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Old 03-22-2007, 12:30 PM   #1
tonzo
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Subaru Stars aftermarket intake manifold

I'm just curious to hear what people think. Now I've been looking at some of these manifolds and I'm just wondering. Do you find 1100 dollars to be a substantial price for a magnus or similar style intake?

If there were an intake that was of similar quality but by a less well known producer would you be willing to try it out if it were half the price of a magnus?
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Old 03-22-2007, 11:08 PM   #2
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i would say there is always a want for a aftermarket manifold
from the few i ve made the only consideration you would have to take while building one is that there aren t as many people that could run it unless they were already at the extreme modded setup because you do away with alot of the bolt on mounting areas that the subies have
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Old 03-22-2007, 11:35 PM   #3
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Yeah, there is definately a want for it, a few more on the market would chop the price down some I'd think.

Most people buying them are already modded pretty heavily anyways so a lack of a few things wouldnt kill the market
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Old 03-23-2007, 12:55 AM   #4
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What sort of advantages do the aftermarket intake manifiolds provide?

Improvent in power or torque across the rev range, or perhaps just in certain parts of the rev range?
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Old 03-23-2007, 01:53 AM   #5
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usually increased low end and definitely increased throttle response. All the designs ive seen were designed with larger "funnelesque" runners and a plenum with a volume in comparison to our engine volume. Some have suffered slightly in the top end.

The advantages of this come mainly when you are looking for more area under your power and torque curve and also for the increased throttle response it offers. Great advtanages in the world of auto-x, rally and other sports.
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Old 03-23-2007, 02:11 AM   #6
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I figured if these became more common, almost as common as exhaust manifolds (well...maybe not tthhat common) that more people would be open to buying them
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Old 03-23-2007, 10:04 AM   #7
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If your thinking of building them for a turbo subi you could do an entire kit that includes a reversed intake manifold that includes a front mount to go with it. I would guess that you could keep the turbo in its stock locations then just develop new piping from the turbo to the intercooler then up to the reversed intake. Should be fairly plug and play unless you need to relocate the ac compressor or alternator.
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Old 03-23-2007, 09:58 AM   #8
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if anyone lives near philadelphia, pa there is a very well known fabricator there who if you gave him a call he may be interested in making SMIM for subys. He makes a SMIM for DSM's that are 1/2 of a magnus price and out perform them. Check out www.JMFABRICATIONS.com, he is always open to suggestions!
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Old 03-23-2007, 10:24 AM   #9
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Just go get the USDM 2.5I manifold and make it work. No TGV's a much bigger plenum, and much better routing of the runners. It won't work with a TMIC though.


TMS
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Old 04-17-2007, 07:02 PM   #10
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Quote:
Originally Posted by TheMadScientist View Post
Just go get the USDM 2.5I manifold and make it work. No TGV's a much bigger plenum, and much better routing of the runners. It won't work with a TMIC though.


TMS
You mean like this.







XX Tuning modifies these 2.5L intakes to fit either a WRX or DBW STI throttle body. They use topfeed injectors. The real gains from this manifold are the air doesn't have to slam into a wall and them break off left and right to make it's way to the heads. These manifolds actually flow so well that the air doesn't start to heat up from friction until the bend just before the heads.

Last edited by Defiantspaz; 04-28-2007 at 12:13 AM.
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Old 06-19-2007, 05:51 PM   #11
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This is a very interesting read, and being probably one of the majority of people that are interested in this idea but are only making modest power, this intake mani below is probably the best for the moderately built cars?

Sorry , I do not mean to dumb this back down.

Quote:
Originally Posted by Defiantspaz View Post
You mean like this.







XX Tuning modifies these 2.5L intakes to fit either a WRX or DBW STI throttle body. They use topfeed injectors. The real gains from this manifold are the air doesn't have to slam into a wall and them break off left and right to make it's way to the heads. These manifolds actually flow so well that the air doesn't start to heat up from friction until the bend just before the heads.
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Old 06-19-2007, 06:21 PM   #12
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Just out of curiosity, has anybody found the part number for those manifolds in the pic above (the one XX Tuning use)?

