DavidBoren

All of this makes so much sense. I am glad it went relatively easily, almost like it was meant to be. You don't see a lot of those gigantic 8.1's being stuffed into much.

Moodified13

Well, we finished buttoning it up today, but left the grill off until we get the Abbott Cable-x (speedo) dialed in. It performed perfectly, 2400 rpm at 70mph, 190 degrees, trans at 100 degrees, ac works great, transmission shifts smoothly and downshifts properly. No leaks anywhere. It has tons of power, is 3 times as quiet as it was (almost as quiet as my 2007 f-150), and if I felt like it would easily do well over 100mph. I took it to 80 just to see how it would do and easily had at least another 50% pedal. At 70 it feels like it is hardly working. It's going to be interesting to see what kind of mpg I'll get. Overall I'm extatic, everything I wanted to accomplish with this swap was met and exceeded.

The only issue is the cruise control. It was non-functional and I'm not sure why. I'm hoping someone might have some insight. All 4 cruise wires are hooked up correctly, and TCC switch is hooked up. (I'll check pin 33 on the ECM and pin 7 on the tcm to make sure they are seeing voltage, but I figure that is probably correct). The only possible cause I've found in one of the forums is that the cruise brake switch needs to see resistance. I just have it on a separate circuit so it's not seeing any type of ground from the bulbs.

DW SD

awesome! congrats

Moodified13

Checked TCC On pin 33 and pin 7 on TCM. Tests correctly. Also wired in a relay to put ground on brake switch wire to simulate bulb resistance. Still does not work. I'm running out of things to check. I thought DBW setups were supposed to be easy to set up cruise.

Michael Yount

iTrader: (1)

I used Dakota Digital DBW cruise on mine - works flawlessly - but the ECU/stock vss is not involved at all.

Moodified13

Cruise control fixed! There were 2 problems, removed relay to provide ground and wired in light bulb to show tac module bulb resistance and changed out the relay that I was using to change the coast button to show 12 positive. Damn tac module is picky because it didn't like it. Went to momentary switch and it worked perfectly. Got 100 miles on it now troubleshooting the cruise and it has been flawless and a pleasure to drive. I'll post mpg when I get them!

Project GatTagO

iTrader: (7)

We need a video of this thing in action!

Andrew

Michael Yount

iTrader: (1)

Outstanding!

Moodified13

I'll see what I can do!

Kenova

iTrader: (4)

A BURNOUT VIDEO!!!!

Ken

mOtOrHeAd MiKe

iTrader: (8)

I am glad that I finally read this - awesome work!

Moodified13

I drove the Airstream to Texas for a rock crawling event today. It got 9 mpg in some pretty good hills. I'm ecstatic with this. The 454 got 5 or 6 on a good day. I was able to talk on the phone and listen to the radio at a reasonable volume. It definitely doesn't lack for power and I have to be careful not to get it going too fast. I really enjoyed the drive. I'm pretty sure that if this power plant was available in 84 Airstream would have put this combo in them instead of the 454/475 combo. I am curious to see what it will get on the interstate without all the hills. After today, I'm hoping for 10-11 but will not be disappointed if it does no better than 9.

Michael Yount

iTrader: (1)

I'd say a 50-75% improvement is pretty significant -- I was pretty sure you'd see a noticeable gain, but that's even better than I thought. Technology is a wonderful thing! Nice job with the swap.

How'd the cruise control work? With the extra torque - just engage it and forget about it?

Moodified13

Cruise worked great. Definitely didn't have to babysit it in the hills like the old vacumn system!

garys 68

iTrader: (1)

That mileage is pretty good. In my experience the 8.1 in trucks got pretty awful gas mileage. But guessing the OD trans made a huge difference for you too.
Btw, you got me looking for a 70s Winnebago again.

Tuskyz28

Gas mileage I bet is neck to neck with a 6.0 LS motor on the highway. Good swap!! I dig the beast

Moodified13

9 mpg in a truck sucks. 9 mpg in the motorhome world is awesome. I'm also betting it will see 10 on the interstate. The diesel pusher crowd are doing great if they see 12. I was hoping for 9 best case and to get it in hilly road conditions is really encouraging!

AnotherWs6

iTrader: (17)

Congrats. And that motor looks right at home there. I'm curious as to how it will do on flat highway as well. If you hit ten that would be amazing. Hell, my empty pickup truck gets 13 on a good day.

DW SD

9 or 9+ mpg is excellent! Congrats on the clean build and great results

Does the 8.1L use premium or regular grade?


My 80s bluebird, which is 40k lb. (pictures earlier in the thread) with the 6V92TA Detroit Diesel and 5 speed Allison gets 6 mpg, whether I'm towing or not it seems. I tow a 6500 lb late model Toyota Land Cruiser. I guess + 6500 lbs almost doesn't register @ 40k.

I think I could get 9 mpg if I went to the Detroit 60 series in my RV as long as the transmission was electronically controlled and added another gear or two. But that is a $15k to $20k project, I'm guessing. So it ain't happening.

For now, I just appreciate that Diesel is under $3 / gallon. With a 300 gallon fuel tank and limited use, at least I don't have to stop often at the pumps

Doug

Moodified13

20k buys a lot of diesel!

I put regular gas in it. Drove it home at 70 mph just to see what worst case is. Got 7.7 on a 110 mile run. I'm pretty happy with that too. I'm taking it to Dallas in 2 weeks for a car show. So I'll probably get a really good idea of what best case will be. 65 mph on almost all interstate. About a 200 mile trip each way.

The performance difference is huge. It is way more pleasurable to drive than it was before. I also found out what it was like to pass cars, I'm not sure that has ever happened before. Cruise control works great and the torque from the 8.1 easily maintains speed. It takes hills very easily and seldom wants to downshift.