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Location:
Sydney
Registered:
January 2004
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Turbo manifold design
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Sun, 01 August 2004 12:25
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Just looking into this at moment...
A picture I found on the net shows one. Just wondering what people thought of how the pipes "collect" into the flange to turbo and any other advice/opinions on it. Thanks
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Turbo manifold design
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Sun, 01 August 2004 12:34
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I've seen better, much better.
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Turbo manifold design
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Sun, 01 August 2004 12:45
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i've seen worse too.
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Location:
Sydney
Registered:
January 2004
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Re: Turbo manifold design
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Sun, 01 August 2004 12:47
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Just the space constraints sort of dictate a similar design...hmm...maybe.
Here's another similar one, from Steve at turbocorollas. Comments please. THanks
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Location:
Sydney
Registered:
January 2004
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Location:
Adelaide
Registered:
June 2002
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Re: Turbo manifold design
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Sun, 01 August 2004 21:46
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The first and second manifolds are the better of the three. The large open chamber collector on the third one results in big exit losses due to the sudden change in velocity of the gas as it moves from the header pipe out into the open chamber. You should always avoid open chamber collectors like that if possible. Although the angles at which that the pipes merge in the first one could be improved, it's still pretty good-especially considering they were probably space constrained. The middle one (Steve's one) I reckon is the best of the three-but I can't quite see where the pipes merge.
=-)
Sean
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Location:
Adelaide
Registered:
September 2003
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Re: Turbo manifold design
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Sun, 01 August 2004 21:52
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I'll agree with Sean, that the centre one is the best of the three.
Here is a phot of one that was for a 3S-GTE (note it is mius the flange plate).
Equal length is best, but it is the flow from the headers into the collector that is pretty important, but in the end, it is a compromise over cost, space, and what level of tune you engine is going to be. Sometimes a crappy log manifold is the best you can do !!!
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Location:
Vancouver
Registered:
June 2004
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Re: Turbo manifold design
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Mon, 02 August 2004 00:07
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matched length matters on a turbo motor just as much as it matters on a naturally aspirated motor.
BUT
as several people mentioned, if you don't have space for a bundle of tubes, then you don't have space for a bundle of tubes, in which case a matched-length header is a moot point, so you'll have to go with whatever will fit.
I know a few people with very high output road-race turbo cars where the turbo has been mounted back by the transmission to get the header sorted out correctly. This all goes back to an article in one of the "HP Books" how-to books that talked about McLaren Engine's work on the M-12 BMW 320i motors for Sillhouette Formula in the late 70's; McLaren found an extra 50+HP on top of the existing 550+HP, and most of the development work centered around exhaust manifold design for turbocharging. The really interesting thing was the article's mention of drivers' reports that turbo lag had been significantly decreased, despite the fact that the newer headers (that produced such big increased power on the dyno) had been made much much longer in primary length than the original manifold - McLaren had removed the original log manifolds after initial baseline testing, then built new matched-length headers with very long primaries, just as they would have for a N/A motor, and found big horsepower gains, and decreases in lag...
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Location:
Sydney
Registered:
January 2004
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Location:
Vancouver
Registered:
June 2004
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Re: Turbo manifold design
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Mon, 02 August 2004 03:08
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consider a few things while you hold the turbo up in the engine bay.
you need to get the following things in and out of the turbo
oil
"intake" air
exhaust
water, depending on the turbo
consider that oil flow OUT of the turbo is very important - make it -12AN to avoid problems, and keep it's level well above the pan...
"intake" air should not be too too bad to deal with...
exhaust may need an external wastegate depending on things, and the diameter of the turbo's outlet pipe can become an issue once you start getting up to 3" and over...
gasses have mass, and therefore kinetic energy - try to keep the header & collector exhaust flow velocity constant, and try to avoid large abrupt changes in cross sectional area to minimize loss of kinetic energy... this will help to minimize things that can cause lag. When the turbo is going, there's so much gas flow, lag isn't such a big consideration, but below the gas flow range for proper turbo operating, any little thing you can do to help the turbine to spin quicker is a good thing to do
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Registered:
June 2002
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Re: Turbo manifold design
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Mon, 02 August 2004 13:41
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just my two cents but the first two are shit , a proper tuned length manifold with a colector is the only way to do it , and who evea said a colecter slows the air flow down oversly has never see a proper tapered colecter !!!!!
Dennis
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Location:
north brisbane
Registered:
September 2003
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Location:
sydney
Registered:
July 2004
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Re: Turbo manifold design
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Tue, 03 August 2004 11:22
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Nothing has been said about the size of the pipes used in those photos.
There HUGE you need to work out what horsepower you realisticly want and then suit the pipe size to that figure.
any where below 400 to the wheels on a four cylinder 1" 1/4 is fine and will greatly decrease turbo lag at the same time.
the gases have got a velocity wich is determined mainly by the size of pipe it's flowing through.
big pipes are great for top end big horsepower big turbo cars but the at low rpms the airspeed is slowed due to size of the pipe.
for some reason smaller pipes have got greater air speed but you do get restrictions at certain horsepowers.
work out what h/p your chasing and think about what size you want to run.
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