Car Chemistry Exhaust Venturi's

Discussion in 'Mustang Chit Chat' started by GlassTop09, Apr 14, 2021.

  1. GlassTop09

    GlassTop09 Member

  2. Forty61

    Forty61 forum member

    Interesting.. never heard of these. I guess they would function in the same way venturis do in carbs but is it gonna make much noticeable difference bolting a couple in your exhaust? I’d be interested to see some actual dyno numbers or personal experiences.
  3. jewc75

    jewc75 S197 Junkie S197 Team Member

  4. GlassTop09

    GlassTop09 Member

    Thanks for the link!

    The science behind this concept I know well....just had never heard of this being applied to vehicle engine exhausts to improve low RPM exhaust scavaging thus improve low end & mid range HP\TQ w\o adversely sacrificing top end HP\TQ...........until now.......

    I'm tempted to try a couple of these as I'm planning soon to cut the Kooks race cats out of my X-pipe to replace them w\ a set of much larger max exhaust poundage treating capacity, Fed EPA cert, OBDII compliant spun 304 SS cats so it would be the right time to install them in exhaust just aft of the cats to take full advantage of the max heat output & optimized exhaust flow velocity thru the X-pipe section along w\ the stabilization of exhaust flow thru the cats (slight deltaP reduction thru the cat substrates would slightly increase flow retention time making cats more effective while potentially giving the exhaust an overall increased deltaP drop across the entire mid pipe section as opposed to w\o them installed by the reduction of flow turbulence thru the entire mid pipe section). I know the original intent is to mount just aft of engine headers but the point is to install where the exhaust flow is highest temp to gain the maximum effect....this will always be aft of cats as long as cats are functioning properly when they are being used in exhaust.

    I like HeadersbyED's venturi designs better.....actually follow airflow venturi dynamics better than the ones in the link I posted so I'm gonna give them a call to find out more.
  5. Flusher

    Flusher Member

  6. Dino Dino Bambino

    Dino Dino Bambino I have a red car

    It appears that venturis are used on race vehicles with open headers where collector length and diameter has a significant effect on the HP/TQ curves.
    I'm not sure if they'd do anything on street driven vehicles with full exhaust systems though. For these, electronically controlled valves can be used in the exhaust system to vary the cross-sectional area and optimize exhaust gas velocity over a wide rpm range. The principle would be the same as that employed by intake manifold runner controls (IMRCs) to improve lower rpm response.
    crjackson2134 likes this.
  7. GlassTop09

    GlassTop09 Member

    Yep, now you know why I said I'm gonna call them for more info. The concept isn't the issue...that's sound, Ford has already done the design work in the current 2 1\2" exhaust system design (the advent of the H-pipe\X-pipe section in midpipe post cats to optimize exhaust flow velocity thus scavaging thru the rest of the exhaust system)....what I'd need to know is what size of orifice along w\ the taper & length of the flute is needed to gain any further velocity post-cats to assist the H-pipe\X-pipe section to further increase scavaging effects across the entire system w\o an excessive hit on top end scavaging & whether it is durable\practical or not (meaning that the necessary flute length is too long to fit in the section of exhaust pipe post cats in my Kooks midpipe & how long will they hold up\last in a permanent install).

    If I just went by what is normally viewed as accepted it's obvious that most see this as not practical....but that alone doesn't mean that it doesn't\won't work. Practical in the instance of these exhaust venturis IMHO is ease of install\maintenance vs effectiveness w\ emphasis on the ease of install\maintenance....not necessarily due to lack of effectiveness & where I plan to install them IF I do at all will most certainly impact the ease of install\maintenance aspect as they would be a permanent install in my scenario.....these questions are what I need answered to move me to go forward. I already know that they would have to be made of at least 304 SS to have a fighting chance at longevity. There's a reason why they're made\touted to be removeable.......

    Thanks for the links!
    I'll definately check it out.
  8. Juice

    Juice forum member

    If the exhaust is sized correctly (not too big) I dont see the need for a restrictor.
    crjackson2134 likes this.
  9. eighty6gt

    eighty6gt forum member

    snake oil
    Bullitt2954 likes this.
  10. Flusher

    Flusher Member

    I'm really curious to know their story.

    Merge collectors work! They maximize scavenging based on volume and velocity of exhaust gasses pulling on adjacent tubes while reducing gaseous expansion and turbulence. The cone after the choke point is for anti-reversion.

