Topic: 2002 Suburban 2500 build thread, Part 5 (Duramax Conversion)

[Flyin6]

OK Folks, I am throwing in the towel on this Burb as a gasser project.

After a super effort spanning a couple of years, I have finally come to the conclusion that the gas 6.0 will never work in this application.

Stock, the truck could get out of its own way, barely but suffered from poor mileage and I doubt it would be worth a crap pulling a camper up over the divide.

Even with a supercharger, it has been only marginally better. A lot more power, but still mileage so poor as to relegate it to a truck to be used on short trips only.

I looked into converting it over to a 12 valve Cummins and I could do that but not with retaining the stock gage cluster and all those wonderful features that make the suburban a great truck to drive and own.

As Charles has said all along, the only thing that would make sense and last would be to transplant a Duramax which the 2400 Silverado's came with.

So, moving forward, I will purchase a donor silverado and remove everything duramax related from it, then just plug all that back together inside the Suburban. I'll probably rebuild the motor and trans and maybe the T-case too, since I think the D-max uses a 63 T-case in lieu of the 46 case I currently own. Anyway, standby for a standby as I source a donor truck

[Flyin6]

All the "I told ya so's" can post in a jeep or ford forum somewhere!

[JR]

Good choice, may have or not been suggested once or twice,,,,,,,,,,,,

 

[KensAuto]

"...then just plug all that back together inside the Suburban."

Oh, brother Don. Hope you realize what you're getting into.

Sounds like fun!

[Flyin6]

"...then just plug all that back together inside the Suburban."

Oh, brother Don. Hope you realize what you're getting into.

Sounds like fun!

I've read about it a time or two...

[TexasRedNeck]

This is gonna be epic.  I have faith in Don’s ability to get it sorted pretty quick.  Lots of how to vids on YouTube


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[JR]

Yes, plenty of info out there on this conversion. I think having a Dmax in the driveway won't hurt either.

To bad your 3k miles away, it will be fun.

[Bigdave_185]

I just wanna know what the current power plant goes into.   Or how much $$$ you make on it when ya sale


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[Flyin6]

I just wanna know what the current power plant goes into.   Or how much $$$ you make on it when ya sale


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I have an offer for the engine/blower w injectors and fuel pumps for $6K

Seems a little light to me. Perhaps I'll break it down further to make a bit more coin to cover the cost of the conversion.

I think my chance of finding a lower mileage 01-02 is about zero, so I'll probably be rebuilding everything and that is going to be costly.

I think Charles had the idea for the engine. What, an LB7 block with LLY heads to swap the injectors outside of the valve cover, but then there is an issue with the wiring harness and the high pressure fuel lines. Might have to just keep it all LB7 and put better rods in it. 1000-1200 ft lab will be my goal. I am used to that power level now and with respect to towing that works perfectly.

Something else that is near perfect are the 37" tire sizing with the 4.56 gearing and the overdrive in the Allison. I enjoy effortless cruising in my D-max between 70-80. Seems when that engine is around 2000-21-- it is totally in its zone, although mileage suffers. I'll see a 3-4 mpg drop from 60 to 75.

[JR]

Just LBZ then. You get all the good stuff, 6sp, open injectors. I just saw a running LBZ for 7k out here, totaled would be way less and you would about break even.

Hmm, I turn 2k at 70mph with 35s right now, seeing about 18mpg. I do not have all your mods but I would say around 500hp.

[TexasRedNeck]

LBZ won’t work in LB7 applications because of the can bus comms protocol is totally different.  The LLY headswap is looking less a and less necessary if you get the LB7 set up right.

Don as long as you get the upgraded SAC injectors and screw in cups the injectors in the LB7 should be bulletproof for 200k

I believe edelbrock has a set of LB7 heads new with screw in cups

LBZ or LML rods should be safe at that level. Can’t remember if the LML rods have to be modified to run in LB7

Of course if I had your money I’d put the Wagler rods in it. Good to 1000hp and about $1700 for the set.

Resist the Don Rule of going overboard. As you know the cost curve is exponential and not linear


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[JR]

Wouldn't the LBZ be fine if he got the whole truck? Dashes have not really changed for those years so all should almost pnp. Sure the harness would need mods as it was a gas rig.

