Col 0 Posted February 4, 2006 what should i be looking for when buying an exhaust for a turbo engine? do i need bigger bore? more or less silencers? any recomended systems? for the 205 like. Share this post Link to post Share on other sites
Hilgie 16 2 Cars Posted February 4, 2006 Big diameter 2.5-3" and as little back pressure as possible. Remember the turbo acts as a silencer as well, so it doesn't harm leaving the mid box out. Share this post Link to post Share on other sites
Jonmurgie 2 Posted February 4, 2006 Yeah, needs to be failry large bore as it needs low back pressure, unlike normally aspirated where it needs back pressure (a common mistake with chavs fit the biggest bore they can find!). Single box will be fine and you'll get that lovely burble from the turbo engine still You planning on having a system made up to suit your car from somewhere like Powerflow? Share this post Link to post Share on other sites
Col 0 Posted February 4, 2006 Yeah, needs to be failry large bore as it needs low back pressure, unlike normally aspirated where it needs back pressure (a common mistake with chavs fit the biggest bore they can find!). Single box will be fine and you'll get that lovely burble from the turbo engine still You planning on having a system made up to suit your car from somewhere like Powerflow? nah, powerflow are gay, the stainless they use is rubbish. i dunno what im gonna do yet, i was wondering what systems are available for normal 205s that are conveniently larger bore? OMP group A that jeram had looked larger than standard? Share this post Link to post Share on other sites
Jonmurgie 2 Posted February 4, 2006 Ah right, so not going for a bespoke system... agree with powerfow usually being uselss but I've used them for a straight through pipe on my 205 and it was a nice job for £20 I would think the largest bore you could get 'off the shelf' for the 205 is going to be 2.5" and if your after the best for your application I'd have thought a litle bigger would be better... Share this post Link to post Share on other sites
Col 0 Posted February 4, 2006 3" bore with one silencer sounds crazy! Share this post Link to post Share on other sites
Guest abmotorsport Posted February 4, 2006 Powerflow are useless??? stainless 304 grade is crap??? 3" bore pipe??!!! Idiots..... Share this post Link to post Share on other sites
sonofsam 5 Posted February 4, 2006 Im using a mixture or 2.1/2" jetex 304 and crazy parts 316 bends,i have a group n intermediate pipe wich im using to gain the correct profile,yep only one silencer for me!! a brand new s/s janspeed backbox i picked up for an Aryton Senna Col heard you was a welder ??? Sam. Share this post Link to post Share on other sites
Jonmurgie 2 Posted February 4, 2006 Powerflow are useless??? stainless 304 grade is crap??? 3" bore pipe??!!! Idiots..... Eh, what you on about...?! You've only just arrived and already calling people idiots perhaps you wold care to expand on your inteligent reply? Share this post Link to post Share on other sites
DrSeuss 0 Posted February 4, 2006 Powerflow are useless??? stainless 304 grade is crap??? 3" bore pipe??!!! Idiots..... Your a powerflow agent, some aren't as reputable as you are. I've heard of various good and bad experiences of powerflow (including use of cheap stainless to improve profit) so your opinion is only relevant when referring to your workmanship (which i'm not drawing into question). Whats wrong with 3" bore, give me some technical reasons. Most of the big power jap turbo nutters run 2-3" dia. systems. Share this post Link to post Share on other sites
Ryan 99 Posted February 4, 2006 Yeah, needs to be failry large bore as it needs low back pressure, unlike normally aspirated where it needs back pressure (a common mistake with chavs fit the biggest bore they can find!). Single box will be fine and you'll get that lovely burble from the turbo engine still It's a total myth that n/a engines like back pressure. They need to have the correct size, due to the effects of gas flow in different sized pipes, but the back pressure is a completly unwanted side-effect. Non of that really applies to turbo exhausts, where you basically want the biggest you can get (but remember the law of diminishing returns...) I found this interesting: http://forum.205gtidrivers.com/index.php?showtopic=12145 Share this post Link to post Share on other sites
tom_m 0 Posted February 4, 2006 Powerflow are useless??? stainless 304 grade is crap??? 3" bore pipe??!!! Idiots..... how to make friends and influence people Share this post Link to post Share on other sites
Guest abmotorsport Posted February 4, 2006 (edited) Eh, what you on about...?! You've only just arrived and already calling people idiots perhaps you wold care to expand on your inteligent reply? If i have offended you then i appologise, you must have thought it aimed at you specifically. I am still trying to understand your inteligent post. Your a powerflow agent, some aren't as reputable as you are. I've heard of various good and bad experiences of powerflow (including use of cheap stainless to improve profit) so your opinion is only relevant when referring to your workmanship (which i'm not drawing into question). Whats wrong with 3" bore, give me some technical reasons. Most of the big power jap turbo nutters run 2-3" dia. systems. Agreed, some agents are less than reputable than others, the comment was aimed at persons / people shunning the product without being specific. remenber a lot of people read things like this and with less knowledge of such things, they are easily influenced. As for the need for 3" bore, please tell me at what bhp is it neccesary to have a 3" bore to avoid horse power loss or variations in torque. how to make friends and influence people Yep Edited February 5, 2006 by pugtorque Share this post Link to post Share on other sites
