05 Vortec 4.8l V8

[mrsilv04]

Originally Posted By: Jim 5
What I don't understand is why a de-stroked 5.3 such as the 4.8 (this being the only real difference) should cost a penny less to buy or manufacture than the 5.3.

In fact, since the 5.3 is the most common and therefore the highest production option, and given that the 4.8 and 5.3 are basically identical (apart from the stroke), then the 5.3 should be, based upon economies of scale, the most inexpensive engine option.

It seems to be marketing, and as an uniformed observer, it appears like the 4.8 exists so that GM can charge "extra" for the 5.3 that most people will choose anyway.

I don't know what I'm talking about here, and am open to being corrected, but I see no other explanation.


The bigger engine always costs more?

The Chevy and GMC dealers in this area will not have an extended cab with a 4.8 on their lots... it will always have the 5.3.

However, in a regular cab, they'll order them with the 4.8.

 

[ekpolk]

But if I were ordering, I see no reason I'd ever order the 4.8L. It produces substantially less hp and tq, while having worse fuel econ than the 5.3. I don't even get why the 4.8L still exists in the line if GM is unwilling to confer upon it the benefit of cylinder deactivation, etc.

 

[Camu Mahubah]

The 4.8 kinda reminds one of the 305. Though I wouldn't go slammin this engine as it is a gutsy little runner. Friend has one in a Chevy 2wd 1500 and runs like a top. Ford has a 4.6 but most pickups come with the 5.4.

If I wanted a new Chevy or GMC I would see if I could find the 4.8. Overbuilt and maybe a bit more economical nah mean?

 

[bretfraz]

Originally Posted By: ekpolk
I'd agree that there's probably a strong marketing influence going on here. But I remained baffled by the continued existence of BOTH the 4.3L V-6 and the 4.8L V-8 in the Silverado line (and the lone 4.8L in the Tahoe line). Wouldn't it just be cheaper for GM to kill one of the engines, thereby cleaning up the supply line, inventory, etc., and leave the survivor to alone fill the role of the "cheap" bottom-of-the-line economy engine? Maybe having both allows sales to commercial buyers who insist upon having a six for their ultra-cheap W/Ts while also having a "higher tech" alternative for those buyers who might value that. Dunno, just me thinking on the fly (usually a very dangerous thing...).


Ya know, I thought the 4.3L was discontinued but I just checked KBB and, lo and behold, you can still get the 4.3L in standard cab Chevys, both the old '07 "classic" style and the new GMT-900 body.

Of course, the 4.3L is way down on HP compared to the 4.8L. 195HP V6 vs. 295HP V8. But, the 4.8L costs $945.00 more, so that's an issue with some buyers, I'm sure.

I'm sure there's still a demand on the commercial side for the V6. Lots of them out there and many fleet customers want to standardize their fleets as much as possible.

 

[GMBoy]

Originally Posted By: MrCritical
We've had 4x4 crew cabs with the 4.8, so I guess the 5.3 isn't standard with 4x's.

EPA rates the 4.8 higher in hiway mileage than the 4.3 v6.


Could you tell me what years those 5.3 crewcabs where? Because my research shows the 4.8 available with an extended cab truck but crewcabs required the 5.3 with 4x4.

 

[GMBoy]

Originally Posted By: ekpolk
Originally Posted By: wapacz
Its a 6 liter in the hybrid. The larger displacement most likely increases the amount of time it can spend with deactivated cylinders. Which would increase fuel economy.

my guess for the 4.8 is that it is a mix displacement and the amount of them they sell.





Car and Driver has an article on the Tahoe Hybrid in the latest issue (March 2008). The author states that GM used the 6.0L version of the engine for the hybrid because of torque advantage at lower rpms.

I'm sure that the 4.8 is a fine engine, but I still don't get why it's (still) there. It has the same external dimensions at the larger displacement versions, produces lower hp/tq, and lower mpgs.

I'm not sure GMBoy will be at liberty to comment, but if he is...



Hello!

