Engine technology thread.

[serialk11r]

Wait if it doesn't have time to mix intake charge, why would it be better at higher speed, when there is less time to mix?
Hmmm but if it switches to port injection at higher speed, that would limit torque at higher rpm since you no longer have the cooling effect of introducing fuel in the compression stroke, which increases thermodynamic efficiency...and this is supposed to get higher max power right? Or maybe the gains are just from better flow.

[Dimman]

Originally Posted by 1GoZoom

Interesting stuff. Both my current cars are VVT DOHC 4V cars. When that Ti-VCT kicks in on the 6S Duratec 30, its a kick in the seat. It'd be gutless before then had I not swapped a larger throttle body from the new Mustang Duratec 37 and a set of shorty headers onto it. Now it pulls hard from 2K to redline. It also has cams, so that might help a teensy bit.

The Saturn's LE5, like I said I think somewhere, is torquey. It has what is called DCVCP. Pulls hard in the low band and at 3900rpm, the VVT kicks in and it roars to life. Just wish it had more power to match the throaty sound. :/

I'm fascinated by VVT systems. A good set of cams on a VVT head sounds like the end of the world, even on a four-pot.

Pet peeve of mine. All the automakers naming their systems differently. I have to research every automakers newly named system just to know what they are talking about.

If everybody just stuck to something more specifically descriptive like 'cam-phasing' (eg: VVT-i) and 'cam profile switching' (eg: VTEC), plus how they operate and which ones (eg: IS300's 2JZGE has 'hydraulic intake cam phasing') I would be a much happier person.

^So what is what on those ones?

[serialk11r]

Well I think for Valvetronic, Valvematic, and whatever valvetrain designs that allow phase, lift, and duration control it'd be a huge mouthful, so maybe acronyms and weird names aren't so bad

[Exage]

Originally Posted by serialk11r

Wait if it doesn't have time to mix intake charge, why would it be better at higher speed, when there is less time to mix?
Hmmm but if it switches to port injection at higher speed, that would limit torque at higher rpm since you no longer have the cooling effect of introducing fuel in the compression stroke, which increases thermodynamic efficiency...and this is supposed to get higher max power right? Or maybe the gains are just from better flow.

This is why I had originally thought that the multi-point was for high rpm, but I read the article and it stated that the intake manifold (on the 2GR-FSE) had "high tumble intake ports". But as stated above DI allows for chamber cooling on the compression stroke, and therefore allowing higher compression ratios.

[Dimman]

Originally Posted by serialk11r

Well I think for Valvetronic, Valvematic, and whatever valvetrain designs that allow phase, lift, and duration control it'd be a huge mouthful, so maybe acronyms and weird names aren't so bad

DOHC eventually became standardized, when companies were using Twincam, and even Quadcam for some of their motors.

Variable lift with cam phasing, is how I would describe Toyota's application of Valvematic.

There's pretty much only the three mechanisms I can think of.

Variable Valve Lift (Valvematic).
Cam Phasing (VVT-i)
Cam profile switching (VTEC)

Most of the named systems like VVTL-i, iVTEC, Valvematic, etc... are just combinations of these.

It's just wishful thinking on my part...

[Exage]

Originally Posted by 1GoZoom

Interesting stuff. Both my current cars are VVT DOHC 4V cars. When that Ti-VCT kicks in on the 6S Duratec 30, its a kick in the seat. It'd be gutless before then had I not swapped a larger throttle body from the new Mustang Duratec 37 and a set of shorty headers onto it. Now it pulls hard from 2K to redline. It also has cams, so that might help a teensy bit.

The Saturn's LE5, like I said I think somewhere, is torquey. It has what is called DCVCP. Pulls hard in the low band and at 3900rpm, the VVT kicks in and it roars to life. Just wish it had more power to match the throaty sound. :/

I'm fascinated by VVT systems. A good set of cams on a VVT head sounds like the end of the world, even on a four-pot.

You should look at the older VTEC, i-VTEC, MIVEC, and VVTL-i systems (among others). You want kick in the seat? Single cam-shift... There is nothing that will replicate those systems in the coming years with Variable Valve Lift mechanisms (see BWM Valvetronic, Toyota Valvematic, Fiat Multi-Air etc...) being implemented. An interesting fact is that BMW Valvetronic and Double VANOS systems control the intake and exhaust valve lift so well that they don't need a conventional throttle plate to control the engine.

