Cowl induction for cold, ram air for the Si?

[ocspray]

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[aki]

I'm still going back and reading through all the pages, I had a question on one thing I noticed:



The lower CRV box looks very airflow-restrictive, as the opening is very small. Do you have plans on opening that up?

[ocspray]

I read quite a bit and skipped to the end. Since it's so close to being together, I figured it'd be best to wait for the final presentation before asking NitrousG35 & soxfan143 more questions, especially since I probably missed earlier answers on pages 5 through 52.

[djdisturbed]

Originally Posted by aki

I'm still going back and reading through all the pages, I had a question on one thing I noticed:



The lower CRV box looks very airflow-restrictive, as the opening is very small. Do you have plans on opening that up?

He is not using the bottom inlet for the (main) airflow, he is cutting a new opening that the cowl induction will run into in the top of the intake box

[NitrousG35]

Originally Posted by aki

I'm still going back and reading through all the pages, I had a question on one thing I noticed:



The lower CRV box looks very airflow-restrictive, as the opening is very small. Do you have plans on opening that up?

Unfortunately, pictures do not show perspective very well. The CRV is in fact, quite a bit deeper and wider than the Si lower portion. Believe me when I say it will flow a lot more air than the Si airbox. The lower opening is quite large, enough to use 4" flexible tubing.

Remember that I am using the CRV airbox primarily as an enclosure for a cone style filter with a larger surface area than a flat style filter. The airbox cover will be opened up to connect to a duct which in turn will connect to the base of the windshield wiper cowl area.

Between the factory cold air inlet and the cowl induction, I should have an enormous amount of air being rammed into the intake.

[Grizam303]

Might it be better to seal off the bottom of the airbox to make the only intake source up at the windshield? It seems that if there was pressure due to the cowl induction within the box, it would leak out through the factory cold air inlet.

[c130turboprop]

Originally Posted by Grizam303

Might it be better to seal off the bottom of the airbox to make the only intake source up at the windshield? It seems that if there was pressure due to the cowl induction within the box, it would leak out through the factory cold air inlet.

it will be sealed up... just isnt in the picture yet

[NitrousG35]

Originally Posted by Grizam303

Might it be better to seal off the bottom of the airbox to make the only intake source up at the windshield? It seems that if there was pressure due to the cowl induction within the box, it would leak out through the factory cold air inlet.

Initially, I was going to only access air from the cowl and seal off the factory cold air inlet. However, when I saw the Gruppe M design and spoke to Nasif who had installed one, I found out that the hole on the side of the Gruppe M has quite a bit of vacuum. He told me it would suck a piece of paper flush against the airbox.

So, with that information, I may initially try out the airbox with both the cowl induction and the factory cold air. I will just have to experiment. I will also try it with the factory cold air inlet sealed off to see if there are any differences with or without the cold air tube.

[Grizam303]

I suppose it's hard to test something that creates power best when the car is moving. I would expect there to be vacuum at a stop, but once the car gets moving, I imagine the added pressure from the cowl induction would turn the vacuum into a pressure leak. I don't doubt that it would suck a paper at stand-still, but whether it would do the same thing with air blowing into the cowl at 35-60mph is the question. I'm sure you could test this with a fan or blowing shop vacuum though.

If this is the case (and I can't see why it wouldn't be at highway speeds), maybe a rudimentary valve/flapper component for the bottom section would benefit the device.

If there's anything I can do to help this along, please PM me. I love tinkering and hate gas mileage. I live in high altitude too (not that I think that matters..)!

[ocspray]

Originally Posted by Grizam303

I don't doubt that it would suck a paper at stand-still, but whether it would do the same thing with air blowing into the cowl at 35-60mph is the question. I'm sure you could test this with a fan or blowing shop vacuum though.

Though crude, a gasoline powered leaf blower would work, since a good one can move quite a bit of air into your cowl inlet, and you can vary speed (on mine, you can lock a throttle position, too).

[NitrousG35]

Grizam303, thanks for the insight. Yes, there may be a pressure drop at speed. The only way to really find out is to test it with and without the cold air inlet attached. I am going on my own intuition and knowledge gleaned from car manufacturers. I wish I could be more scientific, but I have zero instrumentation to measure vacuum, pressure and air velocity.

I wish I could design a flapper valve that would do just what you mentioned. I can fabricate things to a certain extent, but designing valves that open and close is not one of them.

I am also searching [in vane], for some type of grille/inlet/face plate that is about 3 inches tall and maybe 4-6 inches long with downwards angled louvers. I would like to make a cut in the wiper cowl on the driver's side as this is really the most ideal place to pull air in from.

So far, I have come up snake-eyes. If you or anyone else could find something like that for me, I would greatly appreciate it.

