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VERY in depth article about why 4 valves ARE better!

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  • #31
    Oh and if you are still concerned about your low end torque, thats why they invented variable valve timing Like firehawk brought up but nobody continued on about. :wink:
    Yeah yeah, just more shit to break tho right? Meh what do ya do? Run a 2 valve I guess.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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    • #32
      I love the refinement of the more high tech engines, theyre amazing, I just wish I had the money to get one, put it in a car that deserves it (300) and keep enough cash left to maintain it with my abuse.... Yeah... Im dreaming.

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      • #33
        i don't know if any of you have driven a mitsubishi diamante.

        they have a 3.5L single overhead cam but it has 4 valves per cyliner and roller rockers to run it all off a singe overhead cam. its really undertuned from the factory at only 210hp and 250 ft pounds of torque. i wish i could put one in a Z and then turbo it. its a very good strong motor.

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        • #34
          Firehawk wrote: They didn't even mention variable lift valves that many 4valves have. Personally, I am waiting for a nonmechanical, likely elctromagnetic actuated valves. Tuning would take SO much longer, though :shock:
          You got that right.

          The 4V vs 2V argument is just different dogs with the same fleas.

          Here's some good reading...

          http://www.spectrum.ieee.org/print/1420

          No timing chain

          Another case in point is electromechanical valve control. In today's engines, a camshaft acts on the valve stems to open and close the valves. As the crankshaft drives the camshafts through gears or a chain or belt, the timing of the valves' openings and closings is controlled by the cam design, and is fixed relative to piston position. This means that engine performance (in terms of emissions or fuel economy) is optimal over only a narrow range of engine speed.

          If the valves were electromechanically actuated, however, they could be opened and closed without regard to crankshaft position. They could operate optimally at all engine speeds, torque levels, temperatures, and any other variables the designer includes. In fact, valve timing could be made part of a closed-loop emission-control system.

          Moreover, an electromechanical system would eliminate the heavy and complicated camshafts and timing chains or gears. The valves would be actuated by sending current pulses through spring-loaded solenoids with the valve stems as their cores.

          Electromechanical valves offer other interesting possibilities. For example, the valves can all be opened at the beginning of engine start-up, relieving compression and greatly reducing the cranking torque needed, so that smaller batteries and starter motors could be used. In fact, the peak power of the starter motor might be close to that of the alternator, so that a combined starter/alternator might become feasible. The starting torque might even be so low that the engine could be turned over through the fan belt at start-up, and the combined starter/alternator could then simply be mounted in the place now occupied by the alternator.

          Start without moving

          Even more intriguing, when combined with direct fuel injection, electromechanical valves may be able to start an engine statically, with no initial rotation whatsoever. Valves to the appropriate cylinders would be closed, and fuel would be injected into them and ignited, turning over the engine. If static starting should prove feasible, the battery could be designed for energy storage only, not for cranking power, and its size could be much reduced.
          Try not to be a Yahoo

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          • #35
            SATAN wrote: Jason84NA2T wrote : Yeah, I got the vibe as well. I'm not really sure why some people are under the impression that DOHC is somehow "better" overall than SOHC, and SOHC is outdated? Last time I checked, some of the most powerful and technologically advanced engines in the world were still using 2 valves per cylinder.

            The only reason I started this thread is because SOME people here are under the impression that 2 valve is just as good as 4 valve (Its not only Jason). Not because I think everyone should swap over to 4 valve systems. Yes I agree, the VG30E is the best bang for the buck. BUT, I am SQUASHING the rumor that it is just as good as a VG30DE, Or any of the same engine with 2 vs 4 valves. If you dont understand the benifits of running 4 valves apposed to 2 after this thread then there is no hope for you.

            Do I hate 2 valve? NO
            I love my engine!
            Do I understand why 4 valve is better? YES!

            You are completely disregarding the bolded word in my statement and hence (in a way) putting words in my mouth. Think about it for a second.... if you don't get it then I can explain it for you, but you obviously missed the point
            of what I was really saying.

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            • #36
              JK wrote: When choosing an engine for my Z31 buildup, I wanted an engine to produce 400-500rwhp. I looked at the 4 valve VG30 and the 2 valve VG33. Bang for the buck aside, I chose the VG33 because with the torque advantage over the 4 valve, the 33 is more fun to drive. As a street/strip car, much of the appeal is in the 'stop light grand prix' arena. The 2 valve will pull down low, the 4 valve does not.

