Chevy LS V8 Swap into 240sx

From S-Chassis.com Wiki

Well After doing this swap Ive learned a few things.

Plan ahead

If you plan to do a big bore NA motor go ahead and invest in a different block than the LS1/6 block since it cannot be bored much. I believe the max is a 383 stroker motor .010 bore with a 4.00 inch stroke.

The Iron LQ4/9 block or LS2 block are better suited for big bore motor setups.

The Iron block will bolt to anything the LS1 uses only main difference is the alternator bracket will require a drilled/tapped bolt hole and one bolt will not be used but it will hold just fine.

The LQ4/9 and LS2 also have a bigger Cylinder head chamber size. 70cc vrs LS1/6 62cc so if you put LS1/6 heads on a 6.0L block it will increase compression.

Weight:

The Iron blocks weight close the same as an RB. Aluminum blocks close to the SR in weight.

Transmission

T56 is a great transmission but has issues with 2nd/3rd gears being weak

Solution: Viper or Steel hardened gears

Weak shift pads

Solution: Upgraded shift pads for the forks

Weak 6th syncros Solution: Upgraded syncros (cheap upgrade)

The Auto is still good but the 4L60E is a bit weak and looses a lot of power (estimated 20%). Mot will upgrade to a TH350 or 4L80E (truck transmission) with a shift kit to increase the shift time and firmness. Recommend a good Converter also if you plan to drag race.

Install

One thing to remember is have spare money for all the little things. The big parts are not the killer on these swaps even though they do cost more they are easier to find. The lines, conversion fittings, bolts, and other small things can bring a swap to a stand still.

Things needed

Motor Set ( Motor, trans, wiring harness uncut, and PCM/ECU )

KA Factory uncut harness

LS1 universal mounting kit

Camaro transmission mount (6 speed)

KA transmission mount (5 speed if possible)

Wilwood 3/4 bore clutch master cylinder

KA Koyo Rad

Flex A Lite dual fans (optional)

Dakota Digital Fan controller (optional), and speed converter

Custom Radiator hoses

Two heater core lines (different sized cant remeber exactly but I think it was 1" and 1 1/4" ID and about 3 foot long straight on one side. Can be found at any parts store) (optional)

KA Factory PS line

LS1 factory PS line

Drive shaft

Headers (depends on what you want to do. Custom made is the best way but requires good welding skills and bending tools, Hinson's headers are good and are exspensive but work with little modification.)

5 pound sledge (Fire wall retraction purposes )

Walbro 255

Corvette Fuel filter or After market FPR w/return outlet) I used Aeromotive's FPR. If you use the Aeromotive I would use a Z32 fuel filter because of the flow.

Depending on the what rails you use will determine if you need a fuel fitting to go from the quick disconnect to a An or barbed fuel line or just AN fittings to the rails. I bought Fast Rails to make it easier.

Russel Fittings Clutch slave fitting to go to -4AN ( I believe it is made for a jeep)

Steel braided line from clutch master to clutch slave.

GTO (03-06) Oil Pan/Pick up/Windage tray

3 3/4 90* coupler

3 3/4 pipe

Filter

Steps for install

Engine install

Remove old KA (junk )

Clean engine bay out while its out and remove all the unnecessary junk. Including emissions canister/lines, old clutch master, old clutch lines and pressure equalizer.

You will need to move the fuel lines out of the factory location or make a shield for them since they will be close to the passenger side header. I chose to follow them back to the back of the car, cut them and install high pressure compression fittings to an AN fitting. Then ran the line along the out side of the frame rails held in place with brackets screwed into the rails. Next comes the cutting. Start by marking off the front cross member. You'll need to cut a slit I went 2 or 3 inches back (leaving about a 1/4 to 1/2 inch of material left before the rack) and cut almost to the mounting bolts for the rack wide. I cut all the way through and just welded 1/4 inch steel plate in the open gaps. Tested the strength by jumping on it. Make SURE to make good weld penetration.

Once that is done take your GTO pan and lay it in and see if it fits. it will be tight but should fit with about 1/4 inch of space or more around the edges.

I sat my motor low as possible so I ground down the PS mounts where it lips up on the ends to add clearance.

Next brake out the miny sledge and go to town on the fire wall. The main areas of concern are mostly at the opening of the tunnel and some down the middle towards the back. The main issue I found was the tabs on the transmission that do nothing so we ground them off. This is one of those beat it and test fit it situations. Dont be afraid to get violent with it.

As far as the motor mounts go I bought a piece of 1/4 inch steel 3inches wide and how ever long I needed. I then laid this flat on the cross member factory locations. I drilled two holes that fit inside the 2 1/2 to 3 inch slit already on the cross member. I placed two grade 8 bolts the largest that would fit with washers and nylon locking nuts through them. Next I put a doward brace that I drilled a hole through and through the bottom face of the cross member and place a large bolt with washer and nylon nut as before. After that we boxed in the open area between the downward piece and the horizontal piece. We used just a sing angular piece and welded it in place. We then attached the motor mounts to the motor and dropped it in to see where to cut off and weld to the plates we attached to the cross member. This will take a while but make sure your fitment is good before the final cuts and welds.

