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| newxr |
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jonbays wrote: Really not to sure about all this at all.
Some good underlying areodynmaics theory but not well tied to the cause and effect of improving the engine efficiency. I doubt it works at all. Well it will probably keep the back of the car cleaner and assist the exhaust gasses to escape the exhuast faster but is it going to help scavenge the cylinders any better on exhaust stroke I think not or is it going to draw in any more A/F mixture on intake stroke NO WAY. Why not put a super charger on the exhaust and see waht happens. No its a joke right? No joke! It just makes the flow oe exhaust easier - it will increase exhaust flow just like a larger exhaust. This is confirmed by F1 cars having exhaust tips facing down to take advantage of the phenomenon however the gains are small. Seat of the pants - not much as you would expect but the inflow of air into the scoop sounds "good" - well interesting at least
_________________ <b>XR6NA with T Snorkal in Silhouette with Lux Pack + 2nd CAI XR8 Snorkel, Pacemaker Headers, High Flow Cat, Redback Exhaust with Twin Tailpipes - 149kw (G-Tech)</b>, Lower Grill, Side Air Bags, Power Pedals, Boot Lid Carpet, Boot Liner, Rear Sun Screen, Mats, Spats, Scuffs, Tint, Gold Plated Badges |
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| twr7cx |
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newxr wrote: It just makes the flow oe exhaust easier - it will increase exhaust flow just like a larger exhaust. This is confirmed by F1 cars having exhaust tips facing down to take advantage of the phenomenon however the gains are small.
Why not just fit a droopy/drop tip on your ehxuast then? Would be lighter than the second lot of piping, less wieght means faster car too. |
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| newxr |
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twr7cx wrote: newxr wrote: It just makes the flow oe exhaust easier - it will increase exhaust flow just like a larger exhaust. This is confirmed by F1 cars having exhaust tips facing down to take advantage of the phenomenon however the gains are small. Why not just fit a droopy/drop tip on your ehxuast then? Would be lighter than the second lot of piping, less wieght means faster car too. As I said before - in order to get enough effect the tailpipe would have to be a couple centimeters of the groynd - not very practical 
_________________ <b>XR6NA with T Snorkal in Silhouette with Lux Pack + 2nd CAI XR8 Snorkel, Pacemaker Headers, High Flow Cat, Redback Exhaust with Twin Tailpipes - 149kw (G-Tech)</b>, Lower Grill, Side Air Bags, Power Pedals, Boot Lid Carpet, Boot Liner, Rear Sun Screen, Mats, Spats, Scuffs, Tint, Gold Plated Badges |
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| chunkz |
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because.......................
the velocity of the air running under a higher car wouldnt be enough to make an effect?
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| ItchiOne |
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If you use this principle, it may well work and result in a small increase in power, and depending on how the ducting and airodynamics is done, maybe a bit more than a small increase in power. But power isn't the only game in town
To fly, planes use huge power to provide the trust and lift needed and the engineers try hard to reduce drag. Planes have huge power at their disposal (and huge fuel bills). Even in F1, drag is a big problem but their power levels are/were huge - 1100-1400HP from 1.3 litres in qualifying trim during the turbo days). Even today you just lift of the accelerator in an F1 car and you slow down at greater than 1G, just because of the drag thet exists to produce the downforce needed to keep them on the raod 
Using an undercar venturi & exhaust in road cars would translate to a much bigger fuel bill once drag and vehicle stability is worked out. I suspect that the equation would not work out so well, otherwise car manufactures would have done it. The truth is you can't get something for nothing. Pitty
Good luck with it though. Cheers. |
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| EBeast |
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ItchiOne wrote: Using an undercar venturi & exhaust in road cars would translate to a much bigger fuel bill once drag and vehicle stability is worked out. I suspect that the equation would not work out so well, otherwise car manufactures would have done it. The truth is you can't get something for nothing. Pitty Good luck with it though. Cheers. not nessaceraly, correct me if im wrong, but if you only have a smallish scoop under the car (i think he said it ws 3 1/2 inch) theoreticaly wouldnt that create less drag on standard car (eb) that a front spoiler....it is much smaller, AND if you already had a front spoiler (not sure what its called, but i mean the one with the two driving light holes) you could even put the snorkel in place of one of the lights, thus working off the earodynamics of the spoiler.. im probably talking s**t but in my head it works. LOL 
