Z28x

I've seen this rumor a few times out on the internet, can anyone confirm or deny it? This is said to be the rating for GMT900 trucks. I could see this being true given the LS4 specs combined with a freer flowing RWD exhust setup.

96_Camaro_B4C

355? In the 5.3? I don't think so. To get that power, I expect it would need a "bigger" cam, more suitable to a performance car than a truck.

I'm "fairly certain" the 5.3 won't be that strong.

Of course, unless you have a sick desire to go drag racing in your pickup, I think the current 5.3 has more than enough real world go juice. But, since power still sells, more power will be necessary to go against the 'hemi', Nissan's strong 5.6 cammer, and whatever Toyota has up its sleeve for the '07 Tundra.

Z28x

I also forgot to mention, when Chevy released the 310HP aluminum 5.3L for '05 they said The Gen IV 5.3L had more up it's sleeves, or something to that effect.

Gold_Rush

I don't know.

GM's usual way of handling large power increases isn't through heavily tinkering with smaller motors if you know what i mean. That's honda's thing.

The 5.3 is capable of it i think with the right tune, but i don't see GM going through that trouble. Especially when a 6.0L will easily belt out 355 horses and more without breaking a sweat.

That and isn't the 5.3 the base motor? If they have 355hp, where does that leave the larger 6.0L vortecs and such?

Another thing, a 355hp 5.3 will be making most of its power higher up in the revvv range with perhaps a sacrifice in lower-end grunt. Great engine for something like a camaro, but i don't know about a full-sized truck. Most of todays trucks produce their peak power in around the 5200rpm range and tq in the mid 3k's to 4k range. Those kinda rpm's aren exactly hp friendly. It would be great if they can deliver 355hp and equal amounts of tq without sacrificing lower-end grunt though.

I kinda have my doubts, but i could be wrong.

Z28x

The Vortec 6.0L will be making 400hp/400tq for 2007.

The 4.2L DOHC I6 makes 275HP and could probably be tuned to make a little more (can it use direct injection )

So you have a 275HP-300HP base 6 cyl. and a 400HP 6.0L above that and the 5.3L somewhere in the middle. Compression could be bumped from 9.5:1 to 10.0:1 and still run on 87 octane.

PacerX

I would not bet against GM in a horsepower contest where V8's are concerned.

The LS2 is using a baby cam for it's displacement.

The puzzling thing is that there is very little cost difference between a 6.0 liter and a 5.3 liter. The rest of the drivetrain needs more beef, but the engines themselves are so similar as to make one begin to wonder why the 5.3 liter is really needed at all... especially since the 6.0 liter motors can use DOD also and get good fuel economy in the Corvette.

So... that's my vote.

6.0's for everybody!

90 Z28SS

It would be alost too easy to get 355 hp out the 5.3 in the way GM would have to do it . The standard pretty much for V8 now thanx to Nissan is 345hp . Isnt that the stock rating for the titan ?

Z28Wilson

I believe the Titan's base is 305 HP...right now the Hemi has the HP crown at 345 (although doesn't GM's 6.0 make 345 in trucks as well?)

Ken S

maybe they are making the cam's ramps a bit more agressive, having them open and close faster and lift higher, resulting in springs a bit stiffer, etc, along with other small tweaks like a better intake manifold, better exhaust setup, slighting better head ports, etc..


We all know the aftermarket proved its all possible.. So I can believe that GM finally has gotten around(or simply decided its time) in testing/proving a tiny bit more agressive valvetrain setups, while evoloving the design and manufacture of the other components, resultingin a about a 20 hp bump.

Plus, if they are paired up with a 6 speed trans, It could have aggresive low gears, and the smarts and physical amount of gears to choose from to keep the rev's in the right place at all speeds. Having low end tq would still be important, but a smart 6 speed will definantly help manage it all.

PacerX

The 6.0 liter makes 345hp in some applications.

Gold_Rush

The I-6 will see use in the next gen trucks?

Gold_Rush

It's rated @ 305hp, but it's said to feel/run stronger than the ratings indicate.

redzed

Nissan's 5.6 liter puts out more torque (on 87 octane fuel!) than the premium gas swilling 6.0 liter in the Silverado SS and Cadillac Escalade. That's part of the reason it feel stronger than the indicated 305 horsepower.

Darth Xed

Escalade 6.0 litre specs:

345 hp @ 5,200 rpm / 380 lb-ft @ 4,000 rpm


Armada 5.6 litre specs:

Endurance 5.6-liter DOHC 32-valve V8 engine
305 hp @ 4,900 rpm
385 lb-ft of torque @ 3,600 rpm

While I am a torque fan, I'll gladly sacrifice a measly 5 lb-ft of torque for a whopping 40 horsepower gain.

EDIT: Also, according to the Chevy website, RPO LQ9 (H.O. 6.0 litre V8 in Silverado SS) is recomended to be used with REGULAR 87 octaine fuel

http://www.chevrolet.com/silverado/specifications/

Z28x

The 4.8L V8 is said to be droped (too bad, that would have made a nice Colorado/H3 engine) and so is the 4.3L V6, the I6 was suposed to be used on the low end.

400HP/400tq V8's in every truck, SUV and van Back in 1988 the top 1500 engine was a 200HP 350c.i. (5.7L) V8 and everyone was happy. , With gas prices the way they are GM needs to concentrate on fuel efficency just has much as HP/tq output.