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Looking to swap in a RB25DET into my 240z


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I suppose I'll start off my introducing myself. My name is Travis, I am new to hybridz and datsun z's although my father and uncle own a few. So I just recently bought a 240z from someone in the neighborhood and it doesn't run. It needs some carburetor work and a few other things that its missing so rather than fixing it up, I was thinking I could just go ahead with a rb25 swap. My uncle has a 240z that has a v8 conversion as well as a rb20 conversion, so he told me it wouldn’t be too difficult to swap out an rb25 with a 5 speed tranny into it. Now I've never really done any work on a z before but my paps and my uncle said they’d help me out as much as possible.

 

Could you guys give me some information on how to go about this? How much it’ll cost and if it’s a straight swap, or would I have to do various other things along with it. Any information, etc would be absolutely amazing and it seems like everyone here is really cool, seems like a great community here.

 

Could I just do something like purchasing this rb25 for example: RB25. Or is that a bad choice? Like I said, I'm new to the z world and could use all the help and support I can get. Thanks a lot.

 

Travis

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I suppose I'll start off my introducing myself. My name is Travis, I am new to hybridz and datsun z's although my father and uncle own a few. So I just recently bought a 240z from someone in the neighborhood and it doesn't run. It needs some carburetor work and a few other things that its missing so rather than fixing it up, I was thinking I could just go ahead with a rb25 swap. My uncle has a 240z that has a v8 conversion as well as a rb20 conversion, so he told me it wouldn’t be too difficult to swap out an rb25 with a 5 speed tranny into it. Now I've never really done any work on a z before but my paps and my uncle said they’d help me out as much as possible.

 

Could you guys give me some information on how to go about this? How much it’ll cost and if it’s a straight swap, or would I have to do various other things along with it. Any information, etc would be absolutely amazing and it seems like everyone here is really cool, seems like a great community here.

 

Could I just do something like purchasing this rb25 for example: RB25. Or is that a bad choice? Like I said, I'm new to the z world and could use all the help and support I can get. Thanks a lot.

 

Travis

 

 

Travis...welcome to the board. There is a ton of information here regarding the questions you ask about this swap. I would highly suggest that you search through and read as much as you can then ask questions that you may not have an answer to. Here is a direct link to the RB section here at Hybridz.org. This will answer many of your questions.

 

http://forums.hybridz.org/index.php?/forum/31-nissan-rb-forum/

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there is a ton of info on the rb part on this forum. The swap is pretty straight forward. I did a rb20 swap in my 280z and I found it easy. I decided on the rb20 because of the cost. I have seen the rb20's produce about 400hp and that more than enough for my datsun. I have about 1500.00-1800.00 in my swap before I added everything like a bigger turbo,injectors and NIStune and etc. Thats 1500.00-1800 with it running and driving. I added everything else after the swap. The only part thats a pain to find is the rear sump oil pan which nissan does not make anymore. Thats where I can help you. I have been build custom rear sump pans for the rb swaps for the s30's (see my posts on the rb engine part on this forum) Please let me know if you have any questions about this swaps. I would be glad to answer any questions.

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Thanks a lot for your input guys, and I have been doing some research here on the forums before I actually posted but I just couldn't find the sufficient information. Perhaps I'm just blind or I don't know how to read. Nevertheless, I have found some great information on the rb forums (thank you carjway) although I'm still lost. I know I'm going to be in need of some motor mounts, just don't know where to go about getting one. Also, I'm afraid the wiring is going to be a pain in the ***. Any additional information, or perhaps you guys can lead me in the correct direction would be plenty helpful.

 

 

pat1:

The swap is pretty straight forward. I did a rb20 swap in my 280z and I found it easy. I decided on the rb20 because of the cost.

Would you say the swap would be easier with a rb20 rather than the rb25. I'm definitely into conserving as much cash as possible and I'm not looking for intense hp, just a reasonable amount, 300hp would be the most I would ask for. Thanks.

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The rb20 would be easier. I used the stock skyline motor mounts and modified the stock z trans crossmember to use the rb trans mount. With the rb20 you can use the stock z driveshaft. The wiring is cake. It's less than 10 wires plus gauges. The rb25 is the same but you need motor mounts that run 475.00 from Mckenney motorsports or you can make your own. You have to get a driveshaft made which is about 250-400. The wiring is also easy. Tuning is easier with the rb20 vs the rb25. With the rb25 you can't use the stock rb25 ecu. You have to use a rb20 or z32 ECM.

 

 

All and all the rb20 is a little easier and cheaper. It's how much power you want. My rb20 is perfect for me. It hauls a$$. And revs to the moon.

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I am in the midst of doing an RB25 swap myself. Read all the stickies at the top of the Nissan RB Forum. Chris Rummel provided an incredible wiring write up. I am most likely going to use the McKinney Motorsports products for my engine and trans mounts. I purchased by motor from Venus-Auto in Sacramento.

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The rb20 would be easier. I used the stock skyline motor mounts and modified the stock z trans crossmember to use the rb trans mount. With the rb20 you can use the stock z driveshaft. The wiring is cake. It's less than 10 wires plus gauges. The rb25 is the same but you need motor mounts that run 475.00 from Mckenney motorsports or you can make your own. You have to get a driveshaft made which is about 250-400. The wiring is also easy. Tuning is easier with the rb20 vs the rb25. With the rb25 you can't use the stock rb25 ecu. You have to use a rb20 or z32 ECM.

