Building an LN3 from spare parts plus a Supercharger

[2seater]

S/C engine dropped in today. For some reason I like torturing myself by picking the hottest days to do these jobs🤔

 

I wanted to install the engine in as complete a form as possible but found I had to disassemble much of the front drive system along with the power steering pump and alternator plus the big cast bracket. On the stand everything looks just great but much of the rear mounted accessories are right in line with the strut tower making access a trial. It is now mounted and the wire routing, accessories and all the smaller stuff can be done. 

 

 

 

 

 

[Ronnie]

Do you have something under the transmission that supports it while you have the engine out and while  you put the new engine in?

 

 

[Ronnie]

BTW, the rest of this week is supposed to be near a hundred degrees every day for us. I plan to stay inside as much as possible.

[2seater]

We aren't that hot, but mid 90's with dew points in the high 70's melts us further north. My old garage is detached and is semi insulated so it is not too terrible for much of the day, as long as the big door isn't open.

 

No support under the transaxle. The rear passengers corner of the engine is actually supported by a bracket on the trans so the only actually motor mount that gets disconnected is at the passengers front corner under the A/C compressor. I hope to leave the oil filter adapter from the S/C engine in place, the one that curls under the front of the oil pan, but I won't know for certain until I get the oil cooler adapter back in place. I had to remove the oil pressure sender along with the aforementioned items to better access the rear mounts and the hidden bellhousing bolt. I didn't think to take a photo before I removed it but I will when I reinstall. The reason I mention it is the different orientation from the standard LN3 location. It points straight back rather than vertical but I didn't realize how low it was until engine installation. It is only about 1" above the inner drive axle joint. That shouldn't be an issue as they don't move relative to each other, but it was a bit of a surprise.

[2seater]

This is the location of the oil pressure sender. 
I am in the process of taking the main engine harness apart to reroute wiring to the new locations and make it more flexible given the different configurations and locations of the various sensors, something I wanted to do before. In the case of the oil pressure sender, I will need to extend one wire that is common to other items since there is a four wire splice inside the harness. Pink with a black trace in this case.

[Ronnie]

I guess you have considered this, but would the wiring work if you had a 90* elbow to turn the sensor up?

[2seater]

2 hours ago, Ronnie said:

I guess you have considered this, but would the wiring work if you had a 90* elbow to turn the sensor up?

Yes, I did consider that, and it may have worked, but I think it would still be short. I decided against the extra plumbing, partially for strength reasons but also I considered vibration and gravity might cause it to rotate away from vertical. That part of the harness which seems to be common to all Reatta's, contains the oil pressure sender, knock sensor and the VSS. It snakes around the cast bracket for the power steering on the LN3, and would be even a larger pain with the huge casting on the S/C version, so I have wanted to separate that part out and drop it straight down the rear corner of the engine without even getting to the valve cover area. Fairly simple on a 90 where the entire upper engine harness comes directly from the firewall in the vicinity of the heater to the area behind the power steering pump and the large ground stud. 

[2seater]

As it turns out, the oil pressure sender cannot be turned up, the big cast mount sits directly over it with approximately 3/4” of clearance. Rerouting the harness wasn’t a big deal and I only extended the one wire I mentioned earlier. I had previously modified some of the harness on previous engine swaps and the remainder plugged right in. I will need to reroute or replace the alternator output wire. The new location is at the rear of the engine so the existing is too short.
Installing and plumbing the power steering pump was an adventure. It is mounted very low at the rear of the engine and the hard pressure line comes straight down onto the same axle joint as the oil pressure just clears. There is approximately six inches of steel line before it transitions to hose and that allowed me to modify with a small bend, maybe 15deg or so, which worked out fine. It may get replaced in the future if I like the S/C conversion.

[2seater]

Finally got it up on stands today to do the underneath work. It is now almost complete minus installing the radiator, fluids and connecting the starter. The one item that will be determined later is reconnecting the engine oil cooler. The oddly angled oil filter adapter just doesn’t lend itself to a sandwich style oil cooler adapter but the filter fits nicely between frame and front of the oil pan. 

[2seater]

It runs and no leaks. 235 cubic inches of rampaging hp😜 In truth, it sounds pretty good, with the homemade split rear manifold, sort of guttural.

 

There are a few things to clear up while it is still in the air. The oil pressure indication is pinned to maximum. This is one item I did reuse, not the sender, which is new, but the existing oil filter adapter and pressure relief system. The other possibility is this is the part of the harness I modified to reach the sender location so investigation will be required. All of this will need to wait until after this holiday weekend.

 

 

[DAVES89]

Great news! Can't wait to see it. Let me know when you are back in town and we can meet up and take it for a "road" test.

[Ronnie]

Glad to hear you got it started. Looking forwarded to what you have to say once you get it where you can drive it.

 

I think the oil pressure pegs when the sensor is disconnected. Maybe there is still a wiring problem that will be simple to sort out.

[2seater]

12 hours ago, Ronnie said:

Glad to hear you got it started. Looking forwarded to what you have to say once you get it where you can drive it.

 

I think the oil pressure pegs when the sensor is disconnected. Maybe there is still a wiring problem that will be simple to sort out.

You are absolutely correct, it feels like it is loose and not clicked into place. It was bothering me also and I went out late last night for a "feel around" and the connector moves. Unfortunately, I cannot get enough leverage on it from underneath to snap it in. It was difficult to access to start with and now that the power steering and belts are in the way, it is impossible to get to from the top. It will have to wait as I have company coming for the weekend, but it looks like I will need to pull the front wheel and access through the wheelwell.