I'd be keen to try and find one for a play...
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Old 07-18-2007, 09:39 PM   #13
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Good thread guys. Thanks for the productive comments on our manifolds Bill. We have yet to push the limits of either car as we suffer the usual development and budget hurdles associated with big projects like this. We'll be able to get some numbers soon for both cars and hopefully hone our design one way or another based on what we find. We're just trying two very different designs to ensure that we're not going down one wrong direction.

The asymmetry on the last photo which was taken at Wicked Big Meet is deceptive. Both ends share the same volume but the photo makes it look otherwise. Since the cylinders on the motor are actually offset it forces one bank to be further back on the motor than the other.

Someone noticed the wastegate over the dogbone. We are using our own twin scroll up pipe. Both sides of the UP have a pipe going to the wastegate, so it's two to the turbo, then two to the WG.

Nate's "Mad Intern" should be rolling onto the dyno early next week.


Alex
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Old 08-04-2008, 12:03 AM   #14
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Quote:
Originally Posted by Defiantspaz View Post
You mean like this.




XX Tuning modifies these 2.5L intakes to fit either a WRX or DBW STI throttle body. They use topfeed injectors. The real gains from this manifold are the air doesn't have to slam into a wall and them break off left and right to make it's way to the heads. These manifolds actually flow so well that the air doesn't start to heat up from friction until the bend just before the heads.
what exactly needs to be modified to get this to work on a 02-03 wrx motor
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Old 09-10-2008, 02:19 PM   #15
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Default Intake manifold

Hello all,

Yes, we are now a vendor and to clarify we are a manufacture of performance Subaru manifolds. We just had our “open house” HERE and are excited to be a part of the Subaru community.

Big fan of this thread as it is very cool to see everyone finally have some good discussions on the intake system of the Subaru engine. And even better to see those who took it on themselves to actual make a manifold and try their idea. Talk is cheap so well done!

Our take on the stock Subaru manifold is it is very well made and designed manifold that is an excellent example of a cost vs. performance ratio maintained. That said, I believe there are two main faults with the stock intake manifold that are not addresses as much as they should be:

1) Plenum volume
2) Unequal flow

The stock plenum is approximately 725cc (44.24 in^3). I believe Subaru did this for off idle response (drivability) and emissions. But from a performance standpoint this is grossly too small to give maximum capacity at the mid and higher rpms. It is common knowledge that for performance you want a plenum to be around50% to 60% of the total engine displacement. So for a 2.5 liter (2500cc) Subaru boxer engine, you should have a plenum volume of around 1250cc to 1500cc. The stock Subaru manifold being 725cc, represents about 29% of the total engine displacement, a far cry from the recommended 50 to 60%.

Now the biggest issue we have with the stock manifold is unequal flow. Give me a second, I am going to stand on this box and say that again….unequal air flow in the stock manifold is a huge issue. Take a second and look HERE at the white sheet we created on the flow characteristics of the stock manifold. From quite a bit of testing on the flow bench we where able to conclude the stock manifold has about a 10% flow difference from the highest to the lowest flowing runner. The great guys over at MRT also posted similar results from their flow tests of the stock manifold. Think about this, that could mean that one cylinder is running leaner then the richest cylinder by as much as 10%. That is not good for horse power or reliability.

Take a look around at some of the other Built Motor posts. Guys still blow cylinders/pistons even though their tune was professionally done and they watch their AFR’s like a hawk. Why? I think this is happening: (for simplicity I will only talk about an O2 sensor looking at two cylinders and use 14.7 AFR as reference even though we know this is not optimum for performance. And taking liberties with grossly simplifying some of the percentage differences).

