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Hi guys,I have almost put my EJ22 back together after a complete rebuild but have a question for any other 22 users out there....What sort of back pressure do I need. The exhausts that I plan to put on this thing, at this stage, are 2 foot single pipes to each head. I believe the easiest thing to do to get back pressure is to weld an appropriate sized washer into each pipe after the O2 sensor. What size hole is 'appropriate'?Any help would be appreciated... cheersPaul
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Bigger the better.Why choke it?Ignorance is bliss............but only till you realise you were.You can always get the answer you want, if you ask enough experts.
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Paul,You could just weld in a small washer and drill it out in 64ths increments until you get the desired result. I would be turning it for best performance at full power, to pull you out of the pooh if you need it, where as some might go for best cruise performance.I have a 44mm twin exhaust system on an ea81 with hot dogs on it, there is about 4' of tube off each head and 360 degrees of bends on each one to take the exhaust past the prop - timber - gas is not good for same. It performs well and sounds OK in that it is reasonably quiet even at 20' away at full bottle. I concur with birdy and cannot see why you would want to throttle the exhaust other than for noise abatement, but if your exhaust system is of a large diameter this will not happen.Regards,Nick.
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You know, manufacturers spend millions on the development of engines, why don't you install a tuned exhaust. I had an 1800cc VW years ago with seperate exhaust stacks. After installing a tuned exhaust without a silencer, that old girl performed very well after that.
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Thanks for the feedback guys,I am under the impression that with short stacks there is basically no back pressure for the correct flow into and out of the cylinders. A tuned exhaust would be great but I have doubts that it would fit the design AND be light enough. I was hoping that someone out there with an EJ22 may have done something similar. I am using a stock ECU etc so won't have the luxury of tuning the old girl like I would with an after market performance ECULike you said NiqueNaque I may have to just suck it and see.CheersPaul
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Barry,They do, then we gyro pilots and builders go and bugger up the whole idea by sticking them in our gyros, I don't think Subaru have approved the use of their engines in gyros as yet...The use of a car engine for a car is vastly different to a car engine for a gyro, we usually only operate in a car's normal rev range when landing or warming up for take off, so the tuning of a car exhaust system is incompatible with 99% of our engine hours, the bulk of which involves 3/4 to full power settings most of the time, certainly we will be operating from 3/4 to full torque most of the time as well.Paul,As I understand Brian uses a 2.2 suby for his machine, have a chat with him for some clues..RegardsNick.
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Hi Paul, yes I do run a suby 2.2 and Tim McClure made up a two into one on either side, curved a pipe under the sump and joined the two into one there and routed it under the radiator and cut the pipe after the exhaust. There is no muffler and he put in a bit of flex just after the two sides come together. Will measure and take a photo tomorrow. I wasnt looking for performance so an exhaust could be done better ie mayby using extractors ? anybody tried that ? Could be worth contacting Rob Patroney as he has a few ideas on this subject.Brian
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Thanks Brian,Mate, where have you put your O2 sensor in the configuration described. In one of the exhaust headers (ie: two into one section) or in the joined pipe (both headers combined). I have been told that it dosn't really matter where, but am interested to see what others are doing.Looking forward to seeing the pics.... no pressure....CheersPaul
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Image Insert:
20.04
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Tim put the 02 sensor just after the two pipes join. I have no muffler or any restriction fitted.Brian
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Thanks Brian,Good info there. I might not worry about the washers etc. About how long is the total pipe length out of interest...Murray,Not sure if is my settings, but I couldn't view your picture on my computer... just comes up with the little red cross on a white squarePaul
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Yes I couldnt see it either,dont know why. The photo was of a set of pipes Brian Maloney made for Russel Cooks new EJ22. All stainless steel and very light.Image Insert:
20.02
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Still no good.
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hm,I would warn against the use of stainless, my experience of it is that it is very much more susceptible to fatigue, fine for a car - it falls on the ground, not fine for gyros - it goes through the prop, then maybe, the rotor.Regards,Nick.
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G'day Gents. Had Tim's pipe the same as Brians but was too noisy. Modified my ea81 exhaust to fit the ej22 and now it is unbelieveably quiet. It is 2-1 out of each head meeting in a muffler under the sump. A pipe going in each end of the muffler with tailpipe coming out one of these ends. Sensor is in tailpipe. Muffler is about 14"long and 8"round with nothing in it except a plate that comes about 3/4 of the 8'. The pulse from each cylinder hits this plate and it seems to nullify the sound. I can take off and land without the wife even knowing. Now thats quiet! Ken
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