3500-3900 60-degree V6s

[NeonLX]

I'm still amazed that they were able to punch out the 60-degree V6 to 3.9L displacement. There just can't be much meat left in those blocks with those big 3.9" holes.

I remember when the 2.8L V6 first came out in the X cars. When I saw my first one, I was amazed at how puny it looked. I couldn't imagine that it could be bored or stroked any more...but then along came the 3.1L.

Anyone know a good source for info on these engines? I'd love to see the innards. Wikipedia has a decent description but I need visuals!

Thanks.

Edited January 15, 2010 by NeonLX

[CaddyXLR-V]

3.9L

[Robert Hall]

I'm still amazed that they were able to punch out the 60-degree V6 to 3.9L displacement. There just can't be much meat left in those blocks with those big 3.9" holes.

Thanks.

I don't think 3.9L translates to 3.9" (inch) holes. 3.9 is the sum of the volume of all the cylinders in litres, isn't it?

[Drew Dowdell]

I think they staggered the cylinder banks a little bit.

[CaddyXLR-V]

Info and pictures of all GM engines

"This new generation V-6 allows a high level of flexibility, with common castings over a range of displacements. The 3.9L V-6 shares its block, pistons and cylinder heads with GM’s new 3.5L (RPOs LZ4 and LZE). A common bore measures 99 mm; displacement is increased in the 3.9L with a longer stroke (84 mm, compared to 76 mm for the 3.5L). The two engines share 80 percent of their parts.

Thanks to its relatively narrow 60-degree block angle, the 3.9L V-6 is compact, giving vehicles teams more latitude with platform design and styling. More importantly, the 60-degree configuration is inherently balanced, ensuring powertrain smoothness without the additional cost of balance shafts. The new 3.9L V-6 differs from previous GM 60-degree designs in its offset cylinder bores. The centerlines through the bores on each bank do not intersect at the crank axis; rather, they intersect 3 mm below the crank axis. The offset bores present a number of advantages, including room for larger cam journals and flexibility to stroke the engine for more displacement."

Edited January 15, 2010 by CaddyXLR-V

[PurdueGuy]

I don't think 3.9L translates to 3.9" (inch) holes. 3.9 is the sum of the volume of all the cylinders in litres, isn't it?

Essentially correct - it's the displacement. The displacement is affected by not only the size of each cylinder, but the length of the stroke on each piston.

[NeonLX]

I don't think 3.9L translates to 3.9" (inch) holes. 3.9 is the sum of the volume of all the cylinders in litres, isn't it?

Actually, both the 3.5L & 3.9L V6s do have 3.9" bores (99mm ~ 3.9"). The displacement difference between the two is a function of the stroke length.

The "offset bore" concept in the description intrigues me.

On edit: thanks to everyone for the responses!

Edited January 15, 2010 by NeonLX

[Drew Dowdell]

It's like a VW VR6 engine but less extreme.

[trinacriabob]

I like visuals, too. But I also like numbers/stats.

Is there any longevity data on the 3500/3900 versus the previous 3100/3400? All 3500 and 3900 V6s (Chevy) feature VVT, right? Also, is there a longevity difference between these units and the 3800 V6? I didn't want to deal with this "issue," so I defaulted right back into another 3800 V6.

[vonVeezelsnider]

From what I have heard the 3500/3900 don't have the kind of headgasket issues the 3100/3400 had. Also by design of the engine the chronic Intake Manifold Gasket leak has been removed by using some sort of coolant bypass system. All in all completely bulletproof.

All Impala and Monte Carlo applications of the 3900/3500 have been VVT but the 3500 in the earlier G6/Malibu models pre 2007 were non-VVT and that makes a big difference coming from the point of view of having one 3500 VVT (Impala) and one 3500 LX9 (Malibu).

[Drew Dowdell]

Makes a big difference how?

[vonVeezelsnider]

With the VVT the engine runs much smoother.

