Yes, another v8 swap thread

[Size Matters]

ive done alot of searching on the subject but none of the posts are really what im looking for...
i have a 2004 K1500 4X4 5-speed with the 4.3, im in love with the truck but i do want to swap in a 5.7 vortec. it just seems that whatever thread you click on you get a different story on what needs to be done for the swap, so from what ive got out of all of the searching ive done, i still have questions like will the v-6 y-pipe bolt up to the 5.7 exhaust manifolds? im pretty sure you can bolt up the flywheel, clutch, starter and things like that but what about A/C lines will they work, and does anyone know anything about the extra wires you need to add for the two injectors? some say you will need new motor mount is this true

i found a real nice write up on v6 to v8 swaps but that was for 4.8/5.3 and LS1 v8s but i think the 5.7 is a more realistic swap for me, i dont plan on doing any big mods or anything crazy just a cia and exhaust and ofcorse a tune
thanks for any input that you guys give to me on this

[Size Matters]

i would like to get some feedback

[sj250]

Would you mind posting where you found the other swap as I am looking at swapping a 5.3, thanks alot!!

[BowTie95]

Ok, the starter, flywheel, tranny, and clutch will bolt up. You will need new motor mounts also. The whole serp belt setup from your v6 should work with the v8, and you will need a new fam shroud and possibly radiator. I cannot help with the electronic part because I did a carbed swap. Sorry, hope I helped.

[Fast305]

I am going off the L31 swap to replace the 4.3 in a 2004 Express van that I did. I re-used the stock engine mounts and brackets, I just had to move them forward into the V8 frame location. Electronics are not too bad. You will add two wires into the main harness back to the PCM connector and splice two more into the existing injector power connections. The injector connector will need to be replaced with a V8 unit. Its not that hard to resplice the connector. Just use the 2002 L31 express wiring diagram as a guide. The other connections will drop right into place and work with the factory L31 intake. Some of the V6s lacked an EGR valve though. In that case the V8 Calibration will need to be modified to turn off the EGR and the EGR valve on the L31s intake will need to be blocked off. The MAF will swap over between engines. You want to start with a 2002 Express van tune for your PCM. The stock 4.3 radiator will work ok with the V8 swap. You need a fan shroud for a 4.8/5.3 truck though. A/C and power steering lines will fit with some minor re-bending.

[Pauly]

The 4.3 MAf will work, but it is smaller. the 4.3V6 and the LT1 with iron heads used the smaller MAFS. the Vortec V8 MAfs is 75mm, the 99+ trucks use a 85mm MAfs.

peace
PAuly

[Fast305]

Originally Posted by Pauly

The 4.3 MAf will work, but it is smaller. the 4.3V6 and the LT1 with iron heads used the smaller MAFS. the Vortec V8 MAfs is 75mm, the 99+ trucks use a 85mm MAfs.

peace
PAuly

The 2001-2002 4.3/5.0/5.7 Vortec Express all utilized the 85mm MAF. I don't know about the 4.3 in the trucks, I assumed they used the same.

[567234ta]

why go with the 5.7 and not the newer 6.0?

[theheathen]

i wish someone would do this. im considering it i have the 4.3 out of my 05 4x4 5spd. im just afraid ill get something started and not be able to finsh it.

[Fast305]

Originally Posted by 567234ta

why go with the 5.7 and not the newer 6.0?

The 5.7 is an easier swap and has just as much power potential.

[96SLT350]

Originally Posted by Fast305

The 5.7 is an easier swap and has just as much power potential.

5.7 is a great idea. Add a cam, chip and headers before you put it in your truck. you will not be disappointed.

[Fast305]

Originally Posted by 96SLT350

5.7 is a great idea. Add a cam, chip and headers before you put it in your truck. you will not be disappointed.

I agree, in Mexico the NBS trucks came with the 350 Vortec in them. Even thought this truck is lighter than the Hemi ram, it lacks 90 hp and 40 ft/lbs. I think with traction he would have stayed with the Hemi.

http://youtube.com/watch?v=1Ma8Gu3UH-U
(watch carefully as he walks around the driverside front, looking at the exhaust manifold you can easily tell its a V8, the sounds a dead give away too).
http://youtube.com/watch?v=lUJ_0W5-zD8

[theheathen]

will a 96 up vortech work?

[Fast305]

Originally Posted by theheathen

will a 96 up vortech work?

96-02 Vortec 350 is the one I would use.

[96SLT350]

Don't listen to anyone who talks crap about the 96-02's They are fully capable of running just as smooth and if not as much power potential as a LS series new motors.

[theheathen]

what kind of rwhp can you get out of 5.7 with cam and headers and tune

[Fast305]

Originally Posted by theheathen

what kind of rwhp can you get out of 5.7 with cam and headers and tune

My Express van put down over 270 RWHP on the stock heads and stock cam. 1.6:1 roller rockers, cleaned up the manifold base, doug thorley tri-y headers, stock cats, flowmaster muffler. Tuned PCM

[Size Matters]

do any of you know where a 5.7 vortec is for sale mabye close to me???

[theheathen]

id prolly check craigslist

[Size Matters]

i did... no luck
cant wait to find one