K10 8.1L brain transplant MEFI-4 to P59 ECM

[DirtyLarry]

As many of you know I swapped in a 2002 Vortec 8.1L into a 1978 K10 over a year ago and have been running it on a marine style speed density Delphi MEFI-4 engine controller that batch fires the injectors similar to an old TPI 350 but with big block fuel and spark calibrations. While the MEFI-4 controller has served me fine, I was never really able to get the calibrations nailed down to a science where the engine would run perfectly in every heat, load, and altitude variance. We took it on a 2,000 mile desert off-roading trip this past summer where it pinged and jerked like crazy when pulling steep grades in the hot temperatures. If I lived in Phoenix or Cali where there are a lot of experienced MEFI tuners with access to wide band oxygen sensors and dynos that would be a different story but doing the calibrations on my own…it is obvious I needed to look at alternatives as I will never get this thing programmed correctly on my own. Outside of driving it to Phoenix for AZ Speed and Marine to tune I decided to ditch the MEFI-4 operating system all together.

That all said, I am converting it over to an automotive style mass air flow sequential injected Delphi P59 ECM like what is on 2001-2007 8.1L Silverado's. I mounted the ECM yesterday and once I took the desired trunk measurements I ordered a new harness from Howell Engine Development this morning. Howell can calibrate the ECM to accommodate the manual cable operated throttle body unlike the drive by wire system the stock 8.1L engines use and save me the hassle of retrofitting the drive by wire throttle pedal assembly, they can also turn off Torque Management and give it a mild hot tune. I can’t wait to get the harness and start ripping into this project again. Sound be fun!

A few buddys and I are making the last mountain run on this MEFI-4 controller to play in the snow this Friday. The next trip this thing should have an all new personality and a heck of a lot more power!

Yes, the engine is dirty...it never got a full on detail after we got back from Arizona. Had to move the Painless dual battery isolator forward to make room for the P59 controller.

[Billhilly]

Hey Larry, hope the brain surgery is going ok. You'll have it running sweet for the next trip huh?
Slightly off topic, congrats on getting your truck in Peterson's! Even down here I still get January's copy months in advance. Good to see a sharp looking Chevy in there!

Have a good one.
Bill.

[msgross]

Originally Posted by Billhilly

Hey Larry, hope the brain surgery is going ok. You'll have it running sweet for the next trip huh?
Slightly off topic, congrats on getting your truck in Peterson's! Even down here I still get January's copy months in advance. Good to see a sharp looking Chevy in there!

Have a good one.
Bill.

I was getting ready to PM you the same... I noticed your truck in the readers section... nice.

[DirtyLarry]

Thanks guys. I was surprised it made it into the mag as well. I sent those pictures in quite a while ago and pretty much forgot all about it until they called to talk about it.

Yep, should get busy installing the new harness and required sensors next weekend. Wish I would have ordered it sooner so I could have gotten it done over this long weekend.

[DirtyLarry]

Got the new harness the other day and it looks pretty nice! Howell does a great job of labeling all of the connectors. I hope to rip into this project this weekend but have to pull the 700R4 out of my dad’s G-van to replace the front pump seal first.

[Lee Miller]

i installed a 8.1 and allison from an 04 in a 84 short bed i used the street and performance harness pretty much done got to get exhaust and my o2 sensors in drove it around the block seems like its gonna be alot of fun to drive.

[DirtyLarry]

Originally Posted by Lee Miller

i installed a 8.1 and allison from an 04 in a 84 short bed i used the street and performance harness pretty much done got to get exhaust and my o2 sensors in drove it around the block seems like its gonna be alot of fun to drive.

Sweet! Got any pictures? Curious to know what tranfercase you used behind the Allison or did you change the front axle to a driver’s side pinion?

Street and Performance does build very nice top quality harnesses as well. I considered them but have worked with Howell on other projects and have been happy with their services. Actually, the 8.1L harness isn’t that much different than a LSX small block harness. And you can make the 8.1L harness that much simpler by doing away with the EGR valve and ditching the electronic throttle drive-by-wire mess.

On Street and Performances website there is a downloadable PDF document where a Wyotech instructor also installed an 8.1L in a square body style truck. He did a very clean job with the install but went to a lot of unnecessary work hacking up the engine crossmember to clear the oil pan as well as cutting the hell out of the frame to clear the original 8.1L exhaust manifolds and A/C compressor. A little more research would have saved him a lot of time and energy by using the correct accessory brackets, engine cross member, exhaust manifolds and doing away with the EGR valve.

I got the MEFI-4 harness off yesterday but probably won’t have time to get back on this project until later in the week.

[Lee Miller]

i cut the cross member out on mine and just made a new one. will the older big block belt setup work on the 8.1 was looking at your pics and thought thats what you had. i took the guts out of the the factory case and put them in a 231d case. ONLY problem im having now is no heat i used the 04 rad with out the coolant tank

[DirtyLarry]

No, older 7.4L accessory brackets will not fit an 8.1L. The bolt holes in the heads do not line up. You can only use 8.1L brackets or I suppose some kind of aftermarket setup if you can find one.

Would love to know more about that you mean by took the guts out of the factory case and put them in a 231D? What is a 231D anyway? I never heard of that transfercase. The newer trucks use a LH front output while the older trucks had a RH front output. There isn’t a transfercase that fits the Allison with a RH front output and there are no pieces of the transfercase that goes behind the Allison (NVG261/NVG263) that will come close to fitting inside an old 208/231 or 241. What exactly did you do?

