i dont remember for the life of me where i saw these, but it was a throttle plate assembly of sorts that fit into your exhaust piping and you could adjust the plate via cable from inside your car and increase or decrease your backpressure. i think us NT guys might benefit from this greatly. its nice to have mods that will allow less restriction for our top end but they most always hurt us sevearly in the low end. my question is could this be a solution to our low end probs? by adjusting this, we could maintain enough backpressure to get some low end and then just open the thing up all the way so we can benefit from the top end as well. i didnt know if this would be advanced tuning...i think it would be since its so different. let me know what yall think. maybe this will work, maybe not. i dont know all the in's and out's on it so give feedback.
#113779, "RE: adjustable back pressure" In response to Reply # 0
Backpressure is bad, period. Exhausr gas VELOCITY is what you need to concern yourself with. A throttle plate in the exhaust is going to ruin gas velocity, and thus performance.
This is a "not good" idea.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#113780, "RE: adjustable back pressure" In response to Reply # 1
100% what I was going to say^^^
The backpressure thing is just a myth started by people who didn't know how to explain what they were observing. Proper sizing of the exhaust system is the key to increasing power at certain RPM's.
Corbin
'95 ESI-T HRC+FMIC+ETC...
Gimme fuel...Gimme fire...Gimme that which I desire
#113782, "RE: adjustable back pressure" In response to Reply # 3
All it really does it quite the exhaust down, so if you were running a 2.5" catback and you wanted to soften the raspiness you could put that baby on and it would cancel out some of the sound, but it doesnt add power. My one idea used the tb assembly, but you use two pipes one large pipe with a smaller one inside with the tb only blocking the inner one. So at low rpms the tb is closed and the exhaust travels between the the outer and inner pipes with a cross section area less then our stock pipe. Then as rpms increased it would open the tb and you get the full flow of 2.5" or so. Either that or have to catbacks under the car and use a valve to divert gases to either the small one or the larger one. Weight and complication vs gains were the drawbacks.
#113783, "RE: adjustable back pressure" In response to Reply # 4
They have something like this for diesel engines but is called a exhaust brake. When closed it cause the truck to have massive amounts of engine braking due to the restriction of gases on a high compression diesel engine. Techically though you are correct. Engines require a certain amount of back pressure to make peak power. The amount of back pressure varies according to rpm but people just prefer to have the optimal backpressure at the engine peak power rpm.
#113784, "RE: adjustable back pressure" In response to Reply # 5
exhaust gas velocity! Backpressure is BAD, and any sort of need for backpressure "to run right" or "to make better power" is a complete myth.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#113785, "RE: adjustable back pressure" In response to Reply # 6
>exhaust gas velocity! Backpressure is BAD, and any sort of >need for backpressure "to run right" or "to make better power" >is a complete myth.
then why is it if i put in the silencer for my tanabe catback my car performs better is the 2-4k rpm range? i DEFINITELY feel a difference when the silencer is in. w/o it, my car struggles to get up through that range. my 3" exhaust is sooo big on my nt that its a day and night difference. just waiting for that turbo.
Jason --------------------- 99 White GS Tanabe Super Racing Medallion Apex-I S-AFC, Springs AF/X Underdrive Pulley Fully tied suspension
#113786, "RE: adjustable back pressure" In response to Reply # 7
to resteictive is no good...and so is to big, generally 3 inch is perfect for a nice turbo setup imo. a nice catback will make ur car perform better than stock across the board though, duh
#113787, "RE: adjustable back pressure" In response to Reply # 8
>to resteictive is no good...and so is to big, generally 3 >inch is perfect for a nice turbo setup imo. a nice catback >will make ur car perform better than stock across the board >though, duh
uhh, no way....DUH the post had nothing to do with catback systems, we were discussing adjusting backpressure possibilities due to a butterfly plate in the exhaust. i think we all know that a catback will give you gains...duh
#113789, "RE: adjustable back pressure" In response to Reply # 10
There's a company called Power Effects they make this muffler, it's a 3" straight through core with the butterfly valve and a spiral core muffler around the outside of the center. Adjusting the butterfly valve adjusts how much flows through the middle and how much flows around the spiral core and you get differences in both tone and exhaustgas velocity. In tests on Corvettes (the original exhaust this company made) the results from the exhaust were good, but it's not a cheap setup.
15.9 @ 86.7mph
Smooth idle? We don't need no stinking smooth idle.
#113790, "RE: adjustable back pressure" In response to Reply # 11
I think the amount of effort involved in putting this together, let alone trying to hang it on the car far outweigh the 1-2 (3-4?) hp you might see IF you were able to tune it correctly. IMO, this would be a better idea for a test pipe. If you set up a side exhaust that tapped into the main just before the cat with a butterfly there, you could run silent and deadly (not to mention LEGAL) on the streets, but pull a throttle cable at the track just before you stage for increased velocity. You might need to get a second EGT though if you wanted to tune with both pipes. This idea might be nice to scare off ricers who rev on your "quiet" car. You could pull cable and rev back at 145db
#113791, "RE: adjustable back pressure" In response to Reply # 12
>IMO, this would be a better idea for a test pipe. If you set >up a side exhaust that tapped into the main just before the >cat with a butterfly there, you could run silent and deadly >(not to mention LEGAL) on the streets, but pull a throttle >cable at the track just before you stage for increased >velocity. You might need to get a second EGT though if you >wanted to tune with both pipes. This idea might be nice to >scare off ricers who rev on your "quiet" car. You could pull >cable and rev back at 145db
actually they already have these. i saw them on trucks. you have 2 ports one that runs legally through the cat and muffler and out the rear...but if you open up this little gate you run straight pipes. instead of a butterfly plate they actually used a gate that slid down in place like a gillotene (sp?) and it was all motorized..so you could line up with someone at the light, flip a switch and run straight out..then flip it back closed afterwards and not attract any attention.
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the post had nothing to do with catback systems, we were discussing adjusting backpressure possibilities due to a butterfly plate in the exhaust. i think we all know that a catback will give you gains...duh
