Project “Polar Bear”: 1989 V2500 Suburban

[Larry]

Awesome swap Larry!! Just curious what you're doing for a check engine light, if anything... I assume the 8.1L ECM normally communicates CEL status over the buss. ??

Chris

Thanks! The Howell harness has a DLC connector and SES light just like any other OBDII equipped vehicle. Once the final harness routing and clipping is done after the ECM is finalized I may extend the SES light circuit and splice it into the old SES in the cluster. We’ll see. The K10 has the SES light under the hood next to the DLC connector.

 

[Colorado_Outback]

As I mentioned before, I do not recommend using a donor truck harness to run any late model engine as there is way too much in that harness to deal with and the margin of error is too great. The best $600 you can spend on one of these is on a brand new stand-a-lone harness. Yes, on this old Suburban the only circuits on the old TBI harness I needed to keep was the oil pressure sending unit wire, starter, alternator, the keyed on wire that used to go to the coil now goes to the keyed on power for the ECM. Actually the A/C runs its own small harness directly from the low pressure switch at the accumulator. Again, my Sub could be different from your '94 being different platform generations. 94 and 95 GMT400 TBI is even different from 88-93 TBI as far as wiring and fuel pressures. Study the diagrams well.

Cool, that answers my question. Thanks!

I'm with you on letting the engine harness control the engine and let everything else keep doing what its all ready doing in my truck.

 

[1stDeuce]

Thanks! The Howell harness has a DLC connector and SES light just like any other OBDII equipped vehicle. Once the final harness routing and clipping is done after the ECM is finalized I may extend the SES light circuit and splice it into the old SES in the cluster. We'll see. The K10 has the SES light under the hood next to the DLC connector.

Hmmm. Does that mean the SES light is actually NOT a buss message?? Awesome!! I know it wasn't on older GM stuff, but I assume they assimilated it around 2000 like everyone else... On Jeeps it's been packed into the CCD buss since '96, so no way to have a SES light on a 4.0L swap if you use an OBDII controller.

Your awesome swap has me thinking again that I should have gone with an aluminum 5.3L with a 6.0L cam in the Comanche instead of the Camaro 3.4L, but the 3.4L required less parts swapping... There's always next time!!

Keep up to great work!

 

[lt1fire]

any clue what the mpg will be of the suburban once it is all said and done??

 

[Larry]

any clue what the mpg will be of the suburban once it is all said and done??

Too soon to tell as it is still in the operating room waiting on parts, but the ’78 K10 with an 8.1L gets 10-12 MPG. The last long trip that I tracked mileage in the K10 it got 11.72 MPG as an average for an entire 10 day trip which included highway, off-roading around Southern Utah (Hole in the Rock trail), off-roading around Western CO (Imogene, Cork Screw) then through the Sand Dunes over the mountain and back home. Pretty decent mileage in a big heavy big block powered truck with the aerodynamics of a drive in movie theater screen. I expect the Suburban to better than being lighter and without a wind sail on the roof. Although, my stock 2001 Silverado HD with an 8.1L does about the same at 10 to 13 MPG depending on the terrain and driving habit of the moment….in the end, the Suburban probably will be on par with those trucks.

 

[chilliwak]

I am looking forward to seeing pics of the install Larry!:drool:

 

[Larry]

I am looking forward to seeing pics of the install Larry!:drool:

Chilli,

Go back a page or two. There are tons of install pics and a few videos. It’s not running right now as I had to pull the trans out to fix an oil leak thanks to an rear main seal we forgot to install back in November when we had the engine apart

.

Since I had to pull the trans out it was a perfect time to send it out to get a 5th gear synchro problem ironed out. I don't expect to get the trans back until next week. Also installed a fresh set of injectors the other day as the originals were gummed up from sitting for 7 or 8 years and the fuel trims were really goofy from side to side. Anxious to see how it runs now with new injectors then start the fine tuning.

