Valvetronic and golf tee mod question

TheSt|G · 03-28-2014, 01:16 PM

Quote:

Originally Posted by Chrisar82

We need to identical 128i. One with golf tee one without. Have someone test drive them without telling them which one is golf tee'd and see which they think is faster. Elimate the placebo effect

We are talking about such inconsequential amounts of power I'm not sure why anyone cares.

Taskmaster · 03-28-2014, 01:20 PM

Quote:

Originally Posted by TheSt|G

We are talking about such inconsequential amounts of power I'm not sure why anyone cares.

0 power difference I'm sure. It's just there for sound.

TheSt|G · 03-28-2014, 01:29 PM

Quote:

Originally Posted by TheAxiom

0 power difference I'm sure. It's just there for sound.

Exactly.

The difference is TUV noise regs. There is nothing else to it.

Pothole · 03-28-2014, 01:29 PM

Quote:

Originally Posted by TheAxiom

0 power difference I'm sure. It's just there for sound.

I would dare to claim 0.001 HP up until 3500 rpm.

TheSt|G · 03-28-2014, 02:49 PM

Quote:

Originally Posted by Pothole

I would dare to claim 0.001 HP up until 3500 rpm.

Yup, and it felt quicker to rev and flowed more freely just like the rest of the BS power statements.

andrey_gta · 03-28-2014, 06:56 PM

My experience on stock 128i exhaust was some slight drone that was unpleasant. I kept going back and forth on the Zip tie/Golf tee mod

JimD · 03-28-2014, 07:32 PM

The flow of gas creating a slight negative pressure is a real thing. It is part of the design of the n55 turbo. It is also part of the design principle for well designed headers. But the problem with a theory that the flap positively affects horsepower is that it is WAY too far away. This type of effect is very local. Maybe a couple inches. Certainly not a foot. Let alone 6 or more feet back to the muffler. Nonsense.

I also measured my car before and after. The golf tee mod only affects sound level until the engine warms up. Then there is no difference. I have a sound pressure meter and used it to make measurements. I presume the flap opens up after warmup. I like a little more noise, however, so I do it.

Golf tee mod is purely a little more sound for a little while.

chris82 · 03-28-2014, 07:37 PM

Quote:

Originally Posted by TheSt|G

We are talking about such inconsequential amounts of power I'm not sure why anyone cares.

I was being a little sarcastic

Taskmaster · 03-28-2014, 08:04 PM

Tony from Motordyne Engineering did a test on backpressure. It's never good, ever. I'll see if I can pull it up.

Chandon · 03-28-2014, 08:05 PM

Pretty sure the PE's offered here in AUS also don't have a valve at all.

Taskmaster · 03-28-2014, 08:22 PM

Here we go:

http://my350z.com/forum/intake-exhau...ml#post7412469

Quote:

For any system "Y-back" you can't have too large of tubing. There is no compromise of TQ by going larger and larger. With one exception, the only thing a Y-back can do is "potentially" reduce HP if there is excessive back pressure. The one exception would be a diffuser or megaphone which can reduce pressure drop below that of an open pipe.

TQ is determined by the diameter of tubing upstream of the end of the Y-pipe. So in other words, TQ is determined by the Y-pipe primary diameters and a few inches past the merge collector.

You could do a pre/post dyno where you unbolt the JIC from the Y-pipe and it will make no difference in TQ and very little difference in HP.

The only thing a 60MM Y-back can do is reduce the HP a little more with the added possibility of reduced TQ.

...At least this is what I found with a lot of exhaust testing on the dyno.

Taskmaster · 03-28-2014, 08:31 PM

Final answer (including dynos) here:
http://www.e90post.com/forums/showth...1#post15685729

chris82 · 03-28-2014, 09:56 PM

Thanks Axiom. That pretty much sums it up I guess. The flap is purely for sound. Learn something new everyday!

TheSt|G · 03-29-2014, 02:15 PM

Quote:

Originally Posted by Chrisar82

I was being a little sarcastic

Yup I realized, was more a comment on the thread in general.

Quote:

Originally Posted by TheAxiom

Tony from Motordyne Engineering did a test on backpressure. It's never good, ever. I'll see if I can pull it up.

No shocker there.

03-28-2014, 06:56 PM	#28
andrey_gta Brigadier General 298 Rep 4,040 Posts Drives: 130i coupé ;) Join Date: Nov 2011 Location: Bimmerpost iTrader: (1) Garage List 2008 BMW 128i [10.00]	My experience on stock 128i exhaust was some slight drone that was unpleasant. I kept going back and forth on the Zip tie/Golf tee mod __________________ 128i Sport 6MT converted to Euro 130i spec, 3.73 diff, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is
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03-28-2014, 07:32 PM	#29
JimD Brigadier General 368 Rep 3,547 Posts Drives: 128i convertible Join Date: Apr 2009 Location: Lexington, SC iTrader: (0)	The flow of gas creating a slight negative pressure is a real thing. It is part of the design of the n55 turbo. It is also part of the design principle for well designed headers. But the problem with a theory that the flap positively affects horsepower is that it is WAY too far away. This type of effect is very local. Maybe a couple inches. Certainly not a foot. Let alone 6 or more feet back to the muffler. Nonsense. I also measured my car before and after. The golf tee mod only affects sound level until the engine warms up. Then there is no difference. I have a sound pressure meter and used it to make measurements. I presume the flap opens up after warmup. I like a little more noise, however, so I do it. Golf tee mod is purely a little more sound for a little while. __________________ 128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09
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03-28-2014, 08:04 PM	#31
Taskmaster Banned 2465 Rep 9,004 Posts Drives: M235i 6MT / E92 328 Msport 6MT Join Date: Nov 2013 Location: Florida iTrader: (6)	Tony from Motordyne Engineering did a test on backpressure. It's never good, ever. I'll see if I can pull it up.
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03-28-2014, 08:05 PM	#32
Chandon Major 99 Rep 1,102 Posts Drives: 1M Join Date: Apr 2013 Location: Sydney, Australia iTrader: (1)	Pretty sure the PE's offered here in AUS also don't have a valve at all.
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03-28-2014, 08:31 PM	#34
Taskmaster Banned 2465 Rep 9,004 Posts Drives: M235i 6MT / E92 328 Msport 6MT Join Date: Nov 2013 Location: Florida iTrader: (6)	Final answer (including dynos) here: http://www.e90post.com/forums/showth...1#post15685729
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03-28-2014, 09:56 PM	#35
chris82 Brigadier General 827 Rep 3,856 Posts Drives: 128i Join Date: Aug 2012 Location: NY NY iTrader: (8) Garage List 2009 BMW 128i [9.80]	Thanks Axiom. That pretty much sums it up I guess. The flap is purely for sound. Learn something new everyday!
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