If you’re working with a stock setup then you can probably find a downpipe for sale somewhere to bolt up for your swap. But if you’re working with a more custom setup then the downpipe is going to have to be custom fabricated to ensure a proper fit with your exhaust. The reason is because you’re going to want a custom exhaust manifold for the turbo application, and if you’re like me you’ll probably end up with a top mount turbo exhaust manifold.
There are a few things to keep in mind when selecting a turbo manifold:
Never buy a generic EBay Manifold. You are asking for trouble. These are cheaply made, probably won’t support the weight of your turbo, and have a higher chance of cracking. Why take the risk of damaging your new swap?
When planning for the manifold, be sure to take into consideration the downpipe placement with your steering column. There is not a lot of room for the downpipe or an external wastegate, but it can definitely be done.
Not all manifolds will allow for the AC Compressor to be installed. If you want to keep your AC then you will need to make sure the exhaust manifold is built for that purpose.
You can spend a lot of money on manifolds, but the result can be worth it. Besides reliability, proper manifold design will allow for the maximum efficiency in airflow to your turbo. This means quicker spool and more power. Without going into a ton of detail, the main difference between a tubular, equal length manifold and a factory cast iron manifold is that you’re allowing the cylinder exhaust of each port to work in harmony to power the turbo. Otherwise you’re shoving air through the same area from different sources and those sources can fight each other, robbing you of power.
Here is an example of an Ebay manifold vs. two quality manifolds:
When doing a swap one of the first things you’ll need to tackle is how to mount the new engine in the vehicle. Fortunately, for common swaps there are usually several choices for engine mounts.
This is also true with the RB in the S14. Even though I had access to an R32 crossmember when doing my first RB20DET swap, I opted to go with the McKinney Motorsports engine and transmission mounts and retained the S14 crossmember. This allowed everything to mount up perfectly in the vehicle, including the shifter.
When it came time to install the RB25DET I ordered another set of mounts from McKinney and was equally as pleased. They really do a great job and they make the installation a breeze.
People have often asked whether or not a carbon fiber hood is a good upgrade. My opinion is that for a swapped motor in the 240sx it makes a difference in two areas:
It helps with adjusting the weight distribution since you are adding in more engine and engine components in the front of the car. The carbon fiber hood weighs quite a bit less than the factory hood. At the end of the day you’ll want to corner balance the car anyways, but this does help. People laugh at me for saying it, but I can feel it when driving the car.
I prefer a vented hood because it’s going to let some of that heat escape the engine bay. Remember, you’re stuffing a bigger engine in the car and you are generating more heat with performance additions, such as the turbo.
I have a Seibon hood with the vents in front of the engine and after the radiator. This allows the air passing over the hood to pull air through the vent. So the air is pulled off of the radiator and out through the vent instead of blowing additional hot air from the radiator onto the engine itself. This also means that the vents are not directly above sensitive electronic equipment, like the coilpacks.
I think it’s a great, practical upgrade, and it’s not something I did for the looks.
Just remember to install your hood pins to keep it from flying off at high speeds. I didn’t have them when this picture was taken, but I went with the Sparco hood pins for ease of installation. I still have a set of Aero Catch waiting to be installed. Maybe someday…
The factory coil packs, and the various generic replacements, have problems with higher hp applications. The problem seems to occur around 17psi and higher. The coil packs don’t generate enough spark for a good burn, and the only way to get your spark plugs to stay lit is to gap them extremely small. This, of course, reduces the quality of the burn and the overall performance of the vehicle can be compromised. Some solutions, including putting tape or liquid tape around the coil packs to prevent arcing do not solve this problem, as those are not true solutions for high HP applications. Instead of putting my faith in other replacement coil packs, such as the split fires, I have decided to upgrade to a significantly better coil pack… The LS2 Truck Coil.
I’ve created a new website / blog for sharing information about my fairly lengthy and elaborate RB25DET powered S14 240sx project car. I’ll be adding regular updates on the build and tips that you’ll hopefully find useful.