[Flyin6]

LBZ won’t work in LB7 applications because of the can bus comms protocol is totally different.  The LLY headswap is looking less a and less necessary if you get the LB7 set up right.

Don as long as you get the upgraded SAC injectors and screw in cups the injectors in the LB7 should be bulletproof for 200k

I believe edelbrock has a set of LB7 heads new with screw in cups

LBZ or LML rods should be safe at that level. Can’t remember if the LML rods have to be modified to run in LB7

Of course if I had your money I’d put the Wagler rods in it. Good to 1000hp and about $1700 for the set.

Resist the Don Rule of going overboard. As you know the cost curve is exponential and not linear


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We're thinking the same here:
Keep the LB7 architecture intact. Nothing fancy, but the SAC injectors and edelbrock heads sound like a smart move. Sure LML rods are cheaper and make sense.
CP3, nice manifolds, a better turbo and some nice piping and Y-bridge along with a clean and simple rebuild is all I'd ever need.
I'll run a good converter and upgrade the Allison to a six speed and able to handle the torque. Really a rebuild to LML standards with a good converter would work since I almost never hot rod my trucks, just tow, and this burb will always tow light.

[TexasRedNeck]

Wouldn't the LBZ be fine if he got the whole truck? Dashes have not really changed for those years so all should almost pnp. Sure the harness would need mods as it was a gas rig.

Unfortunately, that’s not the case.  All modules and communication components including the dash would have to be changed.  I was really disappointed when I learned that I was stuck with the old architecture.


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[Flyin6]

Wouldn't the LBZ be fine if he got the whole truck? Dashes have not really changed for those years so all should almost pnp. Sure the harness would need mods as it was a gas rig.

Unfortunately, that’s not the case.  All modules and communication components including the dash would have to be changed.  I was really disappointed when I learned that I was stuck with the old architecture.


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But having said that, by simply upgrading the known weaknesses of the LB7 old bus system, you still have a viable setup that will last decades.

[Sammconn]

Too bad the LBZ stuff doesn't play well.
My donor has everything.
It’s not power everything however.

A shame as I don't need a stupid number for it.

Sorry to hear this as the outcome.
I kind of felt the super charger would have done better.

[TexasRedNeck]

Wouldn't the LBZ be fine if he got the whole truck? Dashes have not really changed for those years so all should almost pnp. Sure the harness would need mods as it was a gas rig.

Unfortunately, that’s not the case.  All modules and communication components including the dash would have to be changed.  I was really disappointed when I learned that I was stuck with the old architecture.


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But having said that, by simply upgrading the known weaknesses of the LB7 old bus system, you still have a viable setup that will last decades.

There is nothing really weak about the LB7 in any way.  The early injector design gave them a bad rap because the body would crack and leak under the valve cover “making oil” .  The new design solved for that.

I had mine replaced 80k ago and not a single problem and I run in on tune 5 all the time.  It’s every bit as quick as my LML with the tunes on it, but that’s probably because its also lighter.

I do have a built trans, lift pump, and boost gate valve, but if you get above about 650 to the wheels the rods can get a little bendy…

The screw in injector cups are just nice insurance and sac injectors are just a better design.  The LBZ gets all the love because they were the last non emission duramax and they didnt have the injector issues of the LB7 or the overheating issues of the LLY, both of which were easily solved problems.

Danville or fleece or someone, makes a nice turbo that will get easily 650-700 to the rear, but remember there is no VVT so no real turbo brake. 

My plan for the block I have sitting out back is Wagner rods, edlebrock heads, screw-in cups, sac injectors 45over, and a single strokedCP3 a and a upgraded turbo.  Nothing crazy but pretty darn bulletproof at 650 to the wheels.

https://www.edelbrock.com/edelbrock-cylinder-head-79029-for-gm-2001-2004-lb7-6-6l-duramax-diesel-engines-79029.html

https://www.wcfab.com/i-31352367-2001-2004-lb7-duramaxstealth-g2-67mm-drop-in.html

Correction: the Edelbrock heads have the cups cast in to the heads, so same solution different way.



