Old 5.7 TBI vs Newer 5.3 - at 2200 rpm?

[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.