I agree in that I see no use for the 4.8. We put the 4.8's in base 2WD only Tahoes/Yukons and these are very few. No 4.8 with 4 wheel drive. It does, as mentioned, seem like the 4.8 is the old 305 - except that the 4.8 is a pretty muscular little engine. The 4.8 does not have cylinder deactiviation, whereas the 5.3 does. Of course there are 2 versions of the 5.3 - one E85 and one not. There is no E85 4.8, 6.0, or 6.2. If I were in charge, I would dump the 4.8 because you get more power and MPG with the 5.3 as well as E85 capability.


As for the Hybird, yes, it is the 6.0 with cylinder deactivation. The 6.0 was chosen over the 5.3, which surprised me given the MPG goals. Only thing I can say is that the Hybrid Escalade is due out soon, and we have built several as pilots and they have the exact same drivetrain as the Tahoe/Yukon hybrids - the 6.0L. Regular Escalades get the 403hp 6.2L. So, perhaps GM planned on the 6.0 during Hybrid planning so it could be "excepted" by Cadillac buyers with the 6.0 instead of the smaller 5.3. So Caddy Hybrid buyers don't feel cheated maybe? I'll have to ask somebody that question...

 

[Harley Anderson]

Originally Posted By: ekpolk
But if I were ordering, I see no reason I'd ever order the 4.8L. It produces substantially less hp and tq, while having worse fuel econ than the 5.3. I don't even get why the 4.8L still exists in the line if GM is unwilling to confer upon it the benefit of cylinder deactivation, etc.


If you look at the hp and tq rating for both of these engines, the 4.8 has 15hp and 30tq less then the 5.3. But I do agree with you on why this engine exists unless it is a pitfall of gm turning more profit on the 5.3.

 

[ekpolk]

Harley:

According to the present Chevrolet and GMC sites, the current differences between the 4.8L and the 5.3L are 20 for hp and 33 for tq. Close enough to the numbers you quoted to look like quibbling on my part. What seems more important to me are the rpms at which each engine peaks. The 5.3's peaks, both hp and tq are lower than the 4.8's. And although you can't glean it from the single data points provided, I suspect that the 5.3's curves, particularly the one for torque, are substantially better than the 4.8's.

 

[Norm Olt]

Originally Posted By: Jim 5
Incidentally, the 6.0 is just a bored 5.3. Without looking at the serial number, one wouldn't be able to tell the difference between a 4.8, a 5.3 and a 6.0 by looking at the outside.


I really think it is a little more than just a difference in the diameter of the pistons... Don't you?

 

[Harley Anderson]

Originally Posted By: ekpolk
According to the present Chevrolet and GMC sites, the current differences between the 4.8L and the 5.3L are 20 for hp and 33 for tq. Close enough to the numbers you quoted to look like quibbling on my part.


I knew I was pretty close, my dad's truck is a 01 so maybe the numbers have changed a little since then. I just remember looking them up for him, since I was trying to win an argument. Thanks for the correction.

 

[gtx510]

http://en.wikipedia.org/wiki/GM_Vortec_engine#V8

 

[GMBoy]

Originally Posted By: Norm Olt
Originally Posted By: Jim 5
Incidentally, the 6.0 is just a bored 5.3. Without looking at the serial number, one wouldn't be able to tell the difference between a 4.8, a 5.3 and a 6.0 by looking at the outside.


I really think it is a little more than just a difference in the diameter of the pistons... Don't you?




Actually Jim 5 is pretty close - there are just slight internal differencs like bore/stroke. Externally, You could not tell a 4.8 from a 5.3 from a 6.0 from a 6.2 by sight if they were all in a row. All these engines also take all the SAME external parts like engine covers, alternators, belts, p/s pump etc.

 

[Norm Olt]

GMBoy: I actually was referring to the OTHER internal parts (the ones you CAN'T usually SEE)...

Heads, camshafts, valves, cranks, rods, etc.

Plus exhaust manifolds, maybe?

There will be some unhappy Escalade owners out there if you tell 'em the only difference between their 6.0 and a 4.8 is pistons!

