copied to preserve documentation incase link goes down
http://240skyline.nissanpower.com/custom.html
Q: What is required to make the RB25DET fit into a 240SX?
A: All that is needed is the clip, driveline, tools, patience, and parts for extending/crimping wires.
Q: Do the RB parts interchange with any US-Spec Nissan cars?
A: Yes, in fact, the RB25DET uses the same clutch as the 300ZX Non-turbo. It also shares the same spark plugs, oil filter, and ignition coils.
Q: What extra parts do you recommend with the swap?
A: I recommend getting dual power fans to help with cooling, a Walbro 255LPH fuel pump to supply sufficient fuel, a new air filter for better breathability, NGK Iridium spark plugs for better spark and more HP, a decent sized downpipe and exhaust for better breathability and airflow, a new clutch for longevity and better grip, and a LSD so you are not burning rubber all the way down the track.
Q: Where can I get aftermarket support for the RB?
A: Aftermarket support can be found through me for both new and used parts. Other places are starting to stock parts for the RB swaps such as After-Dark Tuning. Other companies that carry brands such as Greddy, Apexi, HKS, and Blitz can order the parts for you from Japan.
Q: What modifications are necessary to the 240SX?
A: To make the engine fit properly with stock mounts, you will have to accomodate a few things.
1) As with any turbo swap, you will need to cut holes for intercooler piping.
2) You will need to shave (using a dremel or similar tool) a small portion of the turbo manifold that connects to the downpipe. This is necessary for steering rack clearance and does no harm as long as you do not shave too much off.
3) You will need to make approximately a 6" cut of the hood skeleton to achieve hood clearance (which isn't visible from outside the car).
4) You will need either a RB25DET driveshaft or a custom one made to fit the RB25DET engine.
Q: How difficult is the swap?
A: The swap, in my opinion, is fairly easy. Anyone who knows how to take something apart and put it back together again can do this swap. It is a simple plug and play with a few small modifications that are listed above. This was the first swap I ever attempted with no prior knowledge of how to swap engines.
Q: How difficult is the RB25DET to wire?
A: When I wired my car, I kept my 240SX interior harness (runs dash, headlights, tail lights, etc...) and got rid of the KA engine harness and ECU. I replaced that harness with the engine harness and ECU from the RB25DET. I then had to extend wires for the Gauge cluster and Ignition so that they would reach the LHD side of the car. I then integrated 5 wires from each of the harnesses ignition systems and made a power terminal where both harnesses were attached at the front of the car so that they would each receive power.
Q: Is it true that you have to cut into the firewall or extend your front end?
A: No, there is no need for cutting into the firewall or extending the front end. If you wish to use the stock engine fan that attaches to the fan clutch assembly, you will have to re-locate your radiator or extend the front end. This is why I recommend power fans for extra cooling.
Q: Can you use the Stock RB25DET mounts?
A: Yes, the stock engine mounts are bolted to the stock crossmember which shares the same bolt pattern as the KA crossmember when bolting up to the 240SX chassis. The tranny mount can be used, but must be taken off and flipped backwards. After you do this, you should add a spacer 1.5" thick made out of anything such as wood, metal, plastic, rubber, etc... as long as it will not collapse.
Q: What do you use for cooling the RB?
A: I use my stock 240SX radiator and haev no problems. The RB radiators can be used, but modifications must be made for it to fit into the 240SX as it is about 2.5" higher than the stock 240SX radiator. If you are worried about overheating problems, fluidyne radiators are a good option.
Q: What are advantages of the RB25DET over the SR20DET?
A: The RB25DET is an inline six built of practically a bullet proof block. It can handle more boost than the SR in stock trim. It is also capable of a lot more HP than the SR and has a lot more torque to start out with. The average black top SR puts 181-185 HP to the Rear wheels, whereas the average RB25DET puts 240-248 HP to the rear wheels. Simple upgrades on the RB can get you over 400 RWHP and with the right tires can put you into the 10's for the 1/4 mile if you boost and tune correctly.
Q: Is the RB25DET a reliable engine?
A: Yes, if it was not reliable, do you think Nissan would have put it into their signature car...the Skyline? It is the engine series out of their best cars and is daily driven in Japan.
Q: Would the RB25DET make a good daily driver?
A: Mine makes an excellent daily driver running low 13's to mid 12's on street tires. It handles well and has great acceleration. Think about this: are Corvettes good daily driving cars? They have over 300HP and are fairly lightweight for their size and design.
Q: What kind of gas mileage can the RB25DET get?
A: My car got 28-30 mpg highway and 25-26 in town before I fried my turbo. I am not sure if this is average for these engines or if mine just runs exceptionally well.