my 02 camaro with 326 rwhp, with an aluminum but antiquated pushrod v-8, get's 28mpg on the highway compared to my 05 nissan altima 4-cylinder which has been getting 26mpg highway.
"have invested little in engine development"...
what do you call the LS7 (6-liter 505hp) ?
Just because it has pushrods or an iron block means it's junk?
When is GM going to learn? (long)
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The "facts" of the above, are inaccurate to say the least.
The intake leaks are caused by a combination of plastic framed gaskets and in one instance, a composite UIM with a EGR chimney going through the TB neck to vent in the intake stream.
Aluminum framed gaskets, a reduced diameter EGR chimney, and aftermarket UIMs fixes all these V6 issues.
Now that these fixes are known and proven, all is needed is for GM to utilize the 60 degree fix at the factory level. They already have fixed the 3800.
BTW, a 1995 Buick LeSabre was just in my yard over the weekend with 310,000 miles on the engine. This engine has had nothing but sparkplug, oil changes and several water pumps since new.
Not bad for a pushrod antiquity.
Has anyone ever seen a DOHC engine with over 300,000 miles and nothing but plugs,oil and H2o pumps?
And yet, how many times has it been written here that we should all trust the "engineers" -- Follow your manual. The guys that design these engines know what they are doing.
Now, I will wait on the entertaining explainations of how a "bean counter" decided to mate metals with such different coefficients of expansion. Although, I suppose that some will find an interesting way to blame the marketing department.
Thanks for the post, addguy. I like GM too. I think the unwritten question may be "when will they learn?"
505 HP out of a 6-liter engine is not exactly a major accomplishment. 84 BHP per liter. Now lets look at the Honda S2000 at 120 BHP per liter. The Acura NSX 3.0 V6 at nearly 97 BHP per liter. Try to imagine what the LS7 could be to it's parent vehicle if it sported DOHC. Chevrolet's BIGGEST Corvette mistake was abandoning the engineering behind the ZR-1. If that engine had been bumped to 7.0 liters, it would have eaten a current-day Z06 for lunch. Further development could have provided a very sweet, detuned DOHC powerplant for the Camaro and Firebird.
As for the Camaro, I'm not a huge F-body follower so I wasn't aware they had ever dropped an aluminum engine in its bay. Not sure what's plaguing your Altima...my 3.5 SE got better mileage than that.
quote:Counterpoint: When I slow my V-6 G35 down to 72-75 mph on the highway, I get 26 mpg (last recorded 26.6, in fact). The G has a more aggressive version of the same engine as the V-6 Altima. Just how fast are you driving that I-4 Altima???
Originally posted by 1 FMF: my 02 camaro with 326 rwhp, with an aluminum but antiquated pushrod v-8, get's 28mpg on the highway compared to my 05 nissan altima 4-cylinder which has been getting 26mpg highway. (...snip...)
quote:Yes. One of my wife's good friends drives around in, go figure, a 3.0L Nissan Maxima that is into the 300k range now. No rust at all either, btw.
Originally posted by lght1: (...snip...) Has anyone ever seen a DOHC engine with over 300,000 miles and nothing but plugs,oil and H2o pumps?
quote:Yeah, my neighbors '98 V6 Accord.
Originally posted by lght1: Hi The "facts" of the above, are inaccurate to say the least. The intake leaks are caused by a combination of plastic framed gaskets and in one instance, a composite UIM with a EGR chimney going through the TB neck to vent in the intake stream. Aluminum framed gaskets, a reduced diameter EGR chimney, and aftermarket UIMs fixes all these V6 issues. Now that these fixes are known and proven, all is needed is for GM to utilize the 60 degree fix at the factory level. They already have fixed the 3800. BTW, a 1995 Buick LeSabre was just in my yard over the weekend with 310,000 miles on the engine. This engine has had nothing but sparkplug, oil changes and several water pumps since new. Not bad for a pushrod antiquity. Has anyone ever seen a DOHC engine with over 300,000 miles and nothing but plugs,oil and H2o pumps?
