These questions deal with the Chevrolet 3.7 litre 5-cylinder engine; and are for our automotive experts and anybody else who may have had experience with this engine.
My wife and I are considering buying a new truck at some point in the next year or so. Recently, the Chevy Colorado caught our eye. In doing a bit of online looking at the truck, we noticed that among the engine offerings is a 3.7 litre, 5-cylinder, aluminum block engine. Questions:
– I’m a little leery of a 5-cylinder engine. I’m unfamiliar with odd numbers of cylinders in anything except small two-stroke engines, such as lawnmowers. Why did Chevy choose to put an engine with an odd number of cylinders into production? How well does this Chevy 5-cylinder perform, in your experience? How reliable is it?
– The online literature mentioned that this was an aluminum block with “cast-iron inserts.” I’m assuming that these inserts line the cylinders themselves. Didn’t GM try aluminum blocks back in the 1970s with various small Chevys and Pontiacs, and didn’t they turn out to be disasters? IIRC, it had something to do with the differing expansion rates of aluminum and iron when heated (and there is no doubt that an engine heats up), resulting in unpredictable stresses on parts. Has GM fixed this problem? Has it re-engineered these aluminum blocks to account for past problems? Or is it simply trying again and hoping for the best?
I’ll admit I’m attracted to this engine, because the (approx) 150 hp or so 4-cylinder seems a little small for a truck this size, but the 300 hp V-8 seems too much. But as I said, I’m not entirely sure about an aluminum 5-cylinder. I will, of course, look to other published consumer and automotive information as well, but for now … any thoughts?
I had Chevy Vega with an aluminum block. It warped and became a huge problem. They rebuilt it twice. I was without it for a month each time. That was a long time ago. I am sure they are better now.
Aluminum blocks with steel or iron cylinder liners (inserts) have been around for a long time, so i wouldn’t be worried about that.
What I would worry about is the vibration issues with a five-cylinder, their propensity to make all the power of a four while providing the fuel economy of a six (at least VW’s does), and GM’s practice of conducting product durability testing using their customers.
Vibration should be unremarkable - it’s an in-line design, not a V type construction. Seems to be a modern design with dual overhead camshafts. BMW is a prominent producer of in-line fours and sixes and Volvo used to have/still has in-line 5 cylinder engines. They are considered quite smooth. Modern aluminum block engines bear no resemblance to the Vega engine. Cast iron liners are common, along with metallic powder coatings to increase wear resistance. The power and torque increase over the four doesn’t quite split the difference to the V-8 option. Depends on your needs. Are you going to tow trailers and the like?
No. I can see where towing a large camping/RV trailer would require the power of the V-8, but we don’t plan to do any towing. We do plan on loading and moving various building materials and large objects from time to time, which explains our interest in a pickup truck; but for our needs, such a truck doen’t have to be full-sized. Reliability is key though, as is fuel efficiency–I realize we won’t get the best fuel efficiency with any engine that can power a truck, but since we’re not going to (for example) pull heavy RV trailers, the V-8’s power seems like overkill and its comparatively worse (over the I-5) fuel efficiency makes me wonder if the smaller engine is a better choice to meet our needs. Hence my interest in the I-5.
I remember those old Chevy Vegas too, which explains my concerns with aluminum blocks. But it seems that the problems have been largely dealt with, if Volvo can make them work. (And assuming that Chevy is following Volvo’s design and engineering reasonably closely.)
Thanks for the responses so far, folks–looking forward to more, if anybody has more to offer.
I have no practical experience at all with this engine, but I have heard some people complain that it really doesn’t have much more power than the 4 cyl version. The specs I’ve seen don’t seem to agree with these complaints, though (282 vs 185 hp), so make what you will of that.
A lot of folks have made successful aluminum engines. Of course, that doesn’t mean that GM’s version is good, it just means that aluminum isn’t necessarily that it’s bad.
The specs for the V8 don’t seem too bad, though. They list 21 mpg highway for both the 5 cyl and the 8 cyl, and 15 mpg city for the V8 and 16 for the 5 cyl. I personally would probably be more inclined to go with the V8.
I really don’t have much help to offer other than to chime in that I have a 2005 Volvo with an I-5 engine. I get good fuel economy and it has enough power for me (although it does have a turbo on it).
I was thinking of starting a similiar thread but more about the colorado as a package as opposed to just the engine. I was planning on waiting a year or two and buy a used truck but am seriously thinking of taking advantage of the 0% financing, employee pricing, cash back, etc. deals that GM has been promoting recently and buy new.
My brother is a mechanic and he said there was nothing inherently wrong with I5’s. Just more power than a 4 and less than a 6… essentially, exactly what you would expect from a 5 cyl. engine.
I may take one for a drive on Wednesday and will update this thread on my findings but until then hopefully some folks will add their experiences.
I will start by saying I am not an automotive expert but I do have a lot of hands-on experience with engines and other machinery as well as material properties of metals, so FWIW…
I own a 2004 GMC pickup with a 5.3 liter V-8 (my second) and I have owned a full-sized pickup with a slant-6 (Dodge). I can’t see ever driving a full-sized pickup with anything less than a six cylinder. My mileage with the 5.3 is around 17 in the city and upwards of 21-22 on the highway. Better even than what I got with a 5.0 liter V-8 in my last GMC (1997).
