Building an LN3 from spare parts plus a Supercharger

[2seater]

14 minutes ago, DAVES89 said:

sorry, no picture...

I fixed it😖

[Ronnie]

Looks like you are very close to putting into the car. I'm anxious to hear how this engine compares to your turbo.

[jon L]

2Seater, the plug wires go over the top of the supercharger.

[2seater]

Thanks Jon. I made my own custom set which can go under or over. There is actually a lot more room for the rear plug wires under the S/C front drive than the N/A. I’ll know more about what works best when I get to running the wiring harness for the engine

[2seater]

I have had company for the last week but I am actually getting ready to bring the car home from storage and maybe get started on the swap. One of the things I wanted to sort out prior to dropping the engine was installation of the front engine harness which snakes through the front brackets and accessories. It connects the ICM, cam sensor, crank sensor and it plugs in at the right rear of the engine. My donor engine which gave up the supercharger did have this harness in place but it appeared to be damaged after stripping the crusty loom from it. The photo below shows what I mean although as it turns out, only one item is actual damage. The green wire at upper left is indeed damage from unknown cause. The dead end black wire next to it goes nowhere. I imagined there was something missing that connected to it but this is not so. This wire connects to cavity “k” at the ICM which is not actually used so there is nothing wrong with it. The other two items toward the right side are spliced wires that were covered with deteriorating tape, one white and one red set. Again it was assumed to be damage but it is in fact correct as built. This harness has very minor color differences from the LN3 but is otherwise perfectly usable, repairs aside. I ordered a replacement from Jim Finn and while installing new outer loom on the replacement I found a pair of wires that had a section of insulation about 3/8” long missing. The pair of wires were actually stuck together and touching where bare of insulation in a common loom to the cam sensor. I don’t know if this is very common but issues were noted on both harnesses I took apart which seems to be a trend??

 

[jon L]

After you run the engine control wires you will find it pretty tight under the supercharger, the wires can interfere with spark plug wires firing correctly.

[2seater]

24 minutes ago, jon L said:

After you run the engine control wires you will find it pretty tight under the supercharger, the wires can interfere with spark plug wires firing correctly.

A valid point, thanks. I think I have heard the reverse can be the true as well, induced voltage in sensor wires from spark plug cables

[2seater]

I purchased a spare front engine harness from Jim Finn and I have mentioned it before but I finally got it threaded through the front of the engine yesterday and I did need to take the large accessory bracket off the front of the engine to do so. I also installed a new dipstick tube and stick, also from Jim, so it is pretty much ready to drop in place now. 

 

In the mean time, an observation: I copied the supercharged timing table into a chip for use in turbocharged form. Everything else on the chip is exactly the same as I had been using in turbo form. I never got around to optimizing it as I should have so before I swapped engines, I thought I would see how it performs with a stock timing table designed for a boosted engine, albeit a supercharged rather than turbocharged one. This was just for observational purposes but I quickly found it is clearly not correct for an old school turbocharged engine. The low speed performance was so soggy it feels like two cylinders are asleep. It wakes up a little bit when the manifold pressure gauge swings into positive territory, but there is definitely a difference in the needs of the two different engine styles. I know the S/C engines generally have good bottom end response vs an old school single turbocharger which needs to spool up, but this timing change cut the legs out from under the turbo response. I guess it is time to stop procrastinating and get the engine swap on my dance card.

[2seater]

Just to confirm the timing table hypothesis, I burned another chip with the exact same information except I substituted a table from a 12 year old tune from GMTuners, one of the seven or eight files he sent me way back when. The engine is happy again although still a bit soft down low. The low end softness seems to be typical of premium fuel performance in an N/A engine tuned for regular 87 octane. I have noted that before. There is a note to self here: the engine will not start with only half of the chip pins inserted into the socket😖 The low end soft launch is probably a good thing to ease the strain on the trans. when it can least handle it.

[Ronnie]

2 hours ago, 2seater said:

There is a note to self here: the engine will not start with only half of the chip pins inserted into the socket

haha I think all Reatta owners should try to remember that.

[DAVES89]

I have a rebuilt trans in the Red if you want to try it...

[2seater]

I am woefully slow to get on with this project. I planned to get to the swap over a week ago but I realized my ramps, plus two sets of jackstands and both creepers were left at the cottage. While making a run north and returning was only 2-3 hrs to accomplish, my 16 year old cat took sick and after a visit to the vet, regular medication was need for the first few days. In any case, I did finally get a tentative start to the replacement. The front of the car up on ramps, fluids drained, front motor mount and shock absorber by harmonic balancer disconnected, oil cooler disconnected plus rear exhaust disconnected at manifold. This is a small start but important as I am now committed. The holiday weekend will intervene but I will be back to this project next week.

 

Rather than call up the original thread, I will comment that the red car that #2 son has came out of winter storage without issue but after a short distance of driving the engine stalled, restarted but subsequently quit and will not restart. Cam, crank, TPS, O2 as well as timing chain and magnet were new when the project started. The two existing systems that were reused were the coil pack/ICM and the MAF sensor. It also has a new fuel pump. It will be investigated this weekend to determine why it left him stranded.

[2seater]

I am sorry to say the progress has been very slow. I did get everything disconnected from under the car and have rolled the car off of the ramps. The topside work should resume on Monday, much easier to do for an old body🙄

[2seater]

Still plodding along. Even working up top has many breaks to get the back stiffness and general flexibility to improve. I have one item left that is kicking my butt right now, the A/C compressor. I go on to something else for a while and then keep coming back to it. I have been trying to keep the engine as intact as possible, including the turbocharger and associated plumbing but some things have proven to be in the way so partial disassembly must be done. Everything is now loose or removed, including the backwards bellhousing bolt, but the compressor remains. The problem child is the bolt that is close to the engine block. I know I have done this job many times in the past but something must be slightly altered. The bracket for the compressor on the 1995 donor engine has the compressor bolts approximately 180deg from each other, top and bottom. Even my FSM shows the front bolts 180deg apart but that is not the way mine is, and never has been. My front mount bolts are at approximately 90deg to each other, one at top and the other is at the rear of the mount against the engine block. The bracket bolted to the block has reinforcing ribs which will not let me get a straight shot at the bolt head with a 12" extension for my ratchet. I cannot seem to finagle a universal joint in there either plus the motor mount support off the engine is somewhat in the way. I installed this new compressor when I did the last engine swap a few years ago but it was bolted on the engine and dropped in already assembled. The system was reassembled in the car and subsequently charged with R12. Any tips or tricks would be welcome. Maybe just stepping away for a bit will help?

[Ronnie]

I feel your pain man. Something like that use to be a challenge that i would happily accept just to prove I could do it. Now I see things like that as something I dread and avoid it if possible. Just too many aches and pains to enjoy it. Good luck.

[2seater]

Phantom bolt. Appearance in a mirror misunderstood but still must have missed one underneath the bracket on the other end. This should be straightforward but…🤨

[2seater]

Out, finally🥵

 

 

[Ronnie]

And you did it without even removing the hood!

[2seater]

Yes, having done this a few times, I eventually learned to disconnect the hood support struts and use a ratchet strap hooked inside the trunk and extending over the nose of the hood. Just need to protect the rear window and the nose with a pad and the strap never actually touches the roof. Easy, peasy and hood will stand straight up.

[DAVES89]

That is a great trick and one I hope I will never have to to do...