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8.1L/496 Tech

i too wish there was a better way to select 4th. I suspect the PO of my truck had a tune put in, but in tow haul, mine won’t grab OD til like 70 mph , so setting the cruise at 68 works for that.

You could probably go back in the ECU with HPTuners and modify the shift points if you wanted to.

I would love to have the factory OD Off button installed and the TCU flashed as mentioned on Chevrolet tsb 02-07-30-051A


Found this very detailed write-up too:

OD LOCKOUT INSTALLATION INSTRUCTIONS

But I still need the TCU flashed and can't find any infos on that.
 
Stock trans pan.
Stock fan clutch (I've only heard the fan a couple of times when pulling up mountain grades).
No paint peeling.



Water temp is around 190.



I don't have any interest in modifying it. And even if I were, gears is probably the first thing I would do.



IDK how you get 8mpg unloaded. That's what I get pulling a loaded 35ft enclosed.
I don't think you actually read what I posted based on that reply... whatever... but what I can tell you is that I doubt a gear change would benefit you much unless if your that fuc who wants to tow at 45mph in the right lane... :FLIPOFF2:





Also- "bought a 8.1 big block, happily putting gas in it but would like to keep doing so for a while, what to do to ensure it lasts ?" [sic]: keeping it stock is all you have to do to make it last. A stock 8.1, seeing as though you keep the oil filled if yours is one of the lottery 8.1s with an oil appetite, is a damn rugged engine with its 9:1:1 compression ratio, HP limiting mid school style "peanut cam", and lack of stress the rings/converter power adder (turbo, supercharger, ect.)





What I would do if it was mine and I was seeking ultra-reliability: either leave it bone stock and when it finally does blow rebuild it with all forged internals while retaining the same cam and valve sizes, and/or add a camshaft that advertises/focusses on more torque throughout THE WHOLE REV RANGE (depending on your local emission standards and how sly of a fox you are) so your engine is more efficient at “working” (low RPM torque/pig grunt) so as to not have to “work as hard” pulling that load at cruise speed. Have Arnold bench 200lbs all day long and he will never blow a rotator cuff… ya tracking?





Remember, even though the diesel clowns get to brag about high MPG, they NEED a turbo to “make their diesel COUNT”, have a lifelong commitment to fucn with clogged injectors ect, pay outrageous maintenance costs (seeing as though they lack a DYS backbone), have to pay for that DEF if not bypassed (which causes other engine management headaches if bypassed), and over a ten year period will more than likely spend more on maintenance then you will spend on the extra gas you burn (not even counting the bend one over and insert without lube initial cost)…
 
Following along this thread for tech, just picked up an 06 3500 with the 8.1 ally combo.
 
I don't think you actually read what I posted based on that reply... whatever... but what I can tell you is that I doubt a gear change would benefit you much unless if your that fuc who wants to tow at 45mph in the right lane... :FLIPOFF2:





Also- "bought a 8.1 big block, happily putting gas in it but would like to keep doing so for a while, what to do to ensure it lasts ?" [sic]: keeping it stock is all you have to do to make it last. A stock 8.1, seeing as though you keep the oil filled if yours is one of the lottery 8.1s with an oil appetite, is a damn rugged engine with its 9:1:1 compression ratio, HP limiting mid school style "peanut cam", and lack of stress the rings/converter power adder (turbo, supercharger, ect.)





What I would do if it was mine and I was seeking ultra-reliability: either leave it bone stock and when it finally does blow rebuild it with all forged internals while retaining the same cam and valve sizes, and/or add a camshaft that advertises/focusses on more torque throughout THE WHOLE REV RANGE (depending on your local emission standards and how sly of a fox you are) so your engine is more efficient at “working” (low RPM torque/pig grunt) so as to not have to “work as hard” pulling that load at cruise speed. Have Arnold bench 200lbs all day long and he will never blow a rotator cuff… ya tracking?





Remember, even though the diesel clowns get to brag about high MPG, they NEED a turbo to “make their diesel COUNT”, have a lifelong commitment to fucn with clogged injectors ect, pay outrageous maintenance costs (seeing as though they lack a DYS backbone), have to pay for that DEF if not bypassed (which causes other engine management headaches if bypassed), and over a ten year period will more than likely spend more on maintenance then you will spend on the extra gas you burn (not even counting the bend one over and insert without lube initial cost)…

That's a lot of words to tell me to leave it stock.
Thanks.

Added a few more miles pulling my car hauler with it. Average MPG is definitely the following:
Towing : low 8s / high 7s
city : 10
empty hwy at 70mph : 12
 
I gathered plugs, wires, coils up for mine. Once installed I hope for improvement.
 