As to aluminum engines, I had a 1971 Vega with a 2.3 liter aluminum engine that I destroyed (crack in the head allowed oil/water to mix and overheated big-time) but as gonzomax stated, that was a long time ago. VW was building aluminum engines in the Bug for a long time and I never had any problem with them. Steel sleeves in aluminum blocks are no problem these days as Santo Rugger discussed.
As to odd-number cylinders, Subaru (among others) had a three-cylinder engine back in the 80s that, IIRC, was pretty reliable and didn’t have the vibration you mentioned. Mazda’s five-cylinder was an awesome engine, albeit it was a rotary and not subject to the vibration you mentioned.
Although I didn’t really provide any information on the GM five cylinder (because I don’t know anything about it) I hope that my experience with the GM trucks and aluminum engines is helpful. If not… (to paraphrase Wilbon and Kornheiser) I’ll try to do better next time.
Oh dear. That statement didn’t even come close to parsing.
This is a rotary engine:
Mazda never put those in a car. They DID put a Wankel in a number of cars…still do in fact:
It too is called a ‘rotary engine’, but there’s no way it could be mis-construed as a five cylinder anything.
That aside. GM powertrain can easily be considered one of the best engine manufacturers that exist. Their ability to make a strong, long running, great gas mileage engine is unsurpassed. Their current testing methodology puts a design through things you’d never EVER consider doing (like fire up, bury the throttle, and run Wide Open for a week straight. Or cold start a motor in 40 below weather, time after time after time) Folks are accurately stating the Vega design is firmly in the past, but it helps to remember that it was 38 years in the past.
A version of this motor has already been used in this situation since 2004. More than long enough for Inline 5 Colorado Sucks to show up in google if it’s going to. (On the first page, the only sucks comment is by a Tacoma Owner with no firsthand experience)
The only motor I’d have more confidence in is GM’s V8. The Gen IV V8 is an amazing piece of work and I can point you at a TON of information on it, but it doesn’t sound like that’s the direction you’re leaning in.
Audi also had an inline 5-cylinder engine for many years back in the mid '80s. Vibration was never a problem.
Whether GM got it right this time is a separate issue, but the mere fact of it having 5 cylinders doesn’t represent an insurmountable obstacle to smooth operation.
Volvo has been producing 5 cylinder engines since 1992.
This design is known for very low vibration. Rather than having 2 crank throws like a 4 cylinder (2 cylinders up, 2 cylinders down) or 3 crank throws like a 6 cylinder (2 up, 2 down, 2 midway) it has 5 evenly spaced crank throws. Make for much smoother power delivery than an I4.
The Volvo engine is also aluminum with cast iron sleeves. Absolutely no problems with this. Here is the deal. From a emissions and gas mileage standpoint, Aluminum is perfect. It heats up quick, throws off heat easily, and is a snap to cast. The problem is that piston rings really don’t like aluminum (See early Vega). Piston rings like cast iron. Making the entire engine out of CI has some real drawbacks these days. first off it is heavy, secondly it is hard to heat up and it retains heat. All of which are issues from an emissions and gas mileage point of view.
So the solution that engine designers have gone to is a aluminum block with cast iron liners. This way you get the best of both worlds. This is a very common solution used by car makers around the world. I doubt that you could find an aluminum block engine without cast iron liners in current production from anybody. I could be wrong, but I sure can’t think of any car maker that makes aluminum engines w/o liners.
Answering the OP’s other questions. The problem with the Vega engine was not thermal expansion, but rather the piston rings wearing out the cylinder walls. This engine did not have iron liners. Iron liners fixes the problems that were associated with Vega engines.
Why a 5? I6 engines are long, and you can’t build a smooth running 3+ liter I4. It would be just too rough running.
My take? If you like how the truck drives and that engine seems to fill your needs, go for it. I can see nothing in the OP to rule it out.
Thanks for the responses, folks. You’ve made me think that these engines are seriously worth considering–especially since the old Vega engines appear to have all the faults corrected. Thanks again!
And VanLandry, if you do take a test drive, I’d be interested in hearing how you liked it.
Remarkably, I find that in my entire brain I cannot find so much as one single, tiny, low-maintenance thought, of any kind, about a 3.7 liter 5-cylinder Chevy engine, never mind thoughtS. Otherwise I would definitely share them with you.
I just got back from test driving a Colorado. Unfortunately they only had a 4 cyl so I can’t offer any insight on the OP. They’re trying to track one down at another dealer and swap one of their 4 bangers for it. I’ll give them till the weekend and then I’ll go find one myself. I’ll post my findings here if I do get to drive one. On paper the I5 has the exact same displacement as the Dakota V6 and more hp and approximately the same power as the Tacoma. Again, this is on paper so I’m curious to how it actually performs.
Regarding the truck itself there was nothing glaringly good or bad with it as far as I could tell. After all, it is a truck and as long as the 5 cyl has adequate power I’ll seriously consider buying one.
Finally, my apologies for going even further off topic here but they also just got in a 2010 Camaro(all black). Man, what a nice looking ride that is.
Thanks for reminding me of this. I’ve actually owned two cars with an I-5 engine. The 1986 Audi 4000 I drove in university, and the 2005 Volvo V50 I have now. I didn’t do that intentionally.
