Vortec 8100

[Dahoyle]

My 99 K2500 Suburban is in need of an engine because of a broken crankshaft. I have been watching for a good L29 replacement and so far only have a solid lead on one.

While looking for an L29 replacement, I tripped over an L21 from a 2001 K2500 Suburban and I am seriously tempted.

It comes with everything needed to install it, including a complete harness and ECU so I really don't have any questions about that. Will have to figure out the transfer case but that is not a big deal

What really concerns me is getting the harness to talk to my dashboard. From what I understand some of the sensors are a bit different.

If it was going into an older square body it would be a relatively simple proposition, but I am not sure how much my dash is analog and how much is digital.

Does anyone have any experience and possibly some wiring diagrams. I know I can figure it out, but I really don't want to start from scratch if I don't have to

 

[c1500deathtrap]

Isn't the l21 coil near plug and forged internals? i'd jump on that in a heartbeat.

 

[Christian Steffen]

Isn't the l21 coil near plug and forged internals? i'd jump on that in a heartbeat.

I'm thinking he meant l18? Since it was titled 8.1 and he said 01 Burban.

If it was the l21 454, i do believe that is cnp and forged.

Op, it should be possible to run the gauge cluster. Really it shouldn't be different than 0411 swapping, except the entire harness is changing. You may have to swap the gauge cluster plug from your original harness. Just guessing here, I haven't looked at how a gmt800 gauge cluster hooks up.

I say go for it.

Edit. It might be easier to keep the original harness and adapt in any sensors that are different with the 8.1.

 

[someotherguy]

All the 8.1's are CNP dunno about whether it's forged bottom end.

8.1's were used in the 2001-2002 GMT400 3500HD's, no idea if they had to use a different cluster from the previous trucks. I'm betting not.

Richard

 

[454cid]

My 99 K2500 Suburban is in need of an engine because of a broken crankshaft. I have been watching for a good L29 replacement and so far only have a solid lead on one.

While looking for an L29 replacement, I tripped over an L21 from a 2001 K2500 Suburban and I am seriously tempted....

The L21 is a 454 from bigger trucks. The L18 is the 8.1L found in the GMT-800. I'd love to have either engine, to go along with my L29 454.

 

[Dahoyle]

You guys are correct. It is the L18 engine, not the L21. I have too many different RPO codes floating around in my head. The L21 I looked at is still sitting in a U-Haul truck.

 

[L31MaxExpress]

L18 works just fine with the 1999 Escalade cluster in my 1999 Tahoe. Just swapped the 0411 to an Express van tune for the 8.1. I set the fuel tank capacity for the Tahoe tank size. The oil pressure and coolant temperature come from sensors on the 8.1. Tach signal comes from the output of the PCM which gets set to the GMT400 3500 HD 8.1 value. I used the 8.1 van engine harness and married it to the Tahoes engine compartment harness at the PCM and fuse box. Used a 6.5 diesel accelerator pedal after repinning the connector. I used a GMT400 3500HD air intake duct, air cleaner, fan shroud, radiator and radiator mounts. Duramax fan blade on a 6.0L TBSS fan clutch. It drives like a stock 350 until you get on the throttle.

 

[Dahoyle]

That is all good to know, L31Max.

I haven't decided to pull the trigger yet, but it is starting to look like I might.

The engine comes with a complete harness to include the ECM and a 4L80 transmission (The transmission is bad but rebuildable). The easy answer would be to just re-pin my factory harness to mate it to the ECM which came from the engine. That would eliminate the need for a tune since it already contains the correct factory tune for the engine. That still leaves me with some issues that have to be resolved. I am not sure exactly what I would have to do to configure the cruise control, but I suspect that would not be a huge issue. The transfer case is another matter and I need to do some research on that. I know it is controled by a computer, but I do not know if it is the main ECM or if there is another. I have found references to a transfer case control module, but beyond that I don't know much. My suburban is on a transport back from TN where it broke down, so I am not able to trace anything down for at least a week. That is one of the reasons I am seeking out information rather than looking at what I have. I have a limited time frame to work with and I don't have either the truck or the engine at the moment. With that in mind, anything you can tell me would be a huge benefit and help me to make up my mind.