Guest abmotorsport Posted February 5, 2006 Appologies to all who thought we were indicating they were 'idiots'. We get these very flipant coments all the time and it gets annoying, especially when on a medium like this forum when people can be easily influenced. We have so many people wanting big bore exhausts thinking they will be getting more power, it just is not true, in most cases it is detrimental to power. To suggest Powerflow is bad is unfounded, there are over 60 dealers throughout the country and admitted there is a lot to be desired when it comes to the quality of the fit but in the main problems can be dealt with, choose a reputable dealer and travel if needed. If you want a 'cheap' system then mild steel GP N is good enough. We always build a system to a competition car designed to suit the application for free flowing, get more power, and clear the body work, we have not failed yet. The stainless used by powerflow dealers in the main is 304 grade, some use the older 409 grade which gets a surface rust due to the iron content, the customer shgould be given the option when purchasing. We use nothing but the 304 grade because chav's want the shiney appearence. Food for thought when suggesting 3" bore, why do the 200bhp civic type R have 1 3/4 exhausts?, why to the japanese NUR spec R systems use a 3 1/4 inch system but use 2 1/4 bore through the silencers? (they do look the *ollocks though!), why do magnex use a 3" bore pipe on a cossy system but 2" bore though the silencers?? Its about the sound and its the sound that sells the system in most cases. Performance applications are a different animal. Good engine builders, of which there are 'some' on this forum will be able to add the science that creates a manifold for power but the proof is in the pudding, on the road if it works then great, but dont be fooled into thinking a louder exhaust means its faster, people do!! Its an appology with an explanation, if you accept fine, if not tough! Share this post Link to post Share on other sites
Kev-G 1 Posted February 5, 2006 To suggest Powerflow is bad is unfounded, there are over 60 dealers throughout the country and admitted there is a lot to be desired when it comes to the quality of the fit but in the main problems can be dealt with, choose a reputable dealer and travel if needed. If you want a 'cheap' system then mild steel GP N is good enough. The stainless used by powerflow dealers in the main is 304 grade, some use the older 409 grade which gets a surface rust due to the iron content, the customer shgould be given the option when purchasing. We use nothing but the 304 grade because chav's want the shiney appearence. Therein lies the problem....1 'bad' dealer gives the others a bad name ( or in the case of Powerflow several 'bad' dealers)....Guilty by association.... Not all dealers are may be as competent as yourselves.... Share this post Link to post Share on other sites
Hilgie 16 2 Cars Posted February 5, 2006 Anyway, for a 2.0T engine without major mods a 2.5" pipe with only backbox would do fine. A Laser backbox is recommended because it already has a 2.5" dia inlet. Share this post Link to post Share on other sites
PumaRacing 1 Posted February 5, 2006 Yeah, needs to be failry large bore as it needs low back pressure, unlike normally aspirated where it needs back pressure (a common mistake with chavs fit the biggest bore they can find!). Single box will be fine and you'll get that lovely burble from the turbo engine still No engine 'needs' backpressure in an exhaust system whether turbocharged or otherwise. Backpressure means there's a pumping loss taking place and that's always harmful to power output. Quite why this old wive's tale still goes around I'm not sure. If the fueling has been calibrated to suit an engine with a restrictive exhaust and a free flowing one is fitted then power might actually drop initially but this doesn't indicate that back pressure was helping the engine, just that calibration needs to alter. Also small pipe diameters, especially near the engine i.e. manifold and downpipe will usually help low rpm power at the expense of high rpm power but this is a gas speed and reversion issue not a backpressure one. Exhaust systems designed for anti-reversion can run larger pipes to help high rpm output without harming low rpm output. Share this post Link to post Share on other sites
cybernck 400 1 Cars Posted February 5, 2006 col, do you now see why do we need to have so many rules about what's not-acceptable for posting on the forum?! Share this post Link to post Share on other sites
JamieTonks 1 Posted February 5, 2006 i ve got a 3 1/2 inch system with only 1 silencer on my turbo and tbh its quieter then when i once had a magnex on a standard 1.9 8v Share this post Link to post Share on other sites
Dj_mini 7 Posted February 5, 2006 Theres a haynes manual called "forced induction performance tuning" all about charged engines it goes in to great detail about exhaust sizes and number of boxes ect it makes good reading and it points out that the bigger the bore the better is not always true it can totaly transform the way the turbo spools up and boosts. Share this post Link to post Share on other sites
mak 0 Posted February 8, 2006 its written by graham bell, a good read for anyone desinging forced induction systems. Turbo Technics used a 2.5" pipe with single back box. Share this post Link to post Share on other sites
Enfield 0 Posted February 13, 2006 its written by graham bell, a good read for anyone desinging forced induction systems. Turbo Technics used a 2.5" pipe with single back box. Didn't he invent the telephone Share this post Link to post Share on other sites
