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L18 8.1L swap resource thread

Blue85 said:
I thought the same thing when I saw my 8.1L starter shared the same case as a 3800 starter. The larger diameter flex plate/flywheel does give the starter more leverage, though and the little starter had no problem cranking it. I had some questions about this but never posted up here. The 2003+ starter is a different style and it seems the block itself must have changed to accommodate.

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Larry said:
Unlike LS engines, the nice thing about the 8.1L is it has the staggard bolt pattern and same ole 168 tooth ring gear GM has used for decades. Any starter from decades of BBC’s or SBC’s with the staggard bolt pattern and 168 tooth flywheel will work. Don’t feel obligated to spend crazy money to use an “8.1L” application starter

From page 1 of this thread:

- The L18 8.1L has the same foot print as older BBC engines and will bolt in the same as any other older SBC and BBC. In fact, the L18 will accept any exhaust manifold or header from older BBC engines. The starter motor from any older SBC and BBC for use with a 168 tooth flywheel will also fit the L18. Any transmission from an old PowerGlide, TH350, TH400 to Allison, to NV4500, etc. will bolt on to it as well.

I like to run Denso 281-8002 starters on everything. The Denso starter on my Suburban’s 8.1 is the same exact starter that was on the TBI 5.7L before the swap. These starters aren't cheap but they will be the last one you ever buy. This is the starter UPS uses where it lives up to their punishment of starting hundreds of times a day. It will turn ring gear teeth into razer blades long before the starter wears out as the Rockwell hardness of the starter drive gear is harder (55) then the ring gear on the flywheel/flexplate which was around 35. Us guys would probably never see the ring gear teeth get worn down like they do.
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I think the shrouded nose of the Delco style vs the open gear of the Denso style was throwing me off. I have a aluminum inspection cover and not the stamped steel one that came with 8.1L trucks, but I suppose as long as the nose diameter is the same, they will interchange. It's just weird that the Denso style isn't listed as compatible for anything before 2003 and not studying the pictures I just accepted that.

Denso vs Delco starters.png
EDIT: I've had the Denso starter on for a while now and it's great. Sounds good, cranks fast, don't even worry about leaving the radio or lights on for a bit now.
 
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sweetk30 said:
went and looked at a 2001 3500HD std cab today . she has 80,xxx miles on the od and the nice 8.1 / nv4500 combo . told him i would take it for his asking price of 2500 bucks . going to keep it as a work truck for my self . Pics to come soon .
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I'm sure it's been covered but maybe not. Are the GMT400 accessory brackets the same as the GMT800 accessory brackets? Curious because I am looking at an 8.1 for my '93 K2500.
 
i know in the begining of this thread its all layed out . 1/3 the way down page 1 with pics and info .

i will have my here by this weekend i hope . he is waiting on the bank to send the lean release form . he is ready for my payment method and i am ready for the truck .
 
ZooMad75 said:
You need to put a fuel pressure gauge on it and post up what you have when it's running. Normally an 8.1 needs 55-62 psi running. A fuel pressure regulator on a 2001 engine is adjustable. It's a small Allen head screw and little movements make a noticeable change. Watch your fuel pressure gauge as you make the adjustment. IIRC Larry tweaked his above spec slightly by a couple of pounds.
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my 02 looks like a safety torqs and I am currently at 45psi and i am guessing it is this guy?20210724_093113.jpg
 
ZooMad75 said:
That's it.
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man is it beat.. i got it to go ...but started stripping... actually went too high but got it to 58psi... did not go for a run cuz it is hot out and i am frustrated... i replaced rear main but i have oil on filter and dripping...most ikely rear main!!!!
 
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Bent77 said:
Bump

contemplating relocating this thread to the Injection Section. Give me your input @ZooMad75 @Larry
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It could fit in both, but it is an engine swap first the injection side comes along with it.

It really has more detail for the nuts and bolts of completing the swap vs deep dives into the injection side of things. Most are running stock ecms and basic tunes and not too much traffic on self tuning with efilive or hptuners.

I'd say it is best where it is.
 
ZooMad75 said:
It could fit in both, but it is an engine swap first the injection side comes along with it.

It really has more detail for the nuts and bolts of completing the swap vs deep dives into the injection side of things. Most are running stock ecms and basic tunes and not too much traffic on self tuning with efilive or hptuners.

I'd say it is best where it is.
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we try to not dive into that cuz then we are told wrong thread for that...
 
been fixing and driving my 3500-HD with 8.1 and LOVE it . . . gobbs of power and just goes . . . its fun to show people that 10mph and pop it in 4th gear on the nv4500 it just powers threw and goes unlike other engines that need rpm to try this .

i like this truck and engine so much i am already looking for a 2nd truck with the same engine but maybe a auto for more daily driver type use .
 
sweetk30 said:
been fixing and driving my 3500-HD with 8.1 and LOVE it . . . gobbs of power and just goes . . . its fun to show people that 10mph and pop it in 4th gear on the nv4500 it just powers threw and goes unlike other engines that need rpm to try this .

i like this truck and engine so much i am already looking for a 2nd truck with the same engine but maybe a auto for more daily driver type use .
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Pretty cool huh? 8.1's are pretty silly how low you can lug them and they just keep pulling. Get a set of the Taylor 10.4 mm plug wires and you'll get rid of the little wispy miss they have when you really lug at low speed in 3rd or 4th. It will run cleaner all the way around with them.

Another truck with an auto isn't a bad idea, but the Allison sucks some power that the manual does not. They respond to doing some tuning to overcome it. Main thing to turn off is the burst knock retard and then the torque management. They really wake up with those two changes without digging deep into the fuel and timing maps.

Burst knock retard is a funny way of protection as when you get on the throttle the knock sensors catch that initial ramp up of rpm. The ECM sees that and pulls timing out and the engine lays over. It's overkill on the protection side and not really needed.
 
thanks @Larry the 8.1 guru king

got almost 100 miles on this ol girl and LOVE the power infront of the 5 speed stick . she is a animal for sure .

Wheels refurbed . New tires . New brakes . Cut 2ft off back of bed and made hitch . . Got more plans for this winter to clean her up more .

p.s. ...... duct tape on door holes to keep yellow jackets out of the door :zombie15:

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ZooMad75 said:
Pretty cool huh? 8.1's are pretty silly how low you can lug them and they just keep pulling. Get a set of the Taylor 10.4 mm plug wires and you'll get rid of the little wispy miss they have when you really lug at low speed in 3rd or 4th. It will run cleaner all the way around with them.

Another truck with an auto isn't a bad idea, but the Allison sucks some power that the manual does not. They respond to doing some tuning to overcome it. Main thing to turn off is the burst knock retard and then the torque management. They really wake up with those two changes without digging deep into the fuel and timing maps.

Burst knock retard is a funny way of protection as when you get on the throttle the knock sensors catch that initial ramp up of rpm. The ECM sees that and pulls timing out and the engine lays over. It's overkill on the protection side and not really needed.
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I am on vaca but when i get back.. i think we need to start an 8.1L performance tips and to do thread keeping the resource thread clean...
 
I feel like I missed something.
I've been crawling through this thread looking for what Flexplate to use with my 400/203/205 gear train, I've got it built and ready, just, need the flex plate. Any ideas?
 
BoondocK5 said:
I feel like I missed something.
I've been crawling through this thread looking for what Flexplate to use with my 400/203/205 gear train, I've got it built and ready, just, need the flex plate. Any ideas?
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Ya, there is nothing here listed for Automatics but I’d recommend a flexplate for a 8.1/4L80E as was used in an 8.1L Suburban
 
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