88ZNX
Newbie
Ok our project 6.6L Duramax Gas engine conversion was a success... Ok we jokingly call it a Duramax because it’s probably the closest thing to a Diesel that you’re going to get in a gas burner. The 244k mile Vortec 350 wasn’t getting the job done pulling the 11k lb gooseneck trailer like I needed it to. So When we started this project, everyone said “just do a 6.0L LS swap” and that was absolutely NOT what I wanted. There is a place for LS engines, like in light weight Mustangs and such but I was needing something with diesel style torque, there is no naturally aspirated LS engine that can produce this kind of off idle torque.
First I was looking for a 4 bolt main Vortec block to start a 383 build but happened to come across a very nice 400cid short block so this would be even better. Since I would be retaining the OEM ECM, cam sensor and distributor, On this early 70s style production block, I purchased a retro fit timing chain cover to retain the cam sensor. When using the cam sensor and reluctor ring on the crankshaft, the harmonic balancer snout has to be mild down .090 to make up the thickness of the reluctor between the balancer and crank Gear. (Cheap China seal leaked in the new cover and luckily I had a seal from a old 70s kit left over and it fit perfectly and fixed the balancer oil leak) Next we chose Corvette aluminum heads #113s because of there very light weight and small 170cc intake ports that would keep the air flow velocity very high and responsive for low RPM torque. I had to open the 58cc combustion chamber up to 61cc to get the compression down from 11.4 to 10.6. Next we chose a Tuned Port Injection set up because there is no other intake manifold that will produce as much torque on a gas engine as a TPI. We used 24lb injectors because the stock popit style injectors are 24lb. There are plenty of intakes that will make more horse power but that was not the goal here. After everything was assemble and install in the truck, then we had to Swap a few sensor plugs to fit the 1988 style injection. There where only 3 pig tails to change and if I would have had an LT 1 throttle body laying around, I would have only had to change 2 ends because the LT1 TB TPS sensor connector was the same as the Vortec harness. First we purchased an injector harness from FAST and the mail plug to replace the OEM popit injector pigtail on the Vortec harness. Next was the IAC and TPS sensor ends. You can see in the photos that I replaced the complete serpentine belt set up with the 1988/92 style because the 96 and up AC compressor and Alternator sit to close together on top, to allow TPI TB to sit where it needs to. A 3 1/2” 90 and pipe was all that was needed to complete the air inlet pipe from the filter location to the TB. When we turned the key and verified 47psi fuel pressure, it fired right up. There was a few things to adjust in the ECM like cam sink, IAC motor,and max ignition timing. So since we are only 2 1/2 hours from Baton Rouge we drove it to Jeff Skinners shop “Engine Power Systems” and he smoothed every thing out and it’s running like a brand new truck. There was an issue with torque converter lockup on the way there and he was able to program that away. The 4L80e Control module was picking up a misfire signal and would not allow convert lock up. To give this engine swap a little perspective, this is how much more powerful and fuel efficient it is compared to the 350. We made a trip to Jeff’s shop before this to have him try to help the 350 out. The truck has a 20gal tank and it took all 20 gallons to make it to his shop on the first trip. On this trip, with the new 400 engine we made it to his shop on a half of a tank @ 65mph 2500rpm with no lock up. We made it back from his shop with even more that a 1/2, tank @70mph and 2300rpms. The engine makes so much torque that it never comes out of lockup with the cruise control on going up any hills and there ain’t NO LS engine that can say that. Put 3 or more Passengers in a Tahoe or a lawn mower trailer behind a half ton truck and that LS engine is gonna start crying and protesting like a snowflake at a Trump rally. Torque Convertor is gonna kick in and out, transmission can’t make up its mind what gear it wants to be in. No thanks I’ll stick with my old school powerhouse torque monster. Hope you enjoyed the read. . I have pictures if I can figure out how to post them. Or you can go to my FB site A&A Performane.
I am in the process of 411 swap, is there a pin out diagram to help get this done ?
First I was looking for a 4 bolt main Vortec block to start a 383 build but happened to come across a very nice 400cid short block so this would be even better. Since I would be retaining the OEM ECM, cam sensor and distributor, On this early 70s style production block, I purchased a retro fit timing chain cover to retain the cam sensor. When using the cam sensor and reluctor ring on the crankshaft, the harmonic balancer snout has to be mild down .090 to make up the thickness of the reluctor between the balancer and crank Gear. (Cheap China seal leaked in the new cover and luckily I had a seal from a old 70s kit left over and it fit perfectly and fixed the balancer oil leak) Next we chose Corvette aluminum heads #113s because of there very light weight and small 170cc intake ports that would keep the air flow velocity very high and responsive for low RPM torque. I had to open the 58cc combustion chamber up to 61cc to get the compression down from 11.4 to 10.6. Next we chose a Tuned Port Injection set up because there is no other intake manifold that will produce as much torque on a gas engine as a TPI. We used 24lb injectors because the stock popit style injectors are 24lb. There are plenty of intakes that will make more horse power but that was not the goal here. After everything was assemble and install in the truck, then we had to Swap a few sensor plugs to fit the 1988 style injection. There where only 3 pig tails to change and if I would have had an LT 1 throttle body laying around, I would have only had to change 2 ends because the LT1 TB TPS sensor connector was the same as the Vortec harness. First we purchased an injector harness from FAST and the mail plug to replace the OEM popit injector pigtail on the Vortec harness. Next was the IAC and TPS sensor ends. You can see in the photos that I replaced the complete serpentine belt set up with the 1988/92 style because the 96 and up AC compressor and Alternator sit to close together on top, to allow TPI TB to sit where it needs to. A 3 1/2” 90 and pipe was all that was needed to complete the air inlet pipe from the filter location to the TB. When we turned the key and verified 47psi fuel pressure, it fired right up. There was a few things to adjust in the ECM like cam sink, IAC motor,and max ignition timing. So since we are only 2 1/2 hours from Baton Rouge we drove it to Jeff Skinners shop “Engine Power Systems” and he smoothed every thing out and it’s running like a brand new truck. There was an issue with torque converter lockup on the way there and he was able to program that away. The 4L80e Control module was picking up a misfire signal and would not allow convert lock up. To give this engine swap a little perspective, this is how much more powerful and fuel efficient it is compared to the 350. We made a trip to Jeff’s shop before this to have him try to help the 350 out. The truck has a 20gal tank and it took all 20 gallons to make it to his shop on the first trip. On this trip, with the new 400 engine we made it to his shop on a half of a tank @ 65mph 2500rpm with no lock up. We made it back from his shop with even more that a 1/2, tank @70mph and 2300rpms. The engine makes so much torque that it never comes out of lockup with the cruise control on going up any hills and there ain’t NO LS engine that can say that. Put 3 or more Passengers in a Tahoe or a lawn mower trailer behind a half ton truck and that LS engine is gonna start crying and protesting like a snowflake at a Trump rally. Torque Convertor is gonna kick in and out, transmission can’t make up its mind what gear it wants to be in. No thanks I’ll stick with my old school powerhouse torque monster. Hope you enjoyed the read. . I have pictures if I can figure out how to post them. Or you can go to my FB site A&A Performane.
I am in the process of 411 swap, is there a pin out diagram to help get this done ?
