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YOUR RESEARCHAnother Muffler Bypass thread
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Run different throttle body and pull just over 400rwhp
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I run a different throttle body and pull just over 400rwhp.
Leading evidence: 'Run different throttle body and pull just over 400rwhp' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Recommend ssk in parallel' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
If you are going to do the by-pass muffler mod, I would highly recommend the SSK in parallel.
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Suggestion
Also, if you don't wanna pony up for bypass pipes, run around with the PepBoys mod (aka the $7.50 mod) and test for yourself.
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From searching the 1001 posts currently on Rennlist about Muffler bypass pipes it seems to be the general feeling that torque is lost down low in the powerband with the muffler bypass pipes.
I'm curious if anyone has Dyno proof of where the torque is lost and what the "break even" point is to where the pipes are no longer a hinderance.
I have GHL headers and Mufflers on my '99 and at the track it's simply too quiet. If I'm anywhere near loud cars I can't even hear my car and while I generally know where it is in the rev range anyhow it'd be nice to be able to clearly hear my car when i'm driving it at all times.
So...I'm ready to purchase the bypass pipes for track days BUT want to make sure there's no sacrifice in performance. As long as you don't loose torque anywhere north of say 4000rpm then I'm fine...just wondering if there's real world dyno graphs out there to back up my questions.
Andy
Till what RPM?...I doubt my butt-dyno will be able to tell where the torque loss stops? Sure I'll know there's less torque down low...but I never questioned that. What I'm curious to is if the torque loss is all gone by say the 4500rpm mark, 5000rpm mark? etc.
My only intent is to use them at the track and I'm looking for data prooving that they're a worthy track mod and don't decrease HP / TQ in that setting as well where the motor will not likely see < 4500 rpm. I'm all for taking weight off of the back of the car...I just don't want to sacrifice performance at the same time.
Andy
I run my MY00 on the track with bypass pipes. There is no big loss at low RPMs (since you are almost never there) and it's awesome in the high RPMs! And (as a practical matter) - it's a DE, so who cares about low end torque. Seriously, what "performance loss" are we dealing with? You're not racing anyone and you're not being timed. So what if you are 2 seconds slower (if you actually are...)
Don't let the "lose torque" propoganda sway you. Just run without. It's loud, it's fast, and it's fun. And fun is what it's all about.
The only potential downside, is sometimes it's hard to hear your tires talking to you. But this has a counter benefit -> you must develop your backside sensor a little quicker
Also, if you don't wanna pony up for bypass pipes, run around with the PepBoys mod (aka the $7.50 mod) and test for yourself. But, just FYI, you can get a used set of Fabspeeds for around $200 bucks, maybe less...
-td
This is some of the feedback I'm looking for. I read these threads about loss of torque and just wanted to make sure it only effected the lower rev ranges of the motor where I won't even notice it at the track.
That what I"m getting at..as easy as it is to get the mufflers off of there and save weight on the back of the car IF there really is a performance decrease then I question if it's really worth my time....I'm likely blowing this out of proportion...just wish there was data to back up my questions....looks like I'll try the pep boys mod and find out for myself.
On a similar subject, What about taking out the cats? I have gemballa mufflers and they sound good, but looking for something a bit louder. Are the cat bypass pipes louder or quieter than the muffler bypass pipes? Loss in torque?
If you are going to do the by-pass muffler mod, I would highly recommend the SSK in parallel. It completes the "fun" factor driving experience. Yes you loose low end torque BUT they know your coming..and -25 lbs.
DE car here as well - i don't care about the hp loss. it still feels and sounds AMAZING.
td873 - i am in agreement with you. though i must say even sans mufflers, the car is quiet in comparison to most race cars - spec miatas, 944's, etc...basically anything with a straight pipe. i love it best for hearing the downshifts when i heel/toe. what a beautiful sound to hear the engine reving while going down 3 gears
!
mufflers weigh ~30lbs a piece. thats ~60lbs total that you remove that was hanging past the rear axle. critical weight savings, i'd say, though it is probably diffcult for me to say THAT was what made a difference. i think we all did it for the sound.
a catless exhaust would get you pulled over instantly on the street. too loud.
No. It's a double dip. Keep in mind that the mufflers will muffle, that's their job. That is, if you have no cats but keep the mufflers then you wouldn't be very loud. You need to remove both.
In order of loudness (less to more):
Full exhaust (muffler + cat) [eh, so-so]
Muffler by pass (with cat) [pretty loud]
Muffler and cat bypass [um, you're getting a ticket in the city loud
]
-td
he did answer your question.
practically, i havn't seen that done because if you're gonna remove the cats then you're probably in a position where you dont care to have the mufflers on either. at this point you'd just be experimenting to see what makes a less loud of a noise.
Right.
2 other points:
1) I believe if you remove the cats and try to keep the mufflers, you won't have enough pipe to connect the mufflers to the exhaust manifold.
2) And even if you could, removing Cats and not mufflers will most likely cause a CEL.
-td
Your Dyno #'s on removing cans and going to bypass pipes were 39 lbs of torque loss for me on the dyno. Did the run at JT Motorsports but did they did not have a cartidge in the printer and I was too lazy to care enough about waiting for a printout. The loss levels out around 5K and after that, it is not an issue.
