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NeonLX

3500-3900 60-degree V6s

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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.

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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.

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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!

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

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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.

Forged build

Offset ground crankshaft

Chevy small block, small journal H-beam connecting rod.

New heads

Turbo mock up

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Thanks maticulus!

Great pix. Looks like a fun project.

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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.

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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).

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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 by dwightlooi

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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.



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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.

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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.

NorthstarSTSMVC-372S_1.jpg

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.

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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.

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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.

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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.

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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.

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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 by dwightlooi

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