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Thread: The "Tan Brick" aka my 1997 Express Cobra conversion

  1. #76
    Fuel Injected!
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    So I have a few snags to overcome such as rebuilding the dog house area, a new doghouse/engine access cover and finding a frame to motor mount bracket all of which have been discontinued.

    I am going to have to cut the firewall and floor to put in the floor section of a 6.5 or 8.1 van.






    I really don't understand why GM didn't just use the larger doghouse and opening for ALL vans. Would have made things like plug changes, exhaust manifold work and intake work MUCH easier. Especially with the big blocks 4" rearward mounting location.

  2. #77
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    Finally have it dialed in pretty well. Its cool, dry and windy. Was running in my normal testing area but into a bit of a headwind (~15-20 mph out of the North). When I let off around 80-85 mph it had the 100+ mph wind tunnel sound too it. I need to get a video when the wind is calmer for comparison purposes.

    http://www.youtube.com/watch?v=7P8rDokWges

    http://www.youtube.com/watch?v=dtn58oN-snM

  3. #78
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    Had a chance to mess with it a bit more today, then put some E85 in the tank. This was on 93 octane and it pulled nearly 5° of timing on this run!!! After adding 26 gallons of E85 and reflashing the PCM with the correct Stoich value I was still seeing tons of knock retard. Banging my head I took some SeaFoam with a HOT engine and ran it through the vacuum hose that ties into the PCV port. I use a vaccum "T" with one leg open as a vent and one in the SeaFoam. Near the end of the can I tried to stall it by putting my finger over the vent side to pull in more. At the same time I cut the key. The engine actually tried to diesel on the stuff. I let the engine sit for a good hour before trying to start it again. After a little cranking with my foot on the throttle it came to life and blew out a monster smoke cloud. I took it for a 10 minute drive and beat the ever living snot out of it. Finally went back to the shop with a hot engine again and did the same with a quart of distilled water. I took it out and drove it again. NO KNOCK RETARD on 31° of advance and a quick advance curve and it absolutely flies now.

    This was on 93 before I messed with it!
    http://www.youtube.com/watch?v=bpPSgILR6wc
    Last edited by Fast355; 11-23-2015 at 07:28 AM.

  4. #79
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    Well it is time to pull this old pig apart yet again. I pulled the old L31 and opened it up to fix an oiling issue about 6 months ago. I put a Lunati Bare Bones 218/228 cam in it. I failed to notice the spring pressure Lunati recomended and ended up floating valves and scoring a couple of cam lobes and trashed some LS7 lifters. About to order another GM Performance parts cam. Going with the cam in the 357 HP 350 engine. Basically it is a Hotcam revised to work in a stock L31 long block. 215/223 @ .050 roller with .473/.473" lift. Running the GM 330HP HO intake and a set of headers it is rated at 357 Hp @ 5,500 and 407 TQ @ 4,000, looks to make about 400 TQ @ 3,000 according to the advertised GM dyno chart.

    The oiling issue was the use of a 5qt pan with a 4 qt pan windage tray. Ended up going to a 7qt Moroso pan and a big block oil pump with matching Moroso oil pickup. 40 psi idle, 70 psi hot at crusing speed. Yea its overkill but it seems to work well.

    It may end up with TPI on it this time around. I have an Edelbrock Vortec TPI base, fuel rail modified for rear feed and return, and siamesed SLP runners with a fully ported plenum and LT1 throttle body. I also have an accessory setup from a 1995 TBI G-van that looks like it will work in the Express van with an Astro van a/c hose setup if I go that route.

  5. #80
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    Been at this old Express van again. Swapped a 5.13 re-geared 10.5" full floating 14-bolt under it. 1 ton springs. 1 ton front control arms and knuckles up front. All the 1-ton brake parts. Pulled the L31 out of it. Sitting on the stand now. Built a set of 205cc Assault Racing aluminum heads for the future 396 small block. Currently putting those heads on a stock bottem end 5.7. Adding 1.7 roller rockers on them. Should be in the 440 hp range when I am done. Need to get a picture of it now that the suspension is all 1-ton but I have one as a bit of a 1500/3500 hybrid, lol.

    I ended up with the 205cc heads because my 60cc milled Etec170s ended up on the 305 in the Tahoe after finding a crack in one of the heads on it. Got that engine running great again (around 330 hp/350tq) and smoked the 130k mile 4L60E within a few weeks. Work on modified stuff never seems to stop.
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    Last edited by Fast355; 01-26-2019 at 06:31 PM.

