To V8 or not to V8? That is the question

NT1078

Well-Known Member
#1
Hi all,
I realize it has been ages since being on the forum, but that is because our 6cyl Envoy has been remarkably good to us.

I am wondering something:
My Envoy is a bit sluggish when pulling our trailer, naturally. I have a weight distribution hitch, and it does fine in a straight line, but has trouble when towing up hill. It will gear down and do it, but it's a Little Engine That Could kind of thing.

Currently I see a V8 Envoy for sale and am wondering about their reliability, and if it's towing capability is far greater than what I have? I am thinking the V8 will almost be better on gas, as it won't have to work as hard. It has about 350,000km on it, which is a bit high, on the other hand, my 6cyl Envoy is around the same.

Curious to know your thoughts, experience. Thanks!
Adam
 

C-ya

Well-Known Member
#2
If you have your owner's manual handy, it has the chart for towing capacity based on engine, wheel base, 2WD/4WD, and rear gears. With an EXT, V8, 4WD, and 3.73 gears, that gives me 6,500 lbs of trailer weight, 12,500 lbs GCWR. 2WD gives an extra 500 lbs of trailer weight, same GCWR. I would guess the Envoys would be similar (the same??). EXTs were the only TB to get the 5.3 V8 so I'm guessing the V8 Envoy is an XL. Depending on the rear gear, you may get some additional capacity which may help since the trailer doesn't sound like it will be changing.

From an operational point, I love mine now that I have the DOD turned off. Oil consumption is down to about 2 qts per oil change interval based on the OLM which is usually about 5,700 - 6,000 miles. My overall mpg for 6 years is 14. I can do better on long trips, naturally. Yes, pulling may save you a bit as the engine has more power so could drink a little less. You'll lose some - or a lot - of around town mpg. I generally average my average - 14. The winter is less, usually around 10.5 to 11 due to longer warm ups, and the summer is 13-14. Long trips can see as much as 19 to 20. But I don't let mpg determine what I drive. I drive what I like and what does the job.

That's my two cents. Worth exactly what it cost you. Good luck on the decision.
 
#3
EXTs were the only TB to get the 5.3 V8 so I'm guessing the V8 Envoy is an XL.
That is somewhat incorrect. The LM4 5.3L was an option in the LWB in 03-04. 05+ came with the LH6 with DOD and was an option in SWB and LWB.

Anyway you look at it, the V8 will just tow better because of the increased torque and they generally came with the better 3.73 gears. Most 4.2L came with the pathetic 3.42.
 

C-ya

Well-Known Member
#4
@Mooseman , thanks for the correction. I was sure there was some little thing that I wasn't aware of. My '05 manual didn't know of those options so that is what I was going by.
 

Reprise

Lifetime VIP Supporter
#5
Hi all,
I realize it has been ages since being on the forum, but that is because our 6cyl Envoy has been remarkably good to us.

I am wondering something:
My Envoy is a bit sluggish when pulling our trailer, naturally. I have a weight distribution hitch, and it does fine in a straight line, but has trouble when towing up hill. It will gear down and do it, but it's a Little Engine That Could kind of thing.

Currently I see a V8 Envoy for sale and am wondering about their reliability, and if it's towing capability is far greater than what I have? I am thinking the V8 will almost be better on gas, as it won't have to work as hard. It has about 350,000km on it, which is a bit high, on the other hand, my 6cyl Envoy is around the same.

Curious to know your thoughts, experience. Thanks!
Adam

I can tell you're an infrequent visitor / poster, if you haven't seen my 'Towing heavy objects up the Black Hills' thread...lol. Do a scan on my posts, and you'll come across it - it's not old.

I have the 'holy grail' for GMT360 / 370 towing - 2003 LM4 in XL/EXT, 3.73 gear. I say 'holy grail' b/c it was the highest rated of the entire run, towing capacity-wise. 7000 lb in 4WD (+200 in 2WD). WDH above 4K, with a max tongue of about 900 or so. I forget the payload #, but it's easy enough to find.

Now, part of that rating wasn't because GM put anything 'extra' in the 2003-2004, but more because GM revised their tow ratings after then, and everything went down a bit (not just the 360s). Since the '05-ups got a small HP/TQ boost with the LH6 (but also gained AFM), 'real-world' numbers might even be better than my 7K rating. But I'd never advise you do that, from a liability standpoint (seriously).

My engine is stock. The trans was rebuilt a couple of years ago with towing in mind (still a 4L60e; if I had spent the money for a front / rear planetary upgrade, it would technically be a 4L65 - but I didn't). I also have a +10000 BTU trans cooler. Other than that - stock (with a lot of new parts to get her back to spec, maintenance-wise). About 240,000 KM on the clock; mine's not a daily driver.

My rig is a 25' trailer (you can see pics of it in the thread I listed above). Dry weight is 4000lb; last time I weighed at the CAT scales, it was about 5500lb or so (the trailer is rated for just over 7000lb, so it's a nice complement to my Envoy XL.) I do use a WDH w/ adjustable sway control, and if I don't hook up the bars, she will sag noticably in the rear. I have the coil springs in the rear (no self-leveling / air bags)

Now...the part you're interested in...how does she tow?

I'll admit, I'm kind of biased (never owned a 4.2L), but until I started getting into steeper elevations / grades during that trip (above 5000ft / 6% or steeper grade), I never complained about what she had to give.