Ouch...I stirred up something here....
1FMF: The question was what was in the title, and as GMorg pointed out - 'when is GM going to learn (to produce engines that don't have gasket problems from thermal issues)...?
I don't understand why you have taken offence to this post - I think I was fairly straightforward in stating what I saw as factual observations; I never said stuff like 'the idiot hick GM engineers can't build a good engine'..or something like that. Observing that a company or person has a 'problem' doesn't mean you are against them...
I do think what GM has done with the pushrod engine is impressive, especially the 500-plus horsepower, 427 cubic-inch small block V-8. And the performance of late-1990's pushrod F-bodies has always kicked Mustang butt....and also, I'm quite happy with my 2002 OHV Cavalier for daily driving.....
I honestly don't drive it fast by any means. I'm never flying past traffic, although sometimes keeping up can be 70-80 mph but most of the time the speedo is under 70mph and I know it's 4mph fast at highway speed. I'll have fuel mileage to post in a month, comparing all mileage since new vs using fuel power. I have that posted with the camaro somewhere around here. There's been articles claiming a lot of foreign automaker's mileage claims have been exageratted, it was also in relation to that SAE article I read about the LS7 which is why I remember it, describing the new test being used to rate engine power under a more controlled and less variable test because manufacturers were tweaking environment conditions and whatever else they could to produce the greatest hp/tq numbers and i'm sure also the highest fuel economy numbers.
sure you can interpret the numbers as hp per liter so a Honda S2000 or Acura nsx has more, but their total output is only 237 and 290 hp. Putting out 500hp, even 400+, consistently and i'll dare to use the word 'reliably' from a factory production non-assisted engine, running on pump gas, is something different!
I'm not saying pushrods are better, but the reason they are still around are because they are that good, they are reliable, and some will say cost less to produce than an OHC/DOHC engine.
quote:Please explain why hp/l is a meaningful quantity. jeff
Originally posted by CBDFrontier06: 505 HP out of a 6-liter engine is not exactly a major accomplishment. 84 BHP per liter. Now lets look at the Honda S2000 at 120 BHP per liter...
My Dodge 4.7 has an iron block and aluminum heads. I've been keeping my fingers crossed but it's running as good as new at 86,000 miles.
hp/l is meaningful when you're looking at racing engines. It is not necessarily meaningful on the street. The reason GM keeps making "antiquated" pushrod motors is because they have low-end TORQUE.
I know Vtech helps in the high end, but my nice large 3.8L V6 makes a groundshattering 250ftlbs of torque at the rear wheels on the dyno at 1500RPM. From there its a FLAT BAR to 4000 where it increases to 265ftlbs. As a result of all this torque, I don't have to rev her up to climb even the steepest hill - it's like driving a diesel almost ![[Smile]](images/icons/smile.gif)
It keeps me from changing so many gears in traffic too, and makes the engine last longer.
Most, not all, DOHC engines have more hp than torque due to RPM, but the sheer force the motor can make (torque) is still quite low.
It keeps me from changing so many gears in traffic too, and makes the engine last longer.
Most, not all, DOHC engines have more hp than torque due to RPM, but the sheer force the motor can make (torque) is still quite low.It's an explanation of how efficiently an engine can produce power. Why build a hulking 6-liter cast-iron OHV powerplant to produce X horsepower when you could make the engine out of ligher materials and make it produce the same or more power more efficiently, thus allowing a smaller, lighter engine. Porsche, Ferarri, Lamborghini, Maserati, Bentley...all examples of high performance vehicles that use lighter, more efficient engines (not to be confused with more FUEL efficient) to extract more power per liter of displacement, due mainly to number of valves used, and the design of the valvetrain. OHV and 2-valves per cylinder can only be found in the U.S. Yes, it's been an effective setup for recent Corvettes, but why not do it even better? Short-sightedness at GM.
