Old 5.7 TBI vs Newer 5.3 - at 2200 rpm?

[Davidss]

So I have a 1992 Chevy C1500 that is used as a dedicated tow vehicle. I put over 20k miles a year on the truck and almost all of it is chugging along at 2200rpm towing a very lightweight racecar and trailer. The truck has a 5 speed manual transmission and we just keep it in fifth gear all the time. Unless we're heading over a mountain the truck has just enough torque that it never needs to shift.

As the truck is getting older so I am considering either rebuilding the current engine or swapping in a newer 5.3. The 5.3 is really attractive, it is a great value, it's a much better motor, and it obviously make tons more power up top. And I understand that the 5.3 will probably make a little less power under 2000rpm compared to the TBI.

So right at 2200rpm which engine makes more power?

Does anyone have a 5.3 dyno that starts at 2000rpm?

[kerrige]

I am not sure about stock, but with very mild mods or even just boltons the 5.3 will way out perform the old Tbi motor. A small mild cam like a 212/218 cam will make a 5.3 crazy stronger than the old 5.7

[Davidss]

I am not sure about stock, but with very mild mods or even just boltons the 5.3 will way out perform the old Tbi motor. A small mild cam like a 212/218 cam will make a 5.3 crazy stronger than the old 5.7

There is no doubt a modded 5.3 can make tons of midrange and top end power. But that's not what I need.

Do you have any dynos of modded 5.3s that show the low end?

[kerrige]

http://www.truckinweb.com/tech/1110t.../photo_01.html
This one starts at 2500 where it makes 300ft/lbs. a little unfair, because it is a genIV 5.3.

http://www.kandn.com/dynocharts/57-3058_dyno.pdf

This one isn't much better.

The thing you have to keep in mind is that most dynos don't start reading until 3000rpm. As for down low pulling power. I have pulled many trailers with 5.3s without a problem. If you want lots of down low power a 6.0 with a baby cam and boltons will work amazing. These motors make more power than that Tbi motor in every area. I have seen some of obs motors put down in the 125-130hp and torque range at peak rpm. A 5.3 will make more power than that at 3000 rpm let alone it's advantages at 2200. Really if you are looking for mpg while towing.... Buy a diesel.

[Frenchy]

mine makes 300 ft/lbs from 2000 or 2500 (wherever they started the dyno) up to 4400 where it peaks.

[ccreddell]

Think about it in terms of stroke length. A 5.7 has a stroke of 3.48". A 5.3 is 3.622". So the 5.3 has the advantage right out of the box. All things being equal, the 5.3 will have more torque. But things arent equal. The 5.3 has better heads and a better fuel injection setup so its better still. And if you are going to go through the trouble of swapping engines, and arent willing to put a cam into it that addresses your specific needs, then why bother.

[blacstar]

well from owning both a 1994 5.7 reg cab 5 speed and a 2007 classic 5.3(swapped) 5-speed. the power band in the 5.3 is wider than the 5.7. both engines in stock trim pulling the same weight( gsxr600 in the bed, 2 gsxr 1000;s on the trailer); i kinda struggled in the 5.7 to get up to 100mph in 4th/ cruise in 5th @100 with the 5.3. plus the efficent 5.3 is roughly 5-7mpg better pulling the weight mentioned above.

[canada4g63]

If you have access to a cheap 5.3 then go for it but not sure if your trans will work with it so you have to keep in mind a new trans to. I put a cam/header bolt on in my TBI, has pleanty of towing power.

[Show&Go]

I'd say go for it... Biggest issue with the cam and all added to the 5.3 is it may end up out running the Honda that's on the trailer if you kept working on it. Then you will need a tow vechicle for your tow vechicle. * insert Xzibit meme *