A Problem with CAI/SRIs and an Alternative (yes, finally)

[williaty]

Originally Posted by Roke

List of 'mods in mind' shortened.

I can't say that IM spacers and TB spacers are always going to be useless, but they are on our engines at least.

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[Roke]

Project Hybrid Intake is a success! I had to do some more tweaking than I expected, but everything fits nicely now without any tension. Good clearance everywhere. I also like the looks of all the parts combined.

Some visual results:




One hose clamp had to be mounted out of line to get the connection tight. Maybe I'll cut the silicone adapter parallel to that clamp, but it's ok for now. Function over form.



The first vacuum hose connection was positioned quite badly. It was a PITA and it took some more tweaking to get that right. It grinds the metal brace a bit, so I isolated the hose with some good tape. I think this wil hold. Maybe later I'll put something in between or around that part of the vacuum hose just to be sure.



(I have a lot of close-up pictures uploaded online. So please feel free to ask for more if needed / interested.)


I reset the ecu, let the car run for 15 minutes and drove around the block for a bit. So no performance results yet. I did feel some more low throttle response and a bit more pull around 3500 rpm. But I was just carefully testing if everything was ok. I'll let you know when I can say something really useful about that.

[kraxxus]

Keeping my eye on this, looks like a very clean easy install. Minus the hose issue. Let us know how the tune or the general overall performance feels over time. Nice picture quality and good angles - Thank you

[Uncle Scotty]

Originally Posted by williaty

Manifold spacers are useless for other reasons as well.

how much heat does the mass of the manifold absorb???

how much better off are you if that mass doesn't get as hot???

keeping heat out of the engine bay any way you can is a good idea as heat degrades.....everything over time.


some of the benefits of some things just aren't quite as glaringly apparent as others

don't dismiss them off hand without a bit more thought

[williaty]

Originally Posted by Uncle Scotty

don't dismiss them off hand without a bit more thought

I dismiss them after extensive testing. I've run with thermocouples bolted to the IM both with and without the IMS. The IMS do not produce a measurable reduction in IM temperatures. The IM just gets absolutely baked from radiation off the top of the block and from convective heating from the whole thing. Not to mention the heat absorbed through EGR and PCV systems ducting into the IM. The amount of heat it absorbs via conduction through the small cross-section of the shell of the runners is meaningless vs the large amounts of heating it gets in other ways.

Hell, that's even assuming you aren't still heating the IM via the throttle body hot water loop.

Additionally, the IMS increase the effective length of the runners. This moves peak torque lower, which is exactly what this engine doesn't have a problem with. If you want to change runner length on an EJ253, longer is NOT the way to go.

[Uncle Scotty]

the metal upper header tank on the turbo models is one of the places that many don't think of as an IM heat source, but it is one of the MAJOR heat sources to the IM

and I have played around with a lot of this and ....

well....yeah.

keeping the manifold as cool as possible is a good idea.....and it cools off a lot faster if it is isolated, too

3mm spacers don't add enough manifold volume to make any difference, either

[williaty]

Keeping the IM cool would be beneficial, yes. However, the IMS don't contribute meaningfully to that. I've vaguely wanted to experiment with putting a low-emissivity coating on it like Swaintech White Lightning to see if that would reduce the temps and then finding some way to encourage more of the hot air rising off the exhaust and block to go somewhere else. Those two things ought to make a difference.

[Roke]

Originally Posted by kraxxus

Keeping my eye on this, looks like a very clean easy install. Minus the hose issue. Let us know how the tune or the general overall performance feels over time. Nice picture quality and good angles - Thank you

Thanks for your positive reaction. I think it's a clean install too. Everything besides the vacuum hose issue went perfect. Later on I did some minor adjustments like placing all hose clamps nicely in line with the edges of the silicone parts, placed all parallel screws at the same height, minimalised tension on all parts and hoses, etc. I'm a perfectionist.