Let’s say you have an O2 sensor at the collector for these two cylinders and you are happy and content because it shows 14.7 AFR where you want it to. But the O2 sensor is actually reading a collective average of the two cylinders so if both of the cylinders are getting the same amount of air then yes, they could both be at 14.7 AFR. However, if we know there is an imbalance of air flow to the two cylinders that could be as high as 10%, in theory one cylinder could be at 13.9 AFR and the other at 15.4 AFR. This is a HUGE difference with one being rich and the other being lean from where you want to be. And of course the lean cylinder is now very prone to over heating and detonation. But you would have a hard time seeing this coming as the O2 sensor shows the average of the two at 14.7. So when it does final blow you have no idea why as the logs show AFR was just fine. Now make this four cylinders and this lean cylinder is able to “hide” even more due to being averaged out from 3 other cylinders.

As a side effect you also get an imbalanced engine as far as what each cylinder is producing for horse power.

Equal air flow is paramount to achieve a successful and reliable high powered Subaru engine.

Great thread once again and love to see more pictures of what others are doing. Here is a shot of our Front Intake Model to join the pack.

Fin

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Old 09-10-2008, 02:32 PM   #16
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how much??
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Old 09-10-2008, 03:22 PM   #17
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OMG!!!!

Quote:
Originally Posted by bishop333 View Post
Hello all,

Yes, we are now a vendor and to clarify we are a manufacture of performance Subaru manifolds. We just had our “open house” HERE and are excited to be a part of the Subaru community.

Big fan of this thread as it is very cool to see everyone finally have some good discussions on the intake system of the Subaru engine. And even better to see those who took it on themselves to actual make a manifold and try their idea. Talk is cheap so well done!

Our take on the stock Subaru manifold is it is very well made and designed manifold that is an excellent example of a cost vs. performance ratio maintained. That said, I believe there are two main faults with the stock intake manifold that are not addresses as much as they should be:

1) Plenum volume
2) Unequal flow

The stock plenum is approximately 725cc (44.24 in^3). I believe Subaru did this for off idle response (drivability) and emissions. But from a performance standpoint this is grossly too small to give maximum capacity at the mid and higher rpms. It is common knowledge that for performance you want a plenum to be around50% to 60% of the total engine displacement. So for a 2.5 liter (2500cc) Subaru boxer engine, you should have a plenum volume of around 1250cc to 1500cc. The stock Subaru manifold being 725cc, represents about 29% of the total engine displacement, a far cry from the recommended 50 to 60%.

Now the biggest issue we have with the stock manifold is unequal flow. Give me a second, I am going to stand on this box and say that again….unequal air flow in the stock manifold is a huge issue. Take a second and look HERE at the white sheet we created on the flow characteristics of the stock manifold. From quite a bit of testing on the flow bench we where able to conclude the stock manifold has about a 10% flow difference from the highest to the lowest flowing runner. The great guys over at MRT also posted similar results from their flow tests of the stock manifold. Think about this, that could mean that one cylinder is running leaner then the richest cylinder by as much as 10%. That is not good for horse power or reliability.

Take a look around at some of the other Built Motor posts. Guys still blow cylinders/pistons even though their tune was professionally done and they watch their AFR’s like a hawk. Why? I think this is happening: (for simplicity I will only talk about an O2 sensor looking at two cylinders and use 14.7 AFR as reference even though we know this is not optimum for performance. And taking liberties with grossly simplifying some of the percentage differences).

Let’s say you have an O2 sensor at the collector for these two cylinders and you are happy and content because it shows 14.7 AFR where you want it to. But the O2 sensor is actually reading a collective average of the two cylinders so if both of the cylinders are getting the same amount of air then yes, they could both be at 14.7 AFR. However, if we know there is an imbalance of air flow to the two cylinders that could be as high as 10%, in theory one cylinder could be at 13.9 AFR and the other at 15.4 AFR. This is a HUGE difference with one being rich and the other being lean from where you want to be. And of course the lean cylinder is now very prone to over heating and detonation. But you would have a hard time seeing this coming as the O2 sensor shows the average of the two at 14.7. So when it does final blow you have no idea why as the logs show AFR was just fine. Now make this four cylinders and this lean cylinder is able to “hide” even more due to being averaged out from 3 other cylinders.

