Some details of the 2AZ-FE engine
in [Technical]
|
Prev: P0171/P0174 Help!
Next: LTFT1 & LTFT2....ford truck
From: C. E. White on 28 Jul 2008 07:41 "Steve" <no(a)spam.thanks> wrote in message news:ONSdne4rssYfCRXVnZ2dnUVZ_hSdnZ2d(a)texas.net... > Scott Dorsey wrote: > >> >> This means hydraulic lifters, but it also means sealed chassis >> components >> that don't need regular greasing with every oil change but which >> fail >> before 80,000 miles is up. It means "sealed for life" >> transmissions, where >> that life is about half what it should be. > > Here here! Eliminating the dipstick on automatic transmissions has > to be the single most unnecessarily STUPID thing car makers have > done in the last 50 years. Maybe since the dawn of the automobile. Why? All my current cars still have dip sticks on the transmission, but there never seems to be any change in the level. I think eliminating dipsticks was a safety measure more than anything else - I remember reading that a significant number of transmissions were damaged because either they were over filled (people don't follow the instructions for using them) or the wrong lubricant was added tot he transmission through the dip stick hole (wrong ATF or just the wrong stuff - like engine oil). How may car owners ever use the automatic transmission dip stick? Ed
From: Steve on 1 Aug 2008 12:58 >How may car owners ever use the automatic transmission dip stick? > All of them with half a brain. How often do you actually add ENGINE oil? I never need to between changes, but I still CHECK it weekly. Same with the transmission fluid. The whole idea of maintenance is to CATCH a potential problem before it becomes costly. Eliminating the transmission dipstick pretty much guarantees a low-fluid failure will ultimately destroy the transmission, be it at 10,000 miles or 200,000 miles.
From: Steve on 1 Aug 2008 13:03 Dyno wrote: > Steve wrote: > How minuscule are we talking about here? > Sample base circle load calc: > Oil Pr : 60 psi > Adjuster Dia: 0.30 in > # Valves: 16 (4 cylinder) > 60 psi x pi*(.15^2)*16 = 68 lbs is small? Maybe it is, but it certainly > is more than ~0. The base circle pressure doesn't matter if itdoesn't introduce any added friction, and with today's roller followers it just doesnt. > > I don't think this is negligible. And detailed engine friction studies > have verified the reduced friction using mechanical lash systems. > >> 2) With roller followers cam followers, adding base circle pressure >> doesn't increase friction much at all. That's one big reason they're >> used- far far lower friction than flat lifters from base circle all >> the way to full lift. And of course they can follow a lobe profile >> with a much sharper ramp rate so that you can get long duration >> without excessive overlap. > Agreed, roller followers are in a different category and do have low > friction. But, they are costly and tend to be relatively bulky. Yet they are virtually universally used! There's no point having a raging debate about slider followers, it would be like arguing the advantages of going back to drum brakes.
From: Dyno on 2 Aug 2008 22:39 Steve wrote: > Dyno wrote: >> Steve wrote: > >> How minuscule are we talking about here? >> Sample base circle load calc: >> Oil Pr : 60 psi >> Adjuster Dia: 0.30 in >> # Valves: 16 (4 cylinder) >> 60 psi x pi*(.15^2)*16 = 68 lbs is small? Maybe it is, but it >> certainly is more than ~0. > > The base circle pressure doesn't matter if itdoesn't introduce any added > friction, and with today's roller followers it just doesnt. > >> >> I don't think this is negligible. And detailed engine friction studies >> have verified the reduced friction using mechanical lash systems. >> >>> 2) With roller followers cam followers, adding base circle pressure >>> doesn't increase friction much at all. That's one big reason they're >>> used- far far lower friction than flat lifters from base circle all >>> the way to full lift. And of course they can follow a lobe profile >>> with a much sharper ramp rate so that you can get long duration >>> without excessive overlap. >> Agreed, roller followers are in a different category and do have low >> friction. But, they are costly and tend to be relatively bulky. > > > Yet they are virtually universally used! There's no point having a > raging debate about slider followers, it would be like arguing the > advantages of going back to drum brakes. > Roller valvetrains are universally used? Er, ah I don't think so. For example: I-4's in Mazda 3/6, Ford Focus and Fusion I-4's use direct acting mechanical bucket tappets. Ford's 3.0L DOHC is a DAMB. These are pretty mainstream engines. And anyway the original discussion was NOT about roller finger follower or other roller valvetrains. It was about hydraulic vs mechanical. You added the roller valvetrain tangent. And I already agreed with you that a roller valvetrain will have the lowest friction.
From: Steve on 5 Aug 2008 14:36
Vic Smith wrote: > On Fri, 01 Aug 2008 11:58:47 -0500, Steve <no(a)spam.thanks> wrote: > >>> How may car owners ever use the automatic transmission dip stick? >>> >> >> All of them with half a brain. >> >> >> How often do you actually add ENGINE oil? I never need to between >> changes, but I still CHECK it weekly. Same with the transmission fluid. >> The whole idea of maintenance is to CATCH a potential problem before it >> becomes costly. Eliminating the transmission dipstick pretty much >> guarantees a low-fluid failure will ultimately destroy the transmission, >> be it at 10,000 miles or 200,000 miles. > > Hard to imagine not having a trans dipstick. Open the hood of any late model Toyota. :-( |