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4BT + 6L80e

bw1339

Probationary Member
Messages
1
Location
Conn
Very cool build!

Any longer term impressions? I'm very interested in the driving dynamics with the 6L80 and a 4BT. Any changes in MPG?

I have a 4BT in my truck with a NV4500 and I'm tired of the gaps between some gears. I've been pondering doing a 6L80/90 for some time.

Thanks.
 

CaseyS

Well-Known Member
Messages
731
Location
Louisiana
Finally got my intercooler project wrapped up. I started last fall chasing down an oil leak which turned into a missing gasket when I assembled the seal retainer plate. As I was about to work on that under the vehicle I spotted a broken motor mount. That repair was much easier done with the engine out and after pulling the transmission, I was only a few hours of work away from getting the engine free to pull out. During that time period I came across some intercoolers on the intrawebz that were a possible fit that I had not come across in 10 years of searching. Actually I already has the radiators installed for a water to air setup and had purchased the intercooler, pump and plumbing. The intercooler was barely over $100 and I took a flier and ordered one to see if it would fit. Tackling this was much easier with the engine out so now was the window to make it work.

The intercooler is from a Cadillac ATS 2.0L and is a super tight squeeze between the frame rails. It leaves just enough clearance for the plumbing to clear the radiator. I had to grind down two mounting bosses to get it to tuck down far enough between the frame to keep it forward enough. Fitment required some careful trimming of the core support to fit the end tanks. The intercooler needs to push as far forward as possible to let the whole stack fit in. Retaining A/C was a must in Louisiana. The core is 16" tall by 21" wide by 1.25" thick. Unlike aftermarket intercoolers that are usually 2.5" - 3" thick, this thin one left me enough room to stack everything. If this works out there is an aftermarket full aluminum version with a 2" thick core.

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The stack is built up as follows: The A/C condenser is a universal aftermarket one that I already had installed previously. I fabbed a bracket from aluminum to attach it to two mounting bosses at the front upper tanks. Note: the intercooler is upside down from its OEM orientation in the caddy. The lower part of the condenser is attached to the intercooler core with the little zip tie thingys that push through the cooling fins. A 9" pusher fan is mounted to the front of the condenser on the passenger side. Last summer the A/C would kick off and on when the temps got to the upper 90s and stopped in traffic, hopefully this eliminates some of that. Mounting "ears" are attached to the intercooler at the top and the ears set in brackets mounted to the side of the core support. For this project I bought a riv-nut tool and am finding it coming in very handy for some other areas. The intercooler is allowed to float and basically hang from the top supports and the lower supports only provide fore to aft sway movement retention.

Here is the intercooler in place

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And a view from the engine bay side

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The intercooler inlet and outlet are 2.25" HENN connectors. After futzing around with ebay and a cancelled order I just ordered the OEM hoses from Rock auto and cut them up to use the connector and a short stubby piece of the hose. Piping fits inside the hose and is held in place with tbolt clamps. Plumbing is sized to match at 2.25" since anything bigger would continue to be a tight fit and would have to be necked down at the intercooler anyway. With the intercooler/condenser stack in place the radiator slips right down into the outer receiver grommets and is secured with the clamp at the top of the core support. Plumbing is super straightforward with two 90deg bends on the inlet and outlet and a 2"x2.25" silicone elbow at the turbo and the manifold end. I cut up a pair of crimping pliers to make a diy tube beader and its all assembled with silicone couplers and tbolt clamps.

I ordered some color match paint to hit the areas of the core support that had been ground and cut on to prevent any future rust problems and decided that would be a nice touch for the plumbing so they all got a coat of that.

VOPyssE.jpg


Here is a poser shot showing the size of the intercooler taking up the whole frontal area between the core support before I reinstalled the grill and bumber hardware.

u98v2Zn.jpg


I blew off an intercooler boot less than a minute into the first test drive due to a missing tightening a clamp and blew a second about 40 miles later but I think I have them all tight enough now. I have already increased fueling and still have barely gotten the EGTs over 1000. 1200 max is considered safe for continuous power so I still have room to add more power, but I want to log some miles in it first.
 

06 H3

a.k.a. "The Jackal"
Messages
9,350
Location
Meridian, ID
Did you get tap shift finished? How about the PRNDL setup? Do the lights not light up on the gear indicator?
 

