most of us know about the venturi effect and how it works, but ive never really found any hordore evidence of if it really works well for cars. So today i went to home depot and got lots of different sizing of piping and im going to fab up my own venturi intake tube. I wondering if i create two low pressure areas in the intake tube will it increase the air flow more, or will one of the low pressure areas cancel out the other and result in the same air flow rate regardless? Anyone know what will happen with two low pressure areas? Regardless im going to try and fab up a pvc pipe intake tube with one low pressure area and see what happens, then if the results are good then i will try and put a second low pressure area and see what the effects are. Ill post up pics of the tube and the dyno graphs when and if i can get the piping to work with my engine.

by the way ill be doing this on an h22 into a del sol with basic bolt ons.


Modified by gsr778 at 7:13 AM 3/30/2005

 

i'm interested in the results, let us know man!

props to you!

 

well after several hours and a few beers i got the pipes to work together and i made my venturi intake system. im very impressed with the results i got from the experiement. I did a base line run with an aem cold air intake, wrapped with insulation to keep the engine heat off the tubes, and got 169hp and 142trq. after a 20 minute cool down period i installed my venturi intake system and got 174hp and 143trq. A gain of 5hp and 1trq. i have pics of the intake tubes but ive misplaced the dyno sheet. im going to do another run in a few days to confirm todays results and hopefully i will not misplace the dyno sheet next time. also i would like to thank home depot for making ideas become reality... anyways enjoy!

 

did you run the venturi intake without a filter?

 

I have an interesting theory on parallel low press/high velocity areas... What would that do when flowed into one pipe? any conjectures?

 

Time to patent that intake and make some money.

 

i ran it without a filter cause i didnt have a filter to fit the size piping i had. i dont think that there would be any increase in air velocity if you flow the low pressure areas together. but im not a pycisist(sp).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gsr778 &raquo;</TD></TR><TR><TD CLASS="quote">i ran it without a filter cause i didnt have a filter to fit the size piping i had. i dont think that there would be any increase in air velocity if you flow the low pressure areas together. but im not a pycisist(sp). </TD></TR></TABLE>

not to rag on you, but the filter IMO plays a role in the power comparisions between the two...

 

What you have there is not really a venturi. You have a small tube getting bigger, then getting smaller again. You are taking low pressure, high velocity air, slowing it down and raising the pressure in the chamber, then increasing the speed and lowering the pressure to where it was before the chamber. All of this is done before the throttle body and the intake manifold also.

If you're thinking of the concept behind the Spoon Sports venturi plate, that goes right in between the manifold and the head, so the air with increased velocity goes straight into the ports.

What you have is similar to a dual chamber intake, which I couldn't find an example of, but remember seeing. The gains you saw could be due to that, or, probably the fact that there was no air filter used.

I give you credit for experimenting though, I'm just not sure if the concept is correct. Someone chime in if they think I am incorrect in my statements, because I am not 100% sure.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GeeReg &raquo;</TD></TR><TR><TD CLASS="quote">What you have there is not really a venturi. You have a small tube getting bigger, then getting smaller again.</TD></TR></TABLE>True. A venturi gets smaller & then bigger. The expansion section after the throat has to be designed very carefully so your non-recoverable pressure loss is small.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GeeReg &raquo;</TD></TR><TR><TD CLASS="quote">You are taking low pressure, high velocity air, slowing it down and raising the pressure in the chamber, then increasing the speed and lowering the pressure to where it was before the chamber.</TD></TR></TABLE>Yes, but each step gives some non-recoverable losses. So after the expansion & contraction, the pressure is lower than when it started. Plumbing fittings like that expand too sharply - you get separation & lose all the dynamic pressure.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GeeReg &raquo;</TD></TR><TR><TD CLASS="quote">What you have is similar to a dual chamber intake, which I couldn't find an example of, but remember seeing. The gains you saw could be due to that, or, probably the fact that there was no air filter used.</TD></TR></TABLE>Sometimes those work thru resonances, since the flow has some pulsations to it. But much of gsr778's gains are probably from not using a filter.

 

thats just like the ARC pipe, except much less $$



even OBX has something similar.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">True. A venturi gets smaller & then bigger. The expansion section after the throat has to be designed very carefully so your non-recoverable pressure loss is small.</TD></TR></TABLE>

i was under the impression that it was either bigger than smaller, so high velocity, low pressure into high pressure, low velocity OR smaller then bigger.




since this is bernoulli's principle, it would be much more efficent if you were to design it more like 2 wings on top of each other, with one inverted. please enlighten me if im wrong.