The 8.1L works fine with the original ’78 radiator so no need to change radiators as you are not gaining anything but headaches by going with a radiator from the new donor truck. A good ole 4 core radiator is all you need.

[Lee Miller]

hope this dont post twice but its not showing my reply...... i took the input shaft out of the new model and stuck it in an 89ish dodge str8 gear case...
the rad that was in my truck was junk so i just used the new model plus it has the big fittens for the alison trans just cant get no heat

[Lee Miller]

here some pics havent finished all the wiring had to drive it so i hurried alittle on that part

[Lee Miller]

pics suck but its raining so i just guessed where cam was at and snaped the pic

[DirtyLarry]

Lookin’ good Lee. I am still at a loss as to what you did with the transfercase but it looks like it worked out well. What do you mean by str8 gear?

[Lee Miller]

the dodge i took the case out of was a straight gear i also had to drill one hole in the adapter for the t-case bolt

[DirtyLarry]

Well, you did an awesome job figuring out a way to mate a RH drop transfercase to an Allison that is for sure!

What model is that transfercase and what year Dodge did it come out of?

I have access to Allison 1000 and 2200 series transmissions (but with SAE round bell housings) but never bit on one because I didn’t think a RH drop tcase could be mated to it because of the large output shaft diameter on the Allison. Hmmm, I may have rethink that next time I run across a deal on one. I prefer manual transmissions but I would rock an Allison if one landed in my lap for for the right price.

[Lee Miller]

well the alison and the 4l80e have the same out put shaft i THINK. The guy who done the one street and performance has on there used the 205 case. Its wild to drive a truck on 40s with that much power and the alison i love straight gears myself but its deff worth the money for the alison

[Lee Miller]

oh and the drive shaft is really close to the trans im gonna make some kind of plate in case i sling the front shaft dont want to bust it. If it ever stops raining i will take some good pics of it. Im happy somebody thinks its cool all my friends ask why didnt i just build a sb or swap in a 454

[DirtyLarry]

Getting closer to completing the brain transplant. Only a few more connections to make and we’ll be good.

[DirtyLarry]

Okay…..the last post and picture was just a joke….

I laid an old molested G-van TBI engine harness on top the 8.1L for the sake of taking an interesting picture of what people probably perceive of a late model engine swap.

This is how the Howell harness looks tonight in raw form after a rough layout. Much busier than the Marine type MEFI-4 harness but it will be worth it in the end. I still have A LOT of routing and clipping yet to do to make it look better than factory installed. The goal is to make this 8.1L install look better than the factory 8.1L install in my 2001 Silverado. It shouldn't be hard to out do the UAW!

[special-K]

Originally Posted by DirtyLarry

Getting closer to completing the brain transplant. Only a few more connections to make and we’ll be good.

When I saw that my 1st thought was,"Now that`s why I`m a low-tech guy."

Ive been following this thread and am impressed.I have nothing to offer so trap`s been shut.I have a question,what transfer case is used behind the Allisons from factory?

[DirtyLarry]

Originally Posted by special-K

When I saw that my 1st thought was,"Now that`s why I`m a low-tech guy."

Ive been following this thread and am impressed.I have nothing to offer so trap`s been shut.I have a question,what transfer case is used behind the Allisons from factory?

Nothing wrong with being low tech Tim. You save yourself a lot of aggravation and money that way.

The tcases behind the HD trucks with Allison’s are the NVG 261 manual shift and NVG 263 electric shift. Both have LH front outputs. The Topkick/Kodiac 4x4 uses an electric shift NVG 273 with a RH front output. I believe this is a divorced unit.

Lee Miller figured an ingenious way of using a Dodge 241 with 261/263 pieces to create a RH front output that would bolt to an Allison. Pretty dang slick deal. While 205's are awesome, these later model aluminum tcases aren't too shabby either.

[Lee Miller]

wow that first pic would be a pain in the rear! I looked b4 i scrolled down anymore was thinking you got screwed. lol Hope to get exhaust on mine next week

[DirtyLarry]

Well, project bigassgas is pretty much done. It is unbelievable the difference between the P59 ECM and the MEFI-4 system. The truck starts better with no more kickback that sounds like it is about to break off the starter motor off the block, engine idles smoother and just operates smoother through all ranges. No more jerking between shifts and it will actually idle in first gear creaping around a parkign lot without bucking like bull with a cinch around its sack. Oh, and the POWER! She got a lot more power! It will make those 36" swampers squeal when leaving a stop!

After driving it around a while it dropped a MAF code and two alternator codes. Both were inactive history codes so I erased them and drove it some more and they have not returned. So, we’ll see if they ever return. I still need to find or make covers for the DLC connector and fuse box yet.

All and all, I am very happy with the results and wish I would have gone this route last year instead of messing with the MEFI-4 crap.

The RH inner fender is a pretty busy looking place now.

Headed back to the mountains next week to play in the snow so that should be the next test.

YouTube- 8.1L P59 ECM

[Lee Miller]

man a tech 2 would have been a nice thing to have when i done mine

[DirtyLarry]

Originally Posted by Lee Miller

man a tech 2 would have been a nice thing to have when i done mine

Yes, a Tech II is handy to have around a house full of GM products. It is actually my work assigned Tech II and is a real PITA to travel on the airplanes with, as the TSA always has to give it an extra special look over. I am getting ready to participate in betta testing some nifty laptop software that will replace the Tech II for GM Powertrain that begins rollout with the 2010 model year. It will be nice not to travel with a stupid Tech II anymore! A few more years, GM dealers won’t even need Tech II’s. They will be just like the big kids at the diesel engine companies like Cummins and International.....all PC based diagnostic software.