The vaccuum hose issue will be resolved soon. I'm simply going use a piece of black flexible PVC hose cover (with metal rings inside). The same stuff our MAF cabling is protected with. Two tie-wraps. Done!

Performance has definitely improved. I'll leave a separate post about that.


p.s. Pictures were taken with an iPhone 5S. Performs quite well if the surrounding light is good.

[Roke]

Wouldn't a turbo hood, as rice as it may be, help with keeping the IM cool?

If you think about it:
- When driving outside air is blown on top of intake hose / IM area. Cooling everything and pushing down hot air. (Not mentioning dirt and water for now.)
- When standing still hot air from engine and exhaust manifold, which is always rising up, can escape a bit.

(I have a turbo hood in my garage, but I still haven't decided if I want to use it.)

[Roke]

Originally Posted by kraxxus

Minus the hose issue.

"The vacuum hose issue will be resolved soon. I'm simply going use a piece of black flexible PVC hose cover (with metal rings inside)."

It's quiet in my store, so I decided to do something right away. The Legacy is parked in front, so I could keep an eye on the door. There's a small store next to ours selling some basic home improvement products. I went on a 'solution hunt' there and got lucky! 19 mm i.d. 45 degrees bend for PVC (electrical) piping. Luckily they sold grey too. (Normally it's light yellow here in the Netherlands.)

Tweaked it a bit. Fits great! (Cut could be cleaner, but the bad part is out of sight.) It's sitting tight in the metal brace and there's room enough for the vacuum hose to slide and wiggle a bit. It doesn't touch the intake manifold. Just one tie-wrap underneath it so it can't slide down. (picture 3)



I don't think many people will come accross this issue, but if they do this is a good solution. Not pretty, but not really ghetto either if you ask me.

(Excuse me for going berserk with words over this minor upgrade.)

[kraxxus]

Would look better in light yellow!! :-P nice fix dude, looks it was made that way!
No apologies needed, the best feeling is succeeding on even the smallest mod to ones vehicle.

[williaty]

Originally Posted by Roke

Wouldn't a turbo hood, as rice as it may be, help with keeping the IM cool?

Yes, the turbo hood is well worth it even though it's ricey. Measurable and significant decrease in both IAT and IM temps and, MUCH more importantly, it's 16lbs, 6oz lighter than the stock RS hood. It's quite an improvement to the handling!

[Roke]

Originally Posted by kraxxus

Would look better in light yellow!! :-P nice fix dude, looks it was made that way!
No apologies needed, the best feeling is succeeding on even the smallest mod to ones vehicle.

Thanks! Although it probably wouldn't have given any problems, it's nice to be sure everything is ok now.

When I'm enthusiastic I tend to explain everything in detail. That feels like some kind of nerd rage sometimes, but I don't mind. This happens even when using another language so it seems.

[Roke]

Originally Posted by williaty

Yes, the turbo hood is well worth it even though it's ricey. Measurable and significant decrease in both IAT and IM temps and, MUCH more importantly, it's 16lbs, 6oz lighter than the stock RS hood. It's quite an improvement to the handling!

My Legacy already has a aluminium light weight hood, so no gains there. But the fact it helps cooling everything does make it interesting to have it painted.

Someone once told me it's NOT ok to have outside air running into the engine compartment because that might mess things up. His argument was that the engine needs a certain operating temperature to function like it should. Cooler outside air could compromise that according to him. I don't think this is really an issue, but I've never forgotten it.

[Roke]

Time for some results!!!

Please keep in mind I own a 2007 Legacy BP5 2.0R (DOHC and AVCS) with UEL header with MagnaFlow cat and a Invidia 3" > 2.5" catback.

I've driven around with the hybrid intake enough to be able to say something about how it performs. I really couldn't find the time to run tests, so here's some butt dyno data. I could tell a great deal about it, but I'll just sum up everything I felt. My butt dyno is very sensitive and I'm honest about everything.

