VVIS vs. Non-VVIS, Would You Do It? <- I Did.

Post by **bigdaddylee82** » 08 Jun 2010, 09:59

Does anyone have any first hand experience driving the older non-turbo Volvo Variable Intake System (VVIS) equipped 850s vs. the newer ‘95+ 850s?

My big question is simply, “Is it worth it?” the VVIS that is. Seems as though the US model 850 GLTs only got the VVIS system in ’93 and ’94, why did Volvo stop using them? Production cost, mechanical issues, something else?

I ask all of this because I’ve gotten myself in a bit of a predicament. I recently put a VVIS equipped ’94 engine in my ’95 850 GLT. I have no means of controlling the VVIS on my “new” engine as my ’95 model didn’t originally have the VVIS.

I’m sure many of you have already seen Razorx's thread, “N/A tuning 20V, VVIS, something different,” where he has developed a “stand-alone” controller for the VVIS solenoid. While this has peaked my interest, and really got me considering this option for functional VVIS on my car, I find myself asking, “Is it worth it?”

100 EUR, or $119.59 USD at Today’s exchange rate gets me a means to control the solenoid, but I’d still have to find and buy the solenoid, no idea what it costs, and come up with the associated vacuum lines, and wiring.

The only reason I’m even considering this, is because my Volvo is an absolute dog off the line, not like I race or anything, but there’s no power in the bottom of the power band anymore. With no way to control the VVIS, the valves that vary the intake size are in their default full open position, and way too big for efficient air velocity in the lower RPM range. It’s painfully obvious. Before my old motor became a “steam engine,” it had a lot snappier acceleration, than my “new” motor does.

So there’s that scenario. My other option would be to graft my original ’95 model’s non-VVIS intake manifold onto the ’94 model engine. This will surely be the cheapest route, but will still require some fabrication. The non-VVIS manifold’s runners are physically too small to cover the intake ports on the ’94’s head. I would have to build an adapter that would change the larger square ports of the ‘94’s heads to the smaller “kidney-shaped” ports of the ’95 manifold. Luckily my 9 to 5, well in reality 8 to 4:30 is a CAD/CAM Tech, I draw and design stuff in Solidworks every day, as well as program and run a CNC Plasma Cutter. If I sweet talk the boss a little bit, I’m sure he’d let me stay late and develop an adapter on the cheap, if not free.

The big problem I can see with the adapter will be air turbulence on top of the valve, when the air is going from the smaller intake runner to the larger port in the head. I can see good and bad from this. Some claim that a little turbulence will help with the air fuel mix and fuel atomization, but I know that it’s a fine line, and crossing it will hurt much more than help.

I am 100% sure that I’m over thinking this, but writing it all down helps me, work through the options a bit.

So, if someone can convince me that keeping the VVIS is the best solution, I’d be happy to do that, and document the entire procedure for the good of the community, but it’s going to take some convincing, because I just don’t see the performance gains vs. cost involved.

Razrox, feel free to chime in here; I’m dubbing you the “VVIS Expert.”

Well there it is; what would you do, and why?

- Lee

razorx · Post by **razorx** » 08 Jun 2010, 13:30

Hi Lee,

Fitting the '95 non VVIS manifold, on your '94 engine will indeed be a problem.
The difference in hole size will bring an uncontrolled turbulence. The chance it works out right is very small.

You told the engine is sluggish, is it also sluggish above 4100rpm?

As a test to check what a VVIS-controller will bring you under 4100 rpm, you could fix the manifold "toggle stick" in the other position. Sorry English is not my native language.

If you feel a serious improvement, and you decide to use my VVIS controller, be aware that you need some stuff maybe not in your car:
-The "famous" solenoid valve
-a non return valve
-a vacuum reservoir

The vacuum drawings:

But first try to fix the stick hooked to the vacuum actuator (see picture above) to the other position.

Again my respect for the work you did on your car.
Regards,

Yits.

Post by **bigdaddylee82** » 08 Jun 2010, 15:17

Your English is fine, Razorx, in fact it's a lot better than a lot of people I know who only speak "English"

.

I figured you'd try and sway me towards the VVIS, being the salesman and all,

.

I do have more top end power than low. I couldn't say that the cut off is exactly 4100 RPM though, seat of the pants analysis says it seems to pick up around 3500-3800 if I'm sticking my foot in it. Cruising speed ~75 MPH I'm running a tad over 3000 RPM maybe 3100. It's got more "go" from there than it does below there, if that makes sense.