[regfootball]

don't laugh, but one fallback option i have considered to replace the aztek is with either a late gen rendezvoux or something like an uplander / montana. NOT FOREVER! just for a couple years. the RDV had the 3.5 for awhile and i am not sure but the CSV's even had the 3.9 i think. so i am interested in the relaibility as well.

of course if they still have the crappy 4 speed auto then its probably not worth a look again either.

[Drew Dowdell]

The RDV could also have the 3.6HF

[regfootball]

The RDV could also have the 3.6HF

yes for only two years. but it also had the 4 speed. plus, the 3.6 has issues the first couple years.

[vonVeezelsnider]

don't laugh, but one fallback option i have considered to replace the aztek is with either a late gen rendezvoux or something like an uplander / montana. NOT FOREVER! just for a couple years. the RDV had the 3.5 for awhile and i am not sure but the CSV's even had the 3.9 i think. so i am interested in the relaibility as well.

of course if they still have the crappy 4 speed auto then its probably not worth a look again either.

In Canada we had the Uplander and Montana SV6 from MY 2005-2009 (mainly because they sell like hotcakes, I both think combined they were in the top ten best sellers in Canada) and the Buick Terazza and Saturn Relay MY 2005-2007. The 3.5 was used in the CSVs from 2005-2006 and the 3.9 from 2007-2009. The 3.5L was the LX9 (no VVT or E85) and the 3.9L had E85 and VVT.

Again so far as I have heard most of the problems with these vans come from electrical, the transmission and power-train are rock solid.

[Drew Dowdell]

yes for only two years. but it also had the 4 speed. plus, the 3.6 has issues the first couple years.

Really? In just the RDV or everything? I had a first year 3.6 and had no issues with it.

[NeonLX]

We're coming up on 3 years of ownership with our '07 Maxx (hard to believe!). At 61,000 miles, I'm happy to report no mechanical issues whatsoever from the powertrain. We're averaging around 24 MPG with the car, and I've seen over 30 MPG on highway trips. The only "worrying" issue is some clunks from the front suspension over rough pavement--sounds like bushings to me, but it ain't worrying me too much yet.

Coworker of mine with an Accord is amazed at the smoothness and quiet of the 3.5L V6 (though her Accord is powered by a 4-cyl). I'm still impressed with the power of this engine; even with a full load on board, the car will get up to expressway speeds without any fuss.

[vonVeezelsnider]

We're coming up on 3 years of ownership with our '07 Maxx (hard to believe!). At 61,000 miles, I'm happy to report no mechanical issues whatsoever from the powertrain. We're averaging around 24 MPG with the car, and I've seen over 30 MPG on highway trips. The only "worrying" issue is some clunks from the front suspension over rough pavement--sounds like bushings to me, but it ain't worrying me too much yet.

Check the Intermediate Steering Shaft... we've replaced this part twice on our 2006 Maxx but it didn't fix all the clunking, yet they couldn't find anything else wrong... the front suspension is poorly designed it would seem. Ditto for the electric steering but that's another kvetch for another day.

Considering the amount of livery Impalas I see up here the durability simply *has* to be there in the 3500/4spd setup. At least 40% of all the cabs I see nowadays are 06+ Impalas. The last time I took my 07 to Vancouver I got 37MPG (not a word of a lie) too, made the trip on more or less one tank of gas (850km), and you can't beat that.

[NeonLX]

After owning several Mopar vehicles with that unfortunate A604/41TE transaxle, I'm happy to hear that the 4T45 tranny is durable. The Chrysler 4-speed slushbox is a real box of fragile Christmas tree ornaments. I still grit my teeth every time the tranny shifts in my Neon, just waiting for the sound and feel of the grenade going off (got to experience it twice in the old Voyagers we had at work).

[Mike The Canadian]

Ah yes you gotta love the 60 deg pushrod v6

They often return better than advertised mileage.

Gotta love the low end torque for getting up to speed around town while saving gas.

