Intake Idea

[Myxalplyx]

Laugh if you must! I'm a newbie in this world of SVX but the intake of the SVX has been troubling me. All this talk about maf voltages maxing out, timing being retarded and high rpm power being robbed has got me thinking.

I've noticed that on other Subarus (My two XT6s as well as my RX Turbo [rest its soul]) has power dropping off at 5600rpm or so. This was always the case until the air flow was straightened out or opened up through intake/exhaust modifications. Here's one example of how my SVX, XT6 and RX turbo changes their hp slope at 5600rpm.




I have no scientific data to back this up but I really do not like that intake design. It does not seem to support flow at high rpm. As a matter of fact it seems it may hinder flow by having the air come crashing on the sides of the 'torque box' attached to the dual throttle bodies.

I had a chance to stop by Vertex Industries (Now Verocious Motorsports) which is within 10 minutes of my house [Verocious Motorsports.com]. This is the same place I get all my piping and silicone hoses from. I talked to a guy name Tim there and explained the type of intake I needed. He stated he needed the 'engineer' to be there to measure things out to get things perfect. I believe the engineer's name is 'Tom'. He may be there tomorrow or sometime next week so I'll talk to him then. I definitely want to move forward with this and test it to see how it goes. Something inside me tells me it will make a BIG difference in mid and/or high range. I dunno, pretend I'm an idiot. Here's a rough (pre-school) scetch. Yeah, laugh away!





Chike and (Ohh....Supercharger guy.... Sorry...I can't get the name out) knows about this as I've talked briefly to them about it today. I'm going to go ahead with this to see what it does. I'll be sure welding is in place for the vacuum hoses.

I'm fully aware that this may be an out-dated, already tried idea that sucks. I may have over looked the thread. Thanks for any input though.

Thoughts....Ideas!?!

[huck369]

I'd actually like to see two completely seperate intakes, two maf's, and two filters....

I'm sure that someone with electronics background could figure out the wiring issue, and ECU implications....

[Mike621]

Originally Posted by Myxalplyx

Laugh if you must! I'm a newbie in this world of SVX but the intake of the SVX has been troubling me. All this talk about maf voltages maxing out, timing being retarded and high rpm power being robbed has got me thinking.

I've noticed that on other Subarus (My two XT6s as well as my RX Turbo [rest its sould]) has power dropping off at 5600rpm or so. This was always the case until the air flow was straightened out or opened up through intake/exhaust modifications. Here's one example of the my SVX, XT6 and RX turbo chanes a little at 5600rpm.




I have no scientific data to back this up but I really do not like that intake design. It does not seem to support flow at high rpm. As a matter of fact it seems it may hinder flow by having the air come crashing on the sides of the 'torque box' attached to the dual throttle bodies.

I had a chance to stop by Vertex Industries (Now Verocious Motorsports) which is within 10 minutes of my house [Verocious Motorsports.com]. This is the same place I get all my piping and silicone hoses from. I talked to a guy name Tim there and explained the type of intake I needed. He stated he needed the 'engineer' to be there to measure things out to get things perfect. I believe the engineer's name is 'Tom'. He may be there tomorrow or sometime next week so I'll talk to him then. I definitely want to move forward with this and test it to see how it goes. Something inside me tells me it will make a BIG difference in mid and/or high range. I dunno, pretend I'm an idiot. Here's a rough (pre-school) scetch. Yeah, laugh away!





Chike and (Ohh....Supercharger guy..****(SVXFiles..btw)****.. Sorry...I can't get the name out) knows about this as I've talked briefly to them about it today. I'm going to go ahead with this to see what it does. I'll be sure welding is in place for the vacuum hoses.

I'm fully aware that this may be an out-dated, already tried idea that sucks. I may have over looked the thread. Thanks for any input though.

Thoughts....Ideas!?!

the air filter needs to be in the fender, just fyi. itll do **** in the engine compartment (aka..hot air intake)

My SVX came with a pipe extention that went clear thru the airbox into the fender with a cone filter. Looks stock but open the airbox and its just got a hose from the inner part of the upper intake thru a hole in the bottom of the box.