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[Flyin6]

So, I was forced to drive the Burb as my daily for the past few weeks while the D-Max truck has been down for some maintenance.
I don't drive all that much, but the annoying transmission shifting was getting to me, so I started tuning it again with my little laptop and HP tuner.

I found a bunch of problems and started correcting them

First was this annoying thing where if you are running in OD with the converter locked the minute you lift the least bit the thing unlocked then relocked the minute you pressed on the gas. It gave this jerky feeling which is exasperated by the triple disc converter which locks fairly harshly feeling like a firm upshift. The grandkids were looking at me every time it locked going to church a couple of Sunday's ago...I told them the larger winter bumblebees were running into the back of the truck
They believed me!

So by lowering the pedal threshold down into the 20% range, it now stays happily locked, so that annoyance went away.

Next I had way too much torque reduction between shifts in. It felt like the motor was shutting off between shifts. Funny, because that was part of a stock Chevy tune! Well I decreased that 25% 10%, then 10% a second time, then a final 5% and it now feels good there.

I bumped up the idle 50 RPM when cold

All in total, I did 6 test drives with 7 tune mods. I stopped tuning because I needed to get busy on the D-Max.

Overall, I am impressed with how much the minor changes changed the drivability of that truck. Jury is still out, though, but with having no truck to drive and with Kat starting to beat me about the head and shoulders over doing a Duramax conversion, I figured I needed to get something happening.

[Flyin6]

I continued to tune the transmission and now have a fairly driveable situation.

I tested the fuel economy the past tank and it went up nearly 50% to 11.2 MPG.

It has more in it since I am getting an annoying cel that is still pointing to the O2 sensor heater, both of them, having failed. One of the results of the O2 sensor failing to heat is poor fuel economy. So there is something to fetch there for sure. Finally, I have not sorted out when to lock up the converter. And I have not figured out how to achieve a soft lockup. It is still hitting like a bang-shift into second from a 1970's shift kit which is no fun.

Now that I have been driving it a lot, I would say it seems to have adequate power, but "gas-motor-power" You see when we increase the output of a gasoline powered engine, we have to go to a dyno to actually see it, but when we increase the torque of a diesel, the front bucket seat bolts shear off and you are knocked unconscious when your head slams into the rear window. The burb does not suffer from that problem at all. But that speedo gets to 60 pdq and I find myself having to lift off the throttle frequently.

So that's it for now. Haven't found a donor, but not really looking since the duramax swap seems like it could cost an additional $100-$200K because of the added cost of the divorce attorneys.

[Bigdave_185]

That’s $$$ goes real quick when dividing by HALF!!!


I’d still like to see or hear a video of this rig. 


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[JR]

Heck 11mpg hurts even when towing with biden fuel prices.

[Flyin6]

Heck 11mpg hurts even when towing with biden fuel prices.

Yes it does. So I figure these trucks got from 11-13 on the average. Mine is optimized so it has potential for better mileage, but then I added 37" tires, more weight, raised it, and added a host of other things that kill mileage. I may be able to wrangle another .5-1.5mpg from it, but for the most part, it is about at it's best point with the gasser right now. By comparison, should I decide to continue with the D-max conversion for $200,000, I could easily fetch 17-20 from this rig.

Which translates to breaking even over the next 250 years give or take a decade or two. Seems like a smart move to me 8-0

[JR]

Sounds like good trade off when fuel hits $10 a gallon. Maybe its time for that still I shared with you.

[Flyin6]

Phase 1 complete I now have an engine:

Anyone guess which model/series???

[Flyin6]

Anyone??

Its a Vortec 8100! Yepper a 496 cu in big block chevy that I decided to build and go with

Quote from the web:

GM’s 8.1L motor, referred to as 8100 Vortec and first produced in 2001, was employed for Chevy Avalanche 2500, Silverado 2500HD and 3500HD plus their GMC Sierra doubles in 2001-2006. In 2007, a smaller but more high-performance 6.0L V8 substituted it. GM created these motors for pickups to work steadily for a long time.

