ea82 exhaust

rob83ke70 · Post by **rob83ke70** » Sat Jun 21, 2008 4:37 pm

hey
i know everyone has been down the path of "how big an exhaust should i put on my ea82" enough times for it to become a bit boring. I'm happy to put a 2" high flowing exhaust on my car. What I want to do is put custom or aftermarket headers on, and bring the exhaust pipe to the passengers side of the car, then have a high flowing cat just after the flange (yes i want a flange there!!) and a nice well made exhaust with a resonator and muffler and 2" tip from there on back. Is it possible to get aftermarket "extractors"? or do you just pay an exhaust shop to weld them? it seems funny having siamese exhaust ports, there will only be two pipes to join... Anyway, i think that seems like the best way of approaching this, i want a well made exhaust that can be disassembled, and does not catch on anything during 4wd exploits. I think i will end up paying a lot more for my exhaust than most people, but thats just me.

best exhaust i've ever seen, on my bosses modified wrx sti, it has the tidyest, neatest exhaust ever!! I'm assuming its an MRT job because thats who modified the car... worst subaru exhaust i've seen, yet another wrx, but this one has been modified to make it look "cool" or something... 20" wheels that are heavier than stock items and don't look as nice, an exhaust without a cat that doesn't have flanges and looks out of place, and a huge front mount intercooler with the pod filter in the engine bay sucking hot air.... why would you make a car that is already fast, handle and perform worse than it did before to make it look "good"?? i guess i will never know.

robert.

discopotato03 · Post by **discopotato03** » Sun Jun 22, 2008 3:40 pm

I'll get back on this one later but for now search for Michael South on some of the Impreza WRX boards .
I think his business is called MSR and it's on the central coast between Sydney and Newcastle .

http://www.msengineering.com.au/exhaustsystems.html

A .

discopotato03 · Post by **discopotato03** » Mon Jun 23, 2008 8:40 am

Sorry forgot to add than on a fairly std EA82T I'd go one tube size down on Michaels Impreza ones , ie 2.5 and 2.25" instead of 3 and 2.5" .

Anything you can do to the header will make itself felt - a real piece of garbage .

As a cheapie mod you could rat up an RS Lib dump/cat pipe , change the flanges (turbo end) and get an around 60mm head start and one would hope a better flowing cat than EA82T's use . The EA82T front pipe reduces from the innitial ~ 60mm (same as RS one) to a straw where the RS one maintains its size right through to than spring loaded carbon ring swivel joint . I have an EA82T Vortex front pipe and an RS one and the general shape is VERY similar .

Might be an easy way to get an EJ style turbo in if that was the plan .

Cheers A .

brumbyrunner · Post by **brumbyrunner** » Mon Jun 23, 2008 6:43 pm

I think he's talking about an NA motor chief.

rob83ke70 · Post by **rob83ke70** » Mon Jun 23, 2008 6:51 pm

yeah i was talking about a na engine... I think i will get custom headers made up. One of the salesmen at work is trying to stir me up enough to convert the L series to an EJ20. I'm thinking about it but I don't think i'd have the time or money to do so. If I did, it would eat his WRX... I'd make sure of that...

Gannon · Post by **Gannon** » Mon Jun 23, 2008 7:50 pm

There isnt much you can do to the headers. I'd save yourself the hassle and just go a cat back.

discopotato03 · Post by **discopotato03** » Mon Jun 23, 2008 8:47 pm

Fair enough NA it is .

From a performance/economy aspect there is something you can do and that is to link the front pair and rear pair of cylinders to form a 4 2 1 tube header .
Subaru was not looking too seriously at performance by linking the cylinders on each head together then joining the two engine pipes near the cat converter .

From memory the Subaru flat fours firing order is 1324 so to make these engines scavange properly you have to change the header plumbing . If you look from the front of the engine I think the front and back cylinders in the LHS head fire first (1 and 3) then the front and back cylinders in the RHS head (2 and four) fire second .
What then happens is you get two exhaust events close together from each head into its engine pipe followed by a longer pause when the other head/engine pipe does the same trhing .
This is bad because the back cylinders on each bank are exhausting into an area of higher pressure (in its side engine pipe) so the exhaust pulses are not even as in an equal number of crank degrees apart .

A complete four stroke cycle takes 720 degress or two complete revolutions of the crankshaft . In the Sube flat four you get 180 crank degrees between exhaust events on the left bank then a long 360 degree pause before this happens on the same bank again . So the exhaust pulses are from the start 180 deg then 360 deg then 180 again , 180 +360+180 =720 .

If the headers link the front and rear pair of cylinders the cycle goes 360+360 .
Subaru got it right on the twin scroll turbo EJ's where it effectively works like an inline four with a pulse divided manifold linking cylinders 1 and 3 + 2 and 4 .