[Ronnie]

Maybe a pin got bent that is keeping the connector from snapping in.

[2seater]

This is a pic of the oil pressure sensor after I got it plugged in. It was in fact unplugged and the only way I found to access it was through the wheel well with the tire removed. The warning light went away and the gauge now functions normally, albeit being on the high side. The late model oil pump and relief system operates at a higher pressure as predicted. Three choices from here; change the sensor to late model, change the relief spring or just live with it as long as the indicator on the dash stays in a readable range. 

[2seater]

First drive for a short distance in the city. Blubbers and almost quits on cold startup but does get better as it warms and maybe learns. Not very snappy off the line although I am not pushing it very hard since it is fresh internally. The s/c does have a clearly audible scream with a bit of throttle. For some reason it now shows an E026, quad driver code that can’t be cleared, current and history. My guess is the EGR being non existent is what is causing it? I turned off all the EGR activations in the PROM but maybe I missed something. 

Edited July 7, 2022 by 2seater

[Ronnie]

Blubbering sounds like a rich mixture if it were a carburetor engine. Code 26 is a hard one to troubleshoot. It's like a catch-all code for things that don't set a code. There is a troubleshooting guide for a code 26 in the how-to guides but don't know if they will apply to your SC engine. Glad to hear you are able to drive it.

[2seater]

I found the E026 must have been the cruise control module not being installed. I had several of those codes as well and were likely why the 026 wouldn't reset. I installed the cruise module and plugged it in, cleared codes and all is good to go. No codes, no leaks so all is right with the world. I did use the help section as suggested, which was helpful.

 

Performance is certainly not overwhelming. Granted, I am not pushing very hard at this stage, and it does make a nice satisfying scream, even at moderate throttle. The s/c is more a constant push rather than the turbocharger boost that builds as it is fed more, sort of an ever increasing loop. I have seen a couple of psi of boost on the gauge even now, but compared to my lowest 5psi wastegate spring for the turbocharger, it is good but not great. The blubbery starting is smoothing out so some of the ecm learning is helping. I just did a 70 mile loop to a friends house, 80% hiway and it looks and feels totally normal. My normal get up to speed feel (butt dyno) is generally about 5"of vacuum on my gauge, and that seems to be the case no matter the mode of engine on board, N/A, turbo or s/c. I guess this is my comfort level of daily driving. 65mph cruise on relatively flat ground shows the same 10"-12" of vacuum, similar for all engines. The one place the s/c seems to be better is the throttling up to climb small hills just increases thrust with throttle increase without getting in a burst of boost and knock. Overall it is lazier and I believe it could use a few degrees of timing overall to sharpen the response. I am also going to disable the s/c bypass for low load situations per Jon's suggestion to see if it feels better.

 

This wasn't a full on performance build in deference to the transaxle, so I did not expect a lot. My comparison combinations are not exactly equal, but should be as good as I have. Ironically the turbocharged package I took out is my original 1990 block with approx. 110k on it, '88 cam, and the '88 heads I got from Dave. Low mileage but with several badly rusted valves so it got new valves and a fairly extensive porting job, plus the compression ratio was lowered to 8.3:1. The S/C is the '88 block, with '88 replacement cam, plus mildly ported '90 heads from my original engine. It is bored .030" over and compression was raised to 9:1

 

Incidentally, the oil pressure indication is one segment from maximum while under throttle and drops to two segments to the right of halfway at hot idle. Essentially it is using the top third of the gauge in normal operation so I am going to call it good.

 

 

[Ronnie]

1 hour ago, 2seater said:

I found the E026 must have been the cruise control module not being installed.

Glad it was that easy. I might as that to the how-to guide as another thing to look for when troubleshooting a code 26.

 

I enjoy reading your impressions of your SC engine. You compared it to your turbo. How do you think it compares to a stock Reatta 3800 like's in my '88?

[2seater]

3 hours ago, Ronnie said:

Glad it was that easy. I might as that to the how-to guide as another thing to look for when troubleshooting a code 26.

 

I enjoy reading your impressions of your SC engine. You compared it to your turbo. How do you think it compares to a stock Reatta 3800 like's in my '88?

The one advantage the N/A setup has is the lessened concern for protecting parts. Any car driven pedal to the metal constantly, save a diesel perhaps, will have a shorter lifespan. Boost on an otherwise standard engine uses up some of the excess capacity in the system. Silly story but a true one: almost 40 years ago leaving a company meeting offsite, it had been snowing heavily and the roads were in bad shape. As it happened at the time I had a new Isuzu Trooper II, all 85 hp of it. A coworker had an original style Bronco with a V8. We ended up at a traffic signal outside of the city on a 50mph stretch, he had to feather the throttle and slip the clutch to keep from spinning uselessly where I could just hammer down and stay with him easily. It is sort of like that. If you have a vacuum/boost gauge, in an N/A setup, zero on the dial is about the most you can expect unless you can get a ram effect at some point to show a tiny bit of positive pressure. When the needle swings into positive territory is where the power lies all other things being equal. This isn't a factory s/c engine, it is a somewhat improved N/A '88 engine with boost added. I don't know how much power the supercharger eats up, but it must be some, and the turbo version has some losses as well. At a guess, I would say +20%hp and 25%tq or so. The engine is quite tight internally right now. When turned off, it stops right now, no coasting at all.