[serialk11r]

VVTL is probably the best name for Valvematic and whatever, cuz the way they alter lift also shortens duration. And I think VVTi and VTEC have the same effect, so why not just call them both cam phasing lol.

[Dimman]

Originally Posted by serialk11r

VVTL is probably the best name for Valvematic and whatever, cuz the way they alter lift also shortens duration. And I think VVTi and VTEC have the same effect, so why not just call them both cam phasing lol.

VVT-i and VTEC are completely different.

VVT-i alters the cam's position, like you would tuning with cam gears (advance, retard, overlap), on the fly. The ecu has pretty much infinite control of position within the range limit of the system. eg: anywhere within 30 degrees.

VTEC changes the cam profile used, as if you were swapping a cam (or two) on the fly. VTEC can change to a pre-set new profile that has more lift, overlap, duration, but it's either one or the other.

iVTEC and VVTL-i are basically the same, and do both of the above.

Valvematic I'm not super familiar with how it changes to affect the lift part of it, but it is used in conjunction with VVT-i's cam phasing.

[Exage]

Originally Posted by Dimman

Valvematic I'm not super familiar with how it changes to affect the lift part of it, but it is used in conjunction with VVT-i's cam phasing.

Get familiar, they'll become the norm haha.

[Dimman]

Originally Posted by Exage

Get familiar, they'll become the norm haha.

Like a rocker arm that can change it's ratio on the fly, sort of?

What bother's me is that this has been out for a few years in Europe, but why not in North America?

[xantonin]

Originally Posted by Dimman

Like a rocker arm that can change it's ratio on the fly, sort of?

What bother's me is that this has been out for a few years in Europe, but why not in North America?

We are very slow to adapt. Just look at how many people we have on dial up still.

[serialk11r]

Has it? I think it's in some particular American models or something, but only a few.
The base model Lotus Elise (which they don't sell in America, because apparently Americans refuse to buy <1.8 liters lol) has an engine with it I think. Probably are some emissions tests that for some reason they haven't done or had trouble passing for some reason, or maybe they're just trying to squeeze more profits out of the American market by getting rid of the old engines here lol.

Valvematic should give pretty good fuel efficiency increases I'm guessing because if you look at the rocker thingy if the lift is low, the valve also closes very early, so they have a very low pumping loss strategy of throttling, since reducing lift introduces some restriction, but reduces the air taken in as well.

[1GoZoom]

Originally Posted by Dimman

DOHC eventually became standardized, when companies were using Twincam, and even Quadcam for some of their motors.

Variable lift with cam phasing, is how I would describe Toyota's application of Valvematic.

There's pretty much only the three mechanisms I can think of.

Variable Valve Lift (Valvematic).
Cam Phasing (VVT-i)
Cam profile switching (VTEC)

Most of the named systems like VVTL-i, iVTEC, Valvematic, etc... are just combinations of these.

It's just wishful thinking on my part...

Honda wins in this category. VTEC is a household name. Impressive brand marketing for something as mundane as timing of intake and exhaust ports. lol.

Quadcam ftw. My old Tempo had a swapped Yamaha SHO V8 in it. It was technically DOHC, but they called it Quad-cam cuz that sounded beefier. 32-valve V8s with straight pipes and DOHC are delicious to the aural senses.

[Allch Chcar]

Originally Posted by serialk11r

Wait if it doesn't have time to mix intake charge, why would it be better at higher speed, when there is less time to mix?
Hmmm but if it switches to port injection at higher speed, that would limit torque at higher rpm since you no longer have the cooling effect of introducing fuel in the compression stroke, which increases thermodynamic efficiency...and this is supposed to get higher max power right? Or maybe the gains are just from better flow.

DI works better under load, that I am sure. I don't believe fuel mixing is a big problem for high rpm, I just know that more swirl/fuel mixing is better for low rpm torque.

Originally Posted by Exage

This is why I had originally thought that the multi-point was for high rpm, but I read the article and it stated that the intake manifold (on the 2GR-FSE) had "high tumble intake ports". But as stated above DI allows for chamber cooling on the compression stroke, and therefore allowing higher compression ratios.

It might have more to do with the cam and engine design than the fuel system. Otherwise I'm prone to thinking that Throttle Body Injection is better for low RPM torque since it allows a much longer amount of fuel mixing before combustion :hmm:.

The MPFI systems I've seen tend to have problems with high compression for the midrange RPM like 3-4k RPM where VE is better. DI does allow for higher dynamic compression so that could mean higher static compresion and/or boost .