The 3x00 series are all pretty reliable aside from the lower intake manifold gasket leaks.

The only thing you really hear much about is people spinning a bearing; usually as a result of letting

a lower intake manifold gasket leak go for too long.

the 3500/3900 series (VVT and the non-VVT 3500) completely eliminate these problems.

the 4T40E and 4T45E have horrendously tall gears but are otherwise great.

I'd love to experience these engines with a 6 speed! (Or even a 5 speed, know there are a few 5 speed grand am's floating around there).

There's plenty of info about the 60V6 here, visit and enjoy

http://www.60degreev6.com/

[NeonLX]

Hey, thanks for that link Mike! I've got to come up to speed on this particular engine family and that site looks like just the place to do it.

I had some experience with a 3.1L version of the 60-degree V6 engine in a circa-1991 Corsica that was in our fleet at work. The thing had a 3-speed ATX and was a real rocket. Except for the uncomfy driving position, I always enjoyed driving it. We currently have a 2008-ish Chevy Uplander minivan (SWB) with the 3900 in the fleet and it moves right out too.

[ponchoman49]

I can tell you that the 3500/3900 are literally bulletproof from what I have seen. My 2008 3900 has close to 80K miles and has never seen a wrench. My buddies 2006 Impala 3900 with 82K is the same. His 2005 Buick Terrazza 3500 now has 140K and runs like new and has never had an issue. Numerous law enforcement Impalas with 3900's have well over 100K and run as new in my town and there are often high mileage examples on Ebay that run as new. All in all a great engine IMO.

[Paolino]

I frequently consider getting an 09-10 Lucerne with under 30,000 miles on them because they're a steal and they have the 3900 (which affords a little more power and refinement over the 3800). Oldsmoboi recommended it highly--my parents have the Lucerne with the 3800, which although is quiet, it definitely is unrefined especially for the target it was aiming for. From 0-10mph (so every time you launch the car from a light), the sound/vibration resonates in the cabin. I've spoken to others with the 3800 in the Lucerne and they say the same thing happens, but from what I understand, the 3900 doesn't do that.

My only gripe with the 3900 is the low fuel numbers reported, so I'm hoping it returns higher-than-advertised economy as the 3500 does. It'd definitely be a great daily commuter!

Edited May 29, 2011 by Paolino

[Drew Dowdell]

I got 27mpg on a highway cruise to Columbus with a trunk FULL of PCs and flat panel monitors.

Got 27mpg on the way back with an empty trunk and the A/C on.

edit: in the Lucerne.

[ponchoman49]

I got 27mpg on a highway cruise to Columbus with a trunk FULL of PCs and flat panel monitors.

Got 27mpg on the way back with an empty trunk and the A/C on.

edit: in the Lucerne.

Considering that the Lucerne is heavier than the Impala and that this engine no longer uses AFM cylinder shutoff that is admirable for the Lucerne. The 2.93:1 final drive helps on the Buick compared to the Imps 3.29 gear also.

[Potluck]

for all the harassment pushrod engines get, the 3.9 liter with VVT was a good smooth engine that was held back by the 4-speed auto it was always attached to. Wasn't there a Pontiac G6 where you could get the 3.9 plus a 6-speed manual? That would be an engine combo to try so you can really feel what the engine is like.

[Drew Dowdell]

Anyone here ever drive one of those? The G6 with the 3.9 and a manual?

[NeonLX]

84,000 miles and counting on the '07 Maxx. Still runs like a champ. We did do about $1500 worth of work to the front suspension. Took care of most of the clunking but there are still a few odd noises coming from up there on uneven pavement.

After 4.5 years of driving this car, I still can say I love it. My wife says the same thing!

[vonVeezelsnider]

Front suspension has been a never ending pain in the butt on our 06 as well, but nothing bad to say about the powertrain.