  6. #81
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    Been on vacation this week from work. I got the engine in last night and buttoned up today and fired up a few hours ago. I bumped the WOT shift speeds to 6,200 and left the old tune in place. Drove it around a bit. Its actually running a bit rich. At 11:1 afr and only 30° of timing, all I can say is HOLY SMOKES!!! 205cc intake ports on a 350 Vortec with a ported marine intake and a small cam runs like a bat out of hades! I wrapped the headers this time around and it made a tremendous difference in engine compartmemt heat. I need to burn out the nearly year old gas in the tank and do some fine tuning but I am already grinning. Also reminded of how well the a/c in this beast works :) Gotta say at 6,200 it PEGS the 80 psi oil pressure gauge, lol!
    Last edited by Fast355; 01-26-2019 at 06:32 PM.

  7. #82
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    Still have this pig and it now has an 11:1 383 in it. Just upgraded the cam from a 218/228 on a 110 lsa to a 232/244 on a 108 LSA. Waiting on the 1200 cfm 4bbl throttle body to go on the marine dual plane MPI intake I run. Also still waiting on the Camaro crossfire throttle cable that is the correct length and carb style end. Will have to grind the firewall opening square to fit it. I picked up the FAST 4150 throttle bracket kit and turned it with the cables pointing toward the passenger front. Going back to DBC. Mocked up the spectre 4" inlet carb plenum elbow on a carb yesterday. Should be in the 550 hp range when it is all back together and tuned. Also mocked up my 4" intake and 100mm MAF on the plenum yesterday afternoon. The plenum sits further forward and I will have to trim the silicone couplers some to squeeze it all back into place. Hoping to get it cranked up and start tuning on it this weekend. When the 383 went in I installed a re-stalled and strengthened B82 converter. Should stall around 2,800 behind the 383 with the new cam. The cam has an advertised power band of 2,800-6,000 rpm. The Rhoads V-Max lifters I am running should knock 1,000 rpm off the bottom number without hurting the top-end charge.
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    Last edited by Fast355; 12-03-2019 at 02:06 AM.

  8. #83
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    I've read bits and pieces about your G-vans for years...but this is first thread I've seen. haha

    What kind of heads on the 383? It sounds pretty similar to the one going in my Camaro.
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1) sold! for crazy money...but I miss it
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D) gone but not forgotten
    96 Beretta "T56" - 4.8 LS RWD swap / 6spd (0411/2156)
    01 Silverado 2500HD - stock Vortec 8.1 / ZF6 6spd (0411/8322)
    https://www.youtube.com/c/GEARHEADdezign

  9. #84
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    Quote Originally Posted by woody80z28 View Post
    I've read bits and pieces about your G-vans for years...but this is first thread I've seen. haha

    What kind of heads on the 383? It sounds pretty similar to the one going in my Camaro.
    http://www.gearhead-efi.com/Fuel-Inj...ng-205cc-heads

  10. #85
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    Another question- perhaps answered somewhere else, what do you see as a high value w good efficiency (regardless of dollars spent) torque converter supplier for a 4L60E 2200-2400 stall, 383 non oem tuned port 350rwhp/400tq?

  11. #86
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    Ended up going back to a ported stock intake with an AUS 48 lb/hr spider. Put the smaller cam back in a while back too. Just changed out the muffler and tailpipe. Dual 3" in Walker quiet flow muffler and matching 4" tailpipe for an 01-06 3500 HD with a 6.0L or 8.1L fit my van like it was made for it. To me it is very quiet for a 500 hp engine and a bit of a sleeper now.

    https://youtu.be/zJBiw3xkiYY

    https://youtube.com/shorts/bq8CAvqnubU?feature=share

    I also swapped a P59 Green/Blue into it a while back. First fireup after the 383 went back in on the Mexican 2005 L31 GMT800 file base tune with injector size, displacement and MAF edited. Had to do a good bit more tuning. Torque management was pulling a ton of timing out of it. Open headers so it is nice and crackley.

    https://youtu.be/FzEDpuSIwJc

    Idling with a 4" MAF.
    https://youtu.be/iEn1Ht6Ta-s

    Testing the 6,200 rpm rev limit open cutouts.
    https://youtu.be/J4v4Z9rAKio
    Last edited by Fast355; 04-15-2022 at 09:15 AM.

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