2.5 liter to 2.8 v6 swap - S-10 Forum
 
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post #1 of 18 Old 11-02-2015, 11:12 PM Thread Starter
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2.5 liter to 2.8 v6 swap

Hey everyone thanks for the nice warm welcome to the forum.

I purchased a 1986 gmc s15 2.5l s101 5 speed 2wd.
truck has no features. No power options....
Truck had a blown/Crack head.

Well I bought a 1992 chevy s10 2.8l v6. That truck had everything. All options. Abs, ps, pb, ac, smog.. everything.
The guy sold it to me without the smog, ps or ac.. I got the harness and computer. Relays, alt. Starter...

I have bolted the s101 to the new engine and have it all installed in the 86 s15. Ready to roll.

well after my brother and I started to run the wiring harness we found cut/broken wires. So I went online and found some wiring diagrams from a 87 s15 and some wiring diagrams from a 91 s15/sonoma... thought it would be real simple. But it has been everything but plug and play. The guy who sold me the engine said it would be.. I know the engine runs.. but I let him take it out of the donor and he must of been in a hurry...

So my questions are,
What all do I need to run this engine.. sensor wise?
There are 3 plugs inside the cab, 2 for the computer and one extra.. I am guessing dash gauges? The 2 are different the 86 2.5 harness has I think 5 wires.. and the 92 has 9..

Thank you all for reading my gibberish.
I am not needing this truck on the road tomorrow.. but I would like to at least fire up and move under its own power..

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post #2 of 18 Old 11-02-2015, 11:45 PM Thread Starter
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Re: 2.5 liter to 2.8 v6 swap

I have been reading the "finally converting to efi" sticky.. it is helping and with the help of the wiring diagrams I have found and printed.. I am hoping to get it wired. But. I don't know where the 02 sensor goes... also does anyone know what size nut holds the starter solenoid wire to the starter??? Mine does not have the nut.. and I don't feel like dropping the starter just to find out the size. If anyone knows.

I want to say. I probably come off stupid. And I apologize for it. I have never done this before. And after dropping the control arms just to swap motor mounts makes me want to finish it.
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post #3 of 18 Old 11-03-2015, 09:12 PM
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Re: 2.5 liter to 2.8 v6 swap

Man, sorry to hear about your plight. If you had all of the original wiring harness, and most of the major components, you'd be ok.

The nut to the starter (IIRC) solenoid has 2 different nuts. One for the purple wire from the ignition switch, and one for the main + connection.
Which one are you referring to?

It's been so long since I had a 2.8 with an 02 sensor, I seem to remember that it goes to the 'Y' pipe on the passenger side O2 bung. You probably don't have a factory 'Y' pipe, no?

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1)'82 S10, 383, 700R4, Shorty
2) '85 S10, 3.4, 700R4 4x4 stretch cab (Redneck)
3) '90 S10 2.5, 5 speed shorty
4) '91 S10, Built 3.4, 5 speed shorty (Voodoo)
5) '92 S10, 2.5, 5 speed shorty, (Barbie)
6) '92 S10, 2.5 5 speed, Shorty
7) 1979 LUV, Buick 3.8 V6, TH 350 Shorty.
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post #4 of 18 Old 11-03-2015, 10:01 PM
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Re: 2.5 liter to 2.8 v6 swap

Fix the 2.5. The 2.8 isn't worth the effort.

it doesn't get eddie vedder than this
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post #5 of 18 Old 11-04-2015, 01:34 PM
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Re: 2.5 liter to 2.8 v6 swap

02 sensor is on drivers side on mine. Course my truck has headers. I don't know if that's the stock location. Ignore previous naysayer. Put the 4.3 TBI on the bored to match intake. It will be significant improvement. Some tuning will be necessary but that's all. Ask Damanx. He's done the samconversion I have. He's the tuning guy. Shamefully I still have not gotten to mine yet. Too much going on with me.



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EFI swap https://www.s10forum.com/forum/f106/...e-help-513616/

My build thread (3.4L)https://www.s10forum.com/forum/f106/...stions-427168/
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I had to cut my nut in half .
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post #6 of 18 Old 11-04-2015, 05:04 PM Thread Starter
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Re: 2.5 liter to 2.8 v6 swap

I am doing all of this from a phone so sorry if it takes a minute to get back to everyone.. computers at best buy getting fixed...mad max, thank you. There is the battery wire and one other wire on the starter... the solenoid wire??? My wiring diagram says "manual trans." Ppl wire from starter to clutch start switch "on pedal", blk wire to battery... could be wrong though. I am reading the wiring diagram for a 1991 chevy s10... also madmax.. the guy who sold me the engine had docs. To show it had a 4.3l tbi bored, a cam.. can't remember the dimensions. Nothing else was do e to it. He removed the engine. He cut the y pipe right behind the engine, removed smog pump, misc. Vacuum lines, p/s pump, a/c compressor and belt and idler pulley so I had a basic bare engine that ran for $80... I seen it run but dude was in a hurry go remove it and for the dressed engine with everything... he wanted $300.. so this what happened.. but I also got the harness and computer...
I went into it blind not knowing what I was getting myself into and it has been a fun project for my son and i.. with a little help here and there from the wife and my brother... so it has been a learning experience from day one..


