3inch Exhaust and Spool Up
#1
Scooby Regular
Thread Starter
Join Date: Aug 2003
Location: Not sure!!
Posts: 159
Likes: 0
Received 0 Likes
on
0 Posts
3inch Exhaust and Spool Up
Hi Guys
I was just wondering how much effect would a 3inch exhaust have on turbo spool up?
Just drove my friends car with a 3inch freeflow compared to my 63mm freeflow and it feels a lot quicker at lower revs. I can only equate this to the different exhausts.
Is this accurate and why would a bigger exhaust diameter effect the spool up?
Thanks
Edwin
I was just wondering how much effect would a 3inch exhaust have on turbo spool up?
Just drove my friends car with a 3inch freeflow compared to my 63mm freeflow and it feels a lot quicker at lower revs. I can only equate this to the different exhausts.
Is this accurate and why would a bigger exhaust diameter effect the spool up?
Thanks
Edwin
#2
Scooby Regular
iTrader: (2)
Join Date: Dec 2002
Location: All over the place, trying to stop putting the miles on!
Posts: 1,197
Likes: 0
Received 1 Like
on
1 Post
would be interested to know about this too, as im looking at ways of getting my MD304 to spool a bit faster, currently on a H&S 2.5 inch exhaust.
Dan.
Dan.
#3
Recent back to back tests I have completed showed a specific 3" high flow exhaust system with uprated panel filter achieve full boost (1.5bar) @ circa 2800rpm opposed to a standard MY05 STi system with standard panel filter that produced the same boost @ circa 3300rpm.
Car was a Spec C using stock turbo with no mapping changes post exhaust and panel filter change.
Hope this helps.
Regards,
Shaun.
Car was a Spec C using stock turbo with no mapping changes post exhaust and panel filter change.
Hope this helps.
Regards,
Shaun.
#4
Originally Posted by Danny Boy
would be interested to know about this too, as im looking at ways of getting my MD304 to spool a bit faster, currently on a H&S 2.5 inch exhaust.
Dan.
Dan.
Shaun,
Nice result, twin scroll turbos rule!
Paul
#7
Scooby Regular
Join Date: Sep 2003
Location: Lincoln, Yes I know it's Pink
Posts: 864
Likes: 0
Received 0 Likes
on
0 Posts
I think a lot depends on what your final power goal is. If both systems are identically free flowing apart from the size. The the 2.5 inch exhaust sytem would have a higher gas speed than the 3 inch system. This should lower the point at which required boost is produced. But the 2.5 inch system will not ultimatly be able to flow as much gas as the 3 inch system. so would become more restrictive at a lower power figure than the 3 inch system. I think someone on here mentioned the 2.5 inch system doesn`t become restrictive until you aproach the 300Hp region.
Jase
Jase
Trending Topics
#8
Jase,
The testing I have done on a Twin Scroll setup does not substantiate the fact that a 2 1/2" system makes boost sooner than a specific 3" system I tested, it was in fact the other way around (albeit with a change in panel filter as well).
Regards,
Shaun.
The testing I have done on a Twin Scroll setup does not substantiate the fact that a 2 1/2" system makes boost sooner than a specific 3" system I tested, it was in fact the other way around (albeit with a change in panel filter as well).
Regards,
Shaun.
#9
Scooby Regular
iTrader: (1)
Join Date: Apr 2005
Location: In the Flatlands of Lincolnshire
Posts: 2,892
Likes: 0
Received 0 Likes
on
0 Posts
Have had 3" APS Cat system fitted to my bugeye STi along with Gems ECU I already had fitted FMIC and tubular headers. What a difference 360bhp great performance. In 6th pulls from 65mph effortlessly and with increasing gusto. Shame the 3.5" system didn't come with a Cat.
Originally Posted by leeps
Hi Guys
I was just wondering how much effect would a 3inch exhaust have on turbo spool up?
Just drove my friends car with a 3inch freeflow compared to my 63mm freeflow and it feels a lot quicker at lower revs. I can only equate this to the different exhausts.
Is this accurate and why would a bigger exhaust diameter effect the spool up?
Thanks
Edwin
I was just wondering how much effect would a 3inch exhaust have on turbo spool up?
Just drove my friends car with a 3inch freeflow compared to my 63mm freeflow and it feels a lot quicker at lower revs. I can only equate this to the different exhausts.
Is this accurate and why would a bigger exhaust diameter effect the spool up?
Thanks
Edwin
#10
Originally Posted by Pavlo
Better boost control and mapping, depending of course on what is already in place.
