Thread: 2004 GT Top Swap (Lots of Pictures)

I am starting my top swap soon. I plan on running a 3.8" pulley. Nothing serious.

Here is my parts list:
-L67 lower intake manifold
-L67 Heads
-M90 Supercharger
-L32 fuel injectors
-L32 fuel rail
-Idler Pullies
-Bracket to mount coil pack
-Harmonic Crank Balancer
-Coolant Elbow
-Valve Covers
-Supercharger Belt
-PCM retune
-Valve Cover gaskets
-Head bolts
-Plenum Gasket for L67
-Rocker Bolts
-TB gasket
-TB adapter
-180* thermostat
-Supercharger O-ring
-1 step colder plugs
-Head Gaskets

Does that sounds like a 100% complete list?

Also here are a couple of questions about the swap that I was just curious about?

1. Will I need to modify the Gen III supercharger in any way?

2. I have an electronic throttle body. Do I need the L67 TB or can I keep the one I have?

3. What exactly is the harmonic crank balancer? Do I need this?

4. I JUST replaced the LIM gasket with the new aluminum one, do I NEED a new LIM gasket set? Are they different on the L67?

5. I heard some GTPs have 2 belts. With the setup I am going with will I just need a longer belt or will I have 2 separate belts?

6. Will I need any wiring harness for the MAP sensor?

7. Do I need to upgrade the fuel pump since I am using larger injectors?

8. If I understand correctly the L67 uses a return style fuel system. Now I will have L67 injectors and rail, will I maintain a return-less fuel system?

9. Someone mentions o-rings for the GEN III supercharger. What are these for and do I NEED them?

10. Do i reuse my L26 exhaust manifolds? Basically do my L26 manifolds bolt up to the L67 heads?

I really hope you guys don't think I haven't searched. I couldn't find the answers to these specific questions. If I am missing ANYTHING in my build please let me know. I would like this to go as smoothly as possible. I also am very willing to take pictures to help other out.

Thanks for the help!

Can anyone verify the correct injectors and rail for a 2004 top swap application?

I just got into contact with a local salvage yard who says they have a series 2 2800 supercharged engine with 110k on it. He said I can have anything I want for $250. I just have to tear it apart! What do you think. If the parts are good I may very possibly be able to do the top swap for under $500. Awesome!

Vendor Loyalty I have someone on here willing to help me out I will probably go with getting the parts from him.

STOP!!!!!!!!!

to answer the questions

1. you shouldnt be using the Gen 3 See #2 for reason

2. first you will have to find a Gen 3 to GenV adapter that noone Vendor makes unless its custom. Its easier to get a Gen V SC to adapt your current TB onto. And i still wouldnt use the Gen 3 SC because you will be going from 75mm down to 69mm of the charger inlet

3. yes you need the Balancer, it provides the crank grooves for the SC belt to run on

4. yes they are different there are 2 different part numbers for the NA vs SC

5. See #3 response

6.you will need to modify the current map sensor connector or buy the kit from one of the vendors

7. stock fuel pump will be fine,

8. you can not use the L67 Fuel rails and Injectors on the 04+ the L67 had a return style and the L26/32 did not

9. the yellow rings will be included with the supercharger gasket with the Gen 3 Only If you get a Gen V sc and Gen V gasket they are already molded into the gasket

10. yes

So nobody really answered what injectors and rail will 100% work. I am thinking I need an L32 rail and injectors. Also are the rockers the same between the l26 and the l67 so if someone gave me l67 heads without rockers I could just swap mine onto the l67 heads?

You need the L32 fuel rail, period. The L67 rail will not work with your returnless fuel system. The injectors, I would go with L32 injectors if I were you, but you can use any injectors you want. The electrical connections are different on the older injectors, so if you switched to L67 injectors, you'll need to splice in new connectors.

There seems to be some disagreement on the LIM gaskets, but they are the SAME. As long as you haven't been running them too long, you should be able to reuse them.

The rockers are the same.

As was mentioned, you will need to keep your stock throttle body. To switch to the L67 TB would be a lot of work for very little/no gain. As long as minichopper can supply an adapter with the correct inlet and outlet sizes, it shouldn't be too much of a problem.

Awesome guys, thank you for answering the questions. I am getting really close to completely understanding this.

Here are a couple more questions for you.

1. Idler pullies? it was mentioned these are needed. I am assuming it is basically a pulley that is a tensioner pulley for the supercharger? Is that correct?

2. How hard is it to replace the harmonic balancer with the dual ribbed one? seems like it would be a huge pain... maybe not?

3. Do I need the MAF sensor from a GTP? or can I keep my current one?

4. MAP sensor.. a little comfused here do I need the GTP map sensor? Where is the MAP sensor located?

1. There are two idlers and one tensioner. One of the idlers has it's own bracket and one mounts to the coil pack bracket.

2. Depends on the tools available. If you've got a really good impact wrench, it's pretty easy. If not, it can be more difficult to get that huge bolt out. It's been discussed a few times recently. After you get the bolt out, you need a harmonic balancer puller with bolts specific to the 3800.

3. Keep your current one. The L67 MAF is mounted in the TB.

4. Depends on the computer you're using. If you're switching to an L32 tune, you'll need an L32 MAP. If you're keeping your stock tune, you'll need to keep your stock MAF.

Originally Posted by Scimmia

4. Depends on the computer you're using. If you're switching to an L32 tune, you'll need an L32 MAP. If you're keeping your stock tune, you'll need to keep your stock MAF.

Question 4 is regarding my MAP sensor... do the MAP and MAF have to be from the same engine... L26 or L32? I was hoping to keep my current MAF and MAP sensor... will the L26 MAP read boost?

I am going to get my current PCM retuned for the top swap so I will have an L26 PCM with a few parameters changed is my guess.

Originally Posted by matt5112

2) Pop off the inspection cover on the back side of the engine and put some vice grips on the flexplate. Then have at the bolt with a breaker bar or a massive impact. 15/16ths is the size you need.

So I can get the harmonic crank balancer off without a pulley puller?

Originally Posted by Storm

Question 4 is regarding my MAP sensor... do the MAP and MAF have to be from the same engine... L26 or L32? I was hoping to keep my current MAF and MAP sensor... will the L26 MAP read boost?

I am going to get my current PCM retuned for the top swap so I will have an L26 PCM with a few parameters changed is my guess.

I'm not certain on the series III. On the Series II engines, the L36 uses a 1 bar MAP (won't read boost) and the L67 uses a 2 bar. You need to use the correct MAP for the computer you're using, as neither HPT or DHP could switch that. I'm not sure if TinyTuner can, I'm just starting to play with that.

Originally Posted by Storm

So I can get the harmonic crank balancer off without a pulley puller?

No, he's telling you how to get the bolt out. You still need the HB puller.

Originally Posted by minichopper6hp

I was going to supply him with the correct adapter plate and porting the inlet to match the 75mm tb opening. If he still wants the parts, i have them. Also, you can use an l32 fuel rail if you can find it, if not the l67 can be modded.

I will be in contact with you.

I don't think I will need a MAP sensor if I am correct. And please someone correct me if I am wrong. Doesn't the GenIII Supercharger come with a MAP sensor built in? I could just have to get an adapter to plug into the MAP sensor, right?

The believe than I can just keep my MAF sensor and just have that pre-throttle body, in the intake tube somewhere, kinda where it is right now.