Go Back   AstinaGT Forums > Performance & Technical > Performance & General Maintenance

Reply
 
Thread Tools Display Modes
Old 02-10-2003, 05:36 PM   #1
damosp20
Junior Member
 
Join Date: Oct 2003
Posts: 5
2001 SP20, done some mods but no improvements?? help!

Ive done some minor mods to increase performance but i seriously cant feel any difference besides the pedal feeling a little lighter. Can someone tell me what may be wrong or what i can do to make an inprovement?


*cat back 2.5'' with a big hotdog, it then goes into the 2'' rear muffler though
*a K&N panel filter

Any comments or suggestions are helpful
damosp20 is offline   Reply With Quote
Sponsored Links
Old 02-10-2003, 05:40 PM   #2
damosp20
Junior Member
 
Join Date: Oct 2003
Posts: 5
One other thing...
The exhaust doesnt sound very loud at all, it is louder than when it was standard but its only a little bit.
damosp20 is offline   Reply With Quote
Old 02-10-2003, 07:26 PM   #3
dfvadr
Senior Member
 
dfvadr's Avatar
 
Join Date: Feb 2003
Location: Queensland
Car: ss , sp20 , 94ba
Posts: 1,708
well im not sure but my theory is just bye adding those extras [same as mine] the standard computer is tuned to the standard specs ie exhaust an filter so by not having it tuned and adjusted to suit you want notice any difference only sum noise
__________________
2001 SP20 Mazda Astina Turbo
- t28b/b turbo teflon coated forge pistons 20thou o/size , billet rods , whole motor fully balanced
- custom body kit
- 18"ame's
- custom interior
- kenwood head unit , pioneer speakers driven by 800 watt amp , kicker subs driven by 1000 watt amps each sub [135.2db at supernats], two 1th caps 4 tv screens dvd player
- xbox
- airbag suspension with gas strut towers
- custom plates an airbrushing on bonnet
dfvadr is offline   Reply With Quote
Old 02-10-2003, 09:30 PM   #4
wiredone
AstinaGT Regular
 
wiredone's Avatar
 
Join Date: Mar 2003
Location: Sydney, Australia
Car: Evo 8
Posts: 301
not true

well i have an exhaust and even before the turbo it screemed... very loud... just depends where you get it done...

At idle it was quiet unless in a carpark... but sounded like a race car at 4000

if its a BIG exhaust on a stock engine though there isnt enough back pressure to make a big exhaust loud....

and if the ECU doesnt like something just disconnect the battery for 15 mins so it resets and gets used to running in its new environment
__________________
SP2NV
03 Black Sp20 Turbo
_____________________________________
To boost or not to boost - http://www.trafficmesh.com
wiredone is offline   Reply With Quote
Old 02-10-2003, 09:37 PM   #5
damosp20
Junior Member
 
Join Date: Oct 2003
Posts: 5
So maybe 2.5'' is to big? what would be better?
Can you explain what mandrel bent exhausts are?
damosp20 is offline   Reply With Quote
Old 02-10-2003, 11:33 PM   #6
BigMal
1ST BA TURBO MEMBER
 
BigMal's Avatar
 
Join Date: Mar 2002
Location: Sydney
Car: BA Astina Turbo
Posts: 4,195
Send a message via ICQ to BigMal Send a message via MSN to BigMal
But if you go down to a 2" Muffler its only a 2" exhaust.
Is only as good as the smallest part. Or is the 2" a typo error.
For a 2.5" would expect crap bottom end but it screamed up in
the top end when backpressure doesn't matter.

Regards

Mal
p.s also add a cold air to the panel filter.
__________________
If you want wind in your hair add a Hairdryer !!!
BigMal is offline   Reply With Quote
Old 07-10-2003, 06:02 AM   #7
azaudio
Junior Member
 
azaudio's Avatar
 
Join Date: May 2003
Location: South Africa
Car: Astina 1.8i se
Posts: 93
Try getting more cold air into that panel filter , normally does the job
__________________
1.8se astina 16v dohc simota powerstack filter , cold intake , brospeed 4-2-1 header and muffler with double chrome twisted tips

When life gives you lemons - start making cocktails !!
azaudio is offline   Reply With Quote
Old 07-10-2003, 08:52 AM   #8
Aaron
Stiff Member
 
Aaron's Avatar
 
Join Date: Apr 2003
Location: Canberra, ACT
Car: 1994 Lynx BP-T
Posts: 1,198
Good pick-up there Mal... If it does neck down to a 2" after a length of 2.5" the gas velocity will be completely screwed up and it'll be choking the motor very badly.

