GM Inside News Forum banner
1 - 20 of 55 Posts

·
Registered
Joined
·
18,488 Posts
Discussion Starter · #1 ·
Why, must I ask, does the 3900 V6 exist? Of course, as of yet it does not. But when the top-line model of the upcoming Pontiac G6 rolls around, it shall be powered by a 3.9 litre derivative of the "Revised And Updated" 3.5 litre derivative of the "Revised and Updated" 3.4 litre derivative of the "Revised and Updated" 3100 V6, which in and of itself was a revised and updated version of a revised version of a revised version (namely the 2-bbl carburetted 2.8 litre V6 in the 1980 X-body cars).

Why do I not like it?

The High Feature V6.

The first incarnation of the HFV6, the 3.6 litre VVT version currently used in the Cadillac CTS, gives these specs:
3.6 litre displacement
255hp at 6 500rpm
252lb/ft at 6 200rpm

while the 3.9 in the G6 makes 240 or so.

So, why, does GM decide to make a entirely new motor, that has no real raison d'étre?



100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3
 

·
Registered
Joined
·
4,572 Posts
Becuause GM works in mysterious ways. And it needed to Kill Olds so it could waste more money on developments like the 3.9 Liter V-6. :lol:
 

·
Registered
Joined
·
954 Posts
Because it will be cheap, powerful and efficient. Hardly anything these days is designed from scratch, because when you have a good design, you stick with it.
 

·
Premium Member
Joined
·
14,963 Posts
Yes, GM had to destroy Olds to create the turd that is the 3.9 V6 :rolleyes:

The 3.9 follows the line of great push rod engines. Why not just put the 3.6 from Caddy into the G6 and other cars? Well, for startes, its about twice the size. OHC engines are HUGE compared to an equaly or larger displacment OHV engine. Not to mention the money saved by used the OHV, and the ability to create a lighter, smaller car with OHV engines.
So, I ask you...why use the the more expensive, larger, and heavier engine just for a bit more, or equal power?

So why does GM make OHV and OHC engines? Because they can. OHC engines and OHV engines have there own pros and cons and can be used in different applications.
 

·
Registered
Joined
·
1,551 Posts
Originally posted by bigals87z28@Jul 18 2004, 09:25 PM
Yes, GM had to destroy Olds to create the turd that is the 3.9 V6 :rolleyes:

The 3.9 follows the line of great push rod engines. Why not just put the 3.6 from Caddy into the G6 and other cars? Well, for startes, its about twice the size. OHC engines are HUGE compared to an equaly or larger displacment OHV engine. Not to mention the money saved by used the OHV, and the ability to create a lighter, smaller car with OHV engines.
So, I ask you...why use the the more expensive, larger, and heavier engine just for a bit more, or equal power?

So why does GM make OHV and OHC engines? Because they can. OHC engines and OHV engines have there own pros and cons and can be used in different applications.
But the bad side of GM's V6 are that they are made of cast iron, so they aren't as light as the aluminium OHC's V6.
 

·
Premium Member
Joined
·
14,963 Posts
Originally posted by gerardo_zg+Jul 19 2004, 04:50 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (gerardo_zg @ Jul 19 2004, 04:50 AM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-bigals87z28@Jul 18 2004, 09:25 PM
Yes, GM had to destroy Olds to create the turd that is the 3.9 V6  :rolleyes:

The 3.9 follows the line of great push rod engines.  Why not just put the 3.6 from Caddy into the G6 and other cars?  Well, for startes, its about twice the size.  OHC engines are HUGE compared to an equaly or larger displacment OHV engine.  Not to mention the money saved by used the OHV, and the ability to create a lighter, smaller car with OHV engines. 
So, I ask you...why use the the more expensive, larger, and heavier engine just for a bit more, or equal power?

So why does GM make OHV and OHC engines?  Because they can.  OHC engines and OHV engines have there own pros and cons and can be used in different applications.
But the bad side of GM's V6 are that they are made of cast iron, so they aren't as light as the aluminium OHC's V6. [/b][/quote]
In weight, they are probably about equal, but the OHC engine will still be 2x the size. Its a lot easier to package a OHV engine then an OHC.
 

·
Registered
Joined
·
776 Posts
If you dropped a 3.9 in the CTS I wouldn't be surprised if it improved the 0-60 and quarter mile times, due to the superb torque curve the 3.9 is supposed to have. Not only that, it would be cheaper, and get better gas mileage if current push-rod engines are any indication. The question I ask is: Why have a HF 3.6? And the answer is....dumb people that want to pay more for a slower car and buy more gas, so that they can say, "I have DOHC!! It roxors! eleet doodz!!!"
 

·
Premium Member
Joined
·
14,963 Posts
I would also assume that DoD on an OHC engine would be very hard to engineer. I the 3.9, it can use this technology, as well as having the ability for OHV engines to have VVT and 3 valves per cyl in the future.
 

·
Registered
Joined
·
685 Posts
I used to wonder the same thing until I read many discussions on this forum. The 3.9 will be smaller in size than the 3800 SII(way smaller than DOHC) yet will have more displacement and power than the 3800. A 3800 in an N-body would have been a serious straight line hauler. This engine will surpass that one, I believe. I for one am looking forward to a 3.9, 240HP, fatass torque curve, 3100lb car with a six speed and avail AWD.