I did find a pretty good functional description of the NVG 246,

http://www.atraonline.com/gears/2006/2006-07/2006_07_10.pdf

and as near as I can tell it requires no input from the ECM, but if I am not mistaken, the ECM should get a signal from the transfer case telling it whether it is in Hi or Low range, but I don't think it is critical to operation. The greater concern is the vss which is routed thru the ECM to the transfer case control module.

 

[L31MaxExpress]

That is all good to know, L31Max.

I haven't decided to pull the trigger yet, but it is starting to look like I might.

The engine comes with a complete harness to include the ECM and a 4L80 transmission (The transmission is bad but rebuildable). The easy answer would be to just re-pin my factory harness to mate it to the ECM which came from the engine. That would eliminate the need for a tune since it already contains the correct factory tune for the engine. That still leaves me with some issues that have to be resolved. I am not sure exactly what I would have to do to configure the cruise control, but I suspect that would not be a huge issue. The transfer case is another matter and I need to do some research on that. I know it is controled by a computer, but I do not know if it is the main ECM or if there is another. I have found references to a transfer case control module, but beyond that I don't know much. My suburban is on a transport back from TN where it broke down, so I am not able to trace anything down for at least a week. That is one of the reasons I am seeking out information rather than looking at what I have. I have a limited time frame to work with and I don't have either the truck or the engine at the moment. With that in mind, anything you can tell me would be a huge benefit and help me to make up my mind.

I did find a pretty good functional description of the NVG 246,

http://www.atraonline.com/gears/2006/2006-07/2006_07_10.pdf

and as near as I can tell it requires no input from the ECM, but if I am not mistaken, the ECM should get a signal from the transfer case telling it whether it is in Hi or Low range, but I don't think it is critical to operation. The greater concern is the vss which is routed thru the ECM to the transfer case control module.

An Avalance and Suburban were 4x4 4L80E in some cases so I know the tune exits for them. The PCM uses an input to scale the speed signal in 4x4 low.

PcM would need some changes but they are relatively easy ones.

Biggest chore would be finding a GMT400 3500 HD or Express/Savanna van front accessory setup for it.

High mount compressor is the way to go on the older trucks.

The L21 would be a near direct bolt in for your L29. Just have to pull the timing cover and swap the reluctor out. Then put the L29 distributor cap on the L21s cam sensor body. Swap the valve covers and the throttle body and you would be good to go. L21 would be a helluva lot easier if you convert it back to run the L29s stock engine management.

Cruis is easy stupid simple to get to work. The inputs into the TAC module of the 8.1 already go into the cruise module under the hood from the cruise switch and brake switch. Just have to move them to the correct pins. I bolted the TAC module from the 8.1 van direct to the firewall of my Tahoe exactly where the cruise actuator was. Cruise works the same as stock. Set it and forget about it. The TAC module, PCM and DBW throttle body do the same work that the Cruise control did before except without a cable and external linkage. Need to get around a car or merge while the cruise is set, just jump on the gas, when you are done passing, let pff the gas and the cruise takes back over.

 

[Dahoyle]

I know the L21 would probably be simpler, but of the three engines I am looking at, it is the most expensive and just doesn't offer enough gain for the effort. I was already looking into an 0411 swap when the crankshaft broke so I had some of the information, but just hadn't made the connection to using it in the L18 swap. This really is no more complicated than doing an 0411 swap and adding a few wires. If the engine I am considering had come from a 4X4 suburban, I wouldn't even have to worry about that.

the more I think about it, the more I am leaning towards the 8.1 swap. There is no tuning involved other than sorting out the transfer case(and the wiring is already in my truck). By utilizing the ECM that came with the engine, it should run exactly the same it did in the donor vehicle. It simply won't know the difference.

As you said the accessory drive might be an issue. I would probably just install it without the AC compressor if it created an issue, until I managed to acquire or fabricate a bracket to relocate it. Ideally, I would copy the L29 accessory drive layout.

Can you post photos of your install, specifically the accessories. Without having my truck here I am seriously handicapped.