[maticulus]

I stumbled across this forum while searching for some other related info and found this thread. Thought you might be interested in a few pitures of what I did with one of these motors based on the discussion. There are a few others in the Gallery.

[NeonLX]

Thanks maticulus!

Great pix. Looks like a fun project.

[Drew Dowdell]

Thanks for the uploads of your project. What did it go into?

[maticulus]

Thanks for the uploads of your project. What did it go into?

1986 Pontiac Fiero, along with the 6 speed transmission from the 06 Pontiac G6.

[Drew Dowdell]

NEAT! Pics when you're done!

[NeonLX]

104,000 miles on the '07 Malibu Maxx. Powertrain has been flawless, but front suspension has sucked. I'm thinking about throwing another $2K at the car because I really like it (far more than the current Malibu, which doesn't impress me one bit). My wife likes it as well (probably the most important consideration).

[dwightlooi]

The Fiero chassis was, should I say, overweight and flexy. The suspension on everything but the 88s also sucked dirt and steering always felt "lose" and imprecise. Brakes were horrendously weak by modern standards. Compared to the 1st generation MR2, the fiero sucked as a driver's car, although it did have a surprisingly larger and useful trunk (which forces you to look at that red painted 2800 V6 every time you use it). The "GT" body looked really nice though.

I had both the 88 MR2 Supercharged (4A-GZE engine) and a 86 Fiero SE V6 (not the fastback GT). I very much prefer the MR2. Not that it doesn't have its flaws -- the intercooler installation right on top of the engine with a small fan drawing hot air from the exhaust manifold area is class 1 retarded -- but it is faster, more agile and significantly better handling. Having 5 speeds vs 4-speeds on the manual transmission helped too.

Both cars weighed in the mid to upper-mid 2000 lbs range. Both didn't have power steering. Both seat you close to the floor with a tall central tunnel supporting your elbow. It's hard to find a car like that anymore - especially the low seating position which I loved and the under 2800 lbs weight which really makes for an interesting driving experience. I'll gladly pay 10K for a nice MR2 Supercharged if I can still find one. But they are pretty much gone from the market.

Edited July 28, 2013 by dwightlooi

[hyperv6]

The Fiero suffered from the lack of development money and it showed. The 88 was really closer to where they wanted to start but by then it was too later.

The Fiero is not flexy as in frame as the space frame was solid and only a little flexy if you had a T top.

where the early cars issues were was in the rear suspension. it used pretty much a front Suspension package from a Pontiac 6000 moved to the rear. The 84 tied the tie rods off to the body and the toe would change when the body leaned on the bushings for the sub frame. The early models also had great bump steer from the bushing in the control arms and sub frame. This made the front end and rear end work nearly independently. Also the other major omission is the lack of a rear sway bar.

The early cars drove well on smooth roads but they would make you work hard on a uneven back road. Now the early cars can be fixed easily with replacement of the control arm bushing and an upgrade to a new front sway bar and the addition of a rear bar. Pontiac had been working on a rear bar but it never made production. I got to play with the prototype pilot car they were doing the testing in. and saw the several bars they were working with.

Mine is very neutral and the bump steer is gone due to the addition of the Herb Adams VSE suspension kit. Herb the father of the Trans Am suspension did this kit for show room stock. he upgraded the front to a 1 inch bar and the rear to a 1 1/2 inch rear bar. Also he used ball bearing control arm bushings that did not add harshness but did remove the control arm flex removing the bump steer in the rear.

The 88 went to a 3 link system that made it simple and Porsche Engineering was used to help tune the GM designed system. They did most of the work on the front to make the steering lighter and have more feel.

The MR2 was better refined as it got the proper funding. But the car was a pig unless it was the supercharged model and had to be rev'd hard to be rewarded. Most have rusted away and are long gone while Fiero's are not all that hard to find and low mileage models are coming out of storage all the time.

As for the brakes on the Fiero. When cold they were weak, up to temp they were good once the heat was in them but they would fade due to the solid rotors when hot. The range on them were very slim.

