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Old 10-20-2009, 02:29 AM   #1
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Default An idea for decreased spool times (out there but possible)

Well i was sitting in the shop one day about a year ago and i had a 16g turbo in my hand, i was spraying the air from the compressor through the exhaust side of it (dont worry it was a junk turbo). i had an air chuck that was like an 8th inch opening so it wasnt a really high pressure but it was very high volume, i then grabbed a standard spray nozzle with just a pin hole size outlet and noticed a very high increase in wheel acceleration even though i was putting the same amount of air through it.
So i did some looking around on the internet and realized that increasing the velocity of exhaust gas by restricting the flow pre turbo would result in very very fast spool time, however this would also decrease maximum output. So i thought what if you could restrict the flow only until the engine was flowing enough exhaust gasses to keep the turbo spooled. What i came up with was the idea to scale down the "exhaust control tube funnel blades" (only definition i could find) off a jet engine and place them inside the merge collector, you could easily use an electric solenoid to control them or even something similar to a wategate.
My doubts come from the fact that im an uneducated 20 year old dreaming of doing 200mph in the standing mile in a miata, im sure that if it worked some of the engineers working for these billion dollar race teams would have thought of this. Either way tell me what you think.
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Old 10-20-2009, 02:36 AM   #2
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< a semi educated 20 year old says do it and let us know the results.
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Old 10-20-2009, 02:37 AM   #3
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it has been shown that running a small runner tubular manifold helps spool, for exactly the reason you decribe, exhaust velocity, but the increase is negligible compared to the loss in top end power.
Im not so sure a 'restriction' in the collector would have this same effect though, there would be higher velocity at the collector but the velocity would still be low throuout the runners.

Also, There is already something more effective at doing this

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Old 10-20-2009, 03:17 AM   #4
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^ wow very similar to my idea.
i think the idea behind higher spool due to smaller runners is that when you have say 20psi back pressure before the turbo and 5psi after it the gasses will not flow through the turbine housing as fast as they will if you have 50psi before the turbo and 5 after. (numbers are just thrown out there nothing that would necessarily be actual.
Either way that shows me that its been considered, it always boggled my why i had not seen it on some hill climb car or something, maybe one of these days i will have the rescorces to find out for myself.
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Old 10-20-2009, 03:35 AM   #5
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I just realize i didnt explain that picture I posted at all, I think youll like this idea.
Basically you use that butterfly deal on a twin scroll turbo, so that instead of trying to change the aspects of the manifold flow, your basically changing the a/r of the turbine.
So when the butterlfy is closed the turbo has effectively half the A/R that it would normally, then the butterlfy opens and it has its full A/R and makes good top end.
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Old 10-20-2009, 04:35 AM   #6
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I need some posts...
I dont know where to begin to explain the faults in your invention... You seem to have a genuine interest in physics, which is great, but start with the basics man. In so many words by spraying a higher velocity stream of air into a turbo you didnt figure out something "the billion dollar engineering teams" didnt. Be careful man, I dont have many posts here but Ive read enough to know these guys will eat you alive.
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Old 10-20-2009, 09:30 AM   #7
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Quote:
Originally Posted by 1slowna View Post
So i did some looking around on the internet and realized that increasing the velocity of exhaust gas by restricting the flow pre turbo would result in very very fast spool time, however this would also decrease maximum output. So i thought what if you could restrict the flow only until the engine was flowing enough exhaust gasses to keep the turbo spooled. What i came up with was the idea to scale down the "exhaust control tube funnel blades" (only definition i could find) off a jet engine and place them inside the merge collector, you could easily use an electric solenoid to control them or even something similar to a wategate.
By golly you have discovered turbine A/Rs and reinvented the variable-vein turbo.


more restrictive:


Less restrictive:
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Old 10-20-2009, 09:49 AM   #8
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Too bad gasoline engines pwn those to death.
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Old 10-20-2009, 10:11 AM   #9
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Quote:
Originally Posted by neogenesis2004 View Post
Too bad gasoline engines pwn those to death.
Can you please explain why?
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Old 10-20-2009, 10:22 AM   #10
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Higher average EGTs
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Old 10-20-2009, 11:09 AM   #11
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Variable-vein turbos can survive gasoline engines, hence the Peugeot 405 T16, Porsche 911 Turbo, and optional turbo v6 jeep grand Cherokee in the Australia (or at least that's the only place iv seen one). A lil more research turned up a variable nozzle turbo, essentially identical to what i was thinking. Only 500 were produced and used on a shelby csx-vnt which was released as a limited production vehicle in 89. Must not have worked too well.
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Old 10-20-2009, 11:21 AM   #12
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Do some research on those cars and tell me if people report issues with turbo reliability.
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Old 10-20-2009, 11:40 AM   #13
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^ I did a brief search and found nothing on the failing due to heat, alot about them failing due to carbon buildup. However this is a lil off topic and i feel like this thread has run its course, it provides no useful information to anyone.
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Old 10-20-2009, 11:42 AM   #14
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Old 10-20-2009, 12:47 PM   #15
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Any explanations for the cause of failures and corrective actions?
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Old 10-20-2009, 12:49 PM   #16
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Corky would be the best source, as his first turbo kit was built around the aerocharger. It seemed they ran great at 5psi, but as soon as you added more boost they'd straight up die.

I was witness to an original begi aerocharger setup last dyno day:


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Old 10-20-2009, 10:33 PM   #17
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Hmm, my GT2554 made 175 ft-lbs at 3000 RPM.
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Old 10-20-2009, 10:41 PM   #18
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Quote:
Originally Posted by Braineack View Post
By golly you have ... reinvented the variable-vein turbo.
I was going to say that, but didn't want to risk being wrong and suffering MT wrath.
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Old 10-20-2009, 10:44 PM   #19
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Its that or getting the wrath for thinking you just invented it.
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Old 10-20-2009, 11:01 PM   #20
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that butterfly valve for a twin scroll is really interesting. i've been looking into twin scrolls and i'm gonna look into that
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