Exhaust gases expand as they travel out of the chamber through the exhaust, that's becuase they were compressed Hot gasses in the cylinder and they're tryign to return to their 'normal' state.

A good exhaust uses the expansion of the gas in its favour, using it to force flow...overall a good exhaust is designed to keep the sxhaust gases travellling as fast as possible down the length of the pipe. Think of the pipe like a river. Same volume of water but wide river makes slow current, narrow rive makes fast current.

You'd want about 2.25" pipe as a good flowing minimum size for a 2L, and maybe have that expand out into a 2.5" muffler att he end, not the other way around.

A.
__________________
Current:
Stinky the imfamous Lynx
Aaron is offline   Reply With Quote
Old 08-10-2003, 06:27 AM   #9
Asterix
AstinaGT Regular
 
Asterix's Avatar
 
Join Date: Dec 2002
Location: Melbourne, Vic
Car: Ex Astina, ex R34, ex 850R, currently Polo GTi
Posts: 431
Mandrel bending is basically bending the exhaust around the car's underside & axel, etc so as not to change the diameter of the piping. Think of a garden hose. When you bend it too much it kinks & causes loss in water flow. Same deal with gases. It just maximises the emissions flow.
Asterix is offline   Reply With Quote
Old 08-10-2003, 06:45 PM   #10
ezin
AstinaGT Regular
 
ezin's Avatar
 
Join Date: Jul 2003
Location: melb
Posts: 416
Aaron is right! U need 2 keep the exhaust gases flowing as fast & smooth as possible! Just remember, Smaller 2 bigger from front to rear, and ur car should go hard! If it can suck in the air aswell! (Cut out the plastic bit in the front grille for a quick mod to get air to the intake!) DONT make ur centre pipe bigger only 2 put a smaller muffler on the rear! This is a bad idea! Read some modification mags & U will see this is correct! I would recomend a WALKER straight through muffer that flows more than most muffers + it is very quiet REF ZOOM mag! just make the centre pipe smaller 2.25 & the rear mufler 2.5! u should notice it a fair bit! :mrgreen:
ezin is offline   Reply With Quote
Old 10-10-2003, 05:47 PM   #11
damosp20
Junior Member
 
Join Date: Oct 2003
Posts: 5
Thanks everyone for your help,
I think its a bit late for me to change the 2.5" pipe since money doesnt grow on trees! Do you guys think 2.5" will be ok once i make the rear muffler bigger? will it be really loud? or will i loose back pressure? Should i change the rear muffler to 2.5", 3" or bigger??

With the air intake should i just cut out all the plastic thats in the way of the bit that the air sucks in? And what is "cold air intake" and what does it do?

Sorry about all the newbie questions but you guys are really helping me :mrgreen: :mrgreen:
damosp20 is offline   Reply With Quote
Old 11-10-2003, 12:21 AM   #12
BigMal
1ST BA TURBO MEMBER
 
BigMal's Avatar
 
Join Date: Mar 2002
Location: Sydney
Car: BA Astina Turbo
Posts: 4,195
Send a message via ICQ to BigMal Send a message via MSN to BigMal
2.5" all the way through is fine no need for 3" at all unless you go turbo.
Cold Air Intake is simply getting cold air to the air filter.

Regards

Mal
__________________
If you want wind in your hair add a Hairdryer !!!
BigMal is offline   Reply With Quote
Old 11-10-2003, 11:42 AM   #13
JynX
Senior Member
 
JynX's Avatar
 
Join Date: Dec 2002
Location: Sydney
Posts: 1,767
Send a message via ICQ to JynX Send a message via MSN to JynX
It will be loud without resonators. I know from experience
JynX is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gimme some SP20 Mods Please... sherrif Performance & General Maintenance 5 25-01-2006 03:30 PM
Gimme some SP20 Mods please sherrif Performance & General Maintenance 9 17-01-2006 04:38 PM
Quarter Mile times skippy General Automotive Talk 7 08-01-2005 03:49 AM
2001 Mazda 323 Astina SP20 $18,500 YEL020 For Sale/Wanted 4 08-06-2004 02:11 PM
Performance Upgrades for 2001 323 SP20 IzzYTaP Performance & General Maintenance 7 17-09-2003 07:13 PM


All times are GMT +10. The time now is 08:19 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
2001- 2010 AstinaGT