For me personally, I knew the very second it drove the car. My setup is radically different than most with my supercharger and intake system. I run a different throttle body and pull just over 400rwhp. I think the n/a engines don't loose near as much as my setup. I will tell you that I absolutley loved the sound and do miss it but the power loss for me was too substantial.
i ran the pep boys pipes at my last track event to see if i liked them. amazing sound. i didn't notice any decrease in Tq but it seemed the engine was breathing a lot better on the high end. there are only a couple of places on the track where i dip below 4000 rpm so i don't mind any Tq loss if there is any.
my main goal was to get rid of the 60 lbs in the rear which IS noticeable. the rear end pendulum affect is much less. feel great in quick transitions, in the essess.
i am going to change out the pep boys pipes for nicer looking pipes. some guy on ebay sells some that are cheaper than fabspeed.
NO.
keep the pep boys pipes and run with me! that way i won't get made fun of as much. or i'd have someone to share the laughs with. in all honesty a lot of people get a kick out of seeing the nice carrera with pepboys pipes coming out the back.
link to fabspeed knockoffs?
If you are on a track, why not just leave the mufflers off without any tips? You will definitely hear the motor.
Losing the cats but keeping the mufflers will probably be pretty loud as most other cars are I have been around get substantially louder doing this.
How about just open headers?
um. if you remove the mufflers but dont add the angled tip then the exhaust blows right into the rear bumper into the space where the muffler was removed. you need hte 90 degree angle to point the exhaust rearward.
nah, they just a little too ghetto for me
. also the diameter of the pipes pep pipes is 2" but the diameter of the exhaust clamp is 55mm so they fit kinda loose. i used safety wire to hold it on. glad i did because they may have gone flying.
MUFFLER BYPASS ON EBAY
. there's a fabspeed brand set on fleabay right now.
i don't understand, are you asking why the exhaust blows into the rear bumper? if so, look underneath the car and look for yourself. after you remove the mufflers the pipes point into the rear bumper.
I was just asking why do you HAVE to point it to the rear, track regulations?
I drove mine for a day without any tips, just open cat pipes. You can really hear the motor for sure. I was just telling the OP to simply remove the cans and drive around, he would get a sense of the torque loss right away without spending a dime, just 15-20 minutes of work.
I would be very nervous with the exhaust super-heating everything under the rear bumper. Metal expansion, plastic melting, brakes and tires heating all come to mind.
Besides, if you take the time to remove the mufflers, adding a piece of 90� pipe takes all of 1 minute...
-td
td- You wont hurt anything, the entire bumper is lined with a heatshield. Like I said, I was just telling the OP to remove the cans and take it for a spin, he would know right away the difference.
no, i dont think theres anyone telling you that your exhaust must point rearward. but anyone with half a brain would quickly figure out that your exhaust needs some fixin' if it blows out sideways
I would still be extremely cautious with removing the pipes and not adding the 90� turn. It seems to me that the heatshields are not intended to take the full and direct heat of the exhaust for extended periods, but is there to reflect the radiant heat generated from the engine and pipes. Coupling direct exhaust heat with the radiant heat of the engine might be a bit much for some crumply aluminum.
Just seems like common sense. But what do I know.
-td
Here's an old post I did on the pep boys option. It's the easiest - and cheapest - way to tell if you'll like bypass pipes or not:
https://rennlist.com/forums/showthre...ferrerid=12205
My stocks were WAY too quiet so I did the muffler bypass thing. Great sound for tracking and Saturday afternoon. Too loud for daily driving - and I did notice power loss. The car sounded more like a harley - embarassing. Went to sport mufflers (Dansk) perfect sound.
You can control your final sound with a muffler bypass mod.
It is just like ordering from McDonalds. Would you like that small medium or large.
Original - (Yanni)
Small - 1.75" pipe - (REM - think I am superman)
Pretty tame at idle, barely can tell the difference. 3500+ nice little rasp, punch it and it will sound good.
Medium - 2" pipe (Evanesance - when the guitars kick in)
I feel the right size mod. Idle you get...this guy has something going on under the boot. 3500 + very sporty sound, not much different than 1.75" at higher revs.
Large - 2.25" pipe (Soul Asylum)
Idle is very raspy sounding, 3500+ who put a race track in the neighhborhood...
I'll be using a set of these for track use as well. Mostly for the weight savings and for a significant engine bay temp drop (per the GT3 forum guys).
I plan to do a dyno session this winter with my new engine. I hope to be able to do a few runs with the bypass pipes and get some hard data for everyone.
-Paul
my dyno with bypass pipes and no other mods showed a super flat torque curve (like...you could almost draw a straight line it was so flat). 258 or something across roughly. i'll see if i can dig up the graph somewhere.
there's a bit of torque lost at the bottom end, but it shouldn't be a huge deal. spend less time in stoplights
Thanks Omar.
Sorry folks, I had good intentions but just have not had time for things like dyno play. Been busy with life and just taking care of the list of "things to do" on the car before spring like x51 oil pan and 3rd radiator (up next). Also wasted a ton of free time playing with my variocam+ engagement points.
-Paul
