Author Topic: 87 4x4 6.0/6l90 swap  (Read 2254 times)

Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #30 on: July 11, 2018, 09:58:30 AM »
I did look at that website. Only problem. I have is that my e78 ecm and the e38 ecm have quite a few differences. But I think I got it, had to use gmupfitter.com to get my harness pinout diagram and just kinda winged it from there

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Offline ehjorten

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Re: 87 4x4 6.0/6l90 swap
« Reply #31 on: July 11, 2018, 01:31:32 PM »
Usually the psi rating is a safe working pressure...at 65 psi it isn't going to burst!  I will let you know how mine works as that is how I plumbed mine.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #32 on: July 22, 2018, 08:42:04 PM »
Usually the psi rating is a safe working pressure...at 65 psi it isn't going to burst!  I will let you know how mine works as that is how I plumbed mine.
Sounds good

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Offline frotosride

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Re: 87 4x4 6.0/6l90 swap
« Reply #33 on: August 09, 2018, 06:21:01 PM »
It has been a while since I have been on here but I like the swP idea and progress so far. I noticed you plan on keeping the VVT and I really intrested in seeing how it works out! Do your engine have Displacement On Demand?  When. You get to the point of flashing the ECM/PCM I highly recommend Brendan at lt1swap.com he is diligent and will work with you if there are any problems. You may try asking him about the wiring differences with your computer. If you are still working on the harness I highly recommend writing down the numbers for each color connection the pull each pin and work them out after all are unplugged. Have you found an adapter for the np208?
"Beat it like a red-headed ford"
1987 v10 Silverado 4" RC, 35's, 700R-4, 3.73
2006 Boulevard M109R 109 cid, straight pipes, PCMlll,k&n
2009 Jeep XK, 2" lift springs in mail (future LS Swap)
GSXR 750 engine awaiting go kart

Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #34 on: August 11, 2018, 04:34:16 PM »
I've talked to Brendan, he is still working on understanding my ecm as it's different than the e38. Also I did find an adapter, 15724745, I'll take some pictures when I go back home and upload them. I bought a 32 spline input to go into my np208, then I'll send off my output shaft in the transmission and get them to match it to my 32 spline input. The downfall is I'm not going to have 4 low working. However with 4.10 gears and the monster first in the 6l90, I dont care nor do I ever use it now. I also dont have to worry about redoing my speedometer as the transmission communicates with the ecm with an output shaft speed sensor. So the mechanical speed signal it is! In addition, the ly6 and l96 have vvt but no displacement on demand. I've just seen alot of benefits from the vvt and feel like that's the best way to go to keep it a friendly daily driver and have some nice power.

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Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #35 on: August 11, 2018, 04:35:35 PM »
I have also finished my harness. I'm reusing the fuse box from the van (which took a hot minute to figure out). There are a few extra relays I'll have to add to make it work but it shouldn't be an issue.

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Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #36 on: August 22, 2018, 07:58:27 PM »
After talking to texas speed and asking them about a vvt cam swap in the future, they recommended that I delete the vvt in order to save a tuning headache from the swap and a vvt cam. So it looks like I'm going that route and installing a texas speed ls3 stage 1 225/236 .629/.615 112 lsa. The 6l90, from my research, has a higher factory stall speed (2200-2300) than the 6l80 (1700-1800). So it should run quite well. Also down the line I'll be installing a built dana 60 in the rear and do a 6 lug conversion on it to fit my current wheels. The built dana 60 is a better option to me than a 14 bolt because it's free minus me removing it from the truck it's in.

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Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #37 on: September 25, 2018, 08:54:46 PM »
Just got my 2 treperformance 340 lph pumps in. Now to figure out my fuel pump wiring to handle these pumps. Question, how would it be to run a 10 gauge wire from the battery or alternator (which was recommended by tre and racetronix) and choke it down to a 14 gauge wire going into the bulkhead (which is the part they recommended) and going from the bulkhead using 14 gauge wire to the pump. If they say to use 10 and choke it to 14, wouldn't that be too much of a choke down?

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Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #38 on: September 30, 2018, 09:23:36 PM »
Ender up buying a straight through adapter from summit that can handle 12 gauge wire. So ill have 10 gauge wire coming from the battery to a connector and it will choke down to a 12 gauge. The pump only pulls 15 amps and the 12 gauge can handle more than that.

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Offline ehjorten

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Re: 87 4x4 6.0/6l90 swap
« Reply #39 on: October 01, 2018, 10:43:39 AM »
Such a short section of 14-awg could easily handle that 15 amps.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #40 on: October 02, 2018, 08:02:54 PM »
You arent wrong. Funny thing is, the guys that sent me the pump kit sent me 18 gauge wire with the kit. They kept saying it was 14 but it was nothing even close to a 14. So I just said screw it and replaced it with a 12

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Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #41 on: October 02, 2018, 08:08:10 PM »
I was just wondering about why they kept saying 14.

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Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #42 on: October 17, 2018, 09:11:12 PM »
Does anyone know how to hookup the brake booster vacuum line and hvac line on a ls truck intake to my 87? I read about removing the plug on the back of the intake and buying an acdelco fitting thing but are the sizes between the barb and my booster vacuum line the same? Also where do I run the hvac vacuum line?

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Offline ehjorten

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Re: 87 4x4 6.0/6l90 swap
« Reply #43 on: Today at 09:47:46 AM »
There is a quick-connect fitting on the back, driver's side of the intake plenum.  If the donor vehicle didn't have vacuum assist, then there is just a plug in there.  You depress the ring around the fitting...I think they are all RED, and pull the plug out.  There is a vacuum fitting that goes in there that your booster line will fit to.

For the HVAC fitting, I used the port on the passenger's side, about mid-way on the intake plenum.  It is molded shut by default usually, but you can bust off the tab on the end of the port to open it up.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline jobobcat18

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Re: 87 4x4 6.0/6l90 swap
« Reply #44 on: Today at 03:19:08 PM »
Sounds good. Thanks man.

So on my ecm and tcm gmlan wires, since my ecm is an e78 it does not go through the TCM. On the gmlan wires where the used to merge on the van, would it hurt to solder the wires together? As in the ecm black and tan wire to the tcm black and tan wire soldered together. And the ecm tan to the TCM tan?

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