Hi I'm new here and would like to get some of yous good people knowledge on this swap. Questions as to what I will need to do. I only want the engine the donor car is a 5 speed. The car getting the swap my (98 gt) is a automatic I would like to keep my tranny as I'm sure it'll bolt up from what I've been reading. Do I have to swap the timing covers or cab I get by without doing so? Thanks in advance and any knowledge will greatly appreciated and hope everyone has a merry Christmas! I'm doing the swap this weekend
98 gt swap with 03 gt
- Thread starter Ajb98stanggg
- Start date
wmburns
SN Certified Technician
The key to make this swap work is to make the donor motor look the same as the original (electrically). That means:
Put both motors on an engine stand. Make the donor LOOK like the original. Take TONS of pictures before removing any parts to swap.
- same wiring harness
- same ignition system
- same sensors
- same fuel system including injectors.
Put both motors on an engine stand. Make the donor LOOK like the original. Take TONS of pictures before removing any parts to swap.
Where would the pilot bearing and flex plate be behind the engine where it bolts to the flywheel?
wmburns
SN Certified Technician
The 1998 PCM is not capable of controlling the 1999-2004 return-less fuel system which is why it is necessary to swap.
The PI and non-PI motor have different timing curves and fuel requirements. And YES the 1998 PCM will run a PI motor assuming the correct parts have been swapped. BUT it won't make the full PI power without a tune.
One of the key parts to swap is the coil pack ignition. If the coil packs will mount on the PI timing cover then it's not necessary to swap the timing cover.
Even in the best of times a motor swap is a ton of work. Don't start your project off by trying to cut corners. Do what your project needs.
IF the flex plate wouldn't bolt up don't you think that's a detail worth mentioning? In fact that sounds like a serious deal. Both motors have a 6 bolt crank. Yes it will interchange.
I started tearing down the donor car tonight I'm dropping it from the k member I got everything taken out tomorrow will be ready to lift the body. I was wondering if I have to use the same throttle body from my 98 NPI or do I use the stock 03 PI throttlebody? I'll post pics of my progress I got a sct x4 tuner today pretty excited to see what it will do with it, I've never had any of my vehicles tuned before.
The PI computer won't make full PI power without a tune either... I had a 98GT with a 99GT engine dropped right in with the bone ass stock NPI computer running it for years and it ran great. This is about the easiest swap you can do, can be done in a weekend.
Take your old engine out, the 03 will drop right in. You do not have to swap the covers if you relocate the coil packs or just swap to COPs with the RedMonster harness. You will want to replace the PI intake with a new one as they all warp and crack over the years. Right under the water ports to the heads. The 98 harness has 2 coolant temp sensors and the PI intakes only have one sensor hole. The good news is it still has the flat boss so you just drill that out with a 9/16" bit and then I think its a 1/2" NPT tap... Harbor Freight sells the 3 tap NPT tap kit that has the right one...
Everything bolts right up. I've done this swap and last one I did was the 4V swap. Would recommend any 4V swap over 2V. Swap is just as easy especially going into a NPI car. 2V NPI computer will run that one too lol. Mark VIII engines are still out there, if not you can get them out of Aviators or (obviously) NA Cobras.
You should be getting a good tune regardless of what you have though.
Take your old engine out, the 03 will drop right in. You do not have to swap the covers if you relocate the coil packs or just swap to COPs with the RedMonster harness. You will want to replace the PI intake with a new one as they all warp and crack over the years. Right under the water ports to the heads. The 98 harness has 2 coolant temp sensors and the PI intakes only have one sensor hole. The good news is it still has the flat boss so you just drill that out with a 9/16" bit and then I think its a 1/2" NPT tap... Harbor Freight sells the 3 tap NPT tap kit that has the right one...
Everything bolts right up. I've done this swap and last one I did was the 4V swap. Would recommend any 4V swap over 2V. Swap is just as easy especially going into a NPI car. 2V NPI computer will run that one too lol. Mark VIII engines are still out there, if not you can get them out of Aviators or (obviously) NA Cobras.
You should be getting a good tune regardless of what you have though.
I've pulled both engines from k member and dressed the new engine. I did not swap timing cover cause I was able to bolt the brackets on the pi cover. Took some finessing but Its out of the way of the belt. I also pulled my power steering pump and alternator and my ac compressor. Do I need these? I ran into a problem with the exhaust manifold bolts 2 snapped off. But I'm going to try and get them out today with a welder, cause the bolts didn't snap off flush. Was going to weld a washer to the bolt then weld a nut to the washer and back out slowly. Hopefully this works if not I'l be drilling and tapping the head. This is the only thing holding me up getting the engine in. If I'm missing anything let me know! Oh yeah I swapped valve covers, alternator, fuel system, ignition system also pulled the pilot bearing and flex plate! I think I got everything but if I'm missing something let me know! Hope everyone has a great day!
The alternator and AC compressor are the same between both cars. Keep them as spares if you want.
Why did you swap fuel systems though? Like you swapped the tank and pump and rails and lines? 98 is return and 99+ is returnless. If this is what you did that was not a good idea since the 98 computer won't be able to run the 99+ fuel system. Same with the ignition and not sure what you mean you swapped the ignition.
When doing a full engine PI swap into a NPI car you drop in the new engine and that's it. Fuel and everything else you can and should leave alone.
Why did you swap fuel systems though? Like you swapped the tank and pump and rails and lines? 98 is return and 99+ is returnless. If this is what you did that was not a good idea since the 98 computer won't be able to run the 99+ fuel system. Same with the ignition and not sure what you mean you swapped the ignition.
When doing a full engine PI swap into a NPI car you drop in the new engine and that's it. Fuel and everything else you can and should leave alone.
Sorry I should have been more specific. My swap it's completed, I meant I swapped my coil packs and fuel rail and so forth. Car fired right up but wouldn't idle, after I put the tune on it, ran perfect now im having problems with my front end im assuming from all the weight on it when I dropped the k member. Anyways engine runs great and I like the power increase with the pi swap
