most people seem to stick with the stock rb ECU. they have very versatile maps and you can get a lot done just by chipping them. dont know how much that costs in other countries but here in NZ youre looking at $200 tops for a remapped chip

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No problem. To clarify what I am saying before I post pictures tomarrow is: At the top of your gas pedal you have a "flat" area. Basicaly you drill a hole through it then get a ziz wheel or a saw, and cut slot into it. So you will be able to slide the cable in through the slot and the end of the cable is held in place at the hole. Its the same way a stock 240sx pedal has it set up.

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id really like to see some pics of the rb20 installed on the 280z cuz im really leaning towards this engine. also did you go with an aftermarket ecu.

 

It was a stock ecu that had been modified to have a higher rev limit and speed limiter removed. But it is stock other wise.

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into a z or a zx? most people seem to stick with the stock rb ECU. they have very versatile maps and you can get a lot done just by chipping them. dont know how much that costs in other countries but here in NZ youre looking at $200 tops for a remapped chip

 

Im not too sure if anyone here in the states remaps rb20 ecu's. Since there is not too much of a market, as well as you can buy already remapped ones from Japan for around $100-200 on ebay. Though most people I know just get a safc, or Power fc since they are a good bang for the buck, which for rb's run around $500 with comander in good used condition.

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well that makes things very simple.. i'd still appreciate some pics' date=' to minimize the chances of screwing up.

240sx trivia; way down round here theyre called silvia's :D and theyre turbo ;)[/quote']

 

I do wish we had silvias here. But only 240sx's. I did import one, and my friend got one, and another friend got a gtst, and another one got a gtr. But it is a pain in the ass to get over. Mine is stuck in Customs as we speak, with the threat of being crushed:( I did have a bunch of 240sx with different swaps, I should post some pictures of them up some time. But now I want to try something different, so I bought a 240z:)

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hey if i can just hijack this thread for a second, ive got an rb20det sitting in my 280zx, i know its a different platform, but my problem should be a familiar one... basically what's the easiest way to do away with the old solid accelerator linkage and fit a throttle cable? everyone else who's done the swap must have done something at this point, but it doesnt seem to be a modification that anybody bothers to mention? cheers in advance

 

 

hey, i have a RB20DET powered 280ZX.

 

I used a hack-saw to cut through the 280ZX pedal and removed it completly, then i made up a small braket, drilled a hole in the firewall, and mounted the Skyline pedal setup, it was too easy, hardest part was removing the old pedal.

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but the 240sx you swap out the crossmember and the z you swap the oil pan.

 

 

I'm gearing up for a rb26 swap into a s13. you say the crossmember has to be changed??? i was under the impression that the gtr oil pan with the diff cut off will work????? Is this incorrect?

 

Sorry guys, he caught my attention with that little piece of info

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I'm gearing up for a rb26 swap into a s13. you say the crossmember has to be changed??? i was under the impression that the gtr oil pan with the diff cut off will work????? Is this incorrect?

 

Sorry guys' date=' he caught my attention with that little piece of info[/quote']

 

 

One of my friends did it by cutting up the oilpan, by cutting off the front diff (rightside) and welding a plate the oilpan to cover up the hole. What I did was use the rb20det oil pan since when you take off the gtr oilpan it has a set of holes for the the 10mm bolts that rb20's and 25's have. The Gtr oil pan has bolt hole out side the other boltholes, basically to simplify what I am saing is A circle of bolts(gtr oilpan) around another circle of bolts(rb20/25 oilpan) And if I can remember corectly the gtr's oilpan used 12mm bolts. The reason I am explaining in depth is because this is the part that gets tricky. Since the inner set of bolts(10mm) is within the gtr's set of bolts, the stock gtr oil pickup flares out past the 10mm set of bolts by about 1/8-1/4 inch. This means I had to modify the oil pan a little bit. So I got a pip and cut it in half at an angle so it made an elongated 1/4 sphere. This part was about 2" by 1". I cut the oil pan and welded in this peice in order for the oil pan to clear the top (part where it bolts up) of the oil pick up. But that is not all. On the oil pan, the rear part has fins or baffles to keep from oil starvation under acceleration or breaking. Well unlike the rb20 or 25, the rb26 has those fins not in the oilpan, but has the fins bolted from the bottom of the crank going into the oilpan. So basicaly, I just got the zizwheel out, and cut the fins off the oil pan. Once I was done, I just bolted the oil pan up. It took me a couple of days to do the oil pan, because I did it a while ago and did not have any resorces to go by, so it was trial an error. But since then I have learned it would of been 10x easyer to simply get a rb20/25 oil pickup that way your oilpan would clear and would not have to modify it other then just cutting the fins in the rear.