 

 

All and all the rb20 is a little easier and cheaper. It's how much power you want. My rb20 is perfect for me. It hauls a$$. And revs to the moon.

 

What did you do modify the z crossmember in order to use the rb trans mount if you don't mind me asking? If you could help me out here, I'm going to be putting in the order for the engine and tranny most likely by the end of this week/end.

 

It comes with the following:

Engine Block Top and Bottom

Intake Manifold

Turbo Manifold

Turbo

5 Speed rear wheel drive Transmission

A/C Compressor

Alternator

Starter

Power steering pump

Valve Cover

OEM Sensors

IGNITER

SPARK PLUG

COIL PACK

Oil Pan

Complete wiring harness to the ECU!

 

Is there anything missing from the engine or would this be about everything in order to get this bad boy running again? Thanks pat. And I'll probably be sending you a pm soon about your sump pan, saw your thread, looks good.

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You will need a intercooler and piping, get a walbro inline fuel pump. As far as the crossmember goes I modified it by drilling two holes in it and grinding down the sides a bit so the z crossmember will fit right on. I had to slot the stock engine crossmember forward about 1/4 inch and the motor and trans dropped right in.

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You will need a intercooler and piping, get a walbro inline fuel pump. As far as the crossmember goes I modified it by drilling two holes in it and grinding down the sides a bit so the z crossmember will fit right on. I had to slot the stock engine crossmember forward about 1/4 inch and the motor and trans dropped right in.

 

Right, well besides the intercooler and piping and of course the walbro inline fuel pump, is there anything I need or perhaps I'm missing? Any other modifications to the z itself I would have to go through. Perhaps, I would need to upgrade the suspension as well as disk breaks for the rear correct? Or is that not really a necessity for the rb engine? I know that you need it for sure on a v8 conversion, but its not like I'm going to have that crazy amount of hp and I'm definitely not racing it.

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Off the top of my head it sounds like you have everything. I would put a new timing belt, tensioner,idler pulley and a water pump. And a t-stat. I have coilovers on my car with heavier springs. I put the Toyota 4 piston calipers and the bigger master cylinder. I still have the stock rear brakes. The brakes work great for the street.

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Off the top of my head it sounds like you have everything. I would put a new timing belt, tensioner,idler pulley and a water pump. And a t-stat. I have coilovers on my car with heavier springs. I put the Toyota 4 piston calipers and the bigger master cylinder. I still have the stock rear brakes. The brakes work great for the street.

Pat, I greatly appreciate all of your help, couldn't have asked for more. You'll be one of the first I credit for my build. :cheers:

 

Also, if anyone can point me to an awesome store for guages, speedo, boost, oil, water temp, etc.

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  • 1 month later...

there is a ton of info on the rb part on this forum. The swap is pretty straight forward. I did a rb20 swap in my 280z and I found it easy. I decided on the rb20 because of the cost. I have seen the rb20's produce about 400hp and that more than enough for my datsun. I have about 1500.00-1800.00 in my swap before I added everything like a bigger turbo,injectors and NIStune and etc. Thats 1500.00-1800 with it running and driving. I added everything else after the swap. The only part thats a pain to find is the rear sump oil pan which nissan does not make anymore. Thats where I can help you. I have been build custom rear sump pans for the rb swaps for the s30's (see my posts on the rb engine part on this forum) Please let me know if you have any questions about this swaps. I would be glad to answer any questions.

hey how much does a modified oil pan run im starting a rb25 swap on my datsun i could use all the help i can get. thx,jake

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hey how much does a modified oil pan run im starting a rb25 swap on my datsun i could use all the help i can get. thx,jake

 

 

You should be reading in the RB subforum to find out more if you are going to be doing this swap, but I'll start you off with a link to pats thread. He lists prices a couple posts down, you just have to look for it...

http://forums.hybridz.org/index.php?/topic/89219-i-picked-up-a-new-sheetmetal-brake-and-other-toys-for-building-these-oil-pans/

 

RB Subforum

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I'll be glad to build you one. Do you have a rear wheel drive block or a all wheel drive block? The difference between the two is that the rear wheel drive block comes with a steel pan and the all wheel drive block comes with a aluminum pan. Most of the rb25's come rwd and I can build that pan three ways.

 

1: I can modify your stock pan to make it a rear sump pan that pan runs 250.00 plus shipping. I will need your pan and pick up as a core.

 

2: I can use your stock pan and I cut off the flange and build a custom pan from the flange up. this one runs 400.00 plus shipping. I will need your stock pan as a core.

 

3: I can build one from the ground up 100% from scratch. This one does not require a core or a pickup this one runs 475.00

 

 

 

If you have a all wheel drive block I can only make it one way that is 100% from scratch and this one runs 595.00 plus shipping. There is alot more metal work on these pans.

 

 

 

please let me know. I have some stock rb ft sump pans in stock and I can start the work asap. No waiting for your cores to show up. If you have any questions please let me know. I'll be glad to help you out

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