5.7 vortec vs 5.3l or 6.0 swap

[MrPink]

If you tune something it is no longer stock, your point is no longer valid.

 

[L31MaxExpress]

If you tune something it is no longer stock, your point is no longer valid.

Yes and no! Its still a stock engine its just pulling potential out of it that the factory left on the table. Same as if you rejetted a carb or played with the advance curve on a carb engine. Optimize what you have and the results can be surprising.

When you see these dyno tests like Richard Holdener does, they are all on an optimized tune. Even the factory 5.3L tests he has done all have headers, an electric water pump, open throttle body, and an optimized tune.

 

[MrPink]

It's still no longer stock. It may have stock components but is not stock, untouched 5.7L to untouched 5.3L, it's a no brainer what engine runs and performs better. If it was the 5.7L then why did GM move away from it? Why did they stop supporting it in the OEM USDM world? GM Performance sure, but there has not been a vehicle made in the last almost 2 decades that had a 350 SBC based engine that was sold in the states. If I remember correctly the G-van was the last hold out of the production vehicles to get the L31 and that phased out in 04/05 I think.

 

[stutaeng]

It's as easy as this...just follow the numbers if you are towing: 4.3<4.8<5.3<5.7<6.0<7.4<8.1. See a trend? Assuming all are stock, Vortec (SBC and LS Gen III) and naturally aspirated.

Axle gearing and transmissions adds a bit of complexity to the game, and can really help or hurt; but generally, more cubes = better towing experience. It's as simple as that. HP/TQ curves are good to look at too. Insert the 383 in that list accordingly, but that wasn't a stock option for these trucks. I'm not sure where the 5.0 Vortec (never really hear about those anymore) and TBI-series fall in the list though, but probably irrelevant to OP's question.

I think the only direct apples-to-apples comparison would be a 5.7 LT1 ("Gen II") to 5.7 LS1. Seems not much out there on the LT1 anymore though... something about Optispark or something? Dunno.

Did OP ever chime back in? It seemed he was more interested in building his 5.7 Vortec and firsthand experienced from guys that had done that. So are spinning our wheels and arguing for no reason, LOL. Run whatever engine makes you happy. There are no right or wrong answers. Everyone is correct in their mind.

 

[L31MaxExpress]

It's still no longer stock. It may have stock components but is not stock, untouched 5.7L to untouched 5.3L, it's a no brainer what engine runs and performs better. If it was the 5.7L then why did GM move away from it? Why did they stop supporting it in the OEM USDM world? GM Performance sure, but there has not been a vehicle made in the last almost 2 decades that had a 350 SBC based engine that was sold in the states. If I remember correctly the G-van was the last hold out of the production vehicles to get the L31 and that phased out in 04/05 I think.

The last L31 went into production vehicles in 06 or 07 in a GMT800. The 5.3L was a little cleaner, cheaper to build since it shared the LS architecture they were converting to. It was more GM not wanting to foot the bill to retool the small block tooling. The P59 L31 tune running my 97 has an 05 1-ton GMT800 vin.

Then again GM has still cranked them out by the 100s of thousands for Boats, Generators, Pumps, etc since then.

 

[MrPink]

Nope not here in the states it did not. The GMT800 platform did not see the L31 5.7L. It was the LU3,LR4,LM7,LQ4,L18.

Outside the US and Canada, in Mexico and S.A. They offered the L31 up until the start of the GMT900 platform.

And if you can prove me wrong BY VIN with a US based GMT800, by all means do so.

 

[L31MaxExpress]

Nope not here in the states it did not. The GMT800 platform did not see the L31 5.7L. It was the LU3,LR4,LM7,LQ4,L18.

Outside the US and Canada, in Mexico and S.A. They offered the L31 up until the start of the GMT900 platform.

And if you can prove me wrong BY VIN with a US based GMT800, by all means do so.

Should have clarified, it was a Mexican truck. The last L31s I know of in vehicles in the US were in 2003 NPRs.

 

[Curt]

...it's a no brainer what engine runs and performs better. If it was the 5.7L then why did GM move away from it? Why did they stop supporting it in the OEM USDM world?

I'm no environmentalist or nothin', but wasn't there something to do with CAFE? I mean sure the 5.7 doesn't drink much more than the 5.3, but when seen as a whole picture of all the trucks produced with a 5.7 vs. 5.3, those MPGs saved will definitely add up. My guess is even though the 5.7 might have been better suited for truck stuff (ik this statement is argumentative), the 5.3 drank a little less, so it was a better candidate?

Same reason we have these brand new heavy a** Silverados coming out with 4 cylinders in em, whatever will please the environmentalists on paper, and allow the company to produce ICE vehicles... you gotta do what you gotta do.

Also, please correct me if I'm wrong, but don't automotive manufacturers have to support a vehicle they produce for like 10 years or something at minimum? My guess to that second question quoted is that GM already met their minimum requirement and moved on to the more relevant stuff for them (i.e. LS-based engines and resources for future projects). No point in spending money to keep the operations running if the majority of people at the time are not buying the replacement parts being produced.

 

[letitsnow]

I must have missed something, but stock motor performance has no meaning to most of us as not even my cub cadet is left totally stock.

Carry on.

 

[Curt]

I must have missed something, but stock motor performance has no meaning to most of us as not even my cub cadet is left totally stock.

Carry on.

"I'm gonna keep it stock this time, I swear"

You must be registered for see images attach