Being a gas motor, the 8.1L demonstrates an imposingly flat torque curve, being powerful at 1200-1400 rpm and finally coming to nought below 400 lb/ft after 4000 rpm. That’s a range of 2600 rpm of usable torque higher than 400 lb/ft, peaking at 440-455 lb/ft (depending on the year of production) at 3200 rpm. Finally, the power increases to 320-340 hp at 4200 rpm.

[Flyin6]

So, why the big change you ask??

Well recall the recent discussion I had about the 7.3 liter Ford Godzilla? Well that got me thinking.

These Duramax engines are more costly than gold! Then when you get one, you'd (Well I would) need to go through it and improve the rods, do a rebuild, do something with the injectors, new turbo, gaskets, machine work and so forth.
Next, the Duramax never came in a Suburban and therefore I'd have to learn how to re-pin my computer, figure out all that electronic stuff and hope I got it right.
Check out the cost of injectors? What $500 for one??? So for $4000 the cost of just the injectors, I can rebuild my entire engine and upgrade to some forged innards.
And, this 8.1 bolts straight in! Yep, I just bolt it in, hook it up and go driving.
It will get terrible fuel mileage, but that 6,0 is consistently knocking down 7-8 mpg lightly loaded, so for that reason alone the 6.0 is a no-go. I believe these 8.1's were getting something around 12-13 mpg in suburban's. Nick actually has one and it does quite well.
For the cost of those needed new injectors and rods along with studs for a LB7 I can rebuild this thing, and it actually doesn't need it, and add in forged rods and pistons for what I plan to do with this motor
No, Virginia, it will not remain stock.

[Flyin6]

And, gentlemen I did not only score a low mileage (56,000 miles) motor, but I also purchased the Allison 1000 that came in this truck. That Ally has 120,000 miles on it!

Included in the deal was a good Allison TCM that makes this a plug and play!

[Flyin6]

Along with that I got everything else. Every line, hose, bolt, clamp, all the brackets, all the accessories, and the complete wiring harness, the whole thing!

The gentleman, Joseph, had removed this all from a wrecked work truck and planned to install it as is into a 1979 Square-Body, but he gave up on the idea, so I'll sort of make his dream and mine come true

[Flyin6]

He knew of the truck, again, a work truck. An employee blew up the original engine at around 70,000 miles and the owner had GM install another factory 8.1. As you can see the thing is very clean and fresh:

[Flyin6]

So, the plan for this new acquisition is to:

1. Come up with a plan!

I will be consulting with the owner of Raylar engineering, the nations premier builder of 8.1's to figure out how to do this.

I will be including Nick Skaats in this build as well. I am not sure what roles each will play, but both will get involved

My goal is to have something that GM built motivating this truck. I want it to have zero issues, get at least 10 mpg, and have a metric ton of poser. I'd like to create a vehicle that is adverse to weight, meaning it will tow a camper like it was nothing.
I want it to be junkyard serviceable and easy to work on

and

did I

say

I want a ton of power

So there are two ways of getting to 600-800 HP which is 750-1000 ft/lbs of energy.
I could opt to beef up the bottom end, add some Raylar aluminum heads and a cam and get into the 600 HP arena.
I could also add forged rods and pistons, keep the stock heads and bolt on a blower to get easily into the mid 600's.
Or I could swing for the fence and build the bottom end, add the cam/heads and bolt on a blower and have 800+HP and very low in the RPM band as well.

I'll let you all know what we're doing after consulting with the smart guys

https://www.raylarengineering.com/

https://www.youtube.com/watch?v=zTDnr0wj3UU&t=2s

[JR]

Soon as the cover was off I knew it was an 8.1. They tow great, but suck fuel, have to find that happy spot in there.

So what year ally?

[Flyin6]

Soon as the cover was off I knew it was an 8.1. They tow great, but suck fuel, have to find that happy spot in there.

So what year ally?

2001 is the date on the TCM, but the truck was a 2002, same as the year of my burb

As far as sucking fuel, they can't be worse than what I have. The guys I know say theirs are around 10mpg stock. Some have seen much better than that, so it just depends on the variables.

[stlaser]

So this gas motor is gunna put this bellyaching to bed once and for all? 

[Flyin6]

So this gas motor is gunna put this bellyaching to bed once and for all? 