_________________ 1993 EBII GLI, IT'S PERFORMANCE Stage 3 engine,
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| ItchiOne |
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EBeast wrote: ItchiOne wrote: Using an undercar venturi & exhaust in road cars would translate to a much bigger fuel bill once drag and vehicle stability is worked out. I suspect that the equation would not work out so well, otherwise car manufactures would have done it. The truth is you can't get something for nothing. Pitty Good luck with it though. Cheers. not nessaceraly, correct me if im wrong, but if you only have a smallish scoop under the car (i think he said it ws 3 1/2 inch) theoreticaly wouldnt that create less drag on standard car (eb) that a front spoiler....it is much smaller, AND if you already had a front spoiler (not sure what its called, but i mean the one with the two driving light holes) you could even put the snorkel in place of one of the lights, thus working off the earodynamics of the spoiler.. im probably talking s**t but in my head it works. LOL To have any sort of acceptable effect on exhaust backpressure, you will need to have the airflow exiting the venturi travelling at a very much higher speeds than the exhaust gas exit speed. I think this would require something more than small 3 1/2 inch ducting and it would creat drag. If you already have a sploiler, the extra drag of the venturi assist would add to that which already exists for the car . Cheers |
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| chunkz |
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does any one know the speed of exhaust exits?
i'll have my physics teacher do some calc's
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| newxr |
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chunkz wrote: does any one know the speed of exhaust exits?
i'll have my physics teacher do some calc's It all depends on the entry and exit diameters however according to physics with my set up of a 3.5" intake and 1/6" exit at 60km/h the exit speed is over 240km/h and a reduction in pressure of about 10%. There are a numerous online bernoulli/venturii calculators to help with this.
_________________ <b>XR6NA with T Snorkal in Silhouette with Lux Pack + 2nd CAI XR8 Snorkel, Pacemaker Headers, High Flow Cat, Redback Exhaust with Twin Tailpipes - 149kw (G-Tech)</b>, Lower Grill, Side Air Bags, Power Pedals, Boot Lid Carpet, Boot Liner, Rear Sun Screen, Mats, Spats, Scuffs, Tint, Gold Plated Badges |
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| MMD |
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I think i understand....
the black pipe creates a stream of air running faster than the car exhaust fumes, creating a drop in pressure effectivly sucking the fumes out of the car exhaust.... this correct ? if so you "could" use a turbo charger to the same effect.. except it replys on engine exhaust fumes not speed, so as the engine revs higher in each gear the more power u get... meaning a greater overall performance increase from 0 - whatever not just at high speed.... i know this is not feasable cause of he extra weight of the turbo itself but i think i have the principle right.... |
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| newxr |
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MMD wrote: I think i understand....
the black pipe creates a stream of air running faster than the car exhaust fumes, creating a drop in pressure effectivly sucking the fumes out of the car exhaust.... this correct ? if so you "could" use a turbo charger to the same effect.. except it replys on engine exhaust fumes not speed, so as the engine revs higher in each gear the more power u get... meaning a greater overall performance increase from 0 - whatever not just at high speed.... i know this is not feasable cause of he extra weight of the turbo itself but i think i have the principle right.... Spot ON
_________________ <b>XR6NA with T Snorkal in Silhouette with Lux Pack + 2nd CAI XR8 Snorkel, Pacemaker Headers, High Flow Cat, Redback Exhaust with Twin Tailpipes - 149kw (G-Tech)</b>, Lower Grill, Side Air Bags, Power Pedals, Boot Lid Carpet, Boot Liner, Rear Sun Screen, Mats, Spats, Scuffs, Tint, Gold Plated Badges |
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