8.1 4l80e swap

[87silveradok20]

Ok, so this is going to be my questions/ build thread for this project. I have a 1987 k20 that currently has a 350/th400. I am wanting to swap this out for an 8.1 and 4l80e. At this point I have bought nothing for this project but plan to have it done by spring. I am not planning on any mods to the 8.1 right now except maybe a tune. I have a budget of around 5k to do this and will be documenting my costs. Hopefully this thread will contain a lot of Info and can help anyone thinking of doing this in the future. To start off, is there anything special to watch for when buying an engine and trans? Below are some pictures of the truck

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[ajd89]

Wow nice truck and shop! I will be watching to see how it goes for you as at some point this maybe an option for my crew cab!

 

[ajd89]

Dirty Larry over on the 67 to 72 Chevy site has put two l8.1 in one in a regular cab one in a Suburban there also is a PDF file if you search Google of a guy that put one in a crew cab 88

 

[twinturbo427]

Some quick notes I found doing the same searches.

1) The accessory brackets from a van chassis place the a/c compressor high, so no frame mods required.

2) the fuel map for the 8.1L is the same as other LS engines. It just uses bigger injectors.

3) the egr hits the pinch weld ON THE FIREWALL. AN ALLISON trans is tight in the tunnel. (That is why a body lift came on the 2500hd, like my 2007, from the factory.) I know it is not the same body style, just a reference.

4) Torque management is a blessing and a curse. Blessing fir real world driving and easy on parts. A curse when you need to blow a Stangbanger off the road.

Following your build. If I wasn't working on Big Rhonda today, I would post more.

 

[yevgenievich]

Van brackets are a preference but they are hard to find. The tunnel fitment issue is only with allison transmission.

 

[twinturbo427]

Van brackets are a preference but they are hard to find. The tunnel fitment issue is only with allison transmission.

Yes, absolutely right about the Allsion trans!

 

[87silveradok20]

Yes, absolutely right about the Allsion trans!

Ok, so with a 4l80 I should be good without a body lift?


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[yevgenievich]

No lift needed

Ok, so with a 4l80 I should be good without a body lift?


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[twinturbo427]

Ok, so with a 4l80 I should be good without a body lift?


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The egr still hits the pinch weld. Should be able to work around that.

 

[87silveradok20]

The egr still hits the pinch weld. Should be able to work around that.

Could I remove the egr and put a block off plate on?


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[fmxr47]

My 6.5td has a 4l80e behind it with zero clearance issues. It has a stand-alone TCI controller which I could adjust the transmissions drive ability with, if I chose to.

And this is in an 86 not a newer truck.


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[87silveradok20]

My 6.5td has a 4l80e behind it with zero clearance issues. It has a stand-alone TCI controller which I could adjust the transmissions drive ability with, if I chose to.

And this is in an 86 not a newer truck.


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Ok I should be good then I’ve never heard of having trouble with them.


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[4WDKC]

Hey that's how my truck should look when done, if it ever gets there. You will need to lengthen the rods for the 4x4 shifter to make up for the difference with the 4l80. I have seen some posted that claim low oil pressure so a low mileage one maybe the better option unless you want to refresh one up.

 

[87silveradok20]

Hey that's how my truck should look when done, if it ever gets there. You will need to lengthen the rods for the 4x4 shifter to make up for the difference with the 4l80. I have seen some posted that claim low oil pressure so a low mileage one maybe the better option unless you want to refresh one up.

I’m looking for a low mileage block, but i know on the ls motors there’s an o ring that goes bad and causes low oil pressure. Is there something like that on these motors?


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[4WDKC]

I’m looking for a low mileage block, but i know on the ls motors there’s an o ring that goes bad and causes low oil pressure. Is there something like that on these motors?


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Not sure still leaning about them myself..DirtLarry on www.67-72chevytrucks.com would be the guy to talk to as he has rebuilt at least one. I am also unfamiliar with the internals of an LS.