There are many reasons to swap out your Nissan KA Engine. Some of us want big turbo power, others have broken motors, and still others want to be rid of their SOHC headache. If you are a 240SX owner, you have probably considered a KA engine swap.
The KA to KA Engine swap is the most realistic engine swap option for the 240SX because the motors can be affordably acquired. And the fact that KA24’s are readily available all across America. The KA Engines are great candidates for turbo. The KA has a broad base of aftermarket and OE parts, and the KA to KA engine swap can be the easiest of the engine swaps. If you learn anything from this website, let it be that any Nissan KA24 engine can be swapped into any specific 240SX, quite easily.
I’m not going to say that the Nissan KA24E is a bad engine. I’m also not going to try to convince 1989-1990 240SX drivers to dump their KA24E’s and toss in a DOHC KA engine. I can tell you that I am very happy that I did KA engine swap, however.
The main reason of 240SX engine swaps is: You want a DOHC motor and the KA24DE engine is your cheapest & easiest option on hand.
The KA24DE engines came in 2 distinct 240SX flavors: The S13 and S14. Is there any difference between those 2 engines?
The S13 KA24DE engines are came from the 1991-1994 240SX’s. The S13 KA24DE featured some of the same style pieces as the KA24E powerplant that Nissan discarded for the 1991 model year; the spark system being more or less similar between the two S13 motors. The S13 KA24DE features an external ignition coil, like the KA24E. The S13 manual ECU’s also had a speed governor. The MAF is new for the S13B and very few parts are suitable between the single and dual cam KA engine.
The S14 KA24DE had a wee bit more compression, a different upper intake runner design, slightly less agressive cam durations, an internal ignition coil, and a new valve cover design. The KA24DE engine during the S14 production has S14 is OBD-II diagnostic system run as well.
Both KA24DE’s are good for turbo. The cam duration and compression differences among the S13 and S14 usually are not drastic enough to make one significantly better above the other. S13 KA24DE engine are generally cheaper, and S14 KA24DE’s are generally have fewer miles. Buyers on the market for a KA24DE platform generally tend to seek the motor with the least wear on it; one that will be more reliable under boost.
Putting the S13 KA24DE engine into your S13A is easy. All you need is the harness, ECU, and complete motor with subsystems. Power steering lines and radiator piping from the S13B will be needed to make the KA engine swap direct. Most of the A/C system will need to be taken from the S13B donor car as well. You can fabricate coolant hoses, of course, to fit any radiator. The interior control connection is plug and play with the S13A interior harness clip, and the DOHC harness fits into the 2 harness clips by the battery tray.
You can keep your old S13 KA24DE engine transmission swap. The lower wiring harness is compatible with the new S13B wiring harness. In fact, any 240SX transmission from any year is fully compatible with any KA engine, from any year. When you are bolting a manual transmission onto a Nissan KA24 engine that had an automatic transmission on it, you are going to have the manual flywheel, transmission metal gasket, and engine block transmission mount brackets. Do not use the auto tranny flywheel bolts on the manual transmission.
You will also need a gauge cluster from a 1991-1994 240SX engine swap, with the cluster wiring harness. It’s neat to get the gauge cluster from the same car that your engine came from, so that you know the milage of the motor, but it doesn’t always work that way. Some people keep the S13A guage cluster, but many functions will not work, including the tachometer. Mainly because the tachometer signal on the S13A and S13B is little bit different.
The S14 motor is more complicated. Everything is similar to the S13 KA24DE, except the interior harness connection, which is drastically different. Using the S14 ECU with the S14 harness creates a wiring nightmare behind the dash. Each and every wire on the S13 interior harness should be soldered into a new position on the S14 harness, and many functions still will not likely work, including the tachometer.
The easiest way to swap an S14 KA24DE motor into an S13 is to use the S13B wiring harness. With the S13 KA24DE distributor, external coil, MAF, and ECU. This is $200 of parts that will save you 50 hours and a huge headache. WIth these parts, the wiring is plug and play like the S13 KA24DE, and you have an external coil, which is easier to attach an MSD box to. This is what everyone who has swapped an S14 KA into an S13 and I would recommend.
You can also do an S13 KA24DE engine swap into the S14, but doing the reverse of the opposite swap; use the S14 harness, MAF, and sparksystem.
Whatever your KA engine swap, my advice is to drive the engine around for a few days after you bolt in and wire up the motor, before going turbo. You will get a chance to notice any problems the engine has, and get a feel for the new motor. I would also recommend swapping in a beefier fuel pump and filter with any Nissan KA engine swap, especially the SOHC to DOHC swap.