-Car starts faster. (Starting motor turns less at least one time.)
-Car runs smoother at idle. (Also with climate control running.)
-No low RPM torque loss.
-With cold engine car is a bit more restless. (A bit bumpy when using the clutch.)
-Overall better throttle response.
-When shifting fast during normal driving the car 'bumps' sometimes. (When stomping one the clutch pedal fast.)
-Almost insane boost between 1800 and 3000 rpm. (Almost feels like the car is charged somehow. Makes me do Daily driving is a LOT more fun now.)
-A bit more pull between 3000 and 4000 rpm.
-No significant difference in higher rpm's, but some more pull around 6500 and higher. (When reaching max. power. That's around 7200 rpm.)
-Nice intake 'growl' around 3500 rpm's and a bit in high rpm's.


I do have another kind of reverence. I don't know if it worth much, but it is visual proof.

I've shot a video a while ago (with oem intake) while doing 0-150 km/h a fast as I could with normal start and normal shifting.

YouTube

YouTube

After installing the hybrid intake it did the same thing (besides doing almost 200 km/h). Same setup, same road. The only differences where the outside temperature being a bit hotter and a tool box in the trunk. Just one try because I didn't want to push things. The results where a bit better. (0-100 km/h 0.4 seconds faster. Timed both vid's with a stopwatch 10 times and took the average.)

YouTube

YouTube

So it's save to say the hybrid intake performs well. I'm VERY pleased with it and I would like to thank everyone that has been contributing to this thread.

[williaty]

Originally Posted by Roke

Someone once told me it's NOT ok to have outside air running into the engine compartment because that might mess things up. His argument was that the engine needs a certain operating temperature to function like it should. Cooler outside air could compromise that according to him. I don't think this is really an issue, but I've never forgotten it.

This is somewhat true but it's a LOT less true than 40 years ago. Basically, if the outside temp is in the range of -10 to 120F, pretty much any car produced since the mid-90s is going to manage its own engine temp just fine (with some exceptions for, say, towing a giant load up a mountain). Most newer cars will even operate ok, if hotter than normal, under easy driving conditions up to about 140F.

Below -10F, the challenge is getting non-engine things warmed up and keeping them that way. Grease in the axles, tranny/diff oil, etc. Below about -30F, just getting it started to start warming things up becomes difficult and you may need to restrict airflow under the hood as well as switch to different lubricants for just about everything.

[Roke]

Originally Posted by williaty

This is somewhat true but it's a LOT less true than 40 years ago. Basically, if the outside temp is in the range of -10 to 120F, pretty much any car produced since the mid-90s is going to manage its own engine temp just fine (with some exceptions for, say, towing a giant load up a mountain). Most newer cars will even operate ok, if hotter than normal, under easy driving conditions up to about 140F.

Below -10F, the challenge is getting non-engine things warmed up and keeping them that way. Grease in the axles, tranny/diff oil, etc. Below about -30F, just getting it started to start warming things up becomes difficult and you may need to restrict airflow under the hood as well as switch to different lubricants for just about everything.

Thanks for sharing this info. My knowledge of cars just went up a level.

[Kcswimrac]

Wow looks pretty good!

[Roke]

Hi,

Just letting you all know I'm running the hybrid intake for almost 5 months now without any issues. The negative experiences like the minor 'bumping' when shifting have gone. Thay may partly have to do with me getting used to it, but I'm quite sure things just have smoothened out (ECU learning?). It's still performing great.

I've swapped my Cosworth 'performance' panel air filter for a OEM style (Mann Filter) panel air filter because I don't believe in performance air filters any more. They just let through more dirt and the bigger amount of air they claim to let through simply does not noticeable add to performance. I did not feel ANY difference after going back to OEM.
(I think a cleaner intake trajectory does more for performance than a bit of extra air.)

[TMSNile72]

Just getting into the Impreza side of things and am so glad I found this thread! Now my 09 Impreza and my sand drag legacy can breath better! Question though (and it's noobie at best and down right pitiful at worst) Is it possible to for some one to show photos of the snorkus (again, new as can be to subaru world)? Just so I know what I am looking at before I start trying to do this my self.
BTW Roke, nice setup.

