Just curious, what are some of the stock times for the 99-current GM trucks? My friend has a 99 regular cab Z71 (split year right? His is the new body style). He claims his father who works for GM got him the truck with a 5.7L. I've never heard of a 5.7 in this body style and can't fathom why you would want one. I have not looked under the hood, but I'm assuming that he has the 5.3L. If his truck was completely stock, what should it be running? If he has a cat-back exhaust then what? He and some of his other friends seem to think it will do high 14's to low 15's. I'm calling BS, but I'm not real educated in this area. What is the opinion of this board?

Thanks in advance!

 

in 99 if you got a U.S. version regular cab Z71 you got the new body style with only the 4.3L, 4.8L, and 5.3L to chose from. you could get the old body style truck in a half ton yet, but only in an extended cab. i believe you could get the new body style truck with a 5.7L L31 in mexico though. i'm not positive on that though. either way a regular cab 4x4 99' with a 5.3L should run around a 16.0-16.5 stock.

 

Take a peek at his vin #. If the 8th digit is a W = 4.3, if its a V = 4.8, if its a T = 5.3, but only if the first digit is a 1 (US) or 2 (Canada). If its a 3 then it was assembled in Mexico where they came with the L31 Vortec 5700 (255 hp) from 99-02. 03s+ got the 5.3.

I've heard that the 5.7s are a tad slower, but are great for towing. They got a better torque range than the 5.3.

1996-2000 5.7L (L31)
255hp @ 4800rpm & 330 lb/ft torque @ 2850rpm

2000-2002 5.3L (LM7)
265hp @ 4800rpm & 300 lb/ft torque @ 2850rpm
285hp @ 5200rpm & 325 lb/ft torque @ 4000rpm
as per GM Powertrain

99 5.3s have 270hp becuase they had a 115.5 LSA vs 114 LSA for 00+.

hope this helps.

 

 

Well Put Tractionless

 

i've towed with the 5.3L and the 5.7L. the 5.7L sucked for pulling to me. there is nothing at all when the rpm comes up and in my experience when i'm towing i never run the rpm very low anyway. fortunatly the 5.3L has a bit more more torque in the upper rpm which once you get the trailer rolling is where it matters. i'll take that 5.3L for pulling anyday.

 

First off, thank you all so far. I'll check his VIN, but I'm pretty sure already that it is a 5.3L. So at best with the exhaust, he'll be high 15's? Don't have to answer that unless it's wrong, I'll just assume.

One last question. Have any of you experienced a problem where.... Over 3/4 throttle, the rpm's go up but the engine isn't producing anymore power? This is actually on a jeep GCL 5.2L but I haven't been able to get anything to work from other forums like Jeepsunlimited. Just thought I'd give it a shot, sometimes other people have had similar experiences. Thanks again everyone!

 

my best stock e.t. for my stepside 4x4 5.3 with 3.73's was 15.21@87.8. With cold air induction and cat back it ran 15.0@91. The truck weighs 4550 with no driver, no tailgate, and no spare.

 

My ECSB 5.3 Z71 ran a 16.8 best completely stock. What a dog!

 

Mine ran 16.12 at 87.38...a guy here at work has a 00 rcsb Silvy 5.3,3.42,CAI and cat back and ran a 15.52 at 87. Z-71 with same stuff would be a little slower.