Shades of the Chevy/Olds/Pontiac/Caddy 350 cu.in. V8's?

 

[ekpolk]

Originally Posted By: Harley Anderson
Originally Posted By: ekpolk
According to the present Chevrolet and GMC sites, the current differences between the 4.8L and the 5.3L are 20 for hp and 33 for tq. Close enough to the numbers you quoted to look like quibbling on my part.


I knew I was pretty close, my dad's truck is a 01 so maybe the numbers have changed a little since then. I just remember looking them up for him, since I was trying to win an argument. Thanks for the correction.


Of course, my main point was that the what appears to be a relatively small spread in hp and tq, probably feels larger because of the different rpms at which the hp and tq peaks are achieved.

 

[Jim 5]

Originally Posted By: Norm Olt
Originally Posted By: Jim 5
Incidentally, the 6.0 is just a bored 5.3. Without looking at the serial number, one wouldn't be able to tell the difference between a 4.8, a 5.3 and a 6.0 by looking at the outside.


I really think it is a little more than just a difference in the diameter of the pistons... Don't you?


Apart from the pistons, the rings and the software programmed into the PCM, (and in the case of the 4.8, the crankshaft) I am not aware of any differences.

I could list all of the things that are the same (apart from the differences noted above) until I am done listing all of the things needed to build a 4.8, a 5.3 and a 6.0. As far as I know, there wouldn't be any differences on that shopping list.

What differences are you aware of that have led you to this conclusion?

 

[Jim 5]

Originally Posted By: Norm Olt
GMBoy: I actually was referring to the OTHER internal parts (the ones you CAN'T usually SEE)...

Heads, camshafts, valves, cranks, rods, etc.

Plus exhaust manifolds, maybe?

There will be some unhappy Escalade owners out there if you tell 'em the only difference between their 6.0 and a 4.8 is pistons!

Shades of the Chevy/Olds/Pontiac/Caddy 350 cu.in. V8's?


I didn't see this post. Escalade owners are safe. Their 6.0 until 2007 MY I believe (the LQ9) is different than the garden variety 3/4 ton truck/hummer 6.0 (the LQ4) in that the LQ9 has higher compression pistons than the LQ4. This gives about 20 more HP and comparable increases in torque over the 3/4 ton truck/hummer 6.0.

I have done a fair amount of research on this subject with the assistance of GM Boy who works at the GM facility that builds suburbans etc. I am doing this with a view to doing an 5.3-->6.0 conversion on my avalanche. It is great in the city, but doesn't have enough power for it's travel trailer towing duties.

Cylinder heads, intake/exhaust manifolds, throttle bodies, coils, pans, pumps, alternator, block....all identical (some get the aluminum block, such as the trailblazer). In 2007 variable valve timing and cylinder de-activation was added AFAIK. My comments relate to pre-2007 engines.

 

[ekpolk]

Jim:

Not questioning your plan -- you've done the homework, and I have not. I'm curious, though, at what point does it become more practical to simply do an engine swap versus trying to rebuild to the new displacement? Put another way, if you could find a good, low mileage 6.0L in a nearby yard, might it not be easier to just transplant whole engines?

 

[XS650]

Originally Posted By: ekpolk
But if I were ordering, I see no reason I'd ever order the 4.8L. It produces substantially less hp and tq, while having worse fuel econ than the 5.3. I don't even get why the 4.8L still exists in the line if GM is unwilling to confer upon it the benefit of cylinder deactivation, etc.


It exists to make the 5.3 look good.

 

[XS650]

Jim5, what's your plan? a 6.0 short block?

IIRC, the heads are also the same as some 6.2 engines.

 

[rpn453]

Originally Posted By: ekpolk
Car and Driver has an article on the Tahoe Hybrid in the latest issue (March 2008). The author states that GM used the 6.0L version of the engine for the hybrid because of torque advantage at lower rpms.


I just read that article. I was surprised to read that it's an Atkinson cycle engine, so it's not as strong as the regular 6.0L.