[LaurenceDVS35]

Can some one explain the downsides of deleting resonator? I've had mine gone for at least 20K with hybrid intake and nothing bad has happened but what could? I'm unfamiliar with downsides.

Originally Posted by williaty

My extremely well educated guess would be that no, it doesn't work on the NA.

Here's why I think that:

Helmholtz resonators are extremely high-Q resonators. What that means is that they suck out vibrations in a tight, narrow frequency notch. This means they have to be tuned very carefully so that their resonance lands right on the mode you need to damp out. Very small changes to their physical design can produce pretty big changes to their resonant frequency. So if you can tell the two resonators apart by eye, they are likely tuned to VERY different frequencies. It's unlikely that the STi one is properly tuned to the mode that needs damped in the NA intake.


Beyond that, why on earth would you bother? The Helmholtz resonator IS NOT a flow limitation. Changing it can't possibly gain you any power. The only thing it's possible to do by going to the STi part is screw **** up with no possible up-side.

[williaty]

Originally Posted by LaurenceDVS35

Can some one explain the downsides of deleting resonator? I've had mine gone for at least 20K with hybrid intake and nothing bad has happened but what could? I'm unfamiliar with downsides.

What part of the first post are you unable to read?

If you deleted the resonator, YOU ARE NOT RUNNING A HYBRID INTAKE.


The problems with deleting the resonator are shown clearly in the first post and then discussed about another 20 times in the pages that follow. You don't need anyone to explain anything to you, you just need to re-read what has already been said.

[LaurenceDVS35]

That's my question being that the snorkus on the 08-11 is way different shape I just wanted clarification I did read all of that before I asked. Just didn't see anyone that did resonator delete and left everything else up front the same( Imay have overlooked) but if Id everything "hybrid" but also delete the resonator I'm essentially running in to the same issue as SRI correct?

Originally Posted by williaty

What part of the first post are you unable to read?

If you deleted the resonator, YOU ARE NOT RUNNING A HYBRID INTAKE.


The problems with deleting the resonator are shown clearly in the first post and then discussed about another 20 times in the pages that follow. You don't need anyone to explain anything to you, you just need to re-read what has already been said.

[Toyts]

Hey there I'm jumping in kinda late and I admit I did not read all of the 78 previous pages but I think I may have some helpfull ideas and photos. 1st idea is that stock internals can only give what they are capable of so the stock NA subbie really can't effectively give you more just by you trying to feed it more. 2nd idea balance is key. Sound is cool but fast is cooler. I drive a 2002 ts. Engine is bone stock with 212k. I know to much is bad and too little is no fun so all of my more have been in an effort to make the car less restrictive inside stock tuning. I kept the stock headers and increased the front section to 2inch including new cat. Rear cat deleted,2.25 pipe from cat to tip. Intake side is stock air box with the inside trimmed. Also I filed the inlet to the stock filter box to 2.25inches. Basic idea is that the flow of air in and out is balanced. I do realize that more aggressive builds require more flow. But the principal of balance is the same. In my opinion stock parts can and probably should be modified as a part of the initial stages of the build. As I said my car is old and is looking for a donor engine for next year, but it hauls ads. Considerably quicker than stock fom 0-105(current limit 115 ). Here is a link to the exhaust. This is the second setup I've designed for the car. Much better than my uninformed 1st gen designhttps://youtu.be/qqCOIbA2hzU. Hope this wasn't insulting and it provides solid info.

[williaty]

Everything you did was pointless. You need to do a hell of a lot more research on the science of how a normally aspirated gasoline internal combustion engine works before you try to "help" people.

You only changed parts that are not a problem and you didn't change anything that actually improved the flow of the engine.

Intake and exhaust piping diameters should not be equal because intake and exhaust gas volumes are not equal.