 

Now as far as mounts go, you dont have to use a crossmember, you can use aftermarket mount depending on the tranny you use. I had a rb25de tranny which is the same as an rb20 tranny, so I got aftermarket mounts for $250 that set the engine low and back into the optimum position. This way I used the stock drive shaft. If you are using a rb25det tranny then get the rb25 mounts, not because the engine mounts are any different but because of the different tranny mount. If you want to swap out the crossmember, then with an rb20 tranny, you would use the r32 crosmember and rb20 stock mounts. Thought this will sit about an inch higher and and inch forward compared to the after market mounts. You can use any one of the mounts I said, dependent on if you are going single turbo or keeping the twin turbos. I kept the twin turbos, but I converted the car to RHD. The main reason was because the secound turbos down pipe hits the stearing colum. Mykinny sells there kit to clear the steering colum, but while looking at it I was very sceptical on how they managed to clear the rear 3inch down pipe. They would not show the "real" pictures of the down pipe and would not tell how they did it, so about a year later a friend of mine bought the kit as his car was a LHD and he was not happy with it. I went to go check it out, out of curiosity on how they did it, and all they did was take the part of the down pipe that would not clear and cut it in half and welded it back. LOL , so it was a 3inch downpipe the turned into a 3inch semicircle. Talk about restriction and a $500 down pipe that you could of made your self. Anyway you could make your own down pipe by using a semi circle (4"x2") pipe for that section that does not clear, rather then a big semi circle square edged block in you exhaust system.

 

-Snail

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No problem, if its the gtr oilpan you want to keep I will ask my friend for pictures, but basically it goes like this, and I quote:

 

"The second option is to modify the factory aluminum Rb26 oil pan. This is much more involved, but in my opinion is the best way to do it. Just look at the two pans and you will see why. As for modifications, the differential housing must be cut off and ground down. The holes where the axle went through the pan then need to be welded up, and some ribs need to be ground down (for clearance). Although this method solves many issues, it also creates one as well. The factory sway bar will not clear this pan. About all you can do is either notch the front of the pan for clearance, or build a custom sway bar."

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Stony, the short story is that Nissan, being Nissan, made everything interchangable. The crossmember from the 32/33 skyline will bolt into the S13/14, etc. If you do this, the RB26 will go right in with no mods using the 2WD RB mounts. However, steering rack mount will be an issue because the 240 is on the "wrong" side ;) The modded aluminum pan is now in the mail. The front has been notched to clear the Cefiro/Silvia sway bar and may not need any other mods to clear your sway bar. If you need a crossmember, I can see if one is small enough to mail through PSC. If so, I can get them all day long for free. Do you still have the one that came off of the R31?

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Hey stony, I got pics of both.

 

Mine

f5d2bc5f.jpg

 

My friends

DSC02016.JPG

 

 

Also the gtr pan will hit the crossmember/stearing slightly, though you can grind it down a little bit and be fine. The swaybar on the other hand somwhat depends on the mounts, if you use aftermarket 20/25 mounts that set your 26 back one inch then you can clear the stock sway bar by mm's though you can get even better clearence by using extra spacers on the swaybar. If you used stock rb20mounts and and r32 crossmember, then you will not clear you swaybar, and a custom one would have to be made.

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Guest TwistyFriZ

so youre moving from the sx world huh???? i remember your screename from over at zilvia.net, i used to have a white s13 with a redtop and a silvia front... had the z even longer, its just a work in progress though..... i miss my sx so bad(e36 m3 now), im hoping the z will help with that:):)

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