VVTi
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Someone earlier in the thread suggested that variable valve timing is an economy or emissions thing only. I hope they were trolling
BMWs VANOS technology may have an economy advantage but its cheif utility is to widen the torque band of the engine. BMW likes a slightly horsepower biased engine with a slightly rev-happy cam. VANOS allows more torque to be available at a wider variety of load and RPM conditions than the fixed cam profile would allow. Prepared BMW engines will sometimes have the VANOS unit removed as it may not offer any advantages in racing conditions (but removing the attendant valvetrain mass/complexity may)
VANOS is essentially a cam-phasing technology which can retard or advance the intake cam (single vanos) or both cams independantly (double vanos). The cam phasing in VANOS is "stepless" in the sense that there aren't pre-set cam retard/advance settings.. to the extent that it is mechanically possible the cam phase dilation is a continuous function across its range of motion. An easy way to think of it is - everyone has seen adjustable cam gears where you've got the slot and the lock nut - these allow for any cam position within the slot of adjustment. VANOS is the same concept, except the advance or retard of the cam is controlled by the engine management system and servos, not set by you while the engine is stopped
I beleive that single VANOS first appeared on a production BMW in the USA in 1993, on the M50B25TU engine found in the E34 525i series and E36 325i series.
For many years, no other variable valve timing technology provided variable valve lift as **** did, because I beleive Honda had a patent on variable valve lift.
That patent has either expired or been worked around such that newer systems like BMW Valvetronic and the latest Porsche VarioCam also provide variable lift.
The Valvetronic lift profile is also steplessly variable - the effective lift of the valve can be any value between its minimum and maximu adjustment, with sufficient speed and granularity that Valvetronic engines do not have throttle butterflies. The variable lift in valvetronic is acheived by having an eccentric (sort of like a french curve) on a shaft that runs parallel to the cams. IIRC, there is one eccentric lobe per valve pair, and the shaft doesn't ever make a full revolution - it adjusts forward or backward to increase or decrease the effective shim width between the normal camshaft lobe and the valve itself (at least, that' show i remember it working). Conceptually you are steplessly varying the shim thickness if you had a shim-over-bucket valvetrain.
**** is an effective and ingenius system, but at least in its initial versions, it's little more than stuffing 2 sets of cam lobes onto the same camshaft.
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When did valvetronic start being used?
VVT started because the manufactures said goodbye to those hairdriers that are plumbed into the exhaust and wanted a better way to reduce emissions at startup.
Yes, as it evolved they are used more and more for performance purposes...I agree. Its just not as effective for adding power as the hondas (referring to stock cars here. Yes, i realize boost owns all)Its also funny when people talking about their VVT 'kicking in'
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PSI2HI wrote:
14:1 and boost, it just needs to be built...... Yup, ok!If you haven't run the times or built the cars then where do you stand in the end??
When Did I say it JUST NEEDED TO BE BUILT!?!? I never did? I just said it NEEDED to be built. i dont know where you guys are getting this... once again like I said, I never gave any incorrect information in this thread. Why do I need to run a fast time to say something that is obvious? -
slowvo wrote:
When did valvetronic start being used?I beleive on the V8 in the E65 745Li (the current 7 series body style).. so around 2002 or so?
I don't know which other BMW engines feature Valvetronic.
None of the M engines do - BMW has stated that thus far, Valvetronic isn't responsive enough for their M car engines - which all rev to 8000+ rpm now
(8000rpm for the M3 / Z4M, and 8300 for the M5/M6) -
wannabe wrote:
I never gave any incorrect information in this thread. Why do I need to run a fast time to say something that is obvious?What kind of fuel would you run on a forced induction 14:1 engine? What engine management?
Also, why would you run a high static CR instead of a slightly lower one but with more upside in additional boost? You might want the higher CR for a street motor.. but 14:1 boosted doesn't sound very streetable to me.
Audi runs 10.x:1 on their TFSI motors, and run a non-trivial amount of boost, all on pump gas, with a warranty. But to do this apparently requires a bunch of tricks that you don't normally see in the aftermarket - direct sequential injection being cheif amongst them. I've never heard of anyone converting a common-rail setup to a direct-injection setup. Something about drilling an extra hole in the combustion chamber seems to turn people away.
