Well, I had both the RB20DET and KA on the garage floor, so I took some measurements to see where the shifter and driveshaft should be. This discussion will be about the KA with the KA transmission and stock cross-member and the RB with the RB transmission and R32 cross-member. Here's what I found out:
The KA and RB transmission's are quite a bit different. KA is 2" longer than the RB transmission. However, the bell housings are the exact same length, although they are of course not the same design.
The distance from the cross-member mounting bolts to the back end of the transmission on both engines is the exact same length. This means that the driveshaft from the KA should still line up perfectly if the RB x-member is used with the RB engine. The engine does not need to be moved either forward or backward to get the correct placement with respect to the driveshaft.
Unfortunately, the KA shifter sits 5/8" closer to the back end of the transmission than the RB shifter. I say "unfortunately" because it is not exactly the same, but as others have seen with their swaps, 5/8" is not even that noticeable.
Also, both cross-members put their respective engines' oil pans at the same height above the ground. The valve cover on the RB actually sits a bit lower than the KA, but the RB intake piping makes the overall height just a bit higher than when the KA is in the engine bay.
The overall difference in length between the two engines with their trannys is 6". Since the distance between the x-members mounting holes and the ends of the trannys are the same, this means that the front of the RB will be 6" closer to the radiator when using the R32 x-member.
Bottom line: for the perfect fitment with respect to the driveshaft, you can use the R32 x-member. This will also put your oil pan at the correct height with respect to the bottom of your car. Lowering the engine with custom mounts will move the bottom of your oil pan lower than the x-member, which means that the x-member will no longer shield it from road debris or anything else that could dent it. Moving the engine back 5/8" to get the perfect shifter placement will tighten up the driveshaft fitment, although there should be enough free-play so that this is not a problem. Fitting an LSD with ABS sensor may become a problem tho, since there will not be much play left after moving the engine back.
One more thing with respect to weight differences... I dragged both of these engines across my garage floor, and all that I can say is that the KA felt heavier than the RB. So if anyone has a good scale, it would be very interesting to see if the RB is actually any heavier overall.
Shane
RB20 mounting location in S14
My swap is still going. My semester started back up, and I got too busy to finish it right away. So now the details are dragging.
But the engine is in. I used the R32 x-member and transmission mount with no modifications. (No, you do not need to turn the transmission mount around.) As expected, the shifter sits about 1/2" forward, which is no big deal. I have pics showing the shifter in 3rd gear vs. 4th gear to show that there is plenty of room. The driveshaft is of course in the same place as with the KA. The bottom of the oil pan sits at the same height as the KA's pan.
Most people have clearance issues with the steering shaft hitting the O2 sensor housing (turbo outlet), but mine misses by 1/8 to 1/4". Since the engine torques counter-clockwise (engine turns clockwise from the front), there should not be any binding under load. However, when the steering rack is under load, there could be a problem. No worries, tho, since I had already planned to make a custom 3" pipe.
There is actually quite a bit of room in the engine bay, but it would not be possible to move the engine back more than maybe 1/2". So if anyone says they can sell you mounts that move the engine back farther than that, don't believe them. On the front side, there is not much room for fans, although I have seen at least 1 car with electric puller fans mounted. I know my PermaCool 12" will definitely not fit as a puller. There is only maybe 2.5" from the radiator to the pulleys.
I did all of the wiring while I had the engine out, so that's finished. Still need to get a custom PS line, hook up the radiator, fuel, and heater hoses. Find some way to make the throttle cable bracket work. Hook up intake piping and intercooler. And put the N1 dual on. Install the Walbro 255.
The details.... plus, this car sat up for a while and the brake rotors have too much rust. I need to go get them turned or wire brush them or something before I do something stupid like go fast with bad brakes.
But the engine is in. I used the R32 x-member and transmission mount with no modifications. (No, you do not need to turn the transmission mount around.) As expected, the shifter sits about 1/2" forward, which is no big deal. I have pics showing the shifter in 3rd gear vs. 4th gear to show that there is plenty of room. The driveshaft is of course in the same place as with the KA. The bottom of the oil pan sits at the same height as the KA's pan.
Most people have clearance issues with the steering shaft hitting the O2 sensor housing (turbo outlet), but mine misses by 1/8 to 1/4". Since the engine torques counter-clockwise (engine turns clockwise from the front), there should not be any binding under load. However, when the steering rack is under load, there could be a problem. No worries, tho, since I had already planned to make a custom 3" pipe.
There is actually quite a bit of room in the engine bay, but it would not be possible to move the engine back more than maybe 1/2". So if anyone says they can sell you mounts that move the engine back farther than that, don't believe them. On the front side, there is not much room for fans, although I have seen at least 1 car with electric puller fans mounted. I know my PermaCool 12" will definitely not fit as a puller. There is only maybe 2.5" from the radiator to the pulleys.
I did all of the wiring while I had the engine out, so that's finished. Still need to get a custom PS line, hook up the radiator, fuel, and heater hoses. Find some way to make the throttle cable bracket work. Hook up intake piping and intercooler. And put the N1 dual on. Install the Walbro 255.
The details.... plus, this car sat up for a while and the brake rotors have too much rust. I need to go get them turned or wire brush them or something before I do something stupid like go fast with bad brakes.
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NISMO_RB25
- Posts: 1066
- Joined: Thu Nov 06, 2003 4:40 am
- Car: 1992 240SX with RB25DET, 1987 RX-7 TII
I used a flat peice of metal about 3 inches wide and bolts that were flat on one side to make an extension to move the throttle cables forward on top of the plenum. I used dual 12inch puller fans with the stock radiator. they barely fit. I used mckinney mounts(RB25DET) and I don't have any clearance problems with the Oil pan. The front swaybar is level with the bottom of the pan.Glad to see your swap is coming along. The fuel pump won't take but a few minutes.. I like my N1 Dual and it sounds nice.
Yeah, that's what I had planned to do for the throttle cable.
With the McKinney mounts, maybe your engine moved back the 1/2" or so that was available, making barely enough room for the fans. With my setup, I do not think that the fans will fit at all as pullers.
I like my N1 Dual too.... it looks nice sitting in the box
I'll let you know how it sounds when I crank it up (someday... hopefully before xmas).
With the McKinney mounts, maybe your engine moved back the 1/2" or so that was available, making barely enough room for the fans. With my setup, I do not think that the fans will fit at all as pullers.
I like my N1 Dual too.... it looks nice sitting in the box
I'll let you know how it sounds when I crank it up (someday... hopefully before xmas).