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 Post subject: Boost creep
PostPosted: Tue Aug 01, 2017 9:30 am 
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Clubman

Joined: Sat Apr 29, 2017 8:54 am
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Will a full 3 inch exhaust from downpipe cause boost creep

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 Post subject: Re: Boost creep
PostPosted: Wed Aug 02, 2017 9:35 am 
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Joined: Sat Sep 02, 2006 3:13 pm
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Location: Bournemouth
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Sometimes it does, sometimes it doesn't.

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 Post subject: Re: Boost creep
PostPosted: Wed Aug 02, 2017 11:25 am 
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Clubman

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I'm reading about restrictor plates if it happens does that not defeat the object of a 3 inch system
And if needed where do they fit into the system

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 Post subject: Re: Boost creep
PostPosted: Wed Aug 02, 2017 7:27 pm 
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Club Staff
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Joined: Wed Jul 13, 2005 5:10 pm
Posts: 1952
Location: Sunny Fareham, UK
Car Model: ST205
Restrictor plate inserted between downpipe and first section of exhaust.

As Nibbles says, it's hit and miss whether or not a restrictor will be required with a DP and full 3" exhaust...

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 Post subject: Re: Boost creep
PostPosted: Wed Aug 02, 2017 7:40 pm 
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Clubman

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Hmm what's the reason for setting it up front Kris why not mid section?
only asking as it is creeping and over boosting until it hits fuel cut
Saying that it's more pronounced morning and eve when it's cooler but it's definitely going to high
Baz

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 Post subject: Re: Boost creep
PostPosted: Wed Aug 02, 2017 7:56 pm 
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Joined: Wed Jul 13, 2005 12:14 am
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Location: Camberley, Surrey
Car Model: ST205
The front location is easier to access with the car on the driveway.

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 Post subject: Re: Boost creep
PostPosted: Wed Aug 02, 2017 8:14 pm 
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Clubman

Joined: Sat Apr 29, 2017 8:54 am
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[FACE WITH TEARS OF JOY][FACE WITH TEARS OF JOY] really that's it?

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 Post subject: Re: Boost creep
PostPosted: Thu Aug 03, 2017 12:05 am 
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Location: Bournemouth
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To my mind, big exhaust and restrictor is all the restriction of a small exhaust without the faster gas velocity to aid torque. Adding a restrictor makes the car drivable again, although the technically best way is improving wategate flow.

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 Post subject: Re: Boost creep
PostPosted: Thu Aug 03, 2017 11:41 am 
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That may be the next step forward

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 Post subject: Re: Boost creep
PostPosted: Thu Aug 03, 2017 1:01 pm 
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Clubman

Joined: Sat Apr 29, 2017 8:54 am
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Reading about this the supras and the rx7 both suffer from the creep and both use the restrictor plates as a remedy, I was of the same opinion as you as in its kinda pointless to open up your gas ways to choke em again
However it seems that in some way its not the strangle point as you would expect if what I'm reading is correct.
I don't know what to think of it I suppose a run on the dyno would be the test with /without the restrictor to prove one way or the other
I fitted a plate in ladt night and it reduced the boost to 13.5 psi and that plate was a home made at 2.25 inch I've made a couple's more today at 2.5 and 2.75 inch
And will try these today
Interestingly though the Rx7 boys all advocate putting the plate in the midpipe and not on the downpipe, any thoughts on this.?
Baz

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 Post subject: Re: Boost creep
PostPosted: Thu Aug 03, 2017 5:23 pm 
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Clubman

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Bit more of playing about removed the restrictor plates altogether and no boost creep but it's getting 15.5 psi on stock pipes no boost controller valve or any thing which is about 2 psi more than it did on its old exhaust
the interesting thing here is that with the KnN cone filter on and the exhaust it over boosts to about 18psi put my stock airbox and panel filter back on no overboost
So with that in mind the air intake absolutely has to make a difference and the panel filter is clean and not choked up with crud

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 Post subject: Re: Boost creep
PostPosted: Fri Aug 04, 2017 1:02 pm 
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The standard panel filter is restrictive (6BHP on a standard car on our test) - but it's the filter not the airbox & intake that's restrictive.

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 Post subject: Re: Boost creep
PostPosted: Fri Aug 04, 2017 5:04 pm 
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Clubman

Joined: Sat Apr 29, 2017 8:54 am
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Nibbles wrote:
The standard panel filter is restrictive (6BHP on a standard car on our test) - but it's the filter not the airbox & intake that's restrictive.
Hi mate it's not the standard panel filter it's a piper cross foam high flow panel filter

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 Post subject: Re: Boost creep
PostPosted: Fri Aug 04, 2017 8:07 pm 
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Joined: Sat Sep 02, 2006 3:13 pm
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Location: Bournemouth
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Might be worth checking for a mouse nest in the intake pipe :)

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 Post subject: Re: Boost creep
PostPosted: Fri Aug 04, 2017 11:36 pm 
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Clubman

Joined: Sat Apr 29, 2017 8:54 am
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Deffo make a huge difference put the KnN back on and it hit fuel cut again and peaked at 17.9 psi

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