IanPGT

Hi, I just purchased a 03.5 Mazdaspeed three days ago. By the way, wow, thats all I have to say. Back to the point, I use to own a Probe. The intake manifold had a variable intake system using secondary throttle plates. When they boosted there cars, they tied them open. (less restriction) I noticed that on the 2.0, there was a what looked to be a second throttle plate on the passanger side of the intake. I tied it open, and the power pand seems smoother. Has anyone done this before? I tried surching but no luck

kargoboy

Welcome to the forum. Glad you like the car.
You are talking about the VICS?
Sorry, I'm clueless on that subject!

Roddimus Prime

yeah, you'll lose a little lowend torque but you'll have the secondaries open full time so the power curve will raise as it should not having to wait for the rpm limit to be hit. A stock MSP dyno shows a big jump at 4700rpms when the VICS opens. For a turbo-pro this may be a good idea. I've toyed around with the idea of installing a softer spring so it sucks open sooner but it may not make enough difference to justify the time and effort. Just hold the thing open.

TitaniumMSP

Ok Rod explain this in detail (I am not even close to a gear head, but know my basics.) I am curious. Would this be something I can play with or is it really to complicated to fool with and possibly post better 1/4 mile times? See I am a little short on cash now-a-days and always looking for cheap effective ways to make the car run faster....

JHew84

it will help since your MSP has a turbo on it, what the VICS basically does is when you reach a certain rpm (i'm guessing 4700) there is a second plate inside the intake manifold that opens and allows more air to flow through the intake manifold, this is beneficial because more air=more fuel=go faster :P, which is bascially the entire concept behind having a turbo, forcing more air into the cylinder forces the computer to compensate with more fuel, bigger explosions, bam more power...

you would see better 1/4 times only if you can drive the car well, and consistantly, if your times have differences of a few seconds then you probably wont notice much of a gain from this, but if you post consistant times then it will probably knock a small amount off, like roddimus said it will take away a little torque, which isn't a big deal since it is adding a little HP, torque=low end power, horsepower=top end power, torque is basically only useful for launching so loosing a lil bit of it doesn't matter much...

you should be able to do this yourself no problem, i'm going off of my knowledge of probes (the VRIS system sounds suspiciously similar ) but basically there should be a small vacuum housing somewhere on the back of your intake manifold, it will have a small rod in it that you can move in and out, this rod is what opens and closes the VICS plate, if you push it all the way in, and secure it there somehow (ziptie) it will be "tied open" and therefore rendered useless...

hopefully you didn't stop reading half way through my ramblings, its late, i'm tired, and most of that probably doesn't make sense ...

IanPGT

How many plates are there? I tied one open on the side of the mani. Are there more?

Roddimus Prime

Titaniummsp---It's actually very easy to do. The spring is VERY strong so I reccommend a few Nylon ties to hold it down but it can be done almost entirely by hand. I'm going to be installing my haltech today. If you'd like to come over and help with some of the wiring I'll be more than happy to help you open your VICS.

Roddimus Prime

Jhew--almost 100% correct. The reason that this would make more power though isn't because of more airflow. It's because it actually changes the intake manifolds runner length. Long runners (low rpm's) give you more torque. Short runners (high rpm) give you more top-end horse power.

Look at a honda civic intake manifold and then look at ours....look at their torque numbers and then look at ours....you'll get the idea. What MAzda tried to do is build two manifolds in one. Long runners for low rpms and short ones for high rpms. On a turbo car it'll build full boost long before 4700rpms.....the VICS is actually HURTING performance since it's not allowing those extra runners to be used. With it open full time you'll lose some lowend but the turbo wont have to wait for the VICS to let it breath...The curve will be larger and taller from about 3Krpms on.

Ianpgt--- Just that one side..passenger side with the spolenoid. That's it. There is also a VCTS inside the manifold which is an obstruction in the airway to create air turbulence. A lot of people will pull their manifold off, remove the VCTS/VICS and port and polish the intake runners. This is usually good for about 5-7hp on a standard "dremel-port". If you are serious about it you should contact Extrude Hone and get their stage 2 gasket matching...I bet you'd pick up 15-20whp for about $800.

Stueck

torque = pushing the car, HP = how efficent the TQ is