Engine technology thread.

[serialk11r]

Wait Subaru has VVL (variable lift I'm assuming?)? When did this happen? :O I thought it was only BMW, Nissan (with the VQ only) and Toyota (on certain European engines and stuff only).

[Allch Chcar]

Originally Posted by WingsofWar

Some intake designs are already decently optimized. The EJ251 and EJ253 N/A Impreza and Legacy engines sees almost no performance or economical gains with a upgraded/aftermarket intake systems. Only the CAI systems provided gains because of the location of the filter.

and those are ones without subarus VVL and drivebythrottle.

If we throw in the drivebythrottle mix, it greatly effects how mods are registered.

You mean drive-by-wire aka electronic throttlebody control? Almost all Spark Ignited engines tend to be drivebythrottle :P.

Originally Posted by serialk11r

Wait Subaru has VVL (variable lift I'm assuming?)? When did this happen? :O I thought it was only BMW, Nissan (with the VQ only) and Toyota (on certain European engines and stuff only).

VVL is a generic term that say that the Cam timing or duration can be adjusted even just a little while in operation. For Toyota it's VVT, Honda Vtec, Subaru AVCS/AVLS. And then there are the different levels of operation like Toyota's VVT-i etc.

While VVL has been around for a long time many companies didn't make it standard or equip it on all or most of their vehicles until recently. Subaru made VVL standard on all their vehicles by '05 I believe.

[serialk11r]

What does VVL stand for then? I'd think VVT is a better acronym. Toyota always added the i to VVT-i, so there's no confusion there.
Anyways.

[WingsofWar]

Originally Posted by serialk11r

What does VVL stand for then? I'd think VVT is a better acronym. Toyota always added the i to VVT-i, so there's no confusion there.
Anyways.

subarus VVL (variable valve Lift) is called Active-I i believe .but only works on a intake port. Variable Valve Timing is a different operation.

There are a full range of methods that ultimately accomplish the same thing but to certain degrees. Vanos, Mivec, VVTLNeo, VVT-i, Vtec ...the list goes on..

[serialk11r]

Okay I guess I just got confused by terminology, as most of the current methods have switchable cam lobes that vary intake valve operation in both lift and timing.

Speaking of which, I wonder why Valvematic is taking so long to reach the US...I don't think there are any engines with it over here are there? Nissan VVEL and BMW Valvetronic got here at the same time as the rest of the world.

[WingsofWar]

Originally Posted by serialk11r

Okay I guess I just got confused by terminology, as most of the current methods have switchable cam lobes that vary intake valve operation in both lift and timing.

Speaking of which, I wonder why Valvematic is taking so long to reach the US...I don't think there are any engines with it over here are there? Nissan VVEL and BMW Valvetronic got here at the same time as the rest of the world.

I am not sure why Toyota hasn't allured more valematic into their product lines. It could be not as great of a system considering it only works as a simple secondary adjustment to intake lift only and not serve as a VVT, but to serve VVT-i. VVTLi should have been the best toyota cam system.

From my experience Dual Mivec has been the best system iv tested, its like Vtec on steroids. controling cam lift and timing on both intake and exhaust on all RPM ranges.

[Random_Art]

That makes sense. What good is sucking in more air if you can't get it back out?

[serialk11r]

I don't think any Toyota engines don't have VVT-i (not all have dual VVT-i though maybe), Valvematic doesn't interfere with VVT-i, besides probably losing the second cam lobe and hydraulic actuator. Valvematic has the cam push a roller which is attached to a separate shaft, which is connected to a...I think I saw it called "finger follower" which actuates a second roller on a lever which actuates the valve. The camshaft timing can be adjusted independently.

They use the 1.6L 1ZR-FAE on the Lotus Elise base model in Europe...wonder why we Americans don't get that Guess it's not cost effective to give us 2 different engines, when we have the biggest market?

[serialk11r]

Okay I just realized, Valvematic's extra shaft adds like an inch of height to the engine...guess the hopes of seeing it on the FT are pretty slim The 1ZR-FAE is 34mm taller than the 2ZZ-GE, so on a boxer...that's going to be double that. 10mm stroke reduction, increased compression would cover only 1/3 of that extra height although maybe the engine being farther back helps.

[PAImportTuner]

Vvtl-i was on the GTS Celica, Dual vvt-I is on the new tC and Dual AVCS is on Subaru.

[Dimman]

Originally Posted by PAImportTuner

Vvtl-i was on the GTS Celica, Dual vvt-I is on the new tC and Dual AVCS is on Subaru.

Subaru also has AVLS, which is kind of like VTEC but only on one of the intake valves.

[serialk11r]

Originally Posted by serialk11r

Okay I just realized, Valvematic's extra shaft adds like an inch of height to the engine...guess the hopes of seeing it on the FT are pretty slim The 1ZR-FAE is 34mm taller than the 2ZZ-GE, so on a boxer...that's going to be double that. 10mm stroke reduction, increased compression would cover only 1/3 of that extra height although maybe the engine being farther back helps.

So sorry for the bump but did anyone notice this post? Dimman I know you were talking about Valvematic at some point.

[Dimman]

Originally Posted by serialk11r

So sorry for the bump but did anyone notice this post? Dimman I know you were talking about Valvematic at some point.

Valvematic isn't something I've fully wrapped my head around yet. I imagine it as a kind of variable ratio rocker arm. What I also don't get is why it's been out in Europe for a while already but not here.

Vid that's been posted before:

[u2b]RHNXbGGvOdc[/u2b]

[serialk11r]

So Valvematic is the easiest system to understand out of all the variable lift systems. Nissan VVEL is some crazy wack stuff...

So it's actually pretty simple, the camshaft can be thought of as a "high performance cam" with maximum lift and duration. If this cam directly acted on the valves, you'd always have this profile and that would be bad for part load and low rpm operation.

What valvematic has is 2 sets of levers (essentially, they have a lot of parts but they act as levers) between the cam and the valve. The first of these is directly actuated by the cam lobes, and always moves some fixed amount (determined by the cams). It has a second follower attached to the same shaft. The space between the follower and the cam-actuated roller is adjustable.

The follower then actuates the second lever which actuates the valve itself. At low lift setting, the follower has some space between it and the second lever, so most of the distance it travels it doesn't touch the second lever, so the valve doesn't move. At high lift, the space between the follower and second lever is small, and the valve thus moves a lot more. So if you look at a lift vs. time graph, lower lift means you shift the curve down and zero out anything below 0, which gives you reduced duration as well. Combined with VVT-i, you can also horizontally shift the curve by some amount.

http://www.autozine.org/technical_sc...ine/vvt_5.html
That website has a good animation. EDIT: diagram, only VVEL is animated.

So I was pointing out that the 1ZR-FAE has 34mm extra height compared to the 1ZZ-FE because of the second shaft. On a boxer this increase in height would be double that increase in width, so we won't be seeing it most likely If they reduce stroke to 75mm, and then increase compression ratio to say, 12:1, that would take off 32ish mm. If the width grows by a full 36mm, that would create some issues...and 75mm stroke is unlikely as people said. Rather disappointing since Valvematic reduces pumping loss by a ton (especially if the exhaust timing is right), and allows for better flowing ports.