Keep an eye on the brake and fuel lines. They like to rust out in those years.
 
Your empty/70mph is better than my 6.0 :laughing:

:frown:

I'm pretty happy with it. I'm also making a point not to gun it or drive like an asshat.

Keep an eye on the brake and fuel lines. They like to rust out in those years.

This is a 100% southern truck that's pretty clean underneath, but I'll keep an eye on them. Thanks
 
Yeah you guys are lucky there. I have seen some pretty clean trucks rust out the lines though. Where they all run under the cab by the drivers side frame rail / firewall area headed back to the abs unit. And the rear line back by the fuel tank.
 
Following along. I have 4 of them, in various stages of hot rod engines. Funnest is a Dart blocked, aluminum headed 617 CI.
 
Keep an eye on the brake and fuel lines. They like to rust out in those years.
This is the first thing being done to mine, the day I picked up my 06 I had two friends call and say order lines now before they become a problem. I dropped it off at a friends shop before leaving for a work trip for him to check over for me and swap out the brake lines so I can use it when I get home. Will update with anything he finds/fixes to keep some tech in this thread.

Details on my pile, its an 06 4wd 3500 SRW that I won at auction with 98k on it.
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This is the first thing being done to mine, the day I picked up my 06 I had two friends call and say order lines now before they become a problem. I dropped it off at a friends shop before leaving for a work trip for him to check over for me and swap out the brake lines so I can use it when I get home. Will update with anything he finds/fixes to keep some tech in this thread.

Details on my pile, its an 06 4wd 3500 SRW that I won at auction with 98k on it.
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I like that. Tool bed is nice..
 
I am currently machining 2 Dart intakes for injector bosses. The plan is to run an elbow and factory efi.

They will flow better than factory.
 

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3rd time I had random reduced power and couldn't go beyond 2k rpm/1st gear. Ran bad at idle like half block are not firing.

I forgot code it threw P1200, P1500? Came up as powertrain issue.

Time to replace Crankshaft sensor
I started the truck for a minute.

Removed heat shield (10mm)

Removed last coil pack by firewall (8mm)

I used racheting/bendable head wrench for this.

10mm on the sensor.

Twist the sensor.

From bottom.


Mini flathead through existing bolt hole and use that as leverage. I got real lucky it came off much faster than anticipated.

Lube the o ring on the new sensor.

Re-installed from below.

Re-assy on rest of part.

Started up and no issue.

Here's the old and new for comparison.
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I am currently machining 2 Dart intakes for injector bosses. The plan is to run an elbow and factory efi.

They will flow better than factory.
If you plan on modding/improving stock 8.1 manifold, I'd be interested.
 
Well I guess I can join the 8.1 club with my unicorn 2006 c8500 truck with an eaton 5 speed to boot. 34k miles after the cross country trip. The torque is there. Think it has an exhaust leak, but no biggy.
 
I am currently machining 2 Dart intakes for injector bosses. The plan is to run an elbow and factory efi.

They will flow better than factory.

Was always curious how that worked out. But is the intake + machine worth the effort?
 
Was always curious how that worked out. But is the intake + machine worth the effort?
Hell yes. Granted, it takes me about an hour to machine the injector bosses in the Dart intake. I use a throttle body elbow and go all factory EFI.
 
How much would that set up cost roughly, I know you dont like talking money and your shop but still asking anyways? Im doing a 8.1/4l80 swap into a 67 Bel Air and that would be a cooler looking intake then the stock unit.
 
Intake is about 650, all around the net. Elbow 55-160. Fuel rail extrusion is about 100. Then about 100 for machine work, if you can get on a machine.
 
Thank you for the info. Definitely gives me something to think about on my build
 
Well shit, burns oil is right. Been noticing oil pressure gauge low at idle. Check the oil, and dipstick is empty. Filled up 5qt and it was over, so I am guessing it was about 2.5qt low
 
Well shit, burns oil is right. Been noticing oil pressure gauge low at idle. Check the oil, and dipstick is empty. Filled up 5qt and it was over, so I am guessing it was about 2.5qt low
Get rid of the EGR system.
 
just seeing this thread.

I have a 75 GMC 1 ton C3500 with an 8.1, stage II Gearstar 4L80e and stock D80 with 5.13 gears, detroit and stock sized tires :eek: I built the truck this way so I can tow heavy loads up a very steep mountain pass. Making a run down to town today with the 22' GN to get the rest of my metal sheets for the roof of my log cabin. I will take pics.

The motor runs great and is stock other than some tinkering I did in the bin via HP Tuner.
 
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