 

[ADVW/Liam]

Larry, I just read every page of this thread! I've always liked those old Suburbans, and yours is quite the example of how to do it right. I dont have the room or the funds to start a project like that, but I hope one of these days I can rebuild one. Looking at how good the engine bay looks on that thing (all the parts cleaned or repainted) makes me want to tear into my Tacoma, and do some spring cleaning.

Great work Sir!
Rick

 

[Larry]

Larry, I just read every page of this thread! I've always liked those old Suburbans, and yours is quite the example of how to do it right. I dont have the room or the funds to start a project like that, but I hope one of these days I can rebuild one. Looking at how good the engine bay looks on that thing (all the parts cleaned or repainted) makes me want to tear into my Tacoma, and do some spring cleaning.

Great work Sir!
Rick

Thanks Rick! Yeah, anytime I tear something down it gets a thorough steam cleaning and repaint. It’s so much easier to maintain a vehicle when things are clean and tidy. Kills me to see some engine swaps where nothing is cleaned or painted. A greasy engine shoved into a greasy engine bay should be against the law

 

[sean257]

Looks awesome Larry!

Mine is getting between 8 and 10 mpg on highway trips. 8 was into the wind at 80mph though. I'd imagine it would get 11 or better if I drove like a sane person.
Edit - mine also weighs 7k lbs with all of the added steel.

 

[Larry]

Looks awesome Larry!

Mine is getting between 8 and 10 mpg on highway trips. 8 was into the wind at 80mph though. I'd imagine it would get 11 or better if I drove like a sane person.
Edit - mine also weighs 7k lbs with all of the added steel.

Hehe, yeah…single digits are easy in the K10 too above 80 MPH. With it weighing right at 8,000 lbs when loaded for a trip and the aerodynamics of a drive in movie theater screen it eats some gas if it is pushed. Typically, I drive it like a diesel where I shift around 1,500 RPM's and just lug it around. It will squeak out pretty decent mileage when going easy on the loud pedal. Anxious to see how the Burb does.

 

[Larry]

Little update on the Polar Bear. I got the trans reinstalled, did a IAC relearn and reset the fuel trims to accommodate the new injectors she runs a lot better…..and that hot rod lope went away which I am so glad. It still has some little fine ECM tuning to do as runs a bit fuzzy in cold start open loop but other than that, she runs like a scalded dog at wide open throttle. The RayLar cam definitely gave it a lot more top end although at the expense of a little low end grunt loss but I’ll know for sure once the tuning is all dialed in. So far, I’m really happy the way it turned out and it will only get better once the ECM tuning is finalized. It’s pretty funny how such a big truck can flat out scream when you poke it in the neck

Outside of the fine ECM tuning the only other thing left is to have A/C lines built but I probably won’t have time to tackle that until May or June sometime.

Here is how it looks as of right now

And a family photo

 

[56powerwagon]

Only word that comes to mind is "awesome!". Can not wait until I am able to do mine this summer. It will first be with the sm465 and np205, but will soon follow with the nv4500 swap. Thanks Larry for all the great information and pictures and your time to post it all up for us.

 

[justcuz]

Larry,
Do you do your own relearn and reset on the fuel trim? I'd love to be able to do that stuff, but I'd have to improve my computer skills considerably I'm sure.
Your install is clean and factory appearing, it should make the old burb zip right along.
My first drive in an 8.1 was an eye opener compared to a 454. Much zippier, so I can't imagine the RayLar cam making it run even stronger. Did you have to change your valve springs to accommodate the cam? Do the 8.1's run the bee hive valve springs?
It is odd how LS engines peak torque rpm's are so high, yet the cruise RPMs rarely exceed 2500.
The newer engines torque band is way too high as I see it.
To recap, my recollection is your running 35" tires, 4.11 gears and NV4500 trans with a .73 5th gear.
My guess is around 1900 to 2200 rpm at 70mph, sound about right?
Thanks for posting up, I am a big Suburban guy, so I love reading about your modifications.

 

[BigTex]

Well done Larry. Well done.