I have driven many modified models with everything from a N star to 3800 SC and with a little tuning and the addition of brakes from a Vette to a Grand Am they can really be transformed into a solid performer for little money.

The real story of the Fiero is a good example of what flaws GM had and the many mistakes they made on many models. Having been around and studied the car a lot could have been learned by GM from this program but they were too far gone to see their mistakes till the money was gone.

Having owned a Fiero going on 30 years I can say it is far from a perfect car but I have enjoyed mine. I have driven it all over from the Indy Speedway to laps at Mid Ohio. I have shown it at major Pontiac shows and taken many awards with it. It has always drawn attention and many nice comments. It is nice just to have something different. At this point I only have to pay for an oil change and insurance now and then so I will keep this car. It was my first new car and I have had a blast with it. Crashed it rebuilt it showed and just had fun. Nothing better than a nice sunny day with the T tops out that relax you.

The one major issue I have with I is the lack of power. Some day I may install a LS engine or a Turbo Eco in the car. Having driven 300 HP Fiero's they make for a lot of fun.

[loki]

what did the fiero's have stock in HP? 150?

would the ecotec3 5.3L be too much? lol

..but perhaps this is for another topic.

[dwightlooi]

The 2800 V6 (L44) was 140 hp / 160 lb-ft; the MR2's 4A-GZE 145 hp / 140 lb-ft.

Just about ANY GM pushrod 60-degree V6 will fit the fiero and there have been transverse V8 swaps -- up to an including the fat Northstar and not just the small blocks.

Anyhow, back to the 3500/3900 V6es... I believe that their major flaw was that they weren't large enough in displacement and there weren't enough commonality with the Smallblock V8s. Ultimately, this meant that between the V8s and the 60 degree V6es, GM would keep only one of the two engine lines. They kept the V8 and univeralize the high feature V6 in 6-pot applications.

It is unfortunate, because a 4600 V6 using the same feature set as the LT1 will make about 340 hp / 345 lb-ft. With AFM its is likely just as fuel economical than the 3.6 DOHC. The 3.6 DOHC's 18/29 mpg is not that hard to match. It would have made a very good Impala engine and a better base engine for the Camaro than the 3.6 DOHC.

[Drew Dowdell]

But... we got the 4.3 V6 still

[riviera74]

I have a Q: Why does GM insist that all v6 engines in nearly all cars be DOHC?

GM has made the best pushrod v8 engines ever and the best GM v6 is still the Buick 231 (the 3800 for metric), which was derived from a 1962 Buick v8. Supposedly the 3900 was even better than the 3800 when it came out pre-BK, but now it is apparently discontinued in favor of the 3.6 DOHC. (Why?!) The 3.6 is of course from the same family as all those Ecotec 4cyl straight from Opel in Germany (where displacement taxes mandate small-displacement engines). The 3.6 NA needs real torque right now. While a twin turbo patches that up (such as next year's Cadillac XTS), a pushrod v6 derivative of the v8 is what would really solve this issue. Why run away from a strength (pushrod v8 and derivatives) for some illusory upgrade that is DOHC? This is 2013, not 1973. DOHCs need more torque, period.

[David]

I have a Q: Why does GM insist that all v6 engines in nearly all cars be DOHC?

GM has made the best pushrod v8 engines ever and the best GM v6 is still the Buick 231 (the 3800 for metric), which was derived from a 1962 Buick v8. Supposedly the 3900 was even better than the 3800 when it came out pre-BK, but now it is apparently discontinued in favor of the 3.6 DOHC. (Why?!) The 3.6 is of course from the same family as all those Ecotec 4cyl straight from Opel in Germany (where displacement taxes mandate small-displacement engines). The 3.6 NA needs real torque right now. While a twin turbo patches that up (such as next year's Cadillac XTS), a pushrod v6 derivative of the v8 is what would really solve this issue. Why run away from a strength (pushrod v8 and derivatives) for some illusory upgrade that is DOHC? This is 2013, not 1973. DOHCs need more torque, period.

