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02-10-2003, 05:36 PM | #1 |
Junior Member
Join Date: Oct 2003
Posts: 5
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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 |
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02-10-2003, 05:40 PM | #2 |
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Join Date: Oct 2003
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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. |
02-10-2003, 07:26 PM | #3 |
Senior Member
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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
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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 |
02-10-2003, 09:30 PM | #4 |
AstinaGT Regular
Join Date: Mar 2003
Location: Sydney, Australia
Car: Evo 8
Posts: 301
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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
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02-10-2003, 09:37 PM | #5 |
Junior Member
Join Date: Oct 2003
Posts: 5
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So maybe 2.5'' is to big? what would be better?
Can you explain what mandrel bent exhausts are? |
02-10-2003, 11:33 PM | #6 |
1ST BA TURBO MEMBER
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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.
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07-10-2003, 06:02 AM | #7 |
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Join Date: May 2003
Location: South Africa
Car: Astina 1.8i se
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Try getting more cold air into that panel filter , normally does the job
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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 !! |
07-10-2003, 08:52 AM | #8 |
Stiff Member
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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.
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08-10-2003, 06:27 AM | #9 |
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Join Date: Dec 2002
Location: Melbourne, Vic
Car: Ex Astina, ex R34, ex 850R, currently Polo GTi
Posts: 431
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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.
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08-10-2003, 06:45 PM | #10 |
AstinaGT Regular
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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:
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10-10-2003, 05:47 PM | #11 |
Junior Member
Join Date: Oct 2003
Posts: 5
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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: |
11-10-2003, 12:21 AM | #12 |
1ST BA TURBO MEMBER
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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
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11-10-2003, 11:42 AM | #13 |
Senior Member
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It will be loud without resonators. I know from experience
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