I also wanted to let everyone know, whoever wrote the Haynes manual for motor mount replacement must not of removed the motor mount completely. I had to drop my control arms to get to the lock nuts inside the frame.... it didn't say that, but my book not has that note in it. Just figured I would throw that out there for everyone to read. Also had a shit day at work.
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post #7 of 18 Old 11-04-2015, 05:25 PM Thread Starter
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Re: 2.5 liter to 2.8 v6 swap

Also wanted to mention these facts for anyone looking to do something like this.
On a 1986 gmc s15 (truck I am working on) there is literally like no gauges. Speedometer and a fuel gauge and a odometer.. that's it for moving gauges.. other than that it's just the lights for the dash..
On at least a 1990 chevy s10 (my ugly girl) that has the speedometer, fuel, volts, oil press, temp, odometer, trip and all the lights

Note, with these dash clusters.. there is different connectors for each. The 86 has a black 7 wire plug and the 90 dash has a iirc 10? Or so wires.. I am probably wrong about 10 but it has more wires and a white connectors.

Note, the radiators will NOT interchange, so ad a new radiator to the list.
Note, motor mounts are a pita, I dropped the control arms with help from a floor jack my 3 year old and misc other tools... so ad motor mounts to the list with 2/3 hours time if you try to brave it... I wouldn't do it this way again. I would buy a spring compressor and to it right..
Note, I bolted a 1986 isuzu s101 4 speed manual transmission to a 1992 chevy 2.8 60v6, I have heard that this will not work.. something about bolt patterns. But it did bolt up.
Note, the exhaust is also larger on the 2.8... 2.5 exhaust is 2 1/4" on mine.. 2.8l exhaust is 2 1/2"...
Note, don't be dumb like me, if you go engine shopping and can get the whole engine dressed with everything that should be on it, DO IT!!!!
Note, the 5 speed t5 transmissions have a electrical speedometer, my s101 has a cable driven speedometer.
Note, The 2.8l also has a (esc) electronic spark controller.. where the 2.5l does not. I have heard that it is mounted under the dist. On 2.8l engines.. make sure you get it! It also has a special mounting bracket.

Just wanting to throw these few things out for anyone.
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post #8 of 18 Old 11-04-2015, 06:22 PM
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Re: 2.5 liter to 2.8 v6 swap

The gauge cluster differences are a trim level difference, not a model year difference.

The O2 sensor is located in the driver side manifold/down pipe. If you want to move it to the Y-pipe you should also swap it for a heated O2 sensor to ensure that it's remains at operating temperature. The location closer to the engine is hotter and is why it was used back then.

ESC is a box mounted on thh firewall, the ICM that is mounted to the base of the dizzy is found in both the 2.8 and 2.5 among many other engines. The ESC is connected to the knock sensor and then sends a signal to the ECM to indicate that there's knock and how much.

The T5 could have either mechanical or electronic speedo drive, again, this is a model year difference, not a transmission model difference.

Some people have been able to swap the engine mounts without removing the lower control arms, which is likely why the Haynes manual doesn't mention it.

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Tha toy: 1973 Datsun 240z 12.71 @115
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post #9 of 18 Old 11-04-2015, 06:45 PM Thread Starter
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Re: 2.5 liter to 2.8 v6 swap

Quote:
Originally Posted by The_Raven View Post
The gauge cluster differences are a trim level difference, not a model year difference.

The O2 sensor is located in the driver side manifold/down pipe. If you want to move it to the Y-pipe you should also swap it for a heated O2 sensor to ensure that it's remains at operating temperature. The location closer to the engine is hotter and is why it was used back then.

ESC is a box mounted on thh firewall, the ICM that is mounted to the base of the dizzy is found in both the 2.8 and 2.5 among many other engines. The ESC is connected to the knock sensor and then sends a signal to the ECM to indicate that there's knock and how much.

The T5 could have either mechanical or electronic speedo drive, again, this is a model year difference, not a transmission model difference.