    This is not a merge collector. I don't see this as doing anything positive. No disrespect to you intended. Personally, I think this is snake oil, a Tornado for your exhaust. I definitely do not see it working after the cats. Yes, it would increase velocity at the new choke point, but it would reduce velocity everywhere after that.

    I would think that a better entry and exit shape for the cat housing would produce more useful gains. If you have gone through Ed's Infopak, you know how much Ed talks about "gaseous expansion" and how it slows velocity.

    That's not going to happen, it's a closely guarded secret. Mr Burns et al get paid for exactly that. My former coworker and I had a set of collectors specced by Burns, we received everything except the choke and the taper from the cloverleaf, the two critical dimensions. You only receive that information in the form of a collector.

    BTW, Mr Burns is awesome to talk to.
    Bullitt2954 likes this.
  11. Flusher

    Flusher Member

    I can't find it right now, but Don Terrill's, now had a lot of audio interviews with industry professionals on topics such as head porting and exhaust. It was really some good information.
  12. MrBhp

    MrBhp Member

    On the Car Chemistry website they use the analogy of water coming from a hose. "Pinch the hose and the increased backpressure increases water speed". Yes the velocity has increased, but through a smaller aperture. Overall volume of flow has decreased. Doesn't seem like an ideal scenario with your exhaust.
    Laga, Bullitt2954 and eighty6gt like this.
  13. Laga

    Laga Member

    Yep, Back pressure is always bad. Too big of an exhaust is bad. Thats why they have "tuned" exhaust systems. The right size for your engine. This product looks like oil of snake.
    eighty6gt likes this.
  14. GlassTop09

    GlassTop09 Member

    Well taken why I also don't buy Ford's analysis on the CMCV's as they follow the exact same dynamics in reverse in order to gain increased air velocity into a cylinder so in effect they're a slight restriction due to compressibility factors of the airstream thru the CMCV plate....
    I actually saw this occur when I initially installed my FPIM vs the OEM IM w\ CMCV's thru the PCM live data at idle.....the MAF gms\sec actually increased along w\ the TBA decreased to retain the same idle speed proving the CMCV's were a restriction in the OEM IM when closed....
    The ONLY real purpose for these things are for aid in air\fuel EGR mixing in the cylinders by creating turbulence which also has a CC cooling effect so any extra TQ gained is from a cooler cylinder chamber to support increase spark timing and\or maintaining VCT at 0* (full cam advance timing) due to less NOx emissions output......the same output results (both TQ & NOx reduction) can be obtained by installing a larger radiator & cooling fan w\o the CMCV's....

    Now back to this topic. This is why I want to call & speak to these folks to find some things out before I do anything w\ them.......

    When gasses are expanded due to heat they exert less of a restriction thru an orifice as opposed to cooler denser gasses thus can actually speed up flow velocity w\o creating an undue back pressure ahead of the orifice as long as the orifice is sized to not exceed the gasses critical compressibility factor (after this point is exceeded is when gasses can no longer compress which then an actual back pressure or pressure drop is created ahead of the orifice w\ gasses or air flow) until at some point down the tube when the flowing gasses temp has sufficiently dropped increasing it's mass along w\ increasing flowing friction thru the tube to negate any velocity gains.

    The question is how long the full exhaust has to be to maintain the velocity gains.........................

    I understand the dynamic principle. They maintain\claim that these work in full exhaust I'll need to see some verifiable proof of this before I move.....otherwise it's a marketing trick to entice buying by using some general scientific truths....or snake oil as some have referred to. The old saying goes..."The best lies told has some truth lodged within em."

    None taken, Flusher.
    Now what you've posted concerning Ed Burns @ HeadersbyEd I can fully least he has put forth some verifiable data to prove the concept but even he mentions these can work in a full exhaust system but you have to call them to get the sizing specs based on your setup's sizing & layout......

    Why Ed has perked more of my interest w\ this...................

    Just by applying consensus this concept used in a full exhaust system is considered impractical (no laymen are using these in a full exhaust setup) due to having to account for a lot of variables that most won't have\take the time to work thru.....and the OEM's have worked most of this out already from a general standpoint but I think that even they have left some on the table to get......the issue is how much has to be put into it to attain it & if this is worth the effort.

    Why I was wanting to make contact to find out...............otherwise it's all a moot subject but since I've never heard of this before the geek in me wants to know all about it before just dismissing it out of hand.
  15. Rick Simons

    Rick Simons Member

    The length is what would hold me up from trying these. There just isn't room for them with cats installed.
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