GMT900 408/80e conversion
03-03-2010, 11:37 PM
#52
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I'm not quite done yet. Still have to figure out the wiring. I have an 80e TCM that works good but I can't get the speedo output to work for some reason. The input speed sensor is working but for some reason it reads at a higher RPM than the engine when in neutral. Without the rear sensor output the PCM doesn't enrichen the fuel mixture when I drive, it stays close to stoich. I swapped the wires at the trans and added the front sensor. Whats strange is I can put the 60e TCM back in and the speedo works but it starts off in 2nd or 3rd gear.
Maybe Flaco will see this and give me some pointers.
Maybe Flaco will see this and give me some pointers.
03-04-2010, 06:43 AM
#53
wow man thats a great write up. i didnt think itd be as easy as your making it sound. yeah i see your having trouble..what if you were to take the transmisson charts for the 80e an lay it into the 60e tcm? just a thought i think i read thats possible when you swap from a manuel to an auto..i dunno. sorry if thats wasted time.
we need pics of the crossmember
oh also...how much HP are you expecting out of the 408?
we need pics of the crossmember
oh also...how much HP are you expecting out of the 408?
03-04-2010, 10:12 AM
#54
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I would like 500 RWHP but sad to say it only had 400 RWHP in the previous truck. Right now the engine is choked down with a stock exhaust system. When I go back to work I'll buy a set of longtubes to go in there to hopefully help me reach my goal. You'd think a 408 with PP stage 2 LS6 style heads, 2.08 intake, 1.6 exhaust, LS2/90mm NW TB, 234/.608 cam could do it. Hell, I've seen 6L engines put down almost 500 RWHP on the rollers.
03-04-2010, 10:59 AM
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I'd like to go 1-7/8 but 1-3/4 pipes are half the cost. ARH has some nice 1-7/8 pipes but are damn near a grand. $500 buys a nice set of 2007+ stainless headers in 1-3/4 size.
03-05-2010, 09:46 PM
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PCM/TCM...
Conversion is finished, had to get a 2008 Chevrolet Express 4.8L/4L80e van C2500 TCM tune to get the transmission to shift correctly. There was nothing special done to make the TCM work in the Silverado, just swap them out. The TCM was loaded with a factory tune for an 80e transmission, thanks for the help there Nathan.
Type: Chevy Express (V8) 2008
VIN: 1GCGG25C481106014
TCM...
Segment 1: 24239927
Segment 2: 24235887
Segment 3: 24251658
Segment 4: 24235883
Conversion is finished, had to get a 2008 Chevrolet Express 4.8L/4L80e van C2500 TCM tune to get the transmission to shift correctly. There was nothing special done to make the TCM work in the Silverado, just swap them out. The TCM was loaded with a factory tune for an 80e transmission, thanks for the help there Nathan.
Type: Chevy Express (V8) 2008
VIN: 1GCGG25C481106014
TCM...
Segment 1: 24239927
Segment 2: 24235887
Segment 3: 24251658
Segment 4: 24235883
Last edited by Red Heartbeat; 04-29-2010 at 05:59 PM.