engines. 4.9 VS. 5.7 - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 02-20-2002, 03:20 AM Thread Starter
 
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engines. 4.9 VS. 5.7

both engiens are vortec. my buddy is claiming the engine in the soon-to-be his 2001 Z-71 has more Hp and Torque than mine does. i know they haev made some advances in the engines, but i would thin kthat with that much of a difference in CID that it wouldn;t beat me...maybe but not mby much. anyone know for sure?

---Peacock posted this
<font color=red>'96, richmond 3.73, detroit rear, cold air, dual flowmasters, new drive-train,</font color=red>
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post #2 of (permalink) Old 02-20-2002, 07:17 AM
 
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Re: engines. 4.9 VS. 5.7

The 4.8L and 5.3L are both based on the new LS-1 (same family) having an aluminum block and heads. The 4.8L produces 270 Hp @ 5200 rpm and 285 lb-ft of torque @ 4000 rpm. The 5.3L produces 285 hp @ 5200 rpm and 325 lb-ft of torque @ 4000 rpm. I am not sure on the older vortecs but I think around 240 hp, so yes the new motors would have more power.

'02 Silverado 1/2 ton ext. cab, mods to come
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post #3 of (permalink) Old 02-20-2002, 11:27 AM
 
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Re: engines. 4.9 VS. 5.7

Also, I think the Z71 package automatically upgrades to the 5.3L

'02 Silverado 1/2 ton ext. cab, 8.5mm MSD, more to come
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post #4 of (permalink) Old 02-20-2002, 11:41 AM
 
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Re: engines. 4.9 VS. 5.7

I'm pretty sure, that I heard the "Z-71" sticker alone adds 20HP [img]/wwwthreads_images/icons/wink.gif[/img]

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post #5 of (permalink) Old 02-20-2002, 12:10 PM
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Re: engines. 4.9 VS. 5.7

doesn't it matter where in the rpm scale this horsepower and torque number peak? i would assume torque numbers for a larger cid would be lower on the rpm scale. like a deisel. there's a difference between the same horsepower rating on different displacement engines. one being better than the other. so i've heard.
just race him or try a tug of war and let us know what happens.


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post #6 of (permalink) Old 02-20-2002, 12:41 PM Thread Starter
 
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Re: engines. 4.9 VS. 5.7

well damnit. i guess i didnt want to hear that answer. i will go ahead and hook the strap up though. they way i see it. with a locker and a stick. i can just give her hell and sip the clutch. even if i dont win, his truck will be covered in dirt thatnks to my friends at Cooper tires

---Peacock posted this
<font color=red>'96, richmond 3.73, detroit rear, cold air, dual flowmasters, new drive-train,</font color=red>
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post #7 of (permalink) Old 02-20-2002, 12:53 PM
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Re: engines. 4.9 VS. 5.7

I think Hp and Torque numbers published by Chevy are bogus. They're measured at the flywheel usually. Still, all things being equal, every time GM has developed a more efficient Vortec in a smaller CID, they always report higher numbers. From a 4.9 to a 5.7, though...who knows. Plus, all you'll care about is rear wheel horse power, and all sorts of things can change that for you. Who cares who has the stronger engine...who has the stronger truck is what really matters. Better yet, who has the perfectly matched truck to their driving styles.


post #8 of (permalink) Old 02-20-2002, 01:15 PM
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Re: engines. 4.9 VS. 5.7

My wifes '01 Tahoe has a 5.3, and my 97 has a 5.7. I know that the 5.3 is supposed to make more power, but I can tell you right now that my truck would whip that thing up one side and down the other. I know a Tahoe probably weighs a lot more than a pu, but I also have the 33's, toolbox of junk, full grill guard and rear pipe bumper etc,. So, I think right now we are about fair in reguards to weight. The only thing engine wise that I have done to my truck is a K&N...and I do have that "Jetlike" tranny. Still, the Tahoe is fast, but it aint gonna outrun my 97.

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post #9 of (permalink) Old 02-20-2002, 01:49 PM Thread Starter
 
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Re: engines. 4.9 VS. 5.7

well, K&N, dual flowmaster exhaust, locker and 33s....i think i"ll be alright. i wish i knew his gear ratio. i can't imagine on a stock LS it would have anything higher than 3.73 so we'll be ever there. i guess i just dont understand how an engine that much smaller can deliver that much more power perCID. oh well.

---Peacock posted this
<font color=red>'96, richmond 3.73, detroit rear, cold air, dual flowmasters, new drive-train,</font color=red>
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post #10 of (permalink) Old 02-20-2002, 02:00 PM
 
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Re: engines. 4.9 VS. 5.7

3.42 is stock, 3.73 is an upgrade at not charge and for an extra $50 you can get a 4.10. When I got mine off the lot, it was a stock LS with the 3.73 in it.

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