 

sounds like an aem v2 to me, but cheaper and ugly

can the hood close with that?.. possibly eliminates strut tower bar also..

cool

 

i compared both my cold air intake and my venturi intake without and air filter. So the air filter has nothing to to with my gains. but you guys do bring up some very good points. this is still a work in progress and if it goes anywhere im going to be very suprised im just having fun making ideas become reality.

 

and yes the hood can close

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by igo4bmx &raquo;</TD></TR><TR><TD CLASS="quote">not to rag on you, but the filter IMO plays a role in the power comparisions between the two...</TD></TR></TABLE> what do you mean, i dont get if ur pro or anti filter but i have seen people on dyno's produce lower #'s w/o a filter. just like an exhaust system on a n/a motor the intake needs a certain amout of backpressure to function properly, i have used this venturi effect in a few of my exhuast systems i have built, i had a bi turbo saab 900 and had 3" down to 2 1/2 and on the inside of the pipe about every foot i carver a circular/ spiral patter into the metal itself to help the exhust flow in a more uniform pattern. idk if it worked i didnt have a baseline to go from but 8v motor put down close to 275hp at the wheels. but that w/ or w/o a filter i think use a filter all the way see if it makes a difference but thats just my 2cents

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by veggiemaster &raquo;</TD></TR><TR><TD CLASS="quote">i was under the impression that it was either bigger than smaller, so high velocity, low pressure into high pressure, low velocity OR smaller then bigger.</TD></TR></TABLE>Yeah, now I see what you're saying. I was thinking about a venturi flowmeter. In the throat, the velocity goes up & the static pressure goes down.

Then there's a very gradual expansion section where the velocity goes back down & the static pressure is recovered. If the expansion section is too 'steep', the flow separates from the wall & the pressure is NOT recovered.

But there's always some non-recovered portion of the pressure loss. A straight tube with no area changes is always less restriction. The systems with a large chamber work on resonances with the pulsating flow. That's a whole different thing vs. Bernoulli's principle. And I think it reinforces flow at some rpm range, not overall. Besides, sometimes it's about noise reduction, not flow.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by veggiemaster &raquo;</TD></TR><TR><TD CLASS="quote">I have an interesting theory on parallel low press/high velocity areas... What would that do when flowed into one pipe? any conjectures?</TD></TR></TABLE>I'm not sure what you mean here...

 

When i was talking about bernoulli's principle, i wasnt meaning to compare it to a chamber, of course thats a different thing. But the venturi tube shares some of its principles with bernoulli's. (of course)

As for the parallel pipes, ill have to draw up a schematic. Im no expert in fluid dynamics which is why i brought it up.

 

that thing is ugly..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xboostin4funx &raquo;</TD></TR><TR><TD CLASS="quote"> what do you mean, i dont get if ur pro or anti filter but i have seen people on dyno's produce lower #'s w/o a filter.</TD></TR></TABLE>

I had this happen a couple weeks ago on an ITB car. Took the filters off and gained 3 whp

So it all depends on application.

 

Mad props for experimenting... its ugly but if it gets the job done, who the hell cares

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdm_whore &raquo;</TD></TR><TR><TD CLASS="quote">that thing is ugly..</TD></TR></TABLE>

thanks for the technical input.

 

well today i put lots of fiberglass insulation and some reflective tape all over the pvc piping, and i gained an extre 2hp. now im getting some blueprints set up on autocad and sending them to one of my friends who welds. so withing the next few weeks i should have a better prototype made out of metal instead of pvc. this should decrease the amount of air turbulance and also help increase flow. when im done ill see if i canfigure out how to post the blue prints from autocad then and show you all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xboostin4funx &raquo;</TD></TR><TR><TD CLASS="quote"> what do you mean, i dont get if ur pro or anti filter but i have seen people on dyno's produce lower #'s w/o a filter. just like an exhaust system on a n/a motor the intake needs a certain amout of backpressure to function properly, i have used this venturi effect in a few of my exhuast systems i have built, i had a bi turbo saab 900 and had 3" down to 2 1/2 and on the inside of the pipe about every foot i carver a circular/ spiral patter into the metal itself to help the exhust flow in a more uniform pattern. idk if it worked i didnt have a baseline to go from but 8v motor put down close to 275hp at the wheels. but that w/ or w/o a filter i think use a filter all the way see if it makes a difference but thats just my 2cents</TD></TR></TABLE>


i was just noticing that a filter does play a role in power...
but it seems veggie clarified and didn't run a filter with both setups to keep it similiar

 

You guy have to much extra time on your hands.