As the title states, I was thinking of a 4BT swap and found the adapter plates, and flywheel, but what about the electronics for the 4L80E. I was thinking of buying a used Tahoe and doing the swap so I have not really thought much about it. In older Tahoe with the 700R4 would be easy, but I wanted to stick with the 4L80 due to the center support that it has and the 700R/4L60 does not have.

Any help would be appreciated!

I found this one so far:

http://www.transmissioncenter.org/compushift_4l60e_4l80e.htm

It looks like the cost will be almost 3 grand between the flexplate, adapter, computer and motor mounts.

You can use a trany controller out of a 96-00 2500up with a 6.5TD with a 4l80E.

Do you mean retro-fit the one already on the 6.5?

The computer should plug right into your 4l80. The trucks that came with the 6.5td had separate computers for the engine and transmission. You would need the transmission computer and the harness for the transmission.

The computer should plug right into your 4l80. The trucks that came with the 6.5td had separate computers for the engine and transmission. You would need the transmission computer and the harness for the transmission.
Yesterday 08:32 PM




The Factory turbo 6.5s used one PCM for the engine and trans. Only the N/A 6.2 and 6.5 used a seperate trans control module. It is true that the trans connectors are physicly the same between the 4l60 and 4l80. BUT have different pinouts and MAY require different software.

Your options are:
1 Aftermarket controller (around $800.00)
2 Used standalone GM controller
3 Full manual conversion with Transgo kit

Thanks for the correction.^

Thanks guys! So to make the swap easy I should just go for a TH400, as it has a center support and a gear vendors unit to make it a 4 speed. What was the last year for a 6.2/6.5 to use two separate computers? Also would that version have the 4L60/4L60E or the 700R4?

They didn't ever offer them with 2 seperate computers that I know of.

It was either a N/A 6.2/6.5 with a computer that only controlled the 4l80 as the motor was 100% mechanical (like a 4-6BT). These were used up to around 2000 (possibly later??) in P series chasis and in H1s as well. Pickups used N/A diesels up until 1996 but are quite rare after 93 or so. The stand alone controllers were only used on the 4l80e.

Turbo 6.5s were electronicly controlled (kind of like an ISB) and used a PCM that controlled the motor AND the trans.

They didn't ever offer them with 2 seperate computers that I know of.

It was either a N/A 6.2/6.5 with a computer that only controlled the 4l80 as the motor was 100% mechanical (like a 4-6BT). These were used up to around 2000 (possibly later??) in P series chasis and in H1s as well. Pickups used N/A diesels up until 1996 but are quite rare after 93 or so. The stand alone controllers were only used on the 4l80e.

Turbo 6.5s were electronicly controlled (kind of like an ISB) and used a PCM that controlled the motor AND the trans.

Thanks for the info. When they ran a Th400 what did they hook the vacuum modulator up to? Did they have a separate unit that ran off boost?

Turbo 400s were never used behind a turbo 6.5 from the factory.

I believe the 400s used a cable that replaced the vacuum modulator and functioned similar to a TV cable on a 700r4. I'll have to look at the one in the back yard. Which reminds me that I do have a gear vendors/turbo 400 setup from a 6.2l truck for sale. PM me if interested.

Turbo 400s were never used behind a turbo 6.5 from the factory.

I believe the 400s used a cable that replaced the vacuum modulator and functioned similar to a TV cable on a 700r4. I'll have to look at the one in the back yard. Which reminds me that I do have a gear vendors/turbo 400 setup from a 6.2l truck for sale. PM me if interested.

I know the HT400 was used on the military Blazers with 6.5/6.2 and the tranie can be built up fairly cheep. The 400's have a TV cable and a vacuum modulator so I was just contemplating what is truly necessary for the swap.

Thanks again for your time, as a knowledgeable person is almost always more helpful than a service book in determining the work in a engine swap.

Since I live in CA, diesels are supposed to be smoged in 2010, I was hoping to build up a fun pre 98 to avoid having to smog them. With the time and energy it will take with the Tahoe I might as well save an extra 10 grand and do a 92-97 H1 as it would be more fun to play with.