I own both a V6 GM and a 4 cyl. Honda and I like both of them. Both get similar mpg also. Both have pending issues (the 01' Accord is almost certain to give me A/T trouble and the 3.1 GM is almost certain to give me I/T gasket problems).
I agree that GM has to change. Greedy executives and union members have hurt this once proud company greatly. I think it is a sad state of affairs when GM advertising focuses almost entirely on ONSTAR availability rather than superior engineering. (Do you need the ONSTAR to call for help when your I/T gasket fails ![[Frown]](images/icons/frown.gif)
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I believe that GM must free themselves from their contractual obligations which are burying them and start with a new -engineering driven- plan.
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I believe that GM must free themselves from their contractual obligations which are burying them and start with a new -engineering driven- plan.quote:I'm guessing you haven't spent a lot of time driving a DOHC Nissan/Infiniti VQ35-powered car before? Since the coming of variable valve timing, the weak low end issues that once plagued DOHC engines are a thing of the past, particularly in the larger displacement engines. My 3.5L DOHC VQ grunts around as nicely as the NA 3.8L GM engines I've driven, though I'll readily admit that in supercharged form (the one which I owned) the 3.8 has a fatter low end (heck, call it an obese low end!). We have some nice hills in some parts of Pensacola, and as long as I stay out of the throttle (duh...), my G grunts its way up them doing a fair impersonation of a locomotive (OK, maybe that's a bit of an exaggeration...). VVT = cure for low end woes.
Originally posted by Dominic: (...snip...) Most, not all, DOHC engines have more hp than torque due to RPM, but the sheer force the motor can make (torque) is still quite low.
My '02 Altima 3.5 SE 5-speed was the fastest FWD sedan Road & Track had EVER tested. The VQ also enjoyed 11 straight years (in 2002) on the world's best V6 list. 245 hp / 246 ft/lbs doesn't seem too low-end torque challenged to me.
quote:. . .and you've got one of the "mild" versions of the VQ.
Originally posted by CBDFrontier06: My '02 Altima 3.5 SE 5-speed was the fastest FWD sedan Road & Track had EVER tested. The VQ also enjoyed 11 straight years (in 2002) on the world's best V6 list. 245 hp / 246 ft/lbs doesn't seem too low-end torque challenged to me.
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I couldn't keep front tires on it. :-(
quote:What's that little forced induction Solstice going to run? About 138 hp / litre? Who really gives a tinker's darn whether or not it has SOHC, DOHC, or OHV, or hp/ litre except for getting into a peeing contest with someone else? I have a 2004 GTO with an "antiquated" pushrod V8 engine. I have a 2004 Jaguar Xj8 with a "modern" quad cam, quad valve V8 engine with variable valve timing and the whole nine yards, technology wise. The low tech Goat will smoke the high tech Jag seven ways to Sunday, and the Jag is a pretty quick car. Frankly, the more I drive the pushrod engine, the less I feel the need for an OHC engine of any flavor. But if it makes you feel better to dump on someone's else's Corvette because your econobox is OHC and his/hers 500+ HP Corvette is OHV, go for it, I guess ....
Originally posted by CBDFrontier06: Now lets look at the Honda S2000 at 120 BHP per liter. The Acura NSX 3.0 V6 at nearly 97 BHP per liter.
quote:Wait a minute, you're inventing an "efficiency" based on the weight or block material of the engine and the amount of horsepower it can produce? This is an imaginary efficiency that is of no relevance to automobiles! BTW, many of GM's pushrod engines are in fact all aluminum. Real efficiency is shown by considering the fuel efficiency, cost, and performance of various engines intended for similar applications. Not some made up derived quantities that serve no purpose other than backing up your own opinions. jeff
Originally posted by CBDFrontier06: It's an explanation of how efficiently an engine can produce power. Why build a hulking 6-liter cast-iron OHV powerplant to produce X horsepower when you could make the engine out of ligher materials and make it produce the same or more power more efficiently, thus allowing a smaller, lighter engine...
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