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Something I Don't Understand

This is a discussion on Something I Don't Understand within the Internal Engine forums, part of the LSx Technical Help Section category; Why hasnt Chevy gone from a OHV config. to a DOHC config. Wouldnt having more valves per cylinder make for ...

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    Living in Hell alexg69's Avatar
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    Something I Don't Understand

    Why hasnt Chevy gone from a OHV config. to a DOHC config. Wouldnt having more valves per cylinder make for a better breathing engine and increasing power?

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    Moderator Firebirdjones's Avatar
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    Cost is the biggest reason.

    I'm glad they haven't. I like the old pushrod V8's, and GM has shown they can hold their own against all the over head cam stuff out there. No reason to change really.

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    Quote Originally Posted by Firebirdjones View Post
    Cost is the biggest reason.

    I'm glad they haven't. I like the old pushrod V8's, and GM has shown they can hold their own against all the over head cam stuff out there. No reason to change really.
    x2 and to me the pushrod engine is easier to work on

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    Living in Hell alexg69's Avatar
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    Quote Originally Posted by Firebirdjones View Post
    Cost is the biggest reason.

    I'm glad they haven't. I like the old pushrod V8's, and GM has shown they can hold their own against all the over head cam stuff out there. No reason to change really.
    Ohhhh makes sense

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    There are a couple of books out there that tell the story of the LS1. One of them is that in the early to mid-1990's, the engineers did a blind test with two cars. One had a standard push rod V8 and the other had an overhead cam multi-valve setup. Guess which engine won out?

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    I totally agree; the pushrod V8s are an American standard that will probably never be replaced by-and-lare.
    I think one of the main reasons they'll never filter out the pushrod motors is profit - There are tens-of-thousands of aftermarket suppliers out there manufacturing parts for our street cars, race cars, boats and so on and the idea of them having to rebuild the industry to follow the out-trending of an oldie but a goodie is just too much to imagine. The aftermarket manufacturing pool for OHV stuff is pretty small in comparison.
    I'm not saying it could never happen! It just seems unlikely to me
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    Quote Originally Posted by alexg69 View Post
    Why hasnt Chevy gone from a OHV config. to a DOHC config. Wouldnt having more valves per cylinder make for a better breathing engine and increasing power?
    Quote Originally Posted by pajeff02 View Post
    There are a couple of books out there that tell the story of the LS1. One of them is that in the early to mid-1990's, the engineers did a blind test with two cars. One had a standard push rod V8 and the other had an overhead cam multi-valve setup. Guess which engine won out?
    ^ yup the cars in question where c4 corvettes and 1 was fitted with the lt5 if i am not mistaken and the other with a ls1 prototype. it was for a bunch of execs at the proving grounds here in michigan..each got to drive both, not knowing what was under the hood of each. it was the ls1 without a doubt that won.

    the complexity, weight, cost was a big concern. Gm tried with the northstar engines and the cost and complexity was apparent.

    the pushrod engine is so simple it is stupid..this keeps costs down and allows for a insane amount of different configurations relativity easy. i dont see the pushrod going anywhere anytime soon.

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    Quote Originally Posted by alexg69 View Post
    Why hasnt Chevy gone from a OHV config. to a DOHC config. Wouldnt having more valves per cylinder make for a better breathing engine and increasing power?
    Go get a ford

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    Why do you think gm needs to change to an overhead cam design?
    Or is the current 430 and 500 hp motors not enough for you?

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    Quote Originally Posted by c5z28 View Post
    Go get a ford
    HELL NO
    Quote Originally Posted by c5z28 View Post
    Why do you think gm needs to change to an overhead cam design?
    Or is the current 430 and 500 hp motors not enough for you?
    To me, it seemed logical that having more valves per cylinder would make a better breathing engine which then equals more power. Im not asking gm to change anything. Their engines are perfectly fine. It was just something i didn't understand.

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    Quote Originally Posted by alexg69 View Post
    HELL NO


    To me, it seemed logical that having more valves per cylinder would make a better breathing engine which then equals more power. Im not asking gm to change anything. Their engines are perfectly fine. It was just something i didn't understand.
    you are correct in your thought...but as said. there are other factors regarding why the lsx family is not a 4 valve family.

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    Expense, expense, and maintainance.. Usually multi valve engines require a little more work to keep in top running condition as well.. They tend not to like the same types of neglect that push rod engines will endure with not even a twitch.. I'd say 90% of the OHC vehicles in a junk yard, got there because of a broken timing belt and/or a valve strike.. Mostly due to neglecting to change the belt ever.. A chain like in push rod engines with most likely never give the owner trouble over the life of the car.. Yes they wear out, but usually not till after mileage exceeds mechanical limits.. Simply put a push rod engine = ease of maintainance... Been makin' them that way over 100 years.. But I'm a little bit with you I like multi valve engines too.. They, (if nothing else) just sound better too..
    Last edited by Smittro; 07-20-2010 at 01:30 PM.
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    it's not just the V8's.....Gm's 3100/3400 (yes intake gasket issues aside) as well as the 3800 outperformed(gas/torque) the similar accord/camry/maxima (sort of)/ sonata/passat/Intrepid of the day....

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    The ZR1 used a DOHC for a few years, and while it was one of the greatest Vette's made, it can't even come close to the base C6's. Of course the motor was built by Mercury Marine.....just sayin'.

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    Quote Originally Posted by MrKid View Post
    The ZR1 used a DOHC for a few years, and while it was one of the greatest Vette's made, it can't even come close to the base C6's. Of course the motor was built by Mercury Marine.....just sayin'.
    Yes, this was with the LT5 mentioned earlier in this thread. Chevy teamed up with Lotus I believe to build this 32v dohc 5.7 349ci motor that put out a peak of 405hp, which was unmatched until of course the LS6 Z06.

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    Quote Originally Posted by ls1fan74 View Post
    it's not just the V8's.....Gm's 3100/3400 (yes intake gasket issues aside) as well as the 3800 outperformed(gas/torque) the similar accord/camry/maxima (sort of)/ sonata/passat/Intrepid of the day....
    I know a little about the 660's.. The manifold gaskets have long since been updated, as well as the oil pump drive O-ring.... I also know a few things about the TDC (father of the northstar program) 660.... As well as the l36-l67, and 3.8.. Prolly would'nt take much more than a new set of cams degreed with a different grind, and a tune to get the LT5 competative with newer v8's, bottom end could prolly be left untouched too.
    Last edited by Smittro; 07-21-2010 at 07:54 AM.

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    I believe there just wasn't anymore room available under the hood. They had already cramed half the motor under the dash already anyway and descided to spare all the poor peoples Knuckels from cuts and scrapes. Can you imagine trying to change spark plugs on a LS1 with big fat heads on it. Scarry!
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    King 0f n00bz shady milkman's Avatar
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    Quote Originally Posted by BLK2KSS View Post
    Chevy teamed up with Lotus I believe
    nope. it was mercury marine they teamed up with. they used lotus 4v heads that were custom built for the application.

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    Quote Originally Posted by shady milkman View Post
    nope. it was mercury marine they teamed up with. they used lotus 4v heads that were custom built for the application.
    Didn't Lotus work on suspension tweaks also?

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