Hello everyone, like many of you, I've caught the mod bug and have decided to swap out my 4.3 for a Vortec 5.7. I got the engine from a junkyard with 102,000 miles on it for about 600 bucks. It came with all the accessories on it and whatnot. The motor is sitting here waiting to be put in, and i hope to make this a thread to help others who might be interested in the swap. So here is what I have so far in order to do the swap:

-JEGS swap in a box kit with motor mounts, headers, and oil pan.
-45* npt fitting for knock sensor
-MPFI upgrade for v8 already installed.

Im fairly sure that the first two are the only two things I need to get the engine to physically sit in the vehicle, as for making it run, theres my questions. I know I need to do the fuel injector wiring for two extra cylinders as well as repinning my ECU for several things. My question is: why cant I just use the harness/computer off of the van?

 

if I am remembering correctly, I believe the blazer ecu is on the opposite side of the truck compared to vans and trucks.

 

I think you want to retain the original ECU for gauges, and other "Blazer" functions. Running both may be an option Van ECU for engine Blazer ECU for vehicle.

 

I also have a 2003 ZR2 and am thinking about installing a 350 vortec engine that I have sitting in a 2000 Denali, the tranny in the Denali is pooched in drive but the rest of the drive line is great. I have been searching on the web for info on my specific blazer swap and have found some info but seems to be mostly two wheel drives. I think my most concerns would be, can I use the stock exhaust manifolds and any issues with ZR2 engine frame mounts.

 

From the research I have done for an LS blazer I need to use '98-'99 F-body exhaust manifolds for an LS swap into my '04. The ZR2 has different engine mounts ( higher engine placement ) and the 350 has different ex. mans. I think You should have plenty of room for the stock manifolds to work but I would look for a similar swap for ideas. Options for 4x4's is limited
https://jagsthatrun.com/collections/chevy-s10/products/copy-of-v8-s10-2wd-headers-w-1-1-2-in-primary-tubes

 

Strangely enough, I ran into no trouble using the swap in a box headers / motor mounts, although they were pretty difficult to get in. For our specific year of blazer, we had a completely different ECU; you are going to need to buy an 0411 ECU and re-tune it to that of a blazer. I got the 0411 off of a 2002 Express Van 5.7 L and used HPtuners to modify it. The cooling system was incredibly tight, but it just barely fits.

 

2000 - 2004 S-10'S came with 411's and are some of the most sought after ECU's for DBC swaps and stand alone engine controllers. I plan on using HP tuners to perform an OS segment swap From a Flex fuel enabled full size p/u or van.

 

That won't work, you'll need to buy an actual 0411. Your 2004 does not have an 0411, I tried to do the exact same thing that you want to do and hp Tuners will not allow you to do it, the operating system on your blazer is not compatible with the 0411 tune.

https://www.rockauto.com/en/catalog/...computer),2896

 

the operating system on your blazer is not compatible with the "V8" 0411 tune. A segment swap is required.

The "S10" Computer (ECU) Can be used, after it is reflashed with HP Tuners and it is one of the most common of engine swap ECU's used for older cars and trucks for DBC operation.

Computer.
With a 2000 and up, you can use your factory 0411 computer. It will need to be reflashed. Many places do this. https://www.s10forum.com/forum/f10/h...sonoma-504057/
i was reading about doing a vortec 4.3 astro and swapping in a vortec 350. lots of guys on the astro forum just add the extra pins and wires for the 2 additional injectors to the factory harness and pcm connectors and just pick up a same year pcm from a 350 vortec truck. the rest is literally plug and play. i dont see why you could not have your pcm programmed with a 350 vortec truck program. https://grassrootsmotorsports.com/fo...0/34424/page1/ https://grassrootsmotorsports.com/fo...0/34424/page1/
http://lt1swap.com/v6_to_v8_vortec_conversion.htm
would you like me to reflash your stock computer for you ?