Just speculation, but I think having the two hoses un-equal length would cause problems... response time, velocity, etc. would be different per bank. like the difference in midrange TQ between a CAI and a short ram.

[svxfiles]

Originally Posted by xturboexpress

Just speculation, but I think having the two hoses un-equal length would cause problems... response time, velocity, etc. would be different per bank.

Our stock airbox at the throttle is allready un-equal length.
The air has to travel farther to get to the drivers side throttle body.

I have allways liked the idea of a twin air filter, twin runner intake for the SVX, as discribed by Terry McLane, years ago, and now that we know our MAFs max out at 250 hp, or so, this mod might pay off on cammed, or big block 3.3+ engines.

With 1/2 as much air travelling through our stock MAF, it would not be any where near maxed out, so could we just use some form of voltage transformer to double the reading so that the ECU uses the stock, or modified timing maps?

Perhaps a LAN chip, one stock MAF, and a twin intake, twin filter raises the NA, or SC, or NOX engine limits, for the intake components to 500 hp now?!

Now, if some smart guy, Harvey, LAN, Mychailo, Mark(5), can tell us which MAF to use, and how to wire it, all we have to do then is plumb it!

[huck369]

Hmmm 2 intakes, 2 air filters, 1 maf (the stock one) wired to double the signal....sounds very do-able to me......anyone know what it would take to double the MAF signal?

[AFBeefcake]

Maybe a 741 OP amp or some other type of amplifier. But a 741 mite not be the best choice.

Originally Posted by svxfiles

Our stock airbox at the throttle is allready un-equal length.
The air has to travel farther to get to the drivers side throttle body.

With the stock intake, there is a area before the TB's that equalizes the volume between the two, I thought? There is one box with two holes in it for the TB's and one for the intake piping back to the airbox. The sketch above shows two pipes going directly into each TB, which is why I pointed out the length issue.

Again, it might not matter at all, but as he stated hes looking for maximum performance, just a thought.

If after the TB the air paths cross again, like inside the manifold, everything I've said makes no difference, just thought about that. I am saying all this on the basis that after the air passes the TB it does not intersect again with air passing thru the other TB, which is how I thought it was. School me =)

[Chiketkd]

Originally Posted by xturboexpress

If after the TB the air paths cross again, like inside the manifold

That only happens when the IRIS valve is open. When it is shut, there's no cross flow of intake air from one side to another.

-Chike

[svxfiles]

Originally Posted by svxfiles

With 1/2 as much air travelling through our stock MAF, it would not be any where near maxed out, so could we just use some form of voltage transformer to double the reading so that the ECU uses the stock, or modified timing maps?
Now, if some smart guy, Harvey, LAN, Mychailo, Mark(5), can tell us which MAF to use, and how to wire it, all we have to do then is plumb it!

Ok, how about this, we use TWO stock MAFs, and each one reads 1/2 the airflow.
So if a each side reads, say 3 volts, how can we combine them to read 6 volts.
Would it have the correct timing maps?

[Myxalplyx]

Originally Posted by svxfiles

Ok, how about this, we use TWO stock MAFs, and each one reads 1/2 the airflow.
So if a each side reads, say 3 volts, how can we combine them to read 6 volts.
Would it have the correct timing maps?

Would you want them to read six or three volts? Yes, they will only be reading half as much air than is actually going in, however timing can/should be left to the ECU while fuel control be left to the driver. This way, timing will be more advanced than usual due to the lowered voltage and you'd get the fuel you'd need by manual control (Ex: SAFC). Sounds interesting!

BTW: Has anyone installed an Apexi ITC on these cars to control timing?

