Notices

boost dropping off after about 6k rpm

Thread Tools
 
Search this Thread
 
Old 02 March 2005, 01:00 PM
  #1  
austen_wrx
Scooby Regular
Thread Starter
 
austen_wrx's Avatar
 
Join Date: Nov 2002
Location: Birmingham
Posts: 3,282
Likes: 0
Received 0 Likes on 0 Posts
Default boost dropping off after about 6k rpm

Car is an MY04 WRX with full decat. Just fitted boost gauge and noticed the folowing:-

Peak boost about 1.1 bar
levels out to 0.9 bar
after 6000rpm boost slowly drops off to 0.7

Is this normal, is the cars standard ECU mapped to do this??

Note to self, fit all gauges whilst car is standard to compare results
Old 02 March 2005, 01:04 PM
  #2  
davedipster
Scooby Senior
 
davedipster's Avatar
 
Join Date: Sep 2003
Location: Essex
Posts: 2,600
Likes: 0
Received 0 Likes on 0 Posts
Default

Didnt think std cars ran full boost upto the redline.

Dipster
Old 02 March 2005, 01:06 PM
  #3  
Boyakasha
Scooby Regular
iTrader: (2)
 
Boyakasha's Avatar
 
Join Date: Jul 2002
Location: just to your right
Posts: 1,859
Likes: 0
Received 0 Likes on 0 Posts
Thumbs up

Hi Austen, I'm suprised it doesn't start dropping off before that. Standard cars always drop off at the top end. You would need a remap to get the best out of the car. On our 03 WRX we are getting 312bhp and that is at 6750

Marc
Old 02 March 2005, 01:07 PM
  #4  
chiark
Scooby Regular
 
chiark's Avatar
 
Join Date: Jun 2000
Posts: 13,735
Likes: 0
Received 0 Likes on 0 Posts
Default

Sounds about right. The standard turbo can't flow enough air to keep boost up at that level.

Solution? Fit bigger turbo, bigger injectors, remap ecu, fiddle with intercooler (either fit STI8/9 or go FMIC or aftermarket), look at bank balance/credit card bill and go "oooh ****".
Old 02 March 2005, 01:10 PM
  #5  
austen_wrx
Scooby Regular
Thread Starter
 
austen_wrx's Avatar
 
Join Date: Nov 2002
Location: Birmingham
Posts: 3,282
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Boyakasha
Hi Austen, I'm suprised it doesn't start dropping off before that. Standard cars always drop off at the top end. You would need a remap to get the best out of the car. On our 03 WRX we are getting 312bhp and that is at 6750

Marc
It maybe a bit lower, but at that speed, trying to look at the boost gauge, rev counter and road, things get a bit blurry!!

Ok, i'm not worried now. Its going for a remap in a few weeks so looking forward to that!!! What specs are you running to achieve that?
Old 02 March 2005, 01:13 PM
  #6  
AvalancheS8
Scooby Regular
 
AvalancheS8's Avatar
 
Join Date: Jun 2003
Posts: 461
Likes: 0
Received 0 Likes on 0 Posts
Default

Yup, limits of the small turbo. My car is running a TD04 too, with a manual boost controller, so it's trying to hold the set boost all the way to the redline. It holds the set boost - 1.2 bar - up to around 6k and then tails off to about 0.9 at the redline, so that I guess is the absolute limit of the air it can flow.
Old 02 March 2005, 01:48 PM
  #7  
Vipa
Scooby Regular
 
Vipa's Avatar
 
Join Date: Dec 2004
Posts: 397
Likes: 0
Received 0 Likes on 0 Posts
Default

the boost on my 'out of the box' 05 WRX drops VERY noticably after 6k revs (feels like someone nicked the turbo for a fraction of a second!). If I am pushing her hard only bother to go to late 5s before changing gear.

paul
Old 02 March 2005, 01:49 PM
  #8  
Vipa
Scooby Regular
 
Vipa's Avatar
 
Join Date: Dec 2004
Posts: 397
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by AvalancheS8
Yup, limits of the small turbo. My car is running a TD04 too, with a manual boost controller, so it's trying to hold the set boost all the way to the redline. It holds the set boost - 1.2 bar - up to around 6k and then tails off to about 0.9 at the redline, so that I guess is the absolute limit of the air it can flow.
Isn't it also something to do with wastegates etc opening at certain rev/pressure points?
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
fatboy_coach
General Technical
15
18 June 2016 03:48 PM
Mattybr5@MB Developments
Full Cars Breaking For Spares
28
28 December 2015 11:07 PM
psport
Subaru Parts
3
04 October 2015 07:35 PM
Ganz1983
Subaru
5
02 October 2015 09:22 AM
mistermexican
General Technical
2
01 October 2015 04:30 PM



Quick Reply: boost dropping off after about 6k rpm



All times are GMT +1. The time now is 02:49 PM.