y-pipe spfi question

[86subaru]

i can get a y-pipe made with no cat ,but with a O-2 sensor port , how loud will it be ? or what type of muffler needed ? and no center also , what is the thread size for the O-2 sensor port ? any adjustments after wards on motor ? this is on a spfi d/r wagon , has anyone else done this ? what improvement ,mpg , cooler motor , etc... ea82 motor ,thanks

[bgd73]

i can get a y-pipe made with no cat ,but with a O-2 sensor port , how loud will it be ? or what type of muffler needed ? and no center also , what is the thread size for the O-2 sensor port ? any adjustments after wards on motor ? this is on a spfi d/r wagon , has anyone else done this ? what improvement ,mpg , cooler motor , etc... ea82 motor ,thanks

 

I can't answer all of the q's, but the o2 sensor likes the backpressure of the cat- yet again in second thought, the spfi didn't do much with the o2 so putting it anywhere hot enough would be good enough with a cat filled or not (my guess). If putting your own o2, the size you would need could be all yours. The noise is...... Excellent, if legal where you live.I have been running a glasspack and open pipe on an old carbed ea82 to what I was convinced is the loudest thumpiest car vibrating old soob I have heard yet, to learn the heads were machined. I need a full quiet like exhaust, if yours is normal, it isn't all that loud. Going over 9.5:1 is outright painful with open pipes for any length of time, and could even bring a noise pollution ticket.

 

Definately an erratic motor with temps, and opened exhaust,I would not say cooler, as the backpressure actually helps an ambivalence stay with the thermostat and coolant to stay fluid steady

 

Spfi is very good with a tight exhaust, even if it is made louder.

Any 2inch muffler that fits is excellent.

[86subaru]

so would it really gain anything , is it worth it ? i did it on my 88 turbo wagon and it helped alittle , yes turbos are different + 2 inch pipe all the way back + turbo muffler

[NorthWet]

Stock O2 sensor is the same thread as stock spark plugs (you can use a spark plug thread-chaser/tap in the O2 bung). The mufflers are highly subjective, depends on if you want noise and the sendation of power that the noise gives you. I like quiet, so I would go with a large volume units, with the last one having multiple smaller outlets/tailpipes. The SPFI should compensate, and no engine part likes backpressure. You might see some gains with this configuration, but I wouldn't expect any serious advantages over a system with a decent 3-way catcon.