Some people have been able to swap the engine mounts without removing the lower control arms, which is likely why the Haynes manual doesn't mention it.
Raven, thank you for the correction. I learned something.
I figured the dash connector was different because the dash cluster were different.
The engine mount thing maybe there is/was a way.. I didn't see it reading the Haynes manual. I read some people put holes in the frame and other things..
As for the transmission. I didn't know that the t5 had both. Glad to learn that fact.
Esc is mounted in the firewall? I can't find it... tried google and it showed me it mounted under the dist.. hence that comment.
I have read electrical diagram upon electrical diagram for 2.5l and have went over my 1990 2.5l and can't find it.. maybe I'm looking in the wrong place? But from what you just said.. it differs on trim/year/options ect.ect.
02 sensor, I have read that see have one 02 sensor in the passenger side manifold on the y pipe.. just one 02 sensor... correct?

thank you!
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post #10 of 18 Old 11-04-2015, 11:32 PM
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Re: 2.5 liter to 2.8 v6 swap

The connectors are different because the clusters are different, but the full gauge cluster vs light cluster is a trim level difference, not a model year difference.

IIRC the 2.5 didn't have a knock sensor so no ESC if that is the case.

The External ESC typically looks like this:


Typical ESC wiring:


Yes, just one O2 sensor.

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Tha toy: 1973 Datsun 240z 12.71 @115
Tha other Toy: 1923 T-Bucket
Another Toy: 1987 Buick Skyhawk
Typhony Old set-up: 1985 GMC Jimmy. 3.2L Turbocharged/Intercooled hybrid. 13.873 @ 99.08 Currently being reconstructed.


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post #11 of 18 Old 11-05-2015, 01:28 AM Thread Starter
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Re: 2.5 liter to 2.8 v6 swap

Thanks raven, well in your earlier post I thought it said the 2.5l had a esc/knock sensor... but yeah, I added a esc to my shopping list.. there is a lot on my shopping list..
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post #12 of 18 Old 11-07-2015, 04:13 AM
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Re: 2.5 liter to 2.8 v6 swap

Swappin a 4cyl to any other motor takes right at 40+/- hours per advanced adapters & for 125hp of the 2.8 V6 No Thanks!!! Theres Modern Fuel Injected V8s thatll net great MPGs & be Way more Fun to Drive I liked S10s & Blazers before But Now since I did the Solid Axle Swap & LT1 I Love My Truck It started as a 2wd 4cyl 5spd LoL Youll learn after this escapade A 5.3 LSx with 315hp that gets atleast 22mpg beats the shit out of any 60* V6 & 90* V6 That 86 S10 with a stand alone harness & 700R4 with Upgrades woulda been Sweet IF I build a square body crew cab Im thinkin a 400 SBC with Vortec heads & TPI with like a custom retro roller cam ground to XFI 252 specs & a 700R4 bolted to a doubler for trail ridin & rock crawlin Man your doin a Lot of Work for No Gain!!! Atleast You have 2.8 mounts for the V8 next round LoL
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post #13 of 18 Old 11-07-2015, 03:20 PM
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Re: 2.5 liter to 2.8 v6 swap

Some people don't want or can't have a V8. In some areas a vehicle equipped with an engine that was not OEM offered in that vehicle can be difficult or expensive to insure, if not impossible.

There's also some of us that would just rather not have our cylinder count = 8.

I wouldn't claim that ALL swaps are going to be 40+ hours. I've done swaps in much less time, and some I've spent more time on.

Also The LSx is not the greatest gift to hot rodding, like far too many fan boys believe, it's just another engine that has it's pros and cons.

Some of us don't need 300+ HP either, for some people they just need to get around, and like to tinker or work on their vehicles.

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Tha toy: 1973 Datsun 240z 12.71 @115
Tha other Toy: 1923 T-Bucket
Another Toy: 1987 Buick Skyhawk
Typhony Old set-up: 1985 GMC Jimmy. 3.2L Turbocharged/Intercooled hybrid. 13.873 @ 99.08 Currently being reconstructed.


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post #14 of 18 Old 11-08-2015, 05:30 PM Thread Starter
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Re: 2.5 liter to 2.8 v6 swap

Warrior customs, I understand the difference between them, yeah not much of a gain power wise but this truck will tow a 14' Jon flat bottom at its worst... other then that is just using it for work.like raven said, not everyone wants a v8 I could of went 4.3l v6 but didn't want to.. right now it's a learning experience for me and my son, my brother just bought a 84 Camaro that had a 2.8l v6... and we plan on dropping a 350 in it... so it's a learning experience.. and my current (1990 chevy s10 2.5l auto) truck has NO floors, cab curlers rockers are pretty much gone, bed I had to replace due to 6 rusted mounts and it will doesn't have fenders or inner skirts... has 2 bricks holding up the cab.. so my new 86 is a replacement for it... well that and I wanted a stick shift... I am currently in the process of buying a carb setup for the 92 2.8 that is in the 86...

So all in all, this new Truck will get used as my work vehicle and fishing truck.. the 2.8l will be suffencient the 2.5l was. And yes.. I did contemplate a 305... or 350 but right now I don't need or want it.

