98 GMC Twin Turbo with 12200411 PCM--- It's Alive

Performance modifications, tips & tricks

Moderators: flyingpolarbear, Eric@PPE, VicC, James B.

350SS
Posts: 772
Joined: Tue May 17, 2005 8:47 pm
Location: Las Vegas, NV

Post by 350SS »

Intercooler pic:
Image

Lextech
Posts: 965
Joined: Tue Mar 07, 2006 7:27 pm
Location: Oak Forest Illinois,U.S.A.

Post by Lextech »

Thanks for the pic post 350SS. I made the intercooler with 3 SAAB intercooler cores. I had a hard time welding the SAAB parts together. Instead of getting a weld puddle and adding to it and moving it, I basically had to keep feeding rod into the puddle to kind of dilute the puddle until it would flow. You guys have to be patient for several days. I still haven't driven the truck with this PCM. I want to drive it and make sure everything is operating properly before any bad info gets passed out. As of right now everything appears to be good.

MOChev
Posts: 148
Joined: Mon Aug 07, 2006 5:31 am
Location: Missouri - 96 L31 ECSB 2WD

Post by MOChev »

The PCM swap is very interesting. This could definitely unlock the potential of the L31.

hquick
Posts: 4689
Joined: Thu Aug 10, 2006 1:56 pm
Location: Melbourne, Oz-----98 K1500 LT Suburban. RHD, 0411, Whipple, Marine, 4L80E, Trutrac, H/boost,E-Fans

Wow!

Post by hquick »

I'm constantly amazed by the skills of those present on this forum!
Good job!

1998chevy1500
Posts: 131
Joined: Mon Jun 27, 2005 5:46 pm
Location: Bozeman, MT

Post by 1998chevy1500 »

Is this the LSx PCM with just the two plugs (red and blue)? The reason I ask is that picture 3 shows a vortec style 4 plug PCM.

Lextech
Posts: 965
Joined: Tue Mar 07, 2006 7:27 pm
Location: Oak Forest Illinois,U.S.A.

Post by Lextech »

Yes it has the 12200411 PCM wit the 2 80 pin connectors. This is a picture from several weeks ago.

Y2KLimited
Posts: 855
Joined: Sat Jan 01, 2000 12:00 am
Location: the juice is loose!!

Post by Y2KLimited »

nice work, this coming from someone who's been there themself......of course since I've swapped multiple ecms etc. in and out of my truck why din ya get in touch with me I had the pinouts for the 98+ ecm as well.....crap at this poitn I can tell you from memory what most of the wiring is based on color an plug. Wonder if that 411 can run my 502....

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oh wait I wanna sell my truck...or.....I just heard about a 57 hardtop that I might be able to pick up for cheap as a roller.......ya know a 57 chevy with a carbed 502 (ya know sell the ramjet intake and ecu for 2g's on ebay) cammed up with a nitrous plate and put a transbrake on the 4L80.....h'mm.....should be a 10 second ride...or I could just put a glass nose on the thing and two turbos because there would only be a lil bit of room to work with, lol

Gilbert
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Joined: Sat Mar 26, 2005 11:47 am
Location: Arizona

Post by Gilbert »

is any one interested on doing this with the marine intake?? I know IM!

tahoen
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Joined: Wed Aug 09, 2006 7:10 pm
Location: Buffalo, NY

Post by tahoen »

Wow!


Really nice work!

Lextech
Posts: 965
Joined: Tue Mar 07, 2006 7:27 pm
Location: Oak Forest Illinois,U.S.A.

Post by Lextech »

Well I have about 100 miles on the truck with the 411 PCM. Works perfect. All of the gauges work. I tied the 2 green speed input wires together that go into the truck and attached them to 1 of the speed outputs from the 411. Speedo and Cruise work properly. I haven't tested the A/C because I haven't charged the system since the turbo install. Even though in the first post I said I needed to cool it on spending money on this project, I couldn't help myself and ordered EFILive. Hopefully I can put some boost in this thing very soon. I made a mistake in the first post---There are 2 A/C wires that appear not to be used. Every other wire in the 98 harness has a place into the 411. The 411 gets input from 4 wires from the Park/Neutral switch. My 98 truck manual shows these 4 wires inputing to the PCM but, these wires weren't in my harness ( I Don't Know Why ).Edit: as of Jan 07, all 5 of the A/C wires are used and the A/C is working properly.Here goes, I am going to try to post some pictures.Image111Small.jpg[/IMG]Image
Last edited by Lextech on Sat Apr 14, 2007 9:05 pm, edited 3 times in total.