Well, it is going to be the last motor project this truck sees. It will get installed with a wish and a prayer and it will either work or it won't

I strongly suspect it will work

People like both the Duramax and the Vortec 8100 for towing and power

One is extremely thirsty and the other is extremely costly. Kind of a wash in my mind

When first you lay eyes on it, the truck will be thumping on a cam lope and expelling musical BB Chevy notes from the exhaust.

[JR]

"variables" = Don

I just saw a factory duramax late model suburban, 3.0,,,,,,,,

[Flyin6]

"variables" = Don

I just saw a factory duramax late model suburban, 3.0,,,,,,,,

$90K...what?

Forget it

Sick of these new super high prices

and

the Tuck charges an annual tax on your vehicles based on the assessed value on the "oneth" of January.

So this year, I owe $440 tax for the Duramax, and...wait for it...$69 for the Suburban!!!!!!!!!!!!!!

Ya, done for now with this new junk

[Sammconn]

So this gas motor is gunna put this bellyaching to bed once and for all? 

Well, it is going to be the last motor project this truck sees. It will get installed with a wish and a prayer and it will either work or it won't

I strongly suspect it will work

People like both the Duramax and the Vortec 8100 for towing and power

One is extremely thirsty and the other is extremely costly. Kind of a wash in my mind

When first you lay eyes on it, the truck will be thumping on a cam lope and expelling musical BB Chevy notes from the exhaust.

I’ll vouch for the costly.
Still scared to add up my receipts to reseal a stock one.
Lol.

[Flyin6]

So this gas motor is gunna put this bellyaching to bed once and for all? 

Well, it is going to be the last motor project this truck sees. It will get installed with a wish and a prayer and it will either work or it won't

I strongly suspect it will work

People like both the Duramax and the Vortec 8100 for towing and power

One is extremely thirsty and the other is extremely costly. Kind of a wash in my mind

When first you lay eyes on it, the truck will be thumping on a cam lope and expelling musical BB Chevy notes from the exhaust.

I’ll vouch for the costly.
Still scared to add up my receipts to reseal a stock one.
Lol.

Exactly, Sam

I'll pay for the conversion one fill up at a time, but in the mean time enjoy that throaty roar and the feel of a big block Chevy

[Bigdave_185]

So this gas motor is gunna put this bellyaching to bed once and for all? 

Well, it is going to be the last motor project this truck sees. It will get installed with a wish and a prayer and it will either work or it won't

I strongly suspect it will work

People like both the Duramax and the Vortec 8100 for towing and power

One is extremely thirsty and the other is extremely costly. Kind of a wash in my mind

When first you lay eyes on it, the truck will be thumping on a cam lope and expelling musical BB Chevy notes from the exhaust.

I’ll vouch for the costly.
Still scared to add up my receipts to reseal a stock one.
Lol.

Exactly, Sam

I'll pay for the conversion one fill up at a time, but in the mean time enjoy that throaty roar and the feel of a big block Chevy

Who ya kidding throaty roar lol you’ll have four mufflers on that burb and won’t have an ounce of sound


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[Bob Smith]

Yes, that big block rumble sounds really good from the sidewalk but not so much from the interior car seats.

[JR]

"variables" = Don

I just saw a factory duramax late model suburban, 3.0,,,,,,,,

$90K...what?

Forget it

Sick of these new super high prices

and

the Tuck charges an annual tax on your vehicles based on the assessed value on the "oneth" of January.

So this year, I owe $440 tax for the Duramax, and...wait for it...$69 for the Suburban!!!!!!!!!!!!!!

Ya, done for now with this new junk

Low registration, but a value tax? Cheaper out here with that. Do they charge for the "farm equip too?

[TexasRedNeck]

Don my opinion is worth exactly what you are paying for it.

For what you are going to have in this a dmax swap is in range . You wont be happy until you have the earth turning power of a diesel.
 

I hope I’m wrong but you may be two builds into a project that still doesnt meet your needs and way over budget for a lb7 build.

I’ll see you guys in a while after the ban is lifted…


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[Flyin6]

"variables" = Don

I just saw a factory duramax late model suburban, 3.0,,,,,,,,

$90K...what?