Also does the gear vendors unit you have mount behind the transfer case?

No it's for a 2wd, sorry.

That's going to be a long setup for a 2 door Tahoe. The rear driveline is going to be mighty short by the time you put a Gear Vendors on the end of the T-case.

Yea, I saw a new drive shaft set up where you install a CV joint instead of a U-joint which allows for up to a 75 degree drive line angle. If I found any old 6.2-6.5 NA truck in the wrecking yard with a 4L80E I could just grab the trans computer and make it work with the 4bt correct?

With the cost of the system already being over 5 grand with upgrades to the 4bt, if I dumped that into the 6.5 could I get around 300 HP and 600 Tq at the rear wheels? Would it still be reliable as a daily driver?

Thanks, last question :)

Yea, I saw a new drive shaft set up where you install a CV joint instead of a U-joint which allows for up to a 75 degree drive line angle. If I found any old 6.2-6.5 NA truck in the wrecking yard with a 4L80E I could just grab the trans computer and make it work with the 4bt correct?

Yep, make sure you get the TPS as well.

With the cost of the system already being over 5 grand with upgrades to the 4bt, if I dumped that into the 6.5 could I get around 300 HP and 600 Tq at the rear wheels? Would it still be reliable as a daily driver?

Thanks, last question :)


You'd need to get a marine version to have it hold up long term. You could use a production block as long as you used a girdle, good pistons etc. The big thing is getting a pump and injectors to support the power, from what I've seen 250ish horse is about it for stock stuff. I think you'd be into a 6.5 a lot of money to hit those power numbers and have it hold up. Then there's the cost of the turbo and the intercooler and the.........you get the point I'm sure.

I hate to say it on a diesel site but you'd be money and power ahead to build a 454 or 496 than a 6.5. It's not hard to make 400 plus horse and close to 600 ft lbs and still have it pass emissions and get semi-reasonable fuel milage. It'd be a whole lot smoother than a 4BT as well.

Having said that it's apparent you want a diesel. The 4Bt isn't a bad option, a 6BT would be better IMO just because they are smoother/quieter and will make more power. There are lots of older Dodges and industrial B series just waiting for a transplant. The length is a bit of an issue of course but it's still doable. An air/water intercooler cures the lack of room for an air/air. The 4l80 will still hold the power of even a turned up 6BT. I don't think cost will be much different between a 4 and 6. Then the Duramax swaps have been coming down in price a little hmmmmm maybe my 8.1 needs replaced with a diesel.

Thanks again for your detailed information, as I have not worked much on the 6.5's.

Have a good night!

They didn't ever offer them with 2 seperate computers that I know of.

It was either a N/A 6.2/6.5 with a computer that only controlled the 4l80 as the motor was 100% mechanical (like a 4-6BT). These were used up to around 2000 (possibly later??) in P series chasis and in H1s as well. Pickups used N/A diesels up until 1996 but are quite rare after 93 or so. The stand alone controllers were only used on the 4l80e.

Turbo 6.5s were electronicly controlled (kind of like an ISB) and used a PCM that controlled the motor AND the trans.
Standalone 4L80E controllers were also used on trucks with 93 and 94 6.5 turbo motors. I have a 1993 6.5TD/4L80E sitting on my garage floor. The motor has the mechanical IP. The 4L80E is controlled by a stand alone GM controller.
Also, you need to supply a tach signal to the TCU. In the late 6.2/early 6.5 this is done with a sensor that mounts in the old vacuum pump hole. I have a complete setup with harness and ECU. PM me if interested.
Brian
Sacramento

Thanks for the info and year clearifications!

bringing this thread back up. Where is the stand-alone TCU on the NA 6.5's? Under the dash? How big is it?

What sensors besides the tach signal are they looking at that are external to the transmission? (if I pull one out of a junkyard, what else do I need to grab?)

thanks!

There is a stand alone controller for the 4L80E sold on the Destroked web site that is much better. Its under a grand.