4.3L V6 Silverado ~ Information and Advice

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by dark star, Jan 5, 2013.

  1. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    The 4.3 is a great engine when taken care of but honestly alittle long in the tooth. They are reliable and almost bullet proof but thats about it. When the 4.8 came out they were getting close to the same mpg with the v8 having more power. Thats why gm waited until now to update it because unless it was a fleet or wt people went with the 4.8. Dont get me wrong i love the 4.3 and for a long time it was the best full size v6 but shes going on 30 years. Reasons why i wouldnt buy an audi, sure there are fast and have gadgets but after a few ticks on the odometer they develop permanent probs thats multiply. Rather have reliability over power.

    That being said the new one is the same story basically, same as the new gen v (?) v8s missing 2 cylinders. But the new guys are all direct injected and after seeing that 3.6 monster they have im painfully waiting to drive one. Still pushrod though so prob high 200's.
  2. Nargg

    Nargg Rockstar


    So what if they are "long in the tooth", that arguement is not a good one. Cars and trucks in general have been around for centuries, does that make them "long in the tooth" too? Sorry, I don't mean to be ugly on this but it's a problem in retorical logic to make a statement like that. And that arguement really shouldn't be used as it doesn't have any bearing or reasoning. Besides, in this case GM has stated that the 4.3 for 2014 is "all new", in which examining the scant technical data from it so far it is very much quite different than the previous model. I think you've taken the 4.3L displacement as old, and not the actual engine. It's very much different from the engine 30 years ago. And, has gone through a number of major upgrades and changes over the years. The original 4.3L at 160 HP was a simple pushrod design with few features beyond hemispherical heads. The modern 4.3 about to be debuted is quite different with many new features it's never had, and should produce twice that HP easily, and considerably more MPG too. Also, no it's not the 5.3L missing 2 cylinders. If you were to add 2 cylinders to the 4.3L, you'd get 5.7L not 5.3L.

    As I see it, you've falled victim to the OHC sales pitches, and "need for magazine writes to fill space so let's bitch about pushrods engines" rants. OHC engines are sexy and all, and do wonders for smaller displacements. But they simply have not shown to be a must have feature for larger displacement engines. GM continues to produce similar engines year after year while continueing to meet and exceed their competition in doing so. As long as that continues, there is no reason to be negative about their choices in this type of engine style.
  3. dark star

    dark star Member

    Is anybody running headers on the 4.3l V6 ?
    What kind of performance boost would you expect ?
  4. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    dark star I'm going to appologize in advance for hijacking this thread, What year silverado do you have?

    Ok Nargg, I was talking about the current production 4.3 and not the 2014 version and when I said "That being said the new one is the same story basically, same as the new gen v (?) v8s missing 2 cylinders." It has the same design not the same displacement of the new engines minus 2 cylinders. The new engine shares absolutely nothing with the pervious 4.3 other than displacement. The current 4.3ISa dinosaur. It has 195 horsepower for the 2012 model year and it had 200hp in 2000! Granted ford and dodge were in the same boat up until a few years ago but thats no excuse. Ford has the 315hp ecoboost and dodge has the 300hp pentastar both new engine designs. GM has had the 3.6 since 04 and it was always around 300, now its well over it. Gm should have replaced the current 4.3, that has not changed significantly in 30 years, when they had the technology to do so.

    Now on your whole push rod issue, PUSH ROD ENGINES ARE NOT EFFICIENT. There I said it. Its not about whos raving over this and that, its facts. An engine is an airpump and the better it flows air, the better it works in converting energy. With me so far? So how can an engine with 1 intake valve, no matter the size, be as efficient as one with 2 or 3? An engine with 4 valves will generally produce more power than the same engine with a 2 valvehead. And its not just about the amount of air, I dont know if you have heard about this thing called variable valve timing but its not just a marketing term from some magazine article. For example the 3.6 with its direct injection and VVT can reach 18, 19, over 20:1 A/F ratio without detonation. A pushrod engine cannot change the timing or duration of valve action. The DOD, displacement on demand works by turning off lifters but that stops valve action, it does not change it. The fact is you cannot run 4 valves per cylinder in a pushrod configuration. Its not so much that the cams are on top of the heads it the fact that the intake and exhaust valves can actively change their profiles to suit engine needs and pushrods cannot. So tell me, where am I wrong?
  5. a.graham52

    a.graham52 Rockstar 100 Posts

    if you watn to get technical you COULD change vavle timing on an engine with pushrods but you would need one cam per intake and per exhaust valve-set.

    ill loose the mpgs as long as i dont have to deal with them damn timing chain failures.
  6. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    Dont get me wrong I love my 5.3 and I think the reason gm sticks with the pushrod v8 is reliability. But I dont think pushrod design is gonna make it out of this decade due to mpg standards. If you mount 4 cams in the block you could do it with pushrods but they would be redundant and the block would be huge.
  7. Nargg

    Nargg Rockstar

    I think the latest Road & Track article on the LS1 V8 states it well on push rod engines.

