5.7 vortec vs 5.3l or 6.0 swap

[L31MaxExpress]

My point about the old farts is the guys who consistently knock larger tires or built motors but

did you build it off the stock block

I built it off a machined and clearenced stock 880 block but used aluminum heads.

If I were doing it over, would be a 4.125" bore, 3.875" stroke in a 1-piece rear main seal, factory roller cam compatible, 350 main journal sized Dart SHP block. That would be 414 cubes. I would have used cubes and less rear gear. Something like a 4.10 or 4.30.

 

[90west]

Thank you for the info

 

[Supercharged111]

My point about the old farts is the guys who consistently knock larger tires or built motors but

did you build it off the stock block

I tow on 285/70/17, more than you're looking to. I admit my thread is a bit of a read, so here's Cliff's Notes: stock 292k mile 350 with marine cam, 1.6 RR, marine intake, longtubes/full exhaust, 411 swap, Whipple (4# of boost here in CO), 4.10 gears, 4L80. This trailer is somewhere near 9000# loaded, I can tow it in OD here.

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On this particular day it was 11,000# minimum though. Never tried OD, was an in town recovery of our Envoy.

Towed this from ND to WI couple weeks ago like it wasn't there.

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Yes you can tow with bigger tires, but it takes more gear and more grunt to get it done. In the Camaro world, 500whp is a generally accepted figure for the LT1 bottom end. I believe we got the same powdered metal rods and at least similar hypereutectic pistons in the Vortec motors, but I don't know how that limit translates into a torque making truck.

 

[90west]

I tow on 285/70/17, more than you're looking to. I admit my thread is a bit of a read, so here's Cliff's Notes: stock 292k mile 350 with marine cam, 1.6 RR, marine intake, longtubes/full exhaust, 411 swap, Whipple (4# of boost here in CO), 4.10 gears, 4L80. This trailer is somewhere near 9000# loaded, I can tow it in OD here.

You must be registered for see images attach

On this particular day it was 11,000# minimum though. Never tried OD, was an in town recovery of our Envoy.

Towed this from ND to WI couple weeks ago like it wasn't there.

You must be registered for see images attach

Yes you can tow with bigger tires, but it takes more gear and more grunt to get it done. In the Camaro world, 500whp is a generally accepted figure for the LT1 bottom end. I believe we got the same powdered metal rods and at least similar hypereutectic pistons in the Vortec motors, but I don't know how that limit translates into a torque making truck.

Are you running the stock injection

 

[Supercharged111]

Are you running the stock injection

Nope, marine intake with regular 42# injectors. But the spider stuff can be had higher than stock. I am running a stock pump though.

 

[90west]

Nice this is the kinda info I was talking about did you tune the black box ecu or swap in the I wanna say 0411 ecu?

 

[Supercharged111]

Nice this is the kinda info I was talking about did you tune the black box ecu or swap in the I wanna say 0411 ecu?

I initially tuned the blackbox, but later swapped the 411. The 411 got rid of my phantom knock and has been friendlier to work with from a tuning perspective.

 

[letitsnow]

I tow with a stock internal 5.7 blackbear tuned, opened up air box, no A/C, shorty headers and true dual (no cats) exhaust.

My truck has 265/75r16's and 4.10 gears. 3rd gear works great. OD can only be used on flat ground, if it isn't windy.

I put on around 7,000 miles each year, towing this set up.

Lower gears would be nice.

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[L31MaxExpress]

Nice this is the kinda info I was talking about did you tune the black box ecu or swap in the I wanna say 0411 ecu?

I am running a P59 out of an 03-05 Express 6.0L with IAC driver and analog ac provisions and a mexican L31 GMT800 based tune. The P59 is friendly to flex fuel.

Even spinning up the 50 lbs stock body 4L80E converter it revs up about like a 2 stroke dirt bike.

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[L31MaxExpress]

When I still had the old 350, 906 heads with Pac 1218s and Comp 787 retainers, marine intake, 395 marine cam, 1.7 roller rockers, march underdrive pulleys and thorley tri-ys into the factory 3" dual exhaust to the muffler. 4L85E and 3.73 geared 9.5 14-bolt. On 91 octane it made 257 rwhp at 4,900 and 310 rwtq at 3,200. On E85 it made 272 rwhp at 4,700 and 330 rwtq at 2,900. On 91 octane it only ran with 29° of timing at about 3,600. On E85 it liked 34° as early as 2,600 rpm. Down at 2,500 with the timing cranked up it made nearly 40 ft/lbs more on E85. It was nearly 100°F in the shop that day, can hear the duramax fan roaring to keep the old 350 cool. Even at 5,800 rpm it was only about 10-15 hp down from peak at 4,900. I later put more cam in it and made 290 rwhp and 330 rwtq. With a 215/223 on a 108 lsa GM SPO 357 hp cam it made peak torque at 3,500 and peak hp at 5,500. Down at 2,900 it was still making nearly 330 tq, from ~2,800-3,800ish. With the SPO cam torque was table top flat for nearly 1,000 rpm at 330. The old 350 really liked the 108 LSA cam.

This was on 91 octane. Wish I had video of the E85 runs, sounded like a different engine.

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