I had considered just running a vacuum line from the lever apparatus to the manifold and seeing what happened, or I could run a choke cable to the dash like on an old manual choke carburetor, ghetto fabulous

.

I'll do some more experimenting and report back.

Razorx is there any chance you have a larger/higher resolution picture of the diagram you posted? I'll PM you my email address, if you've got one and don't mind sending it to me.

Thanks,

- Lee

Post by **bigdaddylee82** » 15 Jun 2010, 08:48

I've done a lot of head scratching and research on this, and I've got something up my sleeve

. I ordered some parts this morning, so there's no turning back now. I'll let you know how it works out.

- Lee

Post by **bigdaddylee82** » 08 Jul 2010, 22:35

I think I've got something figured out, I've been waiting on parts to show up or I would have gotten to this earlier. I've finally got the parts, and I've got some free time... so I guess I'd better get to it.

In the mean time I present you with Lola's (yeah, my car's name is Lola

) VVIS intake manifold:

Stay tuned

.

- Lee

Post by **bigdaddylee82** » 12 Jul 2010, 21:39

So this was my initial plan of attack:

I wound up substituting one 3-way solenoid in place of the the two solenoids in the crude diagram.

This is what I wound up with:

Here's what I used:
Summit Racing RPM Switch
Summit Racing Vacuum Reservoir
Summit Racing Vacuum Gauge <- Junk & not necessary, just plugs a hole. Reads 15 in/Hg with no Vacuum applied, maybe I got a bad one.
12v 3-Way Solenoid Valve from eBay
12v 30 Amp Relay from eBay
1/8" ID Rubber Fuel/Vacuum Hose
3/8" ID Rubber Fuel/Vacuum Hose
Various & Sundry 1/4" Brass Fittings, i.e. Street 90s, Hose Barbs, Unions, etc.
Radio Shack Power Distribution Block & Jumper Strip
Hose Clamps, Zip-ties, Fuse holder, wire, terminals, and heat shrink tubing

It works (in the garage anyway) I got everything buttoned up, zip-tied out of the way tonight. I'll test drive tomorrow, and hopefully get some video of everything working. I've got a ton more pictures, and will attempt to make this all make sense in more detail.

- Lee

Post by **bigdaddylee82** » 12 Jul 2010, 22:01

Here's how the 3-Way Solenoid works:

: Solenoid On.jpg (29.11 KiB) Viewed 11289 times

: Solenoid Off.jpg (31.14 KiB) Viewed 11289 times

The solenoid is what controls the vacuum to the VVIS actuator. The RPM Switch "turns off" at a set RPM (currently 3700 RPM) which "turns off" the relay that is controling the solenoid. The idea is that @ >3700 RPM the solenoid valve is de-energized and the VVIS actuator is under no vacuum, it is open to the atmosphere. Currently @ <3700 RPM the solenoid valve is energized and allows vacuum from the vacuum reservoir/engine to activate and close the VVIS "shutter" in the intake manifold.

Clear as mud?

- Lee

Post by **jblackburn** » 12 Jul 2010, 23:33

I've been following this as you've been going along with it, just haven't commented on it. It all looks pretty cool, and you obviously put some serious thought into it. Have you had a chance to put it to the test? Can you tell a serious difference if you were to leave the system un-activated?

Post by **matthew1** » 13 Jul 2010, 00:22

Lee, I have a healthy dose of respect for your efforts even if this doesn't work

. Auto-geekery is a beautiful thing.

Entered into VRD (but not yet categorized), and Home page.

Post by **bigdaddylee82** » 13 Jul 2010, 07:52

jablackburn wrote:I've been following this as you've been going along with it, just haven't commented on it. It all looks pretty cool, and you obviously put some serious thought into it. Have you had a chance to put it to the test? Can you tell a serious difference if you were to leave the system un-activated?

No test yet, I've driven it in and out of the garage, but that's about it. I worked this project in with replacing the PCV system and swapping in a 960 throttle plate since I was going to have to have the intake off anyway. Plan is to test drive tonight after work. My wonderful girlfriend has been out of state for a conference so I've been driving her AWESOME '09 TDI Jetta.

matthew1 wrote:Lee, I have a healthy dose of respect for your efforts even if this doesn't work . Auto-geekery is a beautiful thing.

Entered into VRD (but not yet categorized), and Home page.

Thanks, I'm "famous"

. Necessity is the mother of invention. Well I guess this wasn't necessary but I sure wanted it to work.

- Lee