Let's not forget all of those guys who are going to want to drop these things in everything that ever had a 60º v6. Fiero GT Fastback with a 6spd and a 3.9 sounds nice to me. But I must be living in the past cause that isn't "kewl". F'km, I think it is.
 

·
Registered
Joined
·
47 Posts
I'm really looking forward to this engine. It's going to be a low torque monster able to hit 245 ft-lbs at only 2,800 rpm. Plus it's going to get great gas mileage with DoD. What's not to like?
 

·
Registered
Joined
·
2,103 Posts
Originally posted by gerardo_zg+Jul 18 2004, 11:50 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (gerardo_zg @ Jul 18 2004, 11:50 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-bigals87z28@Jul 18 2004, 09:25 PM
Yes, GM had to destroy Olds to create the turd that is the 3.9 V6  :rolleyes:

The 3.9 follows the line of great push rod engines.  Why not just put the 3.6 from Caddy into the G6 and other cars?  Well, for startes, its about twice the size.  OHC engines are HUGE compared to an equaly or larger displacment OHV engine.  Not to mention the money saved by used the OHV, and the ability to create a lighter, smaller car with OHV engines. 
So, I ask you...why use the the more expensive, larger, and heavier engine just for a bit more, or equal power?

So why does GM make OHV and OHC engines?  Because they can.  OHC engines and OHV engines have there own pros and cons and can be used in different applications.
But the bad side of GM's V6 are that they are made of cast iron, so they aren't as light as the aluminium OHC's V6. [/b][/quote]
Not Iron block any more. Go stick a magnet on the block of a new malibu's 3.5 and catch it when it falls.
 

·
Registered
Joined
·
3,994 Posts
Interestingly, as of a year ago, those antique V-6 engines were GM's highest quality in terms of defects. I suppose that shouldn't be a surprise, since they have been in production in some form for so darned long.

Not flashy or high-tech, but certainly durable.
 

·
Registered
Joined
·
524 Posts
It's called product differentiation. Something GM is criticized for endlessly when it comes to platforms, but gets no credit for on engines. GM makes more different engine types than anyone and always has.
 

·
Registered
Joined
·
4,723 Posts
Originally posted by bigals87z28@Jul 18 2004, 11:11 PM
In weight, they are probably about equal, but the OHC engine will still be 2x the size.  Its a lot easier to package a OHV engine then an OHC.
Your point is well taken BigAl, but I doubt that the OHC engine is literally twice the size of the 3.9 -- we'd be talking big block V8- or long V12-size if that were true!

Where V configured OHC engines tend to be larger is in width and hight -- to accomodate the twin cams per bank and associated belt or chain drive. An inch or two difference in width or hight may not sound like a lot, but when needing to package an engine it can be quite significant.

The basic block, howerver, doesn't need to be any bigger for OHC, though if it is a high RPM engine, it may be beefier in the main bearing area.

As far as adopting DoD -- since DoD basically works by allowing the oil to drain out of a lifter -- and since many OHC engines use a hydrolic interface to deal with cold-to-hot valve clearances, I would imagine it wouldn't be much more difficult to engineer DoD for an OHC cam engine. In fact, Honda will do so on the coming Accord Hybrid. Given half the number of valves and a centralized location for lifters, it is probably cheaper to do on something like the 3.9, however.

As part of the value engine family, the 3.9 will be designed to provide good power and torque, be cheap to operate and, from a CAFE point of view, offer good fuel consumption across GM's line. The 3.6 family will be more expensive, probably be capable of more power in performance applications (turbo version are seeing 400 hp) and won't need to be quite as frugal as they will be installed in lower volume, sporting and luxury cars.

Different tools for different tasks -- makes perfect sense to me. Especially if the 3.9 turns out to be as good as it sounds on paper.
 

·
Registered
Joined
·
18,488 Posts
Discussion Starter · #17 ·

·
Premium Member
Joined
·
14,963 Posts
Tone, I have a picture of the DOHC 4.6 from Ford, and Fords old 302 5.0 motor. Look at the size difference. I know its not 2x the size, but you get the picture.



the OHC easily dwarfs the OHV block.

and the 3.5 engine has an Iron block, aluminum heads.
 

·
Premium Member
Joined
·
14,963 Posts
Originally posted by Smaart Aas Saabr@Jul 19 2004, 03:54 PM
Don't get me wrong, I love the idea of a 245hp 6-speed G6...

And the 3.9 looks to be a promising motor, but then why the effort to develop the HFV6?

I don't know if the 3.9 will get such great fuel milage either, but it might.

What is the point of producing two entirely different engines with such similar qualities.
Having both HF and HV engines, GM can offer a wide spectrum of cars that offer high performance but for less when compared to the others.
and I belive in FWD form, the 3.6 makes 245hp as well, in the new LaCrosse.
 

·
Premium Member
Joined
·
14,692 Posts
Originally posted by Smaart Aas Saabr@Jul 19 2004, 10:54 AM
Don't get me wrong, I love the idea of a 245hp 6-speed G6...

And the 3.9 looks to be a promising motor, but then why the effort to develop the HFV6?

I don't know if the 3.9 will get such great fuel milage either, but it might.

What is the point of producing two entirely different engines with such similar qualities.

Keeping some Union factory somewhere running? Often when GM does something illogical, the inability to easily eliminate factories and product lines has something to do with it.
 
1 - 20 of 55 Posts
Top