In the meantime, I'm going to the route in the diagram pic I posted. I just finished taking some more measurements and it is going to be a TIGHT fit. Only 5.5 - 5.75" available from the throttle body to the firewall. Two 2.5" or 2.75" diametered intake piping could fit but they will have to be VERY snug. The passenger side throttle body piping will have to make a very sharp turn but the outside of this piping can be made smooth. It is just talk now though until some pics are posted. I'm thinking about what I can get at Home Depot to scrounge up to make a draft of the actual piping that needs to be made. I'll present this to the shop I mentioned earlier or some other guys I have in mind to see what can be made up.

It would be cool if anyone else would try the dual mafs and such. I'm not ready to splice into any wiring....Yet! Many of you are much more advanced in this area and determining how voltages will go together to get an end result.

[svxistentialist]

Originally Posted by svxfiles

Our stock airbox at the throttle is allready un-equal length.
The air has to travel farther to get to the drivers side throttle body.

I have allways liked the idea of a twin air filter, twin runner intake for the SVX, as discribed by Terry McLane, years ago, and now that we know our MAFs max out at 250 hp, or so, this mod might pay off on cammed, or big block 3.3+ engines.

With 1/2 as much air travelling through our stock MAF, it would not be any where near maxed out, so could we just use some form of voltage transformer to double the reading so that the ECU uses the stock, or modified timing maps?

Perhaps a LAN chip, one stock MAF, and a twin intake, twin filter raises the NA, or SC, or NOX engine limits, for the intake components to 500 hp now?!

Now, if some smart guy, Harvey, LAN, Mychailo, Mark(5), can tell us which MAF to use, and how to wire it, all we have to do then is plumb it!

I'm assuming the custom intake and plenum chamber in gest's pic is feeding two turbos?

If you want to go with Terry McLaine idea, surely one MAF is enough, without complicating the voltage and getting two devices to feed a signal to the ECU?

It looks to be totally symmetrical, so there is no reason to assume that one half is getting more air than the other half, they should be equal.

Once the two feeder tubes are equal in length, diameter and are as smooth as each other, then reading the air flow through one of the pipes will be linearly proportional to the air the both turbos together are sucking in. And this signal will be the voltage the ECU recognises and expects if the stock MAF is used.

Taking this a step further, provided the stock maf is only "seeing" 220 hp or 230 hp as per the NA setup, then it should be possible to use the turbos to generate 440 to 460 hp without going past the max of the stock MAF, because we are now taking in twice the air volume.

Am I seeing this in an oversimplified way, or are my deductions correct?

Joe

[oab_au]

There is no problem getting air into the engine. The flow through that pipe and box, is at a low velocity. It is not like the high velocity in the inlet tract. The way the inlet works on full throttle, is the IRIS valve has opened to join the two haves of the inlets together.

This makes a large chamber that includes, all the inlet tracts, both throttle bodys, the box in front of them and the air delivery pipe. This whole chamber is very close to atmospheric pressure, so it is as if the 6 inlet tracts to the cylinders are breathing from the atmosphere and the rest of the inlet does not count. The chamber acts like a big sponge, that each cylinder pulls its air out of. So the shape, the bends, the wrinkles, don't count.

Harvey.

[Chiketkd]

Originally Posted by Myxalplyx

Chike and (Ohh....Supercharger guy.... Sorry...I can't get the name out) knows about this as I've talked briefly to them about it today. I'm going to go ahead with this to see what it does. I'll be sure welding is in place for the vacuum hoses.

The S/C guy is Tom (Svxfiles). He definitely enjoyed speaking with you Kevin.

As long as the piping is smooth I'm sure you'll see some gains. I would also second Mike's recommendation. If possible, have the cone filter reside in the fender well.

-Chike

[SilverSpear]

I second Huck's suggestion, and got confused with xturboexpress's comment about the unequal intake piping... What about if Myxalplyx's idea was realized but to get the effect of Huck's suggestion (two pipes and two mafs) we can install 1 larger diameter MAF having a higher velocity a little inferior but near the twin system. I once saw on ebay a 300Z MAF but having an increased diameter than stock ...