Subaru VVT which ones have it?

[Ianbott]

Hi guys, have searched a few places but cant seem to find a definitive guide as to which Subaru engines have Variable valve timing, can any of you guys shed any light for me?
Cheers Ian.

[rjes]

There are such a vast range of different engine specs worldwide, that I doubt you will find a definitive guide anywhere.

A rough guide is that STi's had AVCS from MY01 or MY02, and all EZ30 / EZ30R's have it. I think it was also used on some lower spec EJ series post MY02 engines too.

My JDM MY99 engine is a bit of an obscurity. It's a naturally aspirated EJ25, and has AVCS. No UK spec nat asps were fitted with AVCS for a good few years after MY99.

If you are looking at an engine. look for the much longer inlet cam pulleys, and the actuators on top of the cam covers. The latter in particular, are very easy to spot.
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Richard,

R J Engineered Solutions
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[sven]

As far as I know there are two different setup, the earlier EJ's have a similar setup as Honda VTEC engines that switches between two different cam lobes. New engines, the turbos and the six cylinder models uses hydraulic angular movement that is controlled by the ECU. It's available from most models from 2004 and forward.

This is a pretty safe source, themselves:
http://www.drive.subaru.com/Win05_WhatsInside.htm
http://www.subarudrive.com/Spring07_whatmakes.htm

The lower URL describes the newest double lobe system that also is controlled by the ECU.

[rjes]

Hello Sven,
My experience shows that the two systems came into effect the other way around, because I don't think they are including the EZ30R six cylinder engine in the dates:

AVCS - the variable cam phasing system, was first. My Japanese spec MY99 EJ25 n/a has it, and I believe it's a very early example. The inlet cam pulley has an angular actuator built in, driven hydraulically via a PWM valve as shown in your first link. This valve is the bit which is easily identifiable. I had the system to pieces on one bank, as the engine had 8 bent valves when I bought it.

The system, AVLS, as shown in your second link with the two cam lobes is actually a simplified version of the system fitted to the EZ30 engines, but applied to the EJ series. The EZ series engines have both AVCS and AVLS, allowing the ECU control of both the inlet valve lift and phasing. The heads ard covered in sensors and actuators! I think the AVLS part may have been added in 2004 when the EZ30R came out. The old Honda system looks pretty crude compared to the EZ30R! I have an EZ30 R, but have not looked inside it (and don't intend to, as it's nearly new), although I have some excellent cut away drawings from a 2004 issue of Engine Technlogy International magazine.

I guess the 2007 date on the second link is probably talking about the first time the AVLS technology was applied to an EJ series engine.

I think the AVLS system is just for emissions control, and creates better atomisation and more swirl at low engine speeds, rather like the tumbler valves fitted to some turbo engines.
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com

[Ianbott]

The AVLS seems like a better system doesn't it, the other the AVCS just seems to be like a cam advance system, unlikely to get much power gains out of this system am i correct in assuming this?

Richard, i ask this question as i have recently been looking at some accident damaged complete cars, i want an impreza sti preferably post 2002 if possible, would really like a 2.5 but they are demanding a stupid amount of money at present.

Do you have any knowledge on de cats on the later sti engines? is it correct they need a re-map after removing the cat?

Thanks Ian.

[rjes]

Not sure about needing remapping. They'd probably benefit from is, but I doubt then NEED it. If theengine has a lambda sensor both before and after the cat, toy will get an error code if you remove the cat. You need to read up on Subaru forums about this kind of stuff really.

My understanding is that the AVLS system reduces the lift of one of the two inlet valves at low RPM, and is probably only an emissions control device. I think AVCS is likely to give more of a power gain, as it allows the engine to take more advantage of scavenging during valve overlap over a wider range of rpm. I have no evidence for this though. My EJ25 with AVCS is about 5 bhp more than one without AVCS, but that sould equally be due to different mapping, etc. Both AVCS and AVLS may actually only be there for emissions reasons, although that wouldn't explaing why my Jap spec engine had AVCS first, unless they jest released it in the home market first for 'testing' reasons. It's probably just used to improve the spread of torque.
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com

[sven]

I was more than mixing stuff, my previous post was written after non stop 31 hours of work. My boss told me to go home and sleep, but I messed up a post before.

It's for emissions (everything is), but not as only reason. The characteristics these engine gets with the high RPM settings would make the engine die at idle. By moving the cam timing dynamically the tourqe/effect curves is affected and the engine behaves much smoother but with more power available.

This results in improved volumetric efficiency and helps to generate higher power output.

In tuning, VE is (almost) everything. I have a close friend that optimizes performance bikes. I make both adjustable cam wheels and adjustable intake manifolds for him to get the best power curves. Some engines behaves like crap at idle because of the extreme cam timings, but on the other hand they deliver when they should.

I think the links info in my previous post is correct after all, RJES refers to is AVCS which is the advancing mechanism, AVLS is variable lift. Subaru names the newer desings with a prefixed "i-" like i-AVCS. The new engines have both AVCS and AVLS...
I also also know that Richard is correct about his Japan spec engine as they had it earlier than the rest of the world. The rally teams and Scooby tuners here in Scandinavia bought Japan spec engines like crazy, still do but not as much as before.

This is what I found about AVLS:
* 2005: 3.0 liter naturally aspirated H6 Subaru engines (used along with AVCS)
o 250 hp (186 kW), 219 lb·ft (297 N·m) torque in 2005 3.0-liter Subaru Outback
* 2006: all 2.5 liter naturally aspirated Subaru engines
o 173 hp (129 kW), 166 lb·ft (225 N·m) torque in 2006 Subaru Forester and Impreza 2.5i models
o 175 hp (130 kW), 169 lb·ft (229 N·m) torque in 2007 Subaru Legacy model
* 2007: all 2.5-liter naturally aspirated Subaru engines

As all the settings now are controlled by the ECU, everything can be dynamically set with, for example, the SI-drive button. I don't know if Subaru does so. BMW do it for sure on their new models.

Here is some more on the Japan spec engines and beyond:
In mid 2000, the GD/GG-series (aka ‘bug-eye’) WRX was introduced in Japan and, for the first time in the EJ20 turbo’s history, power output took a step backward.

With tightening emission standards, Subaru revised many aspects of the engine design and added its Active Valve Control System (AVCS) which, in other words, means variable inlet cam timing. We believe the Tumble Generator Valves (TGVs) are also installed. The MY01 WRX maintains the high 9:1 static compression ratio of late ‘90s Rexes but, still, max power falls to 184kW while torque holds near-constant at 334Nm. These figures apply to WRX sedans and wagons with a manual or auto trans. Curiously, there have been no major changes to the WRX engine up to the current model.
For real performance in the new series Impreza you need to look at the STi Version 7. With a static compression ratio of just 8:1, AVCS and a large IHI RHF5 turbocharger....

The AVCS was introduced in Australia with YM 2003.
I think Europe got it the same year.
The states may have been one year later, at least according to the Subaru Drive magazine.
I found the similar facts in my rally specs lexicon, but the text above is taken from http://www.autospeed.co.nz/cms/A_2775/article.html

Hope it helped.