A

Gannon · Post by **Gannon** » Mon Jun 23, 2008 9:59 pm

A complete four stroke cycle takes 720 degress or two complete revolutions of the crankshaft . In the Sube flat four you get 180 crank degrees between exhaust events on the left bank then a long 360 degree pause before this happens on the same bank again . So the exhaust pulses are from the start 180 deg then 360 deg then 180 again , 180 +360+180 =720 .

This is what gives subaru its unique exhaust note.

Contrary to popular belief that the 2 left hand cylinders have lower compression ratios than the right two giving an uneven exhaust note

Dave.k · Post by **Dave.k** » Tue Jun 24, 2008 11:05 am

i have a 2.5 inch straight through on my brumby. NO MUFFLERs. sounds like a wrx... people trip out. Have had no problems with exhaust or engine.

discopotato03 · Post by **discopotato03** » Tue Jun 24, 2008 6:44 pm

Sorry to rain on the cause but that exhaust cadence is telling you that Subaru got it very wrong . They must have their reasons and I suspect it comes down to production costs .

If the firing order had been 1234 instead of 1324 it would have been a piece of cake , all they had to do was rephase the camshafts and swap the leads/coil firing order on cylinders 2 and 3 .

Instead to do it properly you have to link cylinders 1+2 and 3+4 in the headers primary pipes . That way you get long even gaps between the cylinders exhaust events and the best chance of getting all the cylinders scavanging properly .
You also lose that silly burble sound (flatulence plus lumps) generated by unequal exhaust pulsing between the cylinders . Even pulsing makes an even note or beat and that's why inline 4's sound different to most Subaru flat fours .

Sound may imply power but wouldn't you rather have the real thing , quiet grunt is a hoot because the cap on backwards brigade don't even know your there until it's too late .

A .

YouTube · Post by **El_Freddo** » Tue Jun 24, 2008 7:45 pm

discopotato03 wrote:You also lose that silly burble sound (flatulence plus lumps) generated by unequal exhaust pulsing between the cylinders . Even pulsing makes an even note or beat and that's why inline 4's sound different to most Subaru flat fours .

Sound may imply power but wouldn't you rather have the real thing , quiet grunt is a hoot because the cap on backwards brigade don't even know your there until it's too late .

Easy big fella - a lot of people love the unique beat of the 'rube exhaust. I know I do. I'm not going to go outta my way to get rid of it for the tiny bit of extra power you gain in doing this.

That said, I realise your into your turbos efficient use of exhaust gases and fuel through proper engineering of your EA82, something that I think cannot be fully achieved with the EA82 (and don't want to start an arguement about it here) but is your goal with your vehicle.

Rob, for your application without looking at getting a bigger engine in there anytime soon (EJ) I'd suggest a cat back system that's the same as it is now or go for something a little larger but not by much - chuck a set of flow through mufflers of the same size and you're done.

Cheers

Bennie

rob83ke70 · Post by **rob83ke70** » Wed Jun 25, 2008 10:49 pm

dumb question time - so how do i separate each bank into each cylinder? i have two exhaust ports, one for 1 and 3, the other for 2 and 4... bit hard to separate into 1 and 2, and 3 and 4.

unless i put an ej engine into the car, i think i'm stuck with that?? there was a twin exhaust port ea engine wasn't there??

sounds like a mash up between fact and fiction about the two cylinders having the lower compression than others, doesn't an air cooled vw engine have slightly different cam timing on cylinder three because it runs hottest and they try and cool it down?? (i wouldn't know, thats just what i've heard)

i think the main reason for changing the headers on an ea82 engine is just to locate the pipe on the left side of the engine, because i want a high flow cat directly after the headers, not as part of the headers, and it needs to be as close as possible to work as efficiently as possible. also having the headers dump at the left side enables the straightest exhaust path to the rear of the car. i know we are only talking a poofteenth of a kilowatt here but the straighter the exhaust the better. i like neat tidy work, and i'm sure if its all neat and tidy it won't catch on stuff if i ever get to go 4wding...

robert.

discopotato03 · Post by **discopotato03** » Thu Jun 26, 2008 9:44 am

Without going to a bit of trouble yes you are stuck with the technicaly incorrect firing order and only two engine pipes . This being the case it's debatable if any serious exhaust tuning is possible .
All you can do is try and get the tube sizes right to minimise pumping losses .

If you went all out on exhaust porting you can make up header flange plates with dividers up to the port dividers up in the heads exhaust ports and make 4tube headers . It's really more trouble than most people would go to on a road car .
Really if anyone wanted sort of half reasonable power out of an EA82 it needs to be the turbo version and even they are far from perfect - just more torque .

The factory solution to the L Series is called Impreza , a long way ahead of anything L Series and the MY93-00 ones are still small and reasonably light compared to many cars .
You can fit the EJ to an L but its only everything else thats a couple of generations behind then ...

A .