CaseyS

Well-Known Member
Messages
731
Location
Louisiana
I've got the buttons and the resistors. I've got a project list for the holiday weekend and may actually get to this during the weekend. Stay posted.
 

atvspeed4

Well-Known Member
Messages
1,173
Location
massachusetts
Did you get tap shift finished? How about the PRNDL setup? Do the lights not light up on the gear indicator?
I was talking with Jeremy about our build he did a few years ago for our 6l90 wiring harness and programming. We landed on the light works for all positions but goes out when gear lever is in "3" which is the position used for manual tap shift. We liked this option because it reminded driver that it was in tap shift mode.
 

CaseyS

Well-Known Member
Messages
731
Location
Louisiana
Ok. My prndl lights do not work. The switches that fit on the quadrant for the 4l60 do not match up to the 6l80e shaft and I could not come up with an acceptable solution. I did write down the logic table of outputs for future reference if I decide to try and encode something but currently the connector is cut back into the harness.

Ok some partial success at tap Shifting. Can get it to work some of the time. I need to dig into the tables to see what's going on. If I drop it to D5 I can tap down and up and it works fine. If I do this from a stop it seems like I need to double tap to get the 1-2. If I'm in tap shift mode and come to a stop it will down shift me to 1 but then when I take off it auto shifts like I'm in D6.

Also scanning when in D5 the shift mode still says NORMAL not TUTD. Gonna study some settings and play with it some more.
 

CaseyS

Well-Known Member
Messages
731
Location
Louisiana
z8MfiPL.jpg


This is my test setup for now. If this works I may get a spare shift knob and see if I can embed these buttons in it. A second option is to use a rocker switch in position 1 like Acer4Lo did. Third option is spend money on an OEM or aftermarket shifter. It looks like Lokar is the only one that has a bang shift position. All the others have knob mounted switches (malibu, traverse, pace). I prefer to keep the look of the Hummer shift knob.

I'm getting closer. Goes into TUTD mode but forces a 2-1 after I shift to 2. I think I see my table issue. Will be tomorrow before I try again.
 

CaseyS

Well-Known Member
Messages
731
Location
Louisiana
Ok. Tap Shifting is sorted. It's pretty slick. You can dictate some specific behaviors depending on how you set up the shift tables when in TUTD mode. Most of the street guys set the table to go ahead and shift up at redline so they can TUTD to roll race gear and just mash the throttle. If you max out the table for upshifts, it will hold gear and not do that. The second part is downshifts. Most tables I have seen will shift you back to first if you come to a stop in tap mode. This is sort of just idiot protection but I routinely forget to down shift when I tap shift in rental vehicles so I see it's purpose. I think if you zero out all the downshift tables it should hold any gear all the way to zero speed. Should be useful in 4 lo. You can also set the tables up to deny up and down shifts based on speed like most OEM setups do but that's lame. I do need to double check all my tables again to prevent me from any overrev downshifts. Definitely want to deny those.

Keep in mind too that the 6L80e has internal input and output speed sensors so there is really no need for a 4lo shift table. Even more so if you can just tap shift and just put it in the gear you want.

Also total cost for this was $1.00 in resistors + shipping and $10 for the buttons. I had wire and loom that I pulled from the shelf. I do want to find the mating amphenol Connector to plug into my 2650 harness when I make it all permanent.
 
Last edited:

06 H3

a.k.a. "The Jackal"
Messages
9,350
Location
Meridian, ID
I found a slick new unit. It comes from zero gravity performance but PHR came up with it. Props to them, it’s genius. Instead of having to wire in relays and crap to make the reverse lights work it’s a new shaft that accepts the transmission range switch on the 4l60e.

It’s in the mail now. I should see it today.

 

CaseyS

Well-Known Member
Messages
731
Location
Louisiana
Well damn that would have saved some headache. There are two sets of switches in the stock quadrant. One set to run the prndl lights. And a second park/neutral that goes into the start circuit. I have the p/n switch wired to a relay inserted in the start circuit and a second reverse relay to make the backup lights work.

This makes another part of this swap that much easier.
 

06 H3

a.k.a. "The Jackal"
Messages
9,350
Location
Meridian, ID
I misspoke, I went to edit the post but can’t.

Zero gravity came up with the idea. PHR manufactured it.
 
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