Measuring Restriction in the Stock Intake System - A GrimmSpeed Report

[EMS Guy]

someone actually doing their homework! kudos!!!!!!!!!!

[FR-Slide]

Trying to decipher the data about the snorkel and its effect on air speed and/or pressure. I've got a drop-in and smooth-bore tube already, and removed the resonators in the engine bay, but I was debating on removing the bumper this weekend to remove the snorkel resonators and/or the snorkel itself.

But, after reading (well, half-reading-half-skimming) this, I can't tell if there is anything to gain from that.

Does removal of the stock snorkel have any effect (positive OR negative) on airflow and/or power? Sound?

[GrimmSpeed]

Originally Posted by FR-Slide

Trying to decipher the data about the snorkel and its effect on air speed and/or pressure. I've got a drop-in and smooth-bore tube already, and removed the resonators in the engine bay, but I was debating on removing the bumper this weekend to remove the snorkel resonators and/or the snorkel itself.

But, after reading (well, half-reading-half-skimming) this, I can't tell if there is anything to gain from that.

Does removal of the stock snorkel have any effect (positive OR negative) on airflow and/or power? Sound?

If I were you, I would take a quick look at this thread we did: http://www.ft86club.com/forums/showthread.php?t=56341

It'll show you real dyno results of the mods you have, and how power increased with a modified snorkel (which we also show pictures of). I believe there is also advice in there about further modifying the snorkel opening for a wider opening with heat and a bottle from Robert@Vishnu I believe.

So read that, and then make your decision. But I would NOT remove the snorkel altogether, or waste your time deleting resonators when there is power to be made with a few saw cuts Weather is keeping us form testing the modified snorkel to see if there is any difference in pressure drop/gain over stock, or else that would already be added to this post, lame I know...

Chase
Engineering

[FR-Slide]

Originally Posted by GrimmSpeed

If I were you, I would take a quick look at this thread we did: http://www.ft86club.com/forums/showthread.php?t=56341

It'll show you real dyno results of the mods you have, and how power increased with a modified snorkel (which we also show pictures of). I believe there is also advice in there about further modifying the snorkel opening for a wider opening with heat and a bottle from Robert@Vishnu I believe.

So read that, and then make your decision. But I would NOT remove the snorkel altogether, or waste your time deleting resonators when there is power to be made with a few saw cuts Weather is keeping us form testing the modified snorkel to see if there is any difference in pressure drop/gain over stock, or else that would already be added to this post, lame I know...

Chase
Engineering

Thanks Chase! Sorry, I should have been more clear; wasn't going to remove the snorkel completely, but basically just break out the Dremel to carve it up. I had an idea that was more or less what you ended up with, in terms of modification.

Had no idea to even try the heating/shaping though! That's awesome, but what are people using to safely heat up the plastic? Bake in the oven?

[GrimmSpeed]

I'm not sure since I haven't done it yet. But based on the fact that I believe it is just ABS plastic I would use a heat gun if you've got one. I don't know if a hair dryer would get the job done, but it could be worth a shot as well.

Chase
Engineering

[Blokatos]

Originally Posted by GrimmSpeed

The effect the snorkel had on the system was very interesting. The snorkel showed a consistent pressure gain of about 3in H2O. The fact that the inlet is smaller than the outlet lends that the decrease in velocity of the air as it passes through should increase the pressure. However, the fact that this number is nearly high enough to cancel out any one other component’s restriction shows that in stock for the intake is very well designed. Each other component seems to have a restriction of about 4in H2O (air filter, MAF housing, intake elbow).

Chase
Engineering

Congrats on the research done and also for posting them on a public forum, open to discussion. It shows a lot about your business mentality and I strongly believe that people with this kind of attitude towards potential customers should be rewarded.

I am no fluids dynamics master but I have some reservation about the findings regarding the snorkel. You state that there is a pressure increase which results from the good snorkel design.
I would like to point out that this pressure increase might not be a result of the snorkel's existence but from the existence of the air filter right downstream of your measuring point. Any restriction will cause a pressure increase as suggested by the physics that dictate the Venturi principle.
The air filter may be the real reason that there is an increase of pressure at that point. I could be wrong though, I know I've been in the past
I just wanted to add a little bit to the discussion as:
a) I am interested in intake design and potential gains from it
b) I have alter the intake of my current car (including its snorkel), a Mazda MX5, and recorded significant gains backed by back to back same day dyno runs that verified each step of the way towards a better performing intake.

Once again, congrats for your research and your thorough approach to your work.

Nik

[GrimmSpeed]

Originally Posted by Blokatos

Congrats on the research done and also for posting them on a public forum, open to discussion. It shows a lot about your business mentality and I strongly believe that people with this kind of attitude towards potential customers should be rewarded.

I am no fluids dynamics master but I have some reservation about the findings regarding the snorkel. You state that there is a pressure increase which results from the good snorkel design.
I would like to point out that this pressure increase might not be a result of the snorkel's existence but from the existence of the air filter right downstream of your measuring point. Any restriction will cause a pressure increase as suggested by the physics that dictate the Venturi principle.
The air filter may be the real reason that there is an increase of pressure at that point. I could be wrong though, I know I've been in the past
I just wanted to add a little bit to the discussion as:
a) I am interested in intake design and potential gains from it
b) I have alter the intake of my current car (including its snorkel), a Mazda MX5, and recorded significant gains backed by back to back same day dyno runs that verified each step of the way towards a better performing intake.

Once again, congrats for your research and your thorough approach to your work.

Nik

Thank you very much Nik, and thanks for taking the time to read the research we did on pressure differentials for the stock intake system.

I would tend to agree with you that the presence of restriction after the snorkel could be a contributing factor to the pressure gain. However, specifically regarding the venturi effect, this portion of the intake is very much a diffuser. The outlet size of the snorkel is 2.875 times the area of the inlet. This change in area from the inlet to the outlet (by almost a factor of 3) results in a decrease in velocity, and thus in increase in pressure. THIS is the venturi effect. It's not so much as a result of the "restriction" in the system, but rather the change in airflow velocity. And since we know the differences in area between the inlet and the outlet and have deduced that this portion of the intake is a diffuser, we're not surprised to see that there is an increase in pressure. Just as it wouldnt be surprising to see that the speed of the airflow from the inlet to the outlet has decreased (if we were to measure that).

A good way to prove this, or an area of further research would be to see the differential pressure from the inlet to the outlet of a modified snorkel, where the difference in area is not nearly as great (and it also doesnt have the 90deg bend that the snorkel has, which is a pretty decent contributor to the restriction in that piece).

The reason I don't think that the air filter is the source of the pressure gain (other than the fact that the snorkel is a diffuser) is that the testing is showing that there is about the same amount of restriction in each portion of the intake (4in H20 across the filter, 4 more across the MAF, and 4 more through the intake elbow). And with there being no changes in area through each of those sections we can conclude the pressure drop is due to pure restriction. But this does not bode well with the theory "there will be a positive pressure gain between X and X2 because there is restriction at X2." Which should certainly be true since we've determined that the amount of restriction from the air filter is the same as the amount of restriction from say the intake elbow. Does that make sense?

If you want to read more on the intake design (and specifically the dyno testing we did in a single day, over 140 pulls and 60 miles at WOT), check out this thread, as it goes through the design process and testing in real time: http://www.ft86club.com/forums/showthread.php?t=50492

Yes it is 48 pages, but you can skip through a lot of it to get to the meat and potatoes, and see what the real world gains are of the final intake, the prototypes, a few other brands, drop in filter, intake elbow, etc. I think you might enjoy it.

Again thank you very much for the kind words!

Chase
Engineering