              It also turns out to be much cheaper to go with the 2 valve VG30 or 33, when considering this HP goal between the 2 and 4 valve configurated engines.
              I think the nail has been hit directly on the head with your statement. Thanks John.

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              • #37
                [quote]Jason84NA2T wrote:
                Originally posted by SATAN
                Jason84NA2T wrote : Yeah, I got the vibe as well. I'm not really sure why some people are under the impression that DOHC is somehow "better" overall than SOHC, and SOHC is outdated? Last time I checked, some of the most powerful and technologically advanced engines in the world were still using 2 valves per cylinder.

                The only reason I started this thread is because SOME people here are under the impression that 2 valve is just as good as 4 valve (Its not only Jason). Not because I think everyone should swap over to 4 valve systems. Yes I agree, the VG30E is the best bang for the buck. BUT, I am SQUASHING the rumor that it is just as good as a VG30DE, Or any of the same engine with 2 vs 4 valves. If you dont understand the benifits of running 4 valves apposed to 2 after this thread then there is no hope for you.

                Do I hate 2 valve? NO I love my engine!
                Do I understand why 4 valve is better? YES!
                You are completely disregarding the bolded word in my statement and hence (in a way) putting words in my mouth. Think about it for a second.... if you don't get it then I can explain it for you, but you obviously missed the point
                of what I was really saying.
                But you and I have touched on this before. Thats why I posted up this topic because overall DOHC 4 valve is better than two valve when coupled with VVT.
                Its not putting words in your mouth you just seem to quick to defend the 2 valve engine. You say some of the most tech and powerful engines in the world are two valve. BECAUSE of this statement alone I call bullshit. This is far from the truth. The Tech. engines ARE the ones running DOHC VVT and the super tech ones are beyond that even. Which the LS7 could never dream of.

                Is the LS7 powerful? yes, but it damn well better be with as much displacement as that pile has. How much better could it be if it had technology. But then it wouldn't be cost effective anymore and you would then have super car that is super pricey as well. But this discusion is not about price its about technology.
                85 Z31 6.0 LSX turbo 766whp/792wtq
                04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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                • #38
                  Chevy has VVT on there new silverado coming out

                  Terrible idea putting those wheels on...

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                  • #39
                    [quote]SATAN wrote: [quote=Jason84NA2T]
                    Originally posted by SATAN

                    Is the LS7 powerful? yes, but it damn well better be with as much displacement as that pile has. How much better could it be if it had technology. But then it wouldn't be cost effective anymore and you would then have super car that is super pricey as well. But this discusion is not about price its about technology.
                    Jeezus Satan you need to come have some beers with my Irish bretheren and c how long you last with a mouth like that.hehehe.

                    I'd hardly call the LS7 a *Pile but I sure as shite wouldn't call it a Technological marvel*(who would cept for American Muscle enthusiasts in denile) so let's all take chill pill shall we. This thread is gonna turn into a lame ass mundane semantics debate and X-mas is in two days.

                    Hell, even that Bugati engine isn't a *marvel* IMVHO. I'll take the N/A McLaren F1 anyday over that pastarocket and turbo it myself if one is going to go insane with his car purchase/s!

                    It's funny how many Car dudes will talk all day about Power to weight ratio's of overall cars but don't consider power to weight ratio of the engine itself. The reason that Chevy went with a 7.0L engine is because it can produce as much power as a V10 with a lighter/smaller engine.

                    You obvioulsy don't completely understand low end torque as well as you should Satan nor do you truly understand Variable Valve technologies if your saying said tech. completely compensates for lack of low end torque or torque in general.

                    Honda has been using their V-tec for years(we wasted countless hours and dollars with V-tec controllers) and Yota has been using *VVT-I* for some time now. Both technolgies make a difference in a stock engine but neither is profound.

                    Here's the Bottom line.....4 or even 5 Valves IS/are superior to a 2 valve engine but the margin of increased performance is relative to the overall engine design and implemented computer control! 4 Valves is *Beter* but how much better is relative to all the other variables?

                    The Nissan VQ35DE is a beaslty N/A(with good cams and headers of course) engine but if said engine had the VVT-I tech. that Yota uses now I'm 100% sure it would be *better*!

                    I like what JK has to say bout the VG and I absolutely plan to play with a VH45DE and a 2JZ-GTE in the near future but I've got a family to worry bout.

                    Peace and Love!
                    Ucked Fup!!!

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                    • #40
                      VG36ET wrote:




                      You obvioulsy don't completely understand low end torque as well as you should Satan nor do you truly understand Variable Valve technologies if your saying said tech. completely compensates for lack of low end torque or torque in general.

