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So I ran across this guys take on overhead valve pushrod engines vs. overhead cam engines.

http://theautoprophet.blogspot.com/2...f-pushrod.html

What do you think? I'm really thinking about getting a 2006 Pontiac G6 GTP Coupe when they come out, but the thing that really turns me off is the 3900 Pushrod V6 that powers it. Is this engine worthy? I've heard numerous comments that pushrod V6's lack refinement, is this true? Try not to be bias, we are all Honda fans, back up your comments with facts or references. I'm interested in the Pontiac because I love the styling and am getting bored with Honda's ho hum coupe design. Lets try to keep this discussion to engine comparisons.

 
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from my experience with the v6 pushrod engines, is that i have no complaints about them. i have had to cars with the 3.1v6(not 3100). my first one was a 93 chevy corsica auto. it had good power and ran very smooth. it had 83,000 miles on it and was decently maintained by thye previous owner. and i ran the crap out of it. and the only thing i had to fix replace a leaky intake manifold gasket. then the car got totaled when a lady puleld out in front of me. and even with major front end damage the engine ran fine. my 2nd 3.1 was a 92 z24 5-speed. My neighbor swapped in a used 3.1 becasue i bought the car with a blown 3.1 due to oil sending unit sensor faliure. that car again once i got all the sensors switched from corsica (not from mine) to z24 sensors ran great. it was very strong and responded well to bolt ons. then i sold the car. The only person i have ever know who has had a problem with the pushrod v6 is my friend with a 97 3100 grand am. but that was just becasue his electronics system sucks and the computer kept frying. the only thing that i would regret buying a car with one of these engines is gettign to the spark plugs or anything on the firewall side of the engine, because it is a royal pain to do anything without removing the powerstearing and what not. i have riddein in a new 05 G6, and it has planty of power and great features, but the only thing i don't like about it is the center consoule setup. just not a fan of how it flows into the dash like it does.

 
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yeah it's an older technology, but still viable. even the LS1, LS6 engines, and such still use pushrods. nothing wrong with that.

 
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Lets just say that Pushrod engines have been around so long that they've pretty much proven its reliability. they may not be the cutting edge of technology, but the design's been around so long that its hard for a company to screw up when building one.

 
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So we've covered that they are not "cutting edge technology" and that the design is reliable, but do they perform well? Are they refined? Do they have any huge disadvantages? how about advantages? Anyone have any specific experience with this 3900 V6? It appears to have variable valve timing,by-wire throttle and variable intake. Doesn't sound all that bad.

 
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i have had a 3800 gm engine. it takes alot of crap and keeps going. hardcore. its jsut a 3800 bump up to a 3900. the 3.8 engine is general motors best v6 they ever made. so maybe the new gen engine is the 3900. i can do either. but the ohc gets better gas mileage.

 
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a link to the some more info about the 3900, apparently it has displacement on demand. http://www.sae.org/automag/techbriefs/01-2004/

 
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yeah i think the cylinders shut off till you need them. maybe it keeps a really lean a/f ratio in 3 of the cylinders, till you accelerate and then it changes it. i think thats what it is. not sure

 
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Pushrods still work just fine! The 3900 V6 is brand new so its hard to tell reliability. The current 3800 is a great engine though. Hell the 3800 in my mothers 2001 Grand Prix was driven for 5 miles without any oil (filter blew off and out came the oil, but she didnt notice/care) and it still runs fine 2 years later.

Ive owned two OHC powered vehicles and 6 OHV powered vehicles. The OHC engines always seem to have very peaky power where the pushrod engines have a very broad powerband.

Enjoy your new G6 when you get it.

 
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Do you feel that the OHV engines lacked refinement or "fun to drive" performance characteristics?

 
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hell no! all these vettes and supercharged gtp's and nice v6's and 8's are fun as crap to drive. i love drivin my gf's gtp. its sweet. there is no lack of fun. just find the right car for you.

 
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i think its ok for a daily driver, but GM is going to go under even faster if they can't join the rest of the world. In stead of being stubborn and refusing to use technology of the last few decades, they should change everything around. especially their reliability since gm obviously sucks at making cars last.

 
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gm does not suck at making cars. the 3800 v6 is still the longest lasting engine they have. the only ones that compete with that is honda and toyota. same class stuff. besides you can't argue with the torque on a gm engine. honda and toyota can't keep up with that. anyway, gm will not die, they are the biggest car company on the planet. don't fix something that ain't broke.

 
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im talking about everything else in the cars, especially the interiors, which are terribly cheap!