Once you get that done you will need to cut the T56 trans cross member int he middle so you just have the mounting hole and bushing area. I then bolted this to the trans and used angle Iron to connect it to the factory bolt holes. Make sure you look to see how much to cut off before doing so because the angle iron will have to line up with th factory bolt holes.

Before installing completely connect any wires or hoses to the back of the intake and block and block off the coolant cross over on the rear. The front cross over must be run back into the coolant system somewhere if not routed back in this will cause pressure build up and poor flow of coolant through the heads.

Next once welding is done install the motor. I connected the clutch line together at the Slave and Master before it went in so I could bleed the clutch before dropping it in. There is no easy way to do it without making brake fluid mess so have a towel ready and let the trans drip dry for a day. (it will have a small amount of fluid in the bell housing from the bleeding.

The Clutch master will require an adapter plate since the factory mounting holes are at a 30* leftward slope. I just used a 1/8 inch round plate. Made two holes for the old master cylinder studs and ran bolts through the other way to hold the new master cylinder. (I recommend Grade 8 or better on any fastener)

The factory U piece that attached to the pedal has a different thread pitch than the wilwood plunger stem so you can either force it on (which I did just dont plan to adjust it any) or drill it out and place a bolt on either side. I would use ones with Nylon locking pieces on them for either side.

If you use the Hinson headers the steering column will have to be pulled off the rack and the U joint on the column will have to be shaved some. I also heated the header runners around the steering column and bent them in some. It wont effect flow much at all but will give you the needed clearance. I found if you go ahead and sit the headers in and attach the rack you can still slide the motor in and cut down on the pain in the as* it is to reinstall the column once the motor is in. The install is pretty much done.

The PS is done by adapting the pump side LS1 hard line to the rack side 240sx hard line. Most hydrolic places should be able to do so. Some people use PS coolers but its personal choice and what you plan to do.

Wiring

Its a daunting task when you first look at it but if you break it down to basics its only about 6 wires and the car will fire up and run.

Things needed

KA harness (mainly just the F3 plug and Wiper harness)

LS1 harness

Three 30 amp relays

Shrink wrap

Solder

Tape ( I used factory fabric tape used on the new Chevy harnesses. Not as sticky/nasty as electrical tape, holds well, and is flexible.)

First what I did was de-loomed the harness and got a wiring pin out of all the connectors and removed any and everything that wasn't necessary.

Then go through and find you switch and constant 12v wires. I put the two main switch 12vs on different relays and the smaller switch 12vs on the other relay. The wire gauge will show you which ones to group. The constant 12v I pulled through the factory F3 plug and the switch 12v for the relays as well.

I tried to hide all of my wires so I lengthened my wires so the relays would mount in the factory fuse box. The main reason i think you should de-loom and re-wrap is because the harness is very thick where it enters the fire wall and can be thinned and wrapped much tighter to make an easier fit.

As for grounds I just put ring terminals on the ground wires that needed them and grounded them as necessary.

As for the wiper harness you will have to pull it out of the KA harness. It can be done with some patience. Once it is out you should just have to supply power to the motor and amplifier box. If you cut these wires on the F3 plug just rewire them back in using an F3 pin out.

As far as starting just run a wire from the factory signal wire located on the side of the fuse box. ( Its been a while but its a fat Black/White I believe).

Make sure to ground the coil packs/injector grounds located in the middle of the harness.

As far as O2 sensors you wont need the rears just the front O2s (they do all the main fuel calculations). I just de-pinned the ECU plug (the plugs are numbered so they are easy to figure out with a pin out image) and switched the rear pins into the front pin holes and the front I took out. This will allow the rear sensors to act like the fronts. Reason for this is because the headers have the O2 bungs at the rear location.

The Tach signal can be directly hooked the the F3 plug since the pulse is a 4 cylinder pulse. The Speedometer will require you remove the cluster or chase down the wires int he harness that exits the drivers side. I found it easy to pull the cluster. Then locate the Speed -/Speed + wires that come into the cluster and attach them appropriately on the Dakota Digital box. Then the switch order on the box is debated so just find one that works and you will need this to be out int he open so you can adjust the signal as you drive to dial it in.

WARNING

You cannot run the speed sensor signal through the F3 plug since the way the KA works the signal enters the cluster first and is is changed and sent to the ECU (hence why you can cut the speed wire at the ECu and the cluster still will work).

Lastly you will need to have all emissions, rear O2s, VATS (Vehical Anti Theft System) and other unnecessary things turned off on the ECU. Any shop with LS1 Edit or HP tuners should be able to do this.

The CEL can be hooked straight into the F3 plug since the LS1 uses a ground trigger like the 240sx.

If I think of anything else Ill post it. Im sure I will.

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