    "Pushrods were once decried as ancient, and proof that US car companies just don't get it. But for a large-displacement V-8, the layout is far more compact and less complicated than an overhead-cam engine. The ciritical ratio is power to volume, and in this metric the small-block is king...Plus fewer parts means lower cost."

    That sums it up quite nicely, and applies equally to the V6 in this case. And less wieght also means better MPG. Any version of the V6 from any year IMHO applies. So, I believe it's very very incorrect to say pushrod engines are not efficient, when in fact they are VERY efficient. Very efficient in almost every way.

    Plus, you are so very wrong on the adjustable part. Pushrod engines today have the same variable timing that OHC engines have. My 2011 5.3L V8 has variable valve timing. And, pushrods have a much better compression abilitiy than OHC. The complexity of OHC is it's downfall. Not to mention OHC being highly inefficient in larger engines. There's a lot of folks here and elsewhere that can tell you about the issues with Ford OHC V8s....

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    And GM already does that. They've had VVT in pushrods for I think over a decade, and it's in the trucks sold today.

    Plus, GM's pushrods are known to get to and over 1 million miles. I doubt you'd ever see that with an OHC engine.

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    Here's more "facts" for you. http://www.cheersandgears.com/topic/53310-why-gm-should-not-build-a-dohc-v8/ Check the MPG between these engines. It's the older 6.2L (without VVT, which is now in the 6.2L) So it's more kin to the older V6's asked about in this thread (i.e. should provide more answers for darkstar.) So, how is OHC more efficient again? Airflow, sure, but that doesn't translate to overall efficiency in weight/power/and fuel. Just because it can breath better doesn't mean you get better performance. Any good muffler guy can tell you that too. Bigger pipes can ruin economy and power. It's a mix of proper air at the right time along with compression. And GM gets that far more often in bigger bore engines with pushrods than any other company.
    Last edited: Jan 7, 2013
  8. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    Apparently you didnt read my explaination on VVT. The vvt you have is on and off. There are 4 solenoids that control the 8 lifters, therefore you can only turn thoses valves ON AND OFF. You cannot change when they open but IF they open. There is NO ADJUSTIBILITY OF THOSE VALVES, THEY SIMPLY DEACTIVATE THE CYLINDER. So you are very wrong, read up in how it works next time.

    I also love your "latest" road and track article on the "ls1". That was probably written when it came out in 97, 16 years ago.
  9. a.graham52

    a.graham52 Rockstar 100 Posts

  10. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    http://en.wikipedia.org/wiki/GM_Vortec_engine#5300 from what I have searched there is no VVT on the 5.3, The 4.8 and 6.2 have it but the VVT you said you had on your 5.3 is active fuel management. Even with the VVT the MPG on the 4.8 stayed the same and the figures for the 6.2 dont exist because its considered a truck engine with no epa estimates.

    "GM's entry-level small block 2010 4.8-liter V-8 with VVT keeps the same gas mileage ratings as 2009's. The Chevy Silverado and GMC Sierra Heavy Duty three-quarter-ton and one-ton pickup trucks also use VVT in the 6.0-liter gas V-8, according to GM powertrain spokesman Tom Read, but trucks in that segment aren't required to rate their fuel economy."

    This is what I have been trying to explain, we have reached the most we can get out of a single camshaft in an engine.

    "Plus, you are so very wrong on the adjustable part. Pushrod engines today have the same variable timing that OHC engines have."

    I didnt say OHC, I was refering to DOHC because the exhaust and intakes need to move independantly to optimize VVT which is why its not very effective on pushrods. In that mind frame the vacuum advance on a distributor is the same. The point is to change the indvidual valves not all at once which is what happens in the 4.8/6.2. In example the 3.6 can advance the opening of the exhaust valve and retard the closing of the intake AT THE SAME TIME, a single cameshaft cannot do both.

    Also look at the displacement on that BMW engine, it is significantly smaller like a 4.7 compared to that 6.2. Also those engines are designed for the cars handling, the bmw disconnected the alternator and dulls the throttle on launch. Both of those engines were tuned for thier application, they were set at their hp levels to optimize performance. That AMG was detuned because the new transmission was only rated at 532 ft/ibs.

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    this is so wrong I dont even know where to start..

    Also went to GM parts direct and there is no cam phaser listed for ANY 2011/10 5.3 equipped silverado.

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