DOHC just needs to die as the marketing of these engines is an illusion that has sold many on a lie. They are weak engines and just because they turn high numbers in HP, that does not make up for the lack of Torque that really get an auto moving.

I for one do not see that the weight and complexity of DOHC engines are worth it.

GM needs to come out with a marketing message that plays up their strengths as to why people should buy their Pushrod engines.

[Drew Dowdell]

I have a Q: Why does GM insist that all v6 engines in nearly all cars be DOHC?

GM has made the best pushrod v8 engines ever and the best GM v6 is still the Buick 231 (the 3800 for metric), which was derived from a 1962 Buick v8. Supposedly the 3900 was even better than the 3800 when it came out pre-BK, but now it is apparently discontinued in favor of the 3.6 DOHC. (Why?!) The 3.6 is of course from the same family as all those Ecotec 4cyl straight from Opel in Germany (where displacement taxes mandate small-displacement engines). The 3.6 NA needs real torque right now. While a twin turbo patches that up (such as next year's Cadillac XTS), a pushrod v6 derivative of the v8 is what would really solve this issue. Why run away from a strength (pushrod v8 and derivatives) for some illusory upgrade that is DOHC? This is 2013, not 1973. DOHCs need more torque, period.

Because the 3900 doesn't have the power density that sells cars. Like it or not, there are still lots of people out there like SMK that say "Oh, you only put out 212 hp from a 3.9 liter? Your engine must suck!" while ignoring the fact that a 260hp 3.6 weighs more and gets lower real world MPG while doing nothing for drivability.

Edit: And that in the same physical space of a 3.6 DOHC V6, GM can, and has, fit 5.3 liter V8s, 5.7 liter Supercharged V8, and 6.2 Liter Supercharged V8s.

[David]

Drew you truly hit the nail on the head as SMK is a poster child for the marketing punch that has many blinded by the whole DHOC with lots more HP is better than a pushrod version with 20% less HP but 45% more Torque.

[dwightlooi]

Actually, it is not true that DOHC engines make less torque. They don't. They actually make MORE torque at the same displacement. A DOHC 3.6 will make more torque, more power and burn more fuel than a Pushrod 3.6 -- the burn more fuel part comes from it's higher parasitic losses from valvetrain friction. The problem of course is that while hp/L scales with the flow rate of your heads, valve area and RPMs, lb-ft/L doesn't (it really only scales with compression ratio). At any given hp rating, a DOHC engine will tend to be of a lower displacment and hence lower torque output. But, at any given displacement a DOHC engine will be superior in both torque and power output, but losing out in fuel economy.

An interesting paradox very few people understand is that the above is true only for gasoline engines. The OPPOSITE is true of DIESEL engines! You see... the reason DOHC 4-valve GASOLINE designs make more power is that despite having higher frictional losses, the gains from reducing pumping losses more than offsets the parasitic friction losses. This is ONLY true when the throttle is wide open. When driven modestly and/or at cruise the engine's pumping loses is caused not by the flow capacity of the head or valve train, but by the partially closed throttle plate. Because in any kind of standard test where fuel economy is measured -- and in any kind of scenario where the driver gives a damn about MPG -- the throttle is not wide, open DOHC 4-valve engines are almost always less fuel efficient than a pushrod or SOHC 2-valve design of the same capacity and similar technological content. A Diesel engine doesn't have a a throttle body. It runs wide open all the time. It simply meters less fuel, burns lean and produce less power when you prod the pedal part ways. Hence, in a Diesel the pumping loss advantages of a DOHC 4-valve design that applies to Gasoline engine only when you floor the pedal, applies all the time. In a Diesel, a DOHC 4-valve design tend to be more fuel efficient than a 2-valve design of the same displacement.

Edited August 16, 2013 by dwightlooi