285HP 4.8L in 2004 Silverado

[TedHam]

I read (somewhere) that GM was increasing the HP/TQ in the 2004 4.8L V8. Does anybody know how they managed this increase? Was it just an enlarged exhaust or better intake ductwork OR something more complex such as cylinder heads, cam or compression?

 

This inquiring mind wants to know...

[Bruce03Silverado]

I asked the same thing but no one really was able to tell me. My buddy, who used to sell Chevy's, said it wouldn't suprise him if it always was rated at that since GM has the reputation for underrating their vehicles..who knows?

[SilveradoWV]

I was thinking it was just under rated, or something to do with the computer to get more power. I dont think they are going to change parts or something like that.

[RyanbabZ71]

the 5.3 was bumped up from 270 to 285HP in 2000 by using the 6.0 liter cam. I heard the recent increase was a computer tuning upgrade

[TedHam]

Ryan, Do you mean the 5.3L increase in 2004 or the 4.8L increase (or both)?

[RyanbabZ71]

the 5.3 was rated at 270HP in 99 and it was bumped up to 285HP in 2000.

 

The 4.8 was 255HP in 99 and 270HP in 00

[Truckman031]

The 04 5.3 is supposed to have 295 HP.

[Roofer]

Yep, the '000-'02 5.3's were rated at 285HP, then 290 for '03, now 295 for '04. I haven't seen the TQ #'s move at all. I really think it is all for marketing.

The new F150 Triton is rated at 300, and now Nissan rates their 5.6 at 305HP.

 

I personally thought the 5.3 needs more torque and the old 5.4 needs more HP. I have not even seen a new F150 up close let alone drive one. I hear they are not what they are hyped up to be as far as power. Same for the Hemi. The 5.3 is one racey engine, but I liked the torque of the old 350 Vortec.

[PunchT37]

All i believe they did was raise the rev limiter. Notice the HP is 295@5600

instead of 285@5200.

[Roofer]

I thought the rev limit was 5600 for '00-'02 models.

[k1500chevy97]

Enough about HP .

We need to know if they increased what really matters ... torque !!!! ???

[Truckman031]

Enough about HP .

We need to know if they increased what really matters ... torque !!!! ???

[TedHam]

Well, I suppose I'll gradually beef up the performance of my light-weight 270hp 4.8L in the form of the following mods (over a long time):

 

K&N filter

Dual Exhaust

MAF Sensor

Throttle Body

Computer Calibration

Hypertech PRogrammer

 

The last four items will be 'way' down the road. Budget is pretty much blown after the duals

 

Thx for all of your input

[99-2door]

Even though they may be hrad to spot, generally every year or 2 there are changes made to the engines. One changes I can think of for 03 was the move to a fly by wire throttle instead of a actual throttle cable. This allowed the removal of several items from the engine (IAC valve etc.), as well as allowing more precise computer control over the engine perfpormance by giving it the ability to manipulate air intake. I know this alone does not account for the HP numbers change, but this is just an example of how small things change on the engines even though they may be basically the same. Since 97 the corvette LS1 (which has always had fly-by-wire) has not included and EGR system. Does anyone know if the 5.3L still has EGR components after 03?

[Tommy'Z 6speed]

I received a seasonal magazine of some sort from GMC yesterday. I talked about the changes for '04. The only changes I remember being mentioned was the elimination of the fuel return line(this, according to the article, reduces the underhood fuel temperature) and the fixed orifice PCV valve.

 

It also had a Hp/Torque chart for all engines and I believe the 5.3 HP was listed at 5200 RPM (295HP).

 

My '03 is listed as 285 HP in the sales brochure.

 

As for other changes, SLE gets the foglights as standard and the base model truck gets Cruise control, chrome bumpers/grill with black bodyside moulding.

There were a couple other things but I forget what they are right now.