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1983 G20 Van, frscke1, Jimkinmd
Total Likes: 18
Original Post (Thread Starter)
1997 Chevy Express Cobra Conversion #776778 05/27/2021 5:49 AM
by 1983 G20 Van
1983 G20 Van
Thought I would show my project van. Parents bought it in 98 with about 13,000 miles on it. I have had it since 2012 when my mom said get it out of my driveway. My dad had passed away in 2011 and it had been his daily driver. Had to make some wiring harness repairs and decided to just go ahead and yank the engine and clean the whole engine compartment. Gave me some much needed time to work on other parts of it. The van was a 1500 but has been converted to full 1 ton specs. Suspension, running gear, brakes and all are right out of a 2002 15 passenger church van.
Liked Replies
Re: LS swap into 1986 G20 Van #786787 Dec 29th a 06:02 AM
by SDMickey
SDMickey
Ditto. Sharing our experiences help everyone, Clean work and your are doing your Van justice,
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #801694 Feb 21st a 06:20 AM
by 1983 G20 Van
1983 G20 Van
https://youtu.be/kGFKIIm0uTE
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #801692 Feb 21st a 06:09 AM
by frscke1
frscke1
Whats money when you want HP N Torc lol
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #801688 Feb 21st a 05:52 AM
by 1983 G20 Van
1983 G20 Van
Originally Posted by frscke1
My 4L80E has a .75 OD .... whats the difference between a 4L80E & a 6L90E ?


Ohhh ... the HP it will handle and its a 6 speed to my 4 speed

Sep 9, 2022 · The 6L90E is a high-performance component suitable for handling as much as 700 horsepower. This 6-speed automatic transmission built by General Motors powers …

Several differences like 2nd gear is nearly as low as 1st on a 4L80E or my 4L85E. Then you get a 0.667 6th gear.

With my current 3.73 gear that 4.07 first gear will give me a lower overall 1st than the 5.13s I had in the 9.5 14-bolt.
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #801506 Feb 14th a 06:23 AM
by frscke1
frscke1
WOW ! ! what nice motor ....
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #801504 Feb 14th a 05:58 AM
by 1983 G20 Van
1983 G20 Van
How it ended up

[Linked Image]

[Linked Image]

[Linked Image]

[Linked Image]

First Startup----Open Headers of course. Mainly because I want to hear it run, before I spend close to an hour fighting header flange bolts. I should have V-band flanged them from day one. With a good bit of tuning, it starts well, has good throttle response cold or hot, I corrected a start and stall issue between 100F and 160F coolant temp that was caused by the programming and a few other things.
https://youtube.com/shorts/w3zBYZp2Tb0?feature=share

Warm Idle
https://youtube.com/shorts/Ajj9aVly6rY?feature=share

Cold Open Loop Lean Stumble or Bog Corrected
https://youtube.com/shorts/NXjqGPX1zZo?feature=share

Warm Closed Loop Lean Bog corrected
https://youtube.com/shorts/X9uqUa7itL0?feature=share

Now for the fun one. ABS light is on because of a defective, nearly new ABS sensor on the LH front wheel. Service Engine Light is because I am tuning the VE tables with the MAF sensor failed in the tuning. I need to see if I can do something about the stepper motor in that speedo too.

https://www.youtube.com/watch?v=mrfrCyXUGKQ

Same acceleration run from the datalogging software in real time, acceleration is smooth despite the speedometer behavior.
https://youtube.com/shorts/f8L8o_MlXAk?feature=share
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #797191 Oct 17th a 06:44 AM
by 1983 G20 Van
1983 G20 Van
Van has been running well, but it is about to go under the knife yet again. At WOT I have always seen the intake manifold pressure dropping as the engine revs up. I turned the MAF sensor off in the PCM calibration and started pulling apart the air intake. First the air cleaner. Then the MAF. Then finally the dumb intake hat that GM used to literally cram our engines into these vans. I temporarily installed the marine flame arrestor that is little more than a mesh screen on top of the throttle body. With the throttle body finally able to draw in air, the manifold pressure went from 88 KPA to 97 KPA at 5,500-6,000 rpm. The engine ran like it has never run before. I would say it probably gained 40-50 HP. That pressure difference observed at the manifold is equivalent to driving at 4,000 ft elevation. I found an intake manifold that I ordered with fuel rails. It will have a 102mm LS style throttle body on the front of it, connected to the 4" silicone inlet ducting and 100mm MAF. The manifold is only 90mm at the face but I already have a 102mm LS style throttle body and a matching 102mm to 90mm adapter laying around unused on a shelf at the shop that came on a LS intake I put the DBW throttle body back on. My 97 Express van has 11" of height between the china wall at the end of the engine block and the bottom of the engine tunnel under the wiper cowls. The upper plenum sits 8" off the china wall and the lip for the throttle body mounting is 9" off the china wall. It will clear both the engine tunnel on the body and the factory doghouse. It is similar to the GM Ramjet manifold. I found engine dyno data for both the Ramjet and the L31 Marine crossram manifold on the same long block. Both the Ramjet and 300 HP Marine engine use the same short block, same 9.1:1 compression ratio with their thicker head gaskets, as well as the 196/206@ 0.050 duration GM 395' camshaft. The Ramjet and Marine intake both make the same torque at 2,500 rpm. At 2,700 rpm the Ramjet intake with its 4" long runners and open plenum starts to pull ahead. By 4,800 rpm the Ramjet 350 is up 61 hp over the marine intake. This manifold has slightly longer runners at 6" long. It should make a little more torque than the Ramjet manifold. That being said a 9.1:1 350 with a Ramjet manifold is already making 390 ft/lbs of torque at 2,500 rpm. With 383 cubic inches of air hungry small block compressing that air to a 9:1 dynamic compression ratio, I do not see this manifold making any less torque than the ported truck manifold or marine manifold. If it does cost a little torque, it will be well under the 2,800 rpm stall speed of my torque converter and a mere touch of the throttle will make the torque loss vanish. I am a little worried about how twitchy the throttle will become with the 102mm throttle body. The 80mm that is currently on the van is already pretty touchy at lower speeds.