Based on what I know of the 4.2L, you'd probably gain +15% on the power end. I tow in 3rd (you should, too), and I don't exceed 65-70mph, because that's what the trailer tires are rated at. I also am mindful of what it takes to safely bring down +10000 lbs at speed.

It's absolutely great on flats / smaller hills. But if you're gonna climb the BIG mountains with regularity, you'll find yourself back in 'little engine that could' territory again. Depending on how serious you are about towing, it would be time to look at power adders (turbo, supercharger). That's where the V8 would really shine, as the LS engine family has *so* much aftermarket support (and it will handle those additions well, as long as you're not looking to go nuts - you can get to 500-600hp on a stock lower end without too much worry at all, although I might be looking for a stronger crank at that point, like from a 6.0L (which is cast, itself, not forged).

If I were keeping mine for towing duty, I'd probably look at a turbo; they do better in higher altitudes / thinner air than blowers do (one reason why Ford's EcoBoost motors do so well towing-wise). I plan on towing heavier, and regularly over the next couple of years - so I bit the bullet and bought a 3/4 ton w/ the 6.0L, and am giving it (most of) the same 'honey & nightshade' treatment that the Voy got. LOL

I absolutely love my Voy; she does everything I ask, within reason. And I DID get up the mountains - just a bit slower than everyone else. She does drink a little oil when towing (and I have a leak that I gave up trying to find), and towing that weight for hours on end does stress her a bit (I had to retighten my thermostat housing bolts). But she has never stranded me in 3 years of ownership.

Besides the oil issue (LS engines aren't exactly known for stellar oil control, either), it's a bit tighter in the engine bay; that 5.3L is really shoehorned in, compared to, say a full-sized pickup w/ the same engine.

Any other questions, just ask. Where in Canada do you live / plan to tow? (Americans don't bother with the metric system...that was a sure tip off that you were north of the 49th... :wink: )
 
OP
OP
NT1078

NT1078

Well-Known Member
#6
Thanks very much for the reply. Since posting this I have elected to purchase it. Fir safety I just need to swap the tires from my 6cyl Envoy to this one and it needed a light bulb. I live near Niagara Falls ON. This past week we went away camping, not with the new to us vehicle yet but soon! The 6cyl did ok but again, a bit sluggish which is understandable. Wow, sounds like lots of mods are possible!

.
 

Attachments

Reprise

Lifetime VIP Supporter
#7
Very nice. Congrats! Yes, mods are available - the V8 has that all over the 4.2L (although the 4.2 with its inherently well-balanced inline six, DOHC, and VVT on the exhaust side is no slouch - that's why I estimated only about a 15% gain with the V8, in stock trim.) Since you now have *both* versions, you can do a 'butt dyno' to see how close that 15% estimate is. :wink:

Check to see what axle you got - I'll bet you got the 3.73, which is RPO 'GT4'. 'GU6' would be the 3.42, so if you're 'unlucky' and got that one, you can do an axle swap and gain a little bit there, too (4wd will require the front diff to match, if you want to retain that - which I certainly would, if you're dropping a boat in the water, for example).

The other axle-related code is 'G80' - which is the locking rear differential (similar to the old Positraction, but works a little differently in practice). Those were available (& common) with both axles, so you might just have that in both of yours. Nice to have, but not essential for getting up the hills.

The last axle code is 'GT5', which is a 4.10. Unfortunately, only two GMT360s got this ratio... some early 4.2L models, before the V8 was made available in the LWB models (and likely rare as proverbial hen's teeth), and the 'SS' Trailblazer (TBSS), which has a full-time AWD system (totally different than our on-demand units). No LWB units got stock 4.10s at all, that I know of.

No matter what axle you got - keep it in '3' while towing, to keep the converter from overheating the trans. And as I always tell people - get an external trans cooler! Simple to do and cheap insurance. You can use an OBD-II compliant smartphone app (like 'Torque' or 'Car Gauge Pro'), along with the appropriate adapter module, to keep an eye on your trans temps (and anything else you might want to look at.)

Make sure you report back once you get the maiden tow done with the V8 - it'll be interesting to hear your experience comparing the two, as we don't often have owners who've had both I6 and V8 versions, fewer still who have them at the same time, and even fewer yet who've used both to tow with. So I'll put a 'watch' on this thread and look forward to reading your thoughts, when you get a chance to compare the two motors & their towing abilities. Of course, you want to tow the same routes, for a fair comparison!

Finally, don't forget about recording fuel usage (although us ignorant Yanks would appreciate good ol' MPG vs. 'litres per 100 Km', if you please, accuracy be damned...LMAO)
 
OP
OP
NT1078

NT1078

Well-Known Member
#8
Thanks again for the reply. We will be making the same trek to Grand Island, NY end of September so I can definitely provide a towing comparison. My first observation is the 5.3 vehicle seems more solid, more heavy duty. Here are the RPO codes, seems I am GU6. This evening I painted the rear hatch. Though mint in appearance it was white. I did it with a colour match rattle can and am pleased with the results.
 

Attachments

16vcabman

Well-Known Member
#9
Just my two bits, as I have owned 6 cyl. and 8 cyl. I have towed the same 5000 lb trailer with both. I have to say V8 was by far better! pulled hills better, didn't seem to feel like it was fighting to do the job.
 

Staff online

Forum statistics

Threads
18,536
Messages
565,621
Members
11,124
Latest member
Lopej18

Staff online

Latest posts

Top Bottom