LC9 swap from donor truck - do it?

[1990Z71Swede]

Well since I have real life experience with both the LC9 an the L05 I might just as well chip in.

These are two VERY VERY different beasts, the LC9 is a fun little screamer, and paired with a Suburban and a 4L60e its is like having a race motor trying to pull a freight train. It works pretty good but it needs revs, and is not particularly fast... and that two gear 75%WOT downshift is going to make people think your an idiot sometimes.

The LO5 on the other hand is a low RPM laid back workhorse with powerband somewhat like a modern turbodiesel, that is also the only thing modern about it The difference in powerband is night and day, when the LC9 is starting to pull the LO5 is shifting into next gear.

To make an LC9 work well in an OBS you most definitely need the gearbox that came with it or atleast try to match its calibration of shift points and lockup release. 3.73 gears or maybe even 4.10 is probably very helpful also. Anything less is likely going to be putting that little screamer out of its powerband most of the time.

AFM has to go, when it works it works and it does save quite a bit o fuel under low load conditions. But "all" that savings is a total wash when/if it craps out. Choose something mild camshaft-wise if you like to tow stuff. Also take a careful look at the cam bearings and educate yourself on the O-ring issues in the path from oil pump pickup to the oil filter.

The LC9 is suuper smooth running, the LO5 is not as smooth, the older technology shows, but once warmed up it is pretty nice too.

ANY of the first gen SBC build combos suitable for a truck is VERY likely to have more low RPM torque than a comparable LS based motor. If you follow up with proper gearing and gearbox calibration that is not necessarily a problem though, but if you don't, your truck could very well be slower and less fun with the LS.

If I where to build an LS OBS I would be looking into an LQ9, 4l80E, 14bolt SF 4.10 combo.

 

[Sean Buick 76]

The money spent deleting the AFM DOD junk cam and lifters would be better spent finding a 6.0…

 

[RDF1]

2011 with LC9 will have the 6L80E also.
This would be a pretty fun swap, but your gonna need the Transfer case control module and all that to make it work right.
IF you have a lowerish gear (3.73-4.10) this setup would be very fun and peppy with the 6L80 transmission

 

[vr1967]

Biggest problem I have found with AFM is lack of maintenance. Most people go by the oil life percentage on the dash. On my 2011, to take it to 0% oil life left is right at 12,000 miles. I change my oil at 5-6k in it. I have 277k on it and have never had an issue.

My SIL has a 2010 with AFM with close to 400K on it, changing the oil like I do. Both engines have never been into.

At 100k and above, about every other oil change, we have been replacing a quart of oil with a quart of Lucas oil stabilizer.

Like RDF1 said, I believe it would be a good swap, but that also depends on what all you can do yourself, and what you have to pay for.

 

[rzr6-4]

After further review (this thread) I thing I'm going to pass on the swap. 1) I thought there was a larger power difference between the two and 2) that lower bottom end torque could be an issue for me as I'm hoping to slowly turn it into a decent off-roader, where the ability to low speed crawl is obviously important.

Thanks for the info.

 

[0xDEADBEEF]

Crawling is going to be more about gearing than torque. Plenty of 4 and 6 cylinder crawlers out there.

 

[Robert Jelen]

My 93 Sierra has the factory 5.7 with 182K miles on it, it has been overheated and oil starved a time or two. Runs good for the most part but has some issues, has what sounds like a vacuum leak that causes it to lurch at low speeds but couldn’t find a leak so IDK. Truck is double salvaged, engine was in for the second wreck and as far as I know it was for the first as well. Overall it does its job but it has definitely seen better days.

A coworker got hit and it totaled out his ’11 Silverado with 77K miles on the LC9 5.7. Truck is pretty messed up from the wreck, very bad side swipe on the drivers side but the engine, tranny, t-case, radiator, fuel tank SHOULD all still be in working order. I told him to see how much he could buy it back for as it could make for a good donor truck.

If it was just an engine I wouldn’t be that interested as I would still have to convert everything to match, but I’m wondering if everything is still intact if I would be able to move all of the aforementioned parts over and have it be a pretty turn key operation. This would be my biggest project ever by far but I have access to lots of tools and spare vehicles to drive in the meantime while working on this.

Question is…..if I get the entire donor truck with and all of those parts are intact, does this seem like a doable/worth while undertaking? I don’t want to spend $1000-1500 on the donor just to find out I need another $2K in random parts. I don’t know for sure if it will be available, but if it does become an option I want to be able to say yes or no right away.

Do it and you will never regret it. I put a L96 into my 94 suburban and love you will fave all the power you want. Might cost you a few bucks. Mine is fun to drive. Left it stock looking.