Contour Enthusiasts Group Archives Forums General Common Interests Who at GM allows this crap?

Hmmm,

Not to be too picky, but OHC engines are OLDER tech than the pushrod engine, IIRC.

There are advantages and disadvantages to each. A pushrod engine is great packaging. The Duratec is a great engine, but takes up a lot of space for the displacement.

Maybe some of our Ford engineers can chime in on this one. What is the package size of a 2.5L or 3.0L Duratec compared to say a 4.6L SOHC Ford V8, or even compare the 3.0L Duratec package to the 3.0L Vulcan package.

The other thing is that with DOHC, you put more weight at the top of the engine. Having the weight at the bottom helps with handling.

Sure, GM and others could make their engines out of all aluminum and reduce the weight quite a bit.

Are there any aluminum pushrod engines in production? Maybe there are some issues with an 'all aluminum' pushrod engine. (We know that they really are not 'all aluminum' right, lest anyone start sniping here.)

Say what you will about the 3.8L GM V6, I had one in the 87 Buick and it was a pretty nice engine. That 3500+ pound car averaged about 24MPG in urban commuter driving at speeds typically 75+ MPH, and achieved over 31MPG in one highway trip, but typically got 27-28 on the highway at about 70MPH.

Heck, my 95 T-Bird (4.6L V8) is averaging about 22, with highway economy of over 26 on a recent trip to Ft. Worth, TX.

Americans buy torque, that is pure and simple. Look at how many buy SUV's. It's not just the size, they have big torquey engines.

You want handling and an aluminum engine, buy a Honda S2000, Mazda Miata, or Toyota MR2, maybe even a Nissan 350Z.

Oh, and to answer my own question, I guess there is an aluminum pushrod engine, I believe you can get one of those in a Corvette.

FWIW,

TB

Hey Tony -

Points all valid and well taken -- I should have made it clearer in my discussion that the references to origins and age were meant only as a comparison between the 90-degree (early 60's) and 60-degree (late 70's) families of GM V6's, and why an updated version of the latter may have been chosen for the G6.

I made no references to or comparison between pushrod and OHC designs, but I agree with the weight-distribution disadvantage commonly levied against OHC designs, along with generally more challenging packaging.

I have no real problems with GM's new V6's save for their somewhat timid power and their iron blocks. But at the same time, I wouldn't trust GM to re-engineer the blocks to aluminum without having either stiffness/harmonics issues or a hefty price tag...nor do they have any real reason to go with lighter blocks, I guess, since the typical carbuyer's focus isn't on things such as weight distribution, manual shifting, and suspension geometry. He just needs all his torque on the bottom, a smooth-shifting slushbox, a place to put his Dale Jr. or Jeff Gordon sticker, and an opening to put gas in...like you say, what sells (well, with tons of incentives) is what they'll do.

GM has a good idea IMO with using simpler pushrod engines for it's bread and butter, everyday cars. Most consumers don't even know or care the difference anyways.

I do believe the new 60 deg. engines use all-alumninum construction and will have variable cam phasing and dual-stage intake manifolds. This is a GOOD thing becuase it saves weight and makes for better packaging. The 3800 and old 4300 are very durable, but thats because they are derived from v8's and use the heavy iron-block design and heavy-duty components for that application. It's really not necessary for a v6 in a passenger car.

GM's problem is that it takes its bread and butter cars and tries to dress them up (Pontiac) and call it "driving excitement" I have to wonder who at GM thinks that plowing understeer and a heavy 3800 engine with it's blender-like sound is "driving excitement"

Hopefully they have put more thought into weight distribution, suspension and steering and engine character with the new pontiacs.