I'm sure when I discussed theory with Hamish he basically said as large as you like.
Here's a nice article: http://www.tercelreference.com/tercel_info/turbo_exhaust_theory/turbo_exhaus t_theory.html "Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure." Of course the normal caveat applies - this is theory, not practise... maybe ;-) M -----Original Message----- From: quantumowners@googlegroups.com [mailto:quantumowners@googlegroups.com] On Behalf Of Jim Hearne Sent: 05 October 2011 08:45 To: quantumowners@googlegroups.com Subject: Re: [Quantum Owners] Re: Endura DE into saloon Actually, you can have a too free flowing exhaust for a turbo. The turbo needs a certain amount of back pressure on the exhaust to make the oil seals in the turbo work properly, if theres not enough pressure you will get oil leaking past the seals into the exhaust and nice blue smoke. But, as long as you have at least one silencer you should be ok, mine is 2.5" right through with one silencer. Jim -------------------------------------------------- From: "Matthew Wastell" <matt...@wastell.eu> Sent: Tuesday, October 04, 2011 7:33 PM To: <quantumowners@googlegroups.com> Subject: RE: [Quantum Owners] Re: Endura DE into saloon > If it's turbo charged, as big an exhaust as you like after the turbo..... > > If it's NA 2-2.5" all the way through for a 2.0 is about right. > > Matthew > > (only what I learned from others....) > > -----Original Message----- > From: quantumowners@googlegroups.com > [mailto:quantumowners@googlegroups.com] > On Behalf Of Jim Hearne > Sent: 04 October 2011 13:37 > To: quantumowners@googlegroups.com > Subject: Re: [Quantum Owners] Re: Endura DE into saloon > > If theres no feedback to the ecu then i can't see why taking out the > cat would cause any problems. > It might affect the turbo backpressure slightly but it shouldn't do > anything bad. > > Hamish will be the man to know for sure. > > Jim > > > -------------------------------------------------- > From: "TonyV" <q...@avies.co.uk> > Sent: Tuesday, October 04, 2011 12:13 PM > To: "Quantum Owners Group" <quantumowners@googlegroups.com> > Subject: [Quantum Owners] Re: Endura DE into saloon > >> Couple more pics on the photobucket site, showing my newly-modified >> inlet manifold. >> I'm quite pleased with how that particular bit turned out. Although >> I'm a little worried that the additional volume of the pipes leading >> around the engine to the intercooler will lead to an increase in >> turbo lag. >> >> I've also started fabricating an upper engine mounting. >> For this, I've used the Mondeo alternator mount (which is also the >> engine mount), cut right back so that it isn't much more than just a >> bracket which bolts to the engine in 4 places. I've welded that to a >> cut-down mount which came from the ERST engine. I'll post more pics >> once I've cleaned up the welds and painted it. >> >> Once that's done, it's just a case of fibreglassing the hole in the >> inner bay once more (I had to grind the first lot out to make more >> room), and then bung the engine back in. Hopefully for the last time! >> >> >> Which brings me to the next question : exhaust. I hadn't remembered, >> but the Mondeo downpipe has a big "dustbin" welded into it. >> Presumably a political converter of some sort. >> There are no sensors (e.g. Lambda, O2) fitted into the exhaust >> anywhere, so would it be OK to simply replace this with a piece of >> straight pipe? >> Will doing so provide any benefits (e.g. increased power) other than >> actually fitting past the steering rack? >> Any downsides? >> >> TonyV >> >> >> >> >> >> On Sep 13, 10:40 am, TonyV <q...@avies.co.uk> wrote: >>> Just to clarify slightly....my photobucket link is OK. >>> >>> Jim is referring to a link in a following spam message which Jim has >>> now deleted. >>> (But it's accidentally repeated in the quoted text... =o) ) >>> >>> TonyV. >>> >>> On Sep 12, 9:07 am, "Jim Hearne" <j...@quantums.info> wrote: >>> >>> >>> >>> >>> >>> >>> >>> > Sorry people, don't follow that link, it's spam. >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Quantum Owners Group" group. >> To post to this group, send email to quantumowners@googlegroups.com >> To unsubscribe from this group, send email to >> quantumowners-unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/quantumowners?hl=en >> >> IMPORTANT NOTE: All information presented herewith is provided on an >> "As Is" basis, without warranty or the implication thereof. 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Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s).