Lextech
Posts: 965
Joined: Tue Mar 07, 2006 7:27 pm
Location: Oak Forest Illinois,U.S.A.

Post by Lextech »

Well that is the only pic I can get to post---So I guess I still can't post pics

1BADAZZSS
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Joined: Fri Aug 25, 2006 7:23 pm
Location: All over the midwest

Post by 1BADAZZSS »

where's the rest of the engine bay? :P Looks like fun!!!

ThunderTT
Posts: 2845
Joined: Sun Apr 03, 2005 10:27 pm
Location: 97 ECSB 2WD 98 CCLB 2WD 00 Escalade 4x4

Post by ThunderTT »

hey, send the pics to Pswired, or myself. im sure we can get them posted.
looks awesome. cant wait to start back on mine, now that im back in town.

350SS
Posts: 772
Joined: Tue May 17, 2005 8:47 pm
Location: Las Vegas, NV

Post by 350SS »

here ya go Jeff :D
These headers are wicked :evil: :evil: :evil:
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Hog
Posts: 5036
Joined: Tue Dec 11, 2001 4:00 pm
Location: 1997 Chev ECSB L31 350 1997 GMC Sierra SLE RCSB, Ontario

Post by Hog »

Simply awesome. I am glad the speedo and cruise control work. Looks like this will help us Vortec 350 guys.

When you get EFILive, could you please set your rev limter to 6500 rpm and tell us if you get more than 5800 rpm? If you can you have made a lot of folks happy.

I am betting this PCM will break the 5800 rpm barrier. teh Vettes/LS1's/GEn 3 trucks can run 7000+ with this 411 PCm. I dont see why the L31 shouldnt.

Awesome work guys.

Who makes those turbo headers?? Are the turbos being supported by the headers alone??

peace
Hog

350SS
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Joined: Tue May 17, 2005 8:47 pm
Location: Las Vegas, NV

Post by 350SS »

To my knowledge all the fabrication is done by Jeff (Lextech). He has some serious skills.

1998chevy1500
Posts: 131
Joined: Mon Jun 27, 2005 5:46 pm
Location: Bozeman, MT

Post by 1998chevy1500 »

350SS wrote: Image
So does that PCM clamp perfectly into the GMT 400 mount? Are all the new LSx PCMs that way so that they can use the same mount as the GMT 400 PCMs?

Conrad

Lextech
Posts: 965
Joined: Tue Mar 07, 2006 7:27 pm
Location: Oak Forest Illinois,U.S.A.

Post by Lextech »

Hog I made the headers--the turbos are only supported by the headers. I have seen countless other turbo setups done like this, so I don't think stress will be a factor--Only time will tell. I have had the truck up to about 6200 rpm in manual 1st. I really did not want to go any higher because this is the stock 305 engine. I have about 95% of the parts to build a nice 355, but I didn't want to chance hurting it while I am learning this turbo/tuning deal. Conrad The PCM is not a perfect fit into the GMT 400 PCM bracket, but it fits very well. Well enough that I don't think anybody would ever notice that is not supposed to be in there.

JR96CK
Posts: 1519
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

Post by JR96CK »

"He has some serious skills"

I second that notion. That fab work on the intercooler and those headers are amazing. Awesome work.

Stealth97
Posts: 3711
Joined: Sat Jan 01, 2000 12:00 am
Location: 97 ECSB Chevy. 100% stock. LA, CA

Post by Stealth97 »

Lextech, were you going to post a writeup or is this thread pretty much it?

I'm going to convert the PCM right away. This interests me tremendously.

Eric

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