silencer removal
08-28-2003, 12:06 AM
#1
Registered User
Thread Starter
Join Date: Jun 2003
Location: In my SUBY!!!
Posts: 564
silencer removal
Does anyone know if you remove the intake silencer will this cause you to lose horsepower? Ive heard that installing a intake filter will cause the horsepower lostage,but isnt removing the silencer almost the same thing because you loose the ram air effect.
08-29-2003, 11:39 AM
#2
Once you get the silencer out of the fender well, you will see that there was no ram-air effect happening with it. I haven't seen enough proof one way or the other as to if it helps or not. Mine is still in, but I did add the K&N drop-in filter since I've heard horror stories about intakes causing problems and not gaining power.
08-30-2003, 09:13 AM
#5
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
I'm on a newsletter list from MRT, here is a small snip from the one I got yesterday:
I put in a Green Filter to replace my K&N and think it's a better quality filter. Pics and thoughts on it here:
Green Filter
Also I don't think you will ever see a ram air effect w/ a turbo. even at very high speeds the amount of pressure generated by the intake opening is minimal (less than 0.5 psig someone once calculated at 120mph) nothing close to the pressure generated by the turbo anyway. I'm not sure what the point of ramming air into the turbine would be...
Tips and Suggestions
Easy Power
If you feel inclined and want some power to upgrade your turbo or non turbo car then try this, the resonator inside the right hand wheel arch on your car not only reduces noise but it also sucks power from your car.
This modification will improve turbo car's more noticeably than non turbo cars, but is worth the effort!
Here are two pictures of the GC and GD Impreza Turbo Resonators so you know what to look for, you will need access to the inner wheel arch of your car. The factory airbox will then suck air from the whole inner guard, instead of through the complicated box as shown.
Easy Power
If you feel inclined and want some power to upgrade your turbo or non turbo car then try this, the resonator inside the right hand wheel arch on your car not only reduces noise but it also sucks power from your car.
This modification will improve turbo car's more noticeably than non turbo cars, but is worth the effort!
Here are two pictures of the GC and GD Impreza Turbo Resonators so you know what to look for, you will need access to the inner wheel arch of your car. The factory airbox will then suck air from the whole inner guard, instead of through the complicated box as shown.
Green Filter
Also I don't think you will ever see a ram air effect w/ a turbo. even at very high speeds the amount of pressure generated by the intake opening is minimal (less than 0.5 psig someone once calculated at 120mph) nothing close to the pressure generated by the turbo anyway. I'm not sure what the point of ramming air into the turbine would be...
Last edited by Peaty; 08-30-2003 at 09:17 AM.
08-31-2003, 08:00 AM
#7
Registered User
Join Date: Jun 2003
Location: Portland, Oregon
Posts: 42
Car Info: 2003 WRB WRX sedan
Don't bother taking the silencer out. The "sound" change is
very minor, and unless you find some way to seal the
box against inside of the fender, you'll do nothing but suck
hot air into the intake.
The stock snorkel takes cool air from the front of the car and
gets it where it needs to go. This supposed "mod" is a waste
of time and can hurt performance if not done properly.
Now the filter is an entirely different matter. A K&N won't do
much for you performance-wise either, but it IS reusable.
Just be careful when you re-oil because if you do over-oil
the filter you'll pull filter oil onto the MAF sensor.
This happened to me with a brand new factory-oiled filter.
You could probably spend that fifty bucks better elsewhere
but to each their own. I wouldn't buy another one.
very minor, and unless you find some way to seal the
box against inside of the fender, you'll do nothing but suck
hot air into the intake.
The stock snorkel takes cool air from the front of the car and
gets it where it needs to go. This supposed "mod" is a waste
of time and can hurt performance if not done properly.
Now the filter is an entirely different matter. A K&N won't do
much for you performance-wise either, but it IS reusable.
Just be careful when you re-oil because if you do over-oil
the filter you'll pull filter oil onto the MAF sensor.
This happened to me with a brand new factory-oiled filter.
You could probably spend that fifty bucks better elsewhere
but to each their own. I wouldn't buy another one.
08-31-2003, 08:20 AM
#8
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
Hot air isn't a problem for a turbo, the air gets heated much higher in the process of being compressed and passing through the turbo itself:
Having said that I did seal the airbox and fender gap nicely. I've done this mod on about 6 cars and have never seen a drop in performance. I'm not exactly sure how you can do it improperly but anything is possible I guess.