The terrible flowing intake hat. I think this part alone is solely responsible for the 10 hp loss both the 305 and 350 in the Express vans have compared to the same engine in a truck.
[Linked Image]

Casting appears to be very clean in the pictures. Will know more about the quality of the manifold when it is in my hands.

[Linked Image]

[Linked Image]

[Linked Image]
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #796722 Oct 4th a 09:56 PM
by 1983 G20 Van
1983 G20 Van
Originally Posted by frscke1
Originally Posted by 1983G20Van
The tires were ao new they still had the molding fuzzies on the tread.


Tires 10 yrs old can still have the little fuzzies on them. What is the DOT date and did you get a matched set ? All made at the same time.

Tires are a matched set and they have this years DOT date (04/22).
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #795089 Aug 29th a 02:49 AM
by 1983 G20 Van
1983 G20 Van
Vanula escaped from the laboratory for a while today. First time I have driven it in several weeks. Actually remembered to take a picture of it today. Everytime I drive this I forget how much I have always enjoyed driving it. Its alot more fun to drive now. It corners with very little body roll, accelerates like a 60s muscle car and also stops very well for its weight. The steering is tight and responsive like it was new.

[Linked Image]
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #776897 May 30th a 01:43 PM
by newkirkinc1
newkirkinc1
Awesome!
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #778386 Jun 29th a 03:26 AM
by 1983 G20 Van
1983 G20 Van
Managed to get some more work done today. Couple of before and afters. Tailights are installed. Also installed my Rockford Fostgate front speakers and tweeters. The main speakers installed right into the OEM brackets but I still have to mount the tweeters. I measured the rear overhead speakers and they are 5x7s. Then I discovered working on the tailights with the music playing that the rear doors have a 2nd pair of rear speakers down low on them behind a fabric covering on the door panels that I never realized were there. Guess I get to order 2 more pairs of Rockford Fostgates for the rear. I know the name is twisted but with the OEM door panel and factory speaker grille over it, nobody will see it. I also mounted the Derale 13224 under the metal support that holds the radiator core support and started plumbing the cooler and the AN lines for the trans and power steering. Forgot to take pictures of that progress.

[Linked Image]

[Linked Image]

[Linked Image]

[Linked Image]

[Linked Image]

[Linked Image]
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #795702 Sep 11th a 07:44 PM
by 1983 G20 Van
1983 G20 Van
As I have been putting a few miles on it, have found a couple of small things to address. One of the AN cooler lines to the auxiliary trans cooler was leaking fluid, had to remove the grille to get to it. Also had a head bolt that started seeping coolant once I was able to get the system to fully pressurize. Had to remove the engine cover and luckily it was an easy head bolt to get to. Other than that it is running great.
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #795096 Aug 29th a 03:41 AM
by SDMickey
SDMickey
Wow ! Nice build
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #794226 Aug 12th a 10:14 PM
by kursed
kursed
Cool! No pun intended... well maybe a little pun intended. lol
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #793940 Aug 7th a 02:26 PM
by 1983 G20 Van
1983 G20 Van
The nearly new TYC radiator failed, put an all aluminum unit in. The 383 is running cooler. Ran it for a solid hour to get all the air out with the front end jacked up. It took a solid 30 minutes of run time before it stopped venting a steady stream of air bubbles.


[/url]

[Linked Image]

[Linked Image]

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[Linked Image]

While I had it running could not resist catching a video clip of the exhaust sound of the sweet 383 at idle.
[url=https://youtube.com/shorts/T29nCd8sifQ?feature=share]
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #784146 Oct 23rd a 05:42 AM
by 1983 G20 Van
1983 G20 Van
Hooked up the exhaust, topped off the cooling system and let it run long enough to get up to full temp with the closed loop enabled. Pulling about 10-15% on the long terms. Still have the cutouts open and need to hook them up again. Tamed down alot in closed loop.  Also disabled the catalyst warmup spark retard.

https://youtu.be/FPEuk8hibPg
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #780367 Aug 11th a 03:21 AM
by 1983 G20 Van
1983 G20 Van
So I finally got around to dropping the 383 in. Still have alot of work to do but the engine is finally bolted backin.

[Linked Image][Linked Image][Linked Image]
1 member likes this
Re: 1997 Chevy Express Cobra Conversion #776891 May 30th a 04:41 AM
by SDMickey
SDMickey
Nice job and it sounds great. chevy
1 member likes this
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