Raven. I old see it being 40 or so hours... maybe. I'm 6 hours in it.. old motor/trans out. Trans bolted to new motor and installed.. 6 hours for me and about 2 hours of help from the wife..
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post #15 of 18 Old 11-25-2015, 08:31 PM Thread Starter
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Hey raven, random questions

I am curious if you know the sizes of vacuum lines on it?
I am looking at redoing it all. Maybe just buying a vacuum line assortment and a connector assortment. But I only want to buy the sizes I need.. if you know.
Fuel line size? I have heard that I can use stainless steel lines. But want input.
Got a vacuum diagram for manual brakes??
I got more questions if I can pick you brain. Email me sometime.
[email protected] is my email... would love to talk more if you are okay with me picking you brain.
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post #16 of 18 Old 12-09-2015, 09:46 AM
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Re: 2.5 liter to 2.8 v6 swap

Updates?

Sorry I have been out for a bit. They blocked the site at work...why? Dunno.

Warrior customs...Why come on here and explain to us the benefits of V8s? I don't think the purpose of this particular forum is to come over and tell us how dumb we are. If you promise not to come over here and do that I promise not to come over and talk about how reliable my truck is and close in power my 3.4 is vs a small V8 and how I don't have to scrape my knuckles on every bolt when working on it, or having to jack the engine off the motor mounts to change the starter, or how I keep the truck from running hot all the time, or how I didn't have to hack up my classic truck to shove a V8 in it or how poorly it handles compared to stock or how much money I saved by NOT hacking up my truck. I'm SO glad I did not go that way. OEvil1, there is a LOT of upgrades to give even your 2.8 much more get up and go without turning your truck into a hacked up deathtrap. I know cause I've done em!

By the way. The easiest way to remove the motor mounts? Drill an access hole through the frame. That is one helpful hint I got from JTR V8 conversion book before I decided to not do that.

Keep us updated!



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The S-5 trailer-Half a 1st Gen LWB S-10


EFI swap https://www.s10forum.com/forum/f106/...e-help-513616/

My build thread (3.4L)https://www.s10forum.com/forum/f106/...stions-427168/
Quote:
Originally Posted by Racer_X View Post
I had to cut my nut in half .
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post #17 of 18 Old 12-10-2015, 09:00 AM
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Re: 2.5 liter to 2.8 v6 swap

I have too many S10s as you guys probably know by now.
I have a mad 327 SBC powered 83, the "Barbie" truck that has a 2.5 in it, the "Voodoo" truck which has a stout 3.4 V6 in it - just to mention a few.

Each one has a totally different personality, and each is a blast to drive.

I just drove the Barbie truck from New York to Baton Rouge and ran 70 - 75 MPH almost the whole way over 1400 miles. 22 MPG with one of my Harleys in the back (600 or so extra pounds). What a great rig.

Ok, what am I getting at?

I like each one for what it is.
The 2.5 Duke (5 speed) is a great slug. It has a certain sound and power. It moves the truck in a it's own way.

The 3.4 V6 (5 speed) is set up and also has a certain sound and power. It moves the truck pretty quickly if need be. A lot of fun.

The 327 truck is too crazy to drive as a daily. You get in it, light the fuse and hang on. If you are not careful, you end up wrapped around a pole or something. It can drift way to easy.

So, 2.5, 2.8 stock or not, they serve the purpose.

It sounds like Oevil is happy with what he has... No V8 required.

S10 addiction:
1)'82 S10, 383, 700R4, Shorty
2) '85 S10, 3.4, 700R4 4x4 stretch cab (Redneck)
3) '90 S10 2.5, 5 speed shorty
4) '91 S10, Built 3.4, 5 speed shorty (Voodoo)
5) '92 S10, 2.5, 5 speed shorty, (Barbie)
6) '92 S10, 2.5 5 speed, Shorty
7) 1979 LUV, Buick 3.8 V6, TH 350 Shorty.
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post #18 of 18 Old 12-22-2015, 04:43 PM
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Re: 2.5 liter to 2.8 v6 swap

Good point there Max...My uncle had one too with a V8. We did it way before there were kits. Truck was a ton of fun, but it was a deathtrap. Sounds like the 327 you got. I only mentioned that cause it didn't really add to the conversation about the truck and what he was doing...rather just poking at him why what he was doing was dumb...I mean, I don't go over there to the V8 forum and say, "why for the love of god are you guys doing this when a 3.4 is such a better option??"

Ha...fun times!



1984 xcab s-10 3.4L GM crate engine 91 S10 TBI swap w bored intake, Edelbrock headers. 2" Rough Country Lift. Flowmaster, shift kit, e-fan.
The S-5 trailer-Half a 1st Gen LWB S-10


EFI swap https://www.s10forum.com/forum/f106/...e-help-513616/

My build thread (3.4L)https://www.s10forum.com/forum/f106/...stions-427168/
Quote:
Originally Posted by Racer_X View Post
I had to cut my nut in half .
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