Quote:
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