[NitrousG35]

Originally Posted by ocspray

Though crude, a gasoline powered leaf blower would work, since a good one can move quite a bit of air into your cowl inlet, and you can vary speed (on mine, you can lock a throttle position, too).

I have a Sears shop vac that can blow air up to 265 mph. You might have a great idea to test things out.

[ocspray]

That'd probably work ok. If variability becomes desirable, then a gas model could be used.

Here's some thoughts on your grillwork. Browse through a local salvage yard until you happen upon the perfect part. Lots of oddball interior HVAC vents might be in that size range. If that doesn't work, a local tinner at a HVAC shop might be able to make something functional for you. A quick, temporary option might be to pull some pantyhose or some other mesh fabric over the cowl inlet.

[NitrousG35]

Originally Posted by ocspray

That'd probably work ok. If variability becomes desirable, then a gas model could be used.

Here's some thoughts on your grillwork. Browse through a local salvage yard until you happen upon the perfect part. Lots of oddball interior HVAC vents might be in that size range. If that doesn't work, a local tinner at a HVAC shop might be able to make something functional for you. A quick, temporary option might be to pull some pantyhose or some other mesh fabric over the cowl inlet.

Bro, if I used pantyhouse, I really would have one sexy Si.

[c130turboprop]

Originally Posted by Grizam303

I suppose it's hard to test something that creates power best when the car is moving. I would expect there to be vacuum at a stop, but once the car gets moving, I imagine the added pressure from the cowl induction would turn the vacuum into a pressure leak. I don't doubt that it would suck a paper at stand-still, but whether it would do the same thing with air blowing into the cowl at 35-60mph is the question. I'm sure you could test this with a fan or blowing shop vacuum though.

If this is the case (and I can't see why it wouldn't be at highway speeds), maybe a rudimentary valve/flapper component for the bottom section would benefit the device.

If there's anything I can do to help this along, please PM me. I love tinkering and hate gas mileage. I live in high altitude too (not that I think that matters..)!

ya, your right, it is hard to know what exactly is goin on inside the engine bay when your moving... hummm, maybe mounting a video camera inside the engine bay area would work, it sounds kindof lame, but it would show you whats going on with the intake area. just tie on a streamer thing on the inlet crv tubing and see where it blows to with the video camera pointed at it.... just an idea that could work. just make sure the video camera is mounted good though, wouldnt be good for it to fall out the bottom of the car, lol... i guess making sure the streamer or whatever u decide to use would also be a good idea to ensure it is tied on good to so it isnt sucked into the engine

[Grizam303]

When I think flapper, I think of the dealy on the bottom of the toilet tank.. I'd guess that there might be some plumbing part that could do the job, but I really can't tell the dimensions that you're working with in regards to both the box and clearances for the filter. I doubt it would have to be very complex though, you wouldn't even need it to be air-tight.

However, as far as testing pressure goes, you really only need to know if pressure exists in the box at speed, not so much the magnitude. Again, I can't really see the box, but could you use some kind of cork (this could probably be as simple as a pen cap or something) so that if the box became pressurized, it would pop out?

I really wouldn't expect the box not to be pressurized at speed. If the box had a vacuum, that would defeat the premise for cowl induction in its entirety, would it not?

[mattsbobo]

Bump Bill

Bill, how much was your CRV airbox? You did say it fit exactly like the Si box, with no modding correct?

[NitrousG35]

Originally Posted by mattsbobo

Bump Bill

Bill, how much was your CRV airbox? You did say it fit exactly like the Si box, with no modding correct?

Matt, the CRV airbox fits just like the Si airbox. The only modifications needed are to cut the plastic/metal shelf a little so that the cover will have enough clearance as it sits a little higher and farther back. It connects to the stock intake tube and factory cold air as well. The only other issue is that the mounting point on the CRV airbox on the right side sits higher than the Si airbox, so I will have to fashion a little bracket.

I got Soxfan's MAF housing on Monday, so I will try and finish things up this weekend. I will first do a trial run with just the modded MAF housing and CRV airbox and share the results for those interested in just that mod.

I may not post a DIY or show the final product as I have been attacked pretty viciously by 5 or 6 people both on the forum and in PM's. I am getting sick and tired of the nastiness of some people who feel that it would be best if I left the forum.

So, I will PM people like you and Koop and a few others with pics and results and just let the thread die. Some people have accused me of thinking I own the site or that I think I know everything. This has never been my intent and I do things to try and help others out. As a result, I don't post much in the Bolt On Section anymore.

Matt, I'll PM you when I get finished. Maybe we can talk on the phone.

[Phalanx]

There are really people that PM you constantly with that crap? Are they highly respected members of the community?