Shaun,
Nice result, twin scroll turbos rule!
Paul
Shaun,
Nice result, twin scroll turbos rule!
Paul
sorry for all the questions but at the moment im thinking of of a hybrid td04 and the twin scroll sounds good.
oh and sorry to hijack the thread.i also have a 3" all the way through
#11
The twin scoll requires an up pipe, headers and down pipe IIRC and it will not fit a MY99 without these. The twin scroll has 2 exhaust entries for better spool IIRC.
F
F
#12
Scooby Regular
Join Date: Sep 2003
Location: Lincoln, Yes I know it's Pink
Posts: 864
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by webmaster
Jase,
The testing I have done on a Twin Scroll setup does not substantiate the fact that a 2 1/2" system makes boost sooner than a specific 3" system I tested, it was in fact the other way around (albeit with a change in panel filter as well).
Regards,
Shaun.
The testing I have done on a Twin Scroll setup does not substantiate the fact that a 2 1/2" system makes boost sooner than a specific 3" system I tested, it was in fact the other way around (albeit with a change in panel filter as well).
Regards,
Shaun.
Jase
Last edited by Barmyclown; 04 July 2005 at 10:58 PM.
#13
Scooby Regular
iTrader: (2)
Join Date: Dec 2002
Location: All over the place, trying to stop putting the miles on!
Posts: 1,197
Likes: 0
Received 1 Like
on
1 Post
Paul
Three port and ECutek mapped by Bob so i don't see any problems there.
Currently dynod at 322bhp at powerstation so i think the bottleneck is either the exhaust of the standard airbox.
I have removed the resonator and got an STI panel filter in but it's still in the standard box.
Dan.
Three port and ECutek mapped by Bob so i don't see any problems there.
Currently dynod at 322bhp at powerstation so i think the bottleneck is either the exhaust of the standard airbox.
I have removed the resonator and got an STI panel filter in but it's still in the standard box.
Dan.
#15
Originally Posted by Danny Boy
Paul
Three port and ECutek mapped by Bob so i don't see any problems there.
Currently dynod at 322bhp at powerstation so i think the bottleneck is either the exhaust of the standard airbox.
I have removed the resonator and got an STI panel filter in but it's still in the standard box.
Dan.
Three port and ECutek mapped by Bob so i don't see any problems there.
Currently dynod at 322bhp at powerstation so i think the bottleneck is either the exhaust of the standard airbox.
I have removed the resonator and got an STI panel filter in but it's still in the standard box.
Dan.
A good 2.5 system will be better than a poor 3" system, especially 3" jap boxes with bungs fitted that have a 2" exit.
Paul
#16
Scooby Regular
Thread Starter
Join Date: Aug 2003
Location: Not sure!!
Posts: 159
Likes: 0
Received 0 Likes
on
0 Posts
Thanks Guys
Well the reason for my question is because I recently drove my friends MY99 and I have an MY98 only difference other than that was I have a 2.5 vs his 3 inch and his car had a much better pick up down low...
Therefore I am thinking it can only be the exhaust!!
Well the reason for my question is because I recently drove my friends MY99 and I have an MY98 only difference other than that was I have a 2.5 vs his 3 inch and his car had a much better pick up down low...
Therefore I am thinking it can only be the exhaust!!
#18
V5-APS,
I am presently testing a multitude of products and theories, and as soon as I have come to a point that final testing and conclusions has been completed I will be publishing an article (hopefully within the next month). Unfortunately until then I do not want to give away any specifics.
Regards,
Shaun.
I am presently testing a multitude of products and theories, and as soon as I have come to a point that final testing and conclusions has been completed I will be publishing an article (hopefully within the next month). Unfortunately until then I do not want to give away any specifics.
Regards,
Shaun.
#19
Scooby Regular
iTrader: (2)
Join Date: Dec 2002
Location: All over the place, trying to stop putting the miles on!
Posts: 1,197
Likes: 0
Received 1 Like
on
1 Post
airbox rather than exhaust, but I would stick with the standard airbox until such time that you can make a partition to keep a cone filter seperated from the hot air of the engine bay.
A good 2.5 system will be better than a poor 3" system, especially 3" jap boxes with bungs fitted that have a 2" exit.
Paul
A good 2.5 system will be better than a poor 3" system, especially 3" jap boxes with bungs fitted that have a 2" exit.
Paul
Dan.
Last edited by Danny Boy; 06 July 2005 at 01:15 PM.
Thread
Thread Starter
Forum
Replies
Last Post
fatboy_coach
General Technical
15
18 June 2016 03:48 PM