Forget it

Sick of these new super high prices

and

the Tuck charges an annual tax on your vehicles based on the assessed value on the "oneth" of January.

So this year, I owe $440 tax for the Duramax, and...wait for it...$69 for the Suburban!!!!!!!!!!!!!!

Ya, done for now with this new junk

Low registration, but a value tax? Cheaper out here with that. Do they charge for the "farm equip too?

In kentucky everything you register gets taxed. Its the reason I never registered my camper.

[Flyin6]

Don my opinion is worth exactly what you are paying for it.

For what you are going to have in this a dmax swap is in range . You wont be happy until you have the earth turning power of a diesel.
 

I hope I’m wrong but you may be two builds into a project that still doesnt meet your needs and way over budget for a lb7 build.

I’ll see you guys in a while after the ban is lifted…


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Well, like it or not, this is the final solution. No more engine changes for the Burb.

[KensAuto]

Don my opinion is worth exactly what you are paying for it.

For what you are going to have in this a dmax swap is in range . You wont be happy until you have the earth turning power of a diesel.
 

I hope I’m wrong but you may be two builds into a project that still doesnt meet your needs and way over budget for a lb7 build.

I’ll see you guys in a while after the ban is lifted…


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Well that makes 2 posts you've made today that I won't touch with a 10 foot pole, and I agree with one of them.

[JR]

For what you have in the Burb and the motor, I think a duramax converted Suburban would have been cheaper.

See them all the time for sale, probably more $$ now.

[Flyin6]

For what you have in the Burb and the motor, I think a duramax converted Suburban would have been cheaper.

See them all the time for sale, probably more $$ now.

But JR, the whole point with this suburban is that it is still like new. Any Suburban I would get would likely be rusty somewhere. This one is perfect. Get this engine done and a fresh interior in there and it's a lifetime keeper.
I looked at some d-max burbs. Every one of them was a piece of crap. Their condition was what turned me off to the idea. This one is absolutely one of the best in the nation. Chances of finding another one and diesel approaches 0%

I'm keeping THIS burb...

[Flyin6]

Well, shoot
That 496 project didn't get legs to even walk.
I started costing out everything and by the time I built this big block engine I would easily have Duramax dollars in it.
I suppose I am getting pretty done with dumping huge buckets of money into my trucks so I decided to do the smart thing and abort on the Vortec 8100 swap too.
So where did that leave me?
Well, funny thing, but both Nick, my tuner and engine guy and John the transmission guy started talking to me.
Nick was good on the big block swap, but also pretty good on improving what I currently have
And funny thing about that, When I stop driving the Suburban like a duramax, it actually wakes up and moves right along!

John is convinced that Circle-D torque converter is junk and the culprit for all the revving and consequent loss of mileage the truck suffers from.
He has also built a ton of LS 6.0 motors and thinks the right converter/cam/heads on a LSA motor makes plenty of power.
So, knowing I have to get along building a cabin this summer, they more or less pointed me down a practical path.
John ordered a billet cover stock LSA converter to be built for my truck. Now, it won't have triple discs, but it also won't be revving to nearly 3,000 to get things done. It will stall a thousand RPM less and use some boost to move instead of RPM.
We also think I should swap the cathedral port heads for some good square-port heads and maybe change out the camshaft. That gets rid of these crazy cathedral port to square-port adapter plates which to me seem to close off a third of the intake port or more.
I think I'll bolt on a real LSA supercharger drive which will put the accessories on one belt and the supercharger on its own dedicated 8-rib belt. I'll add in a custom harmonic balancer that I can do a 10% overdrive pulley on to make more boost at lower RPM's and see how all that runs. I am still chasing after the two O2 sensors that remain unheated keeping the motor in a fuel enrichment mode.
When it is all said and done we hope to bring up the mileage 30% and make more power in a useable range. With that done, I think I may be done, except to pop in a 408" short block down the road. That combo should pull the little off road camper and be able to travel all over hill and dale.
Oh and now I have both trucks and the camper all wearing the same wheels!

[KensAuto]

Looks darn good.

[Sammconn]

Looks darn good.

Agreed.

And a seemingly sensible decision has been made to not throw more money away hand over fist.