550 exhaust performance, engineering question

550 exhaust performance, engineering question

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Mario149

Original Poster:

7,758 posts

179 months

Wednesday 22nd January 2014
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Just found this:

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EXHAUST

The Maranello’s insulated stainless steel exhaust system employs variable back pressure through bypass valves situated on the rear silencers. The bypass valves are electropneumatically actuated by the engine management system, based on engine speed and throttle opening. Varying back pressure makes it possible to optimize engine efficiency in various conditions. Greater back pressure allows higher torque under average load, while lower back pressure enhances full load engine efficiency.
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on here: http://www.topspeed.com/cars/ferrari/1996-2001-fer...

and it doesn't make sense to me. I always though you wanted as little back pressure as possible regardless of engine speed and that the valve was only there for noise regs??

FerrariV8

357 posts

193 months

Wednesday 22nd January 2014
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Not with a flat plane crank - being used for road and performance - back pressure will increase torque a little, higher up the rev range you need to just get the gasses out!

Whether you need to intergrate both banks or run as two separate engines - jury is out, we've tried separate for the last two race seasons, this year were joining both banks, i'll report back after testing.

T.

roygarth

2,674 posts

249 months

Wednesday 22nd January 2014
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Does this system still work if Tubi rear silencers are fitted?

Mario149

Original Poster:

7,758 posts

179 months

Wednesday 22nd January 2014
quotequote all
roygarth said:
Does this system still work if Tubi rear silencers are fitted?
On my previous 550 Tubis there was no valving, and QV confirmed that that was correct when they inspected the car

Mario149

Original Poster:

7,758 posts

179 months

Thursday 23rd January 2014
quotequote all
FerrariV8 said:
Whether you need to intergrate both banks or run as two separate engines - jury is out, we've tried separate for the last two race seasons, this year were joining both banks, i'll report back after testing.

T.
Interesting, I had the x pipe removed on mine and replaced with 2 separate ones. Whatever it does to the power, it makes it sound better smile

FerrariV8

357 posts

193 months

Thursday 23rd January 2014
quotequote all
Tubi's do not have valves but still have a degree of back pressure, with some 360's certain cheaper systems can put the engine light on - probably from a lack of back pressure?

T.

roygarth

2,674 posts

249 months

Thursday 23rd January 2014
quotequote all
Mario149 said:
FerrariV8 said:
Whether you need to intergrate both banks or run as two separate engines - jury is out, we've tried separate for the last two race seasons, this year were joining both banks, i'll report back after testing.

T.
Interesting, I had the x pipe removed on mine and replaced with 2 separate ones. Whatever it does to the power, it makes it sound better smile
If you are ever in North Norfolk let me know as would love to hear this combo!

Mario149

Original Poster:

7,758 posts

179 months

Thursday 23rd January 2014
quotequote all
It's distorted due to iPhone and car park, but here: http://www.youtube.com/watch?v=uYxPw0B_Ab4

Mario149

Original Poster:

7,758 posts

179 months

Thursday 23rd January 2014
quotequote all
FerrariV8 said:
Tubi's do not have valves but still have a degree of back pressure, with some 360's certain cheaper systems can put the engine light on - probably from a lack of back pressure?

T.
Out of interest, do you know what sort of %tage difference in torque we are talking (boom boom) about when comparing standard mufflers closed vs standard mufflers valves (wired) open at low revs?