 
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the new interiors are actually pretty nice. The G6 looks like the quality is pretty good. I checked out a chevy cobalt at the dealership and the fit and finish of the interior was outstanding for GM. It was at least as good as a civic, if not better. Anyways, back to engines.....the big downside I see is the crappy fuel efficiency resulting in poor gas mileage

 
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new LS7 Zo6 (corvette) engine:
7 liter, pushrod, all aluminum, composite manifold
500HP@6300RPM 7100RPM redline, 475 Lb*ft-torque curve as broad as the mississippi

new M5 motor:
5 liter, DOHC,infinitely variable timing and lift(no throttle bodies, throttle is controlled with the lift of the valves)
500HP@8000RPMs (don't know the torque)
this engine is MUCH heavier than the LS7 (the shortblock is only 90lbs)

 
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I prefer not to look at the Corvette engine. Its a bit more high end than most of GM's offerings, and I'm not convinced it represents their engines as a whole. Lets talk V6's here. When it comes to the 240hp V6 in the Accord and the new 3900 240hp V6 from GM it starts to get tougher to compare. The GM engine has no obvous advantage. I don't even think torque can be used as an advantage because I'm sure the Honda has plenty of low end grunt as well. What I am curious to know though is are these engines equal? Are they both good powerplants? Does the 3900 crap out at higher RPMs?

 
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Engine: 3.9L 3900 V6 SFI: 240 HP @6000 rpm, Torque 241 lb.-ft @ 2800 rpm
Transmission: 6-speed Manual
Wheels: 18", Flangeless
Axle 3.55 ratio
Wheelbase: 122.3"
Steering: Hydraulic power
Brakes: Front Power 296-mm Vented Disc and Rear Power 270-mm Solid Disc Brakes

Doesn't it have variable valve timing?

Anyway, this engine has pretty good low-midrange torque. The engine is cheap in case something needs to be replaced because of the less complex parts. It runs on regular gas. In case it blows up on you, you can easily replace it

 
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I'm just about convinved that the 3900 is worthy and I should seriously consider a G6 with this in it, however, I'm still dissapointed in its fuel efficiency, also, does anyone know how this engine does on emissions? Anyone know if the G6 is LEV or better? I didn't see anyting on the pontiac website.

 
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To some, they may lack refinement. I feel they are more fun to drive having such great low end power.

 
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So do they "fizzle out" and have nothing left to give at higher RPMs?

 
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Not at all... the power starts low and just continues up. The autos shift before the power fizzles.

 
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Resale value sucks however, because of all the incentive and discount crap

 
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This is true, however, I believe as their vehicles begin to improve they will be moving away from incentives and deep discounts. I guess I hadn't really thought about resale all that much until now....

 
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My other $.02 the G6 is a very nice car, i drove my friends 3900 auto, the power is very nice, it is really competitive feeling between 1800-5600 rpm, the redline is i think 6200rpm which is good for a pushrod v6 actually any v6, i only stepped on it through 1st and 2nd gear. my only complaint is the interior setup, just kind of cheap looking, except the guage cluster thats really sexy. and all the options are soooo nice, expecially that sun roof. But this car could imo keep up with any accord that i have driven the newest being the 2002 V6 auto, and from my experiance with a friends are keep up or pass the newer camery V6's really easily. SO this car is a very nice car if your lookign for something in the same class that is fun to drive i would say go with the accord. it is alot more responsive in handling, and i believe the new hybrid v6 gives more power 240 something HP. but its up to you i would just say go test drive it and if you like it buy it. GM has proven that thier pushrod V6's are very reliable and have good power. ANd comapred to the accord about 1/3 cheaper to fix things down the road, but honda has also proven you don't usually need to fix things down the road on thier cars wth basic maitnence.

 
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Has anyone heard how OHV engines do for emissions? I hate to buy a car with the 3900 V6 if its going to be spewing more than its fair share of crap.

 
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i had a 3800 buick. it was an 89. sold it right before i got the vic. never failed emmissions once. in fact, it made better emmissions than the vic i am driving, if you beleive that.

 
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Are you serious? That doesn't sound right... A Honda ULEV I-4 vs. an 89 Buick 3800 Series 1? That just doesn't sound right...

But between my mom's Riviera, my buddies GTP, and my friends mom's Accord, I'd have to go with the Riv and the GTP. Although, they are both supercharged, I don't think I can really compare

 
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yeah the riviera is the ****. i like the old school ones better. the 1970-72 with the 455 in them. stock 300 hp and 375 tq. i wish i had one...