I'm not sure what standalone systems support sequential injection and non-waste spark ignition.. 034EFI probably does. I'm sure something like Motec does. Most people doing at-home or even at-shop builds aren't running Motec though...
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AEM lets you run sequential injection and non wasted-spark ignition.
That's what we use in almost everything. -
wannabe wrote:
When Did I say it JUST NEEDED TO BE BUILT!?!? I never did? I just said it NEEDED to be built. i dont know where you guys are getting this... once again like I said, I never gave any incorrect information in this thread. Why do I need to run a fast time to say something that is obvious?wannabe wrote:
I meant 14:1 compression, tired post, wasn'treading it right...wannabe wrote:
its not like you can't boost a high compression motor... it just needs to be built...Because you learn from hands on first hand experience not reading it on the internet. if you've never built anything or run the time how do you think you know, cuz you read it online? I see it every week..... And we get the PITA to fix it half the time too!
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slowvo wrote:
When did valvetronic start being used?
VVT started because the manufactures said goodbye to those hairdriers that are plumbed into the exhaust and wanted a better way to reduce emissions at startup.
Yes, as it evolved they are used more and more for performance purposes...I agree. Its just not as effective for adding power as the hondas (referring to stock cars here. Yes, i realize boost owns all)Its also funny when people talking about their VVT 'kicking in'
I think when people hit that crossover point, its easier to say **** kicked in, than Damn, my cams just changed over to a much more aggressive profile. -
I've never known the feeling of **** to be a "damn."
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^^stir stir stir^^
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Street racing is bad. Very dangerous
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wannabe wrote:
No I think he just wants other people to race his car because he is scared of it... Who was driving in this video?link removed belongs in protected forums
Damn, your really digging. Is there something your trying to prove or wtf does what you just posted have to do w/ anything? i can take you out in it too on the street tires w/o a seat belt and probably make you piss your pants!
Neither GSR's car nor Kevin's hatch will stay in its own lane under 120mph and personally i wont drive anything on the street @ those speeds on slicks.
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integra_gsr98 wrote:
Ever run a decent time? Tune a car? How about a high comp boosted car? Own one?Didn't think so.
Misinformation spreads when people who have zero knowledge on a subject pretend that they do.EDIT See http://www.honda-tech.com/ for examples.
Al I was doing, tufte, was bringing up the fact that while he might own a High compression boosted car, He doesn't race it on the streets, and when he's at the track he doesn't run decent times for the cars potential. I never claimed to know all, and he talks a lot of shit for someone who can't handle his car. Not saying I can do better, but I'm not the one running my mouth... -
wannabe wrote:
. Not saying I can do better, but I'm not the one running my mouth...Then you shouldn't be talking @ all then.....
The motor is 9.8:1, nothing crazy. When you build a 500whp fwd setup you come find me and we'll take it out on radials and see how you'll push it.
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wannabe wrote:
Al I was doing, tufte, was bringing up the fact that while he might own a High compression boosted car, He doesn't race it on the streets, and when he's at the track he doesn't run decent times for the cars potential. I never claimed to know all, and he talks a lot of shit for someone who can't handle his car. Not saying I can do better, but I'm not the one running my mouth...Define a decent time? The 10th pass out on a STREET tune this year it ran 10.8 @ 136. It's run low 11s more times than you've ever seen the 15s.
Define my potential of my car? What do you know about it? Single stage boost no traction bars, 3 year old tires and 10.8 @ 136 on the 10th pass of the year, fuck thats horrible. Oh then it didn't do it again, but weird, that failing fuel pump completely fucked the tune over on the last weekend. I must really suck.
I've raced plenty of shit on the street, don't care to do it anymore period. Why risk my drivers license, my insurance, MY JOB, or my life. If you knew the back story on that night against the bike's you'd probably be able to talk shit, but I guess you really have no clue.
Go back to running back and forth and stirring shit up between shops because that's about all you are good at.
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