As a side effect you also get an imbalanced engine as far as what each cylinder is producing for horse power.

Equal air flow is paramount to achieve a successful and reliable high powered Subaru engine.

Great thread once again and love to see more pictures of what others are doing. Here is a shot of our Front Intake Model to join the pack.

Fin

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Old 03-24-2007, 09:06 PM   #18
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Alright, I have to be carefull how I do this untill I pay for vedor fees. We have a new intake manifold that will be available very soon. It has already gone through the flowbench testing phase and we will have one at subiefest 2 in a couple of weeks. I am sharing a booth with enduratech coilovers so stop in and check it out. This manifold will be less expensive than the other options currently on the market and should outperform them as well. I have shown pics of the prototype to a few vendors that we hope will be our distributers (we will see, and hopefully we can meet the expectations)

Keep an eye out for Brewpubeavers car as he will be the test bed. This manifold will be setup to allow it to be rotated and we will have tubing kits to match up with the major FMIC options.


Mods I hope this hasnt crossed the bounds and I appoligize in advance if it has.

Last edited by Sinister redlines; 03-25-2007 at 02:03 PM.
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Old 03-28-2007, 05:04 PM   #19
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Quote:
Originally Posted by Sinister redlines View Post
Alright, I have to be carefull how I do this untill I pay for vedor fees. We have a new intake manifold that will be available very soon. It has already gone through the flowbench testing phase and we will have one at subiefest 2 in a couple of weeks. I am sharing a booth with enduratech coilovers so stop in and check it out. This manifold will be less expensive than the other options currently on the market and should outperform them as well. I have shown pics of the prototype to a few vendors that we hope will be our distributers (we will see, and hopefully we can meet the expectations)

Keep an eye out for Brewpubeavers car as he will be the test bed. This manifold will be setup to allow it to be rotated and we will have tubing kits to match up with the major FMIC options.


Mods I hope this hasnt crossed the bounds and I appoligize in advance if it has.


seems like you worded it just right, lol..

i can not wait to get this on the car
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Old 03-25-2007, 10:09 AM   #20
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Heard too many bad things about the Magnus and it's construction - I was in the market but quickly changed my mind after reading some reviews.
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Old 03-25-2007, 11:07 AM   #21
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Quote:
Originally Posted by PeteDucati View Post
Heard too many bad things about the Magnus and it's construction - I was in the market but quickly changed my mind after reading some reviews.
Yeah I think it's a little pricey for a piece with questionable quality...it will be nice to see some competition on the market
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Old 03-27-2007, 02:24 AM   #22
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has anyone heard or seen this here in the states. http://www.tracktive.co.uk/content.php?page=139

I dont even recall how I found this site
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Old 03-27-2007, 11:09 AM   #23
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This is what is going on my car. You need to use a FMIC and DBW throttle, and a little bit of work to use it. But I don't care I really like the way it looks, and it is an OEM part.

TMS
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Old 03-28-2007, 04:35 PM   #24
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Quote:
Originally Posted by TheMadScientist View Post
This is what is going on my car. You need to use a FMIC and DBW throttle, and a little bit of work to use it. But I don't care I really like the way it looks, and it is an OEM part.
Does the 2.5i have a topfeed or sidefeed injector setup?
Will any existing fuel rails bolt up?
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Old 03-28-2007, 05:00 PM   #25
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Quote:
Originally Posted by x99percent View Post
Does the 2.5i have a topfeed or sidefeed injector setup?
Will any existing fuel rails bolt up?
Top feed.
I will be using the stock 2.5i rails converted to parallel feed. They are ~$35 side. I don't know about aftermarket ones.

TMS
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