                      Honda has been using their V-tec for years(we wasted countless hours and dollars with V-tec controllers) and Yota has been using *VVT-I* for some time now. Both technolgies make a difference in a stock engine but neither is profound.
                      Dammit man, I should kick you in the nuts for that statement! :lol:

                      Answer this then, if two valves make more torque than 4 then what the hell is wrong with the difference in these two engines???????

                      VG30E torque=182 ft lbs Hp=153
                      VG30DE torque=198ft lbs Hp=222 no VVT either!

                      DE makes 16 ft/lbs more torque. Ok i'll say that at best case scenario the better head design along with the intake "might" make the torque about the same as the vg30e IF the 4 valve design makes less torque like everyone says it does. BUT do you think just by better head and intake design they made the torque not only equal, but, 16 ft/lbs MORE than the E! I dont think so! And thats not even using VVT yet!

                      Now lets look at the HP factor. Whats this?? 69 more horsepower just by using a DOHC 4 valve design?! THE HELL YOU SAY!



                      I'm sorry but the two valve argument has lost its case.

                      I just for the record!!!! I'm not mad at any of you guys. I like having debates like this because this is how smart people get smarter. I'm glad I have people to converse with about this stuff.
                      85 Z31 6.0 LSX turbo 766whp/792wtq
                      04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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                      • #41
                        satan. you are my hero. You come into a world of people set in their ways, you learn from all sides, and make an objective and unopinionated decision based on emperical and observable evidence. When you're wrong you STFU and learn exactly what makes you wrong rather than getting angry, defensive, and wanting to be right.

                        keep up the good work. This forum needs more people like you.
                        Funny stories!

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                        • #42
                          homestar wrote: satan. you are my hero. You come into a world of people set in their ways, you learn from all sides, and make an objective and unopinionated decision based on emperical and observable evidence. When you're wrong you STFU and learn exactly what makes you wrong rather than getting angry, defensive, and wanting to be right.

                          keep up the good work. This forum needs more people like you.
                          THANK YOU! I am the FIRST person to admit it when I am wrong but when I feel that I am not, and people dont prove me wrong well... Then I will argue my point till I am blue in the face and long after everyone else has given up. :twisted:

                          Like I said in the what is your life thread. "People either REALLY like me or REALLY hate me(very few inbetween and I'm Happy with that.) "
                          85 Z31 6.0 LSX turbo 766whp/792wtq
                          04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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                          • #43
                            Satan.. as much as i dont really like our name...lol... our minds think Exactly the same when it comes to this subject. Im behind you all the way. I still love my 2 Valve VG... but im not going to let it blind me from the truth. I would really like to see a dyno of a VG30E stock and VG30DE stock next to each other... to really see how this "low end torque" thing pans out. Im sceptical as to how true it is.. i think 2 valve has always been assosiated with low end torque because all the huge engines which always have low end also all seem to be 2 valve. most of the 4 valve engines out there, are smaller engines.

                            Also... VG36ET.... VQ35DEs do have variable valve timeing.. infinitly variable..Those moters rule.. i just wish they were iron block closed deck.. then they would be unstopable. o well.. sleaves work.

                            Jerm

                            o and.. ive got a stock VG30E dyno.. now someone just needs to come up with a VG30DE one..

                            12.88 @ 114 mph.. in a 91 maxima at 14 psi

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                            • #44
                              Stock VG30DE



                              Another stock VG30DE



                              Stock VG30E



                              Another VG30E



                              Nearly identical in the low end.. but the VG30DE dosnt Die up top.

                              anyone with more stock dynos to help improve accruracy..?

                              12.88 @ 114 mph.. in a 91 maxima at 14 psi

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                              • #45
                                One thing to consider over the number of valves is flow. Flow is power (which is why turbo cars rule). The lsx motors flow very well, which is why they have great top end power, and the two valve helps with the low end. More valves just help top end flow. The technology is out there to make a really nice motor using variable lift valves, variable length runners, individual throttle bodies, electronic control (just disregard emissions and fuel economy), and of course turbo.

                                Also, with its greater displacement, 4 valves that are variable, the Z33 still have less low end power than a Z31T.

                                Oh well, I am not sure why this thread is still going on, but maybe something interesting will pop up again.
                                Chuck Stong
                                300+ Parts and Performance owner
                                http://www.300-plus.com
                                2002 ZCOT president and always active member

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