GS and DOHC Swap Experts - Replicating GS from Scratch

[dexter]

I am trying to recreate the NA 2.4 DOHC GS powertrain in a 6-bolt version. I think I've figured out everything I need to do to make this work, but I would really like some input from people with more experience with this type of thing. I should let you know, I've been wrenching on DSMs for almost 10 years now - so I'm really familiar with 4G63s. I've been trolling and searching your forums for about a month; but if I've missed something that's been beaten to death all ready, please share a link.

Mechanically, I'm planning on running a G4CS (4G64) block with a G4CN (4G67) head. I'm going to use 4G63 rods from a 1G DSM and am leaning towards the 7-bolt 16v SOHC 4G64 pistons found in a lot of the mid-90's Galants and Expo/Summit wagovans. I am aware that I'll have to enlarge the small end for the 22mm wrist pins. I'm fairly confident this will be straight forward, but I am slightly concerned that there may be geometrical differences in the valve layout. Which brings me to my first question.

Have any of you that swapped from the SOHC to the DOHC noticed any interference issues? From the swap threads I've seen here so far, it appears that you just toss the DOHC head on and run with it.

My biggest hurdle is figuring out the electronics. I believe I can use a turbo 1G DSM wiring harness with a 94 Galant GS ECU to get a factory tune to run this setup. From what I've gathered, the 94 GS is OBD1 and has the same style ECU connectors as the 1G DSM. Also, you 7G guys run what looks like a turbo 2G DSM MAF. What's the deal with your knock sensors and CAS? Are they 1G or 2G?

Correct me if I'm wrong. To use a 1G harness with a 94 GS ECU, I'll need to rewire the CAS, MAF, knock sensor, and rearrange some of the pins at the ECU. There's also a good possibility I'll have some tach issues. Basically I think it's looking like I'll have to do a lot of the electrical work that's involved with doing a 6-bolt swap in a 2G DSM. I do plan on purchasing a set 94 GS FSMs to help with the wiring to ensure I get everything right.


Any help or input is greatly appreciated. I just wanted to get some other people's thoughts on this, especially if they've got any 2.4 DOHC experience.

Thanks in advance.

[mysticj]

Have any of you that swapped from the SOHC to the DOHC noticed any interference issues? From the swap threads I've seen here so far, it appears that you just toss the DOHC head on and run with it.

No interference unless you are running a lot lift on the cams.

My biggest hurdle is figuring out the electronics. I believe I can use a turbo 1G DSM wiring harness with a 94 Galant GS ECU to get a factory tune to run this setup. From what I've gathered, the 94 GS is OBD1 and has the same style ECU connectors as the 1G DSM. Also, you 7G guys run what looks like a turbo 2G DSM MAF. What's the deal with your knock sensors and CAS? Are they 1G or 2G?

The GS is OBD1 but not the same pinout/ECU as the 1G, it's more like the Evo 1-3 ECU. You will need the 94/95 Galant ECU harness or an ECU from the 94/95 Mirage and Expo. Knock sensor is the 2G and the CAS is actually a 2G type(the 96-98 Sonata has the same sensor)

[mko]

I did full GS harness + ECU swap in my ES and it works great. Its pretty much P'n'P for the most part.

The 94 GS cam sensor is the same as 95-96 DSM sensor so if you want to run 1g CAS then you need to rewire the injectors and the switch the firing order of the spark plugs.

[dexter]

The GS is OBD1 but not the same pinout/ECU as the 1G, it's more like the Evo 1-3 ECU. You will need the 94/95 Galant ECU harness or an ECU from the 94/95 Mirage and Expo. Knock sensor is the 2G and the CAS is actually a 2G type(the 96-98 Sonata has the same sensor)

So you're saying that the plugs for the ECU are not the same? I'm mostly concerned with whether or not I can connect the harness to the box. Again, pinout differences are not an issue, the plugs not fitting into the ECU are.

If that's the case, than I'm assuming you're saying that the Mirage/Expo/Summit ECU will plug into the 1G DSM harness. Do you know if there's a knock sensor? Don't they use a distributor?

The 94 GS cam sensor is the same as 95-96 DSM sensor so if you want to run 1g CAS then you need to rewire the injectors and the switch the firing order of the spark plugs.

Right on. Now that you mention it, I do remember seeing the trigger plate on the cam gear.

A GS harness would be nice. Then I would just need to do the CAS adjustments.

Thanks for the replies.

[mysticj]

So you're saying that the plugs for the ECU are not the same? I'm mostly concerned with whether or not I can connect the harness to the box. Again, pinout differences are not an issue, the plugs not fitting into the ECU are.

If that's the case, than I'm assuming you're saying that the Mirage/Expo/Summit ECU will plug into the 1G DSM harness. Do you know if there's a knock sensor? Don't they use a distributor?

The plugs for the GS ECU is the same, minus the smallest plug, as the 2G ECU harness and the 94-95 Expo/Mirage/Galant have the same ECU harness as the GS. In other words, NO the 1G ECU harness will NOT plug into the GS ECU. Only the Galant GS, Evo 1-3, RVR, and 95/96 Euro Eclipse ECU has a knock sensor, the others don't use or have a knock sensor circuity.