downpipes and detonation

Headers, cats, uppipes, downpipes, midpipes and mufflers.

Moderators: Helpinators, Moderators

Post Reply
know1
Second Gear
Posts: 520
Joined: Thu Jan 18, 2007 9:28 am
Location: Vancouver, Canada

downpipes and detonation

Post by know1 »

I have been doing a lot of research about downpipes recently, and have decided that i am going to go catless downpipe (most likely bellmouth) to an electric cutout (http://www.quicktimeperformance.com/QTEC/index.php) so I can really roar when I want to but be quiet when the cops are around. While telling my friend about this, however, he brought up the fact that this might cause me to detonate. He said "when you increase exhaust flow.. you're trying to compress more air because your turbo is going to spool faster... when thath appens your intake temps increase which will heat up your combustion chamber more which MAY cause detonation". I was wondering if this could be the case? and should I go ic at the same time as I go dp?
1994 Crimson Pearl SS [ td04, 06 fxt tmic,3" catless dp -> apex GT spec exhaust, EDM Tails ]
gto7419
Second Gear
Posts: 483
Joined: Wed Dec 13, 2006 10:53 pm
Location: Long Island, NY

Post by gto7419 »

I dont think ONLY adding a downpipe is going to cause problems with detonation. If you have the funds for an i/c, its ALWAYS a good investment.

Also, all an i/c does, is make the charge cooler so more air can fit inside the combustion chamber. Hence, its real application is so you can run MORE boost without detonating.

If you dont alter your boost settings, but run an i/c, you may see your boost level drop a little. It will help prevent detonation though because of the cooler charge and the boost drop.
500cc Shifterkart, 125cc Shifterkart, 01 MX5, 93 Legacy Wagon (DIY Turbo)
555BCTurbo
Knowledgeable
Knowledgeable
Posts: 3335
Joined: Wed Feb 16, 2005 9:40 pm
Location: Oregon

Post by 555BCTurbo »

That is complete bullshit...


A downpipe won't make your SS start to detonate...
Nick

1987 Audi 4000CS quattro...soon to be 20VT
1994 Dodge Ram 2500 4x4 CTD, #11 plate, 30 psi, Scotty II intake, 4" exhaust
know1
Second Gear
Posts: 520
Joined: Thu Jan 18, 2007 9:28 am
Location: Vancouver, Canada

Post by know1 »

awesome guys thanks! In all the research I had done I read nothing about this and using my judgement I didn't think it made sence BUT...this being my first car I thought I would just double check with you guys.

P.S. a wrx downpipe will fit right? just kidding! I have searched through about a bagillion threads so I know it will fit but will be a little long. I am really looking forward to the sound of an exaust with a 3" catless dp and the cutout right after the dp >:)
1994 Crimson Pearl SS [ td04, 06 fxt tmic,3" catless dp -> apex GT spec exhaust, EDM Tails ]
rallysam
Fourth Gear
Posts: 1162
Joined: Tue Oct 15, 2002 3:49 pm
Location: London (originally from Wash DC)
Contact:

Post by rallysam »

Your friend doesn't know what he's talking about.

Detonation would happen if you were running higher boost, but that's not what you're doing.

More exhaust would cause your turbo to spool up to the correct speed SOONER, but then it's going to stop there and go the correct speed and no faster. There's this thing called the boost controller which is there to control the boost. It will take any extra exhaust and route it out the wastegate so that your turbo doesn't go too fast.
'00 Impr RS - sold
'91 Legacy Turbo 5MT - mothballed
13psi, TurboXS TBE, WRX IC, Hallman MBC, TurboXS FCD, KYB AGX, Phil's STI seat, SPT short shifter, David Carter hood, Zeitronix widebandO2, Kuhmo rally tires, STI IC spray, thanks:gearboxtech.com
Post Reply