As far as grabbing air from the front of the car (some grab behind the headlamp some above the radiator), it's cooler in the fender than just above the radiator especially during stop and go traffic. I've measured it, you also get heat soak in the parts under the hood that will contribute to increased temp. Which is more of a problem with a NA motor but every little bit helps I suppose.
Also opening up the airbox itself helps reduce the restriction:
This is an RS airbox but the WRX / Legacy / and F-XT airbox is the same too. All MAF based ones I've come across are similar .
Having said that I did seal the airbox and fender gap nicely. I've done this mod on about 6 cars and have never seen a drop in performance. I'm not exactly sure how you can do it improperly but anything is possible I guess.
As far as grabbing air from the front of the car (some grab behind the headlamp some above the radiator), it's cooler in the fender than just above the radiator especially during stop and go traffic. I've measured it, you also get heat soak in the parts under the hood that will contribute to increased temp. Which is more of a problem with a NA motor but every little bit helps I suppose.
Also opening up the airbox itself helps reduce the restriction:
This is an RS airbox but the WRX / Legacy / and F-XT airbox is the same too. All MAF based ones I've come across are similar .
08-31-2003, 09:11 AM
#9
Registered User
Join Date: Jun 2003
Location: Portland, Oregon
Posts: 42
Car Info: 2003 WRB WRX sedan
Thanks for the turbo lesson.
Having said that, is there any data indicating this "mod"
is worth the 30 minutes of your time to perform?
Any dyno data at all? If there is, I'd sure like to see it.
Having said that, is there any data indicating this "mod"
is worth the 30 minutes of your time to perform?
Any dyno data at all? If there is, I'd sure like to see it.
08-31-2003, 09:31 AM
#10
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
You're welcome,
Have any to show it don't? 30 minutes isn't a lot of time to give it a try and find out for something that's free. People do sillier things like spend money on turbo times that aren't even needed.
MRT I would think is a pretty good source for information wouldn't you say?
I don't know it just seems logical that reducing the intake restriction is a good thing along w/ cold air. People have commented that the turbo spools up quicker all sorts of subjective comments. For as long as I've been messing with cars reducing intake restriction (along with exhaust restriction reduction for the most benefit) has been a good thing if done right.
If nothing else your reducing weight
Also it's good to plug the fender PN 46059FA000:
Funny I've been on Subaru lists since 99 and the snorkus removal battle rages on. If there were a 4 wheel dyno w/in reach I'd love to test it either way but alas there isn't one for many miles...
Have any to show it don't? 30 minutes isn't a lot of time to give it a try and find out for something that's free. People do sillier things like spend money on turbo times that aren't even needed.
MRT I would think is a pretty good source for information wouldn't you say?
I don't know it just seems logical that reducing the intake restriction is a good thing along w/ cold air. People have commented that the turbo spools up quicker all sorts of subjective comments. For as long as I've been messing with cars reducing intake restriction (along with exhaust restriction reduction for the most benefit) has been a good thing if done right.
If nothing else your reducing weight
Also it's good to plug the fender PN 46059FA000:
Funny I've been on Subaru lists since 99 and the snorkus removal battle rages on. If there were a 4 wheel dyno w/in reach I'd love to test it either way but alas there isn't one for many miles...
Last edited by Peaty; 08-31-2003 at 09:33 AM.
08-31-2003, 10:38 AM
#12
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
OK I had to dig but if you look at the May 2000 issue of SCC where they are tuning the project Impreza that has by that time has been converted to a turbo, there is a lot of info on removing the silencer starting page 230. They (by they I mean Shiv) seemed to think it was worth while since they went into some detail on how to do it, devoting 3 pictures to the procedure.
Also info on putting in a K&N filter
Page 232:
Also info on putting in a K&N filter
Page 232:
Since we were forced to stick with the stock air filter box, we replaced the stock filter with a high flow K&N unit. Surprisingly, this simple change increased boost pressure by 2 psi! Obviously the stock filter is very restrictive at ths power level.
08-31-2003, 01:25 PM
#13
Registered User
Join Date: Jun 2003
Location: Portland, Oregon
Posts: 42
Car Info: 2003 WRB WRX sedan
Peaty, thanks for posting those pictures.
Please don't get me wrong, I know I sound sarcastic, but
let's face it, big power comes from big mods. It's wishful
thinking to believe little stuff like this is worth a squat.
Afterall our favorite monster, the STi makes 300 h.p. with
stock filter and silencer in place.
I admit, the induction noise is noticable. Although I can't
even hear the difference with my windows down. My
cat-back pretty much drowns out what little change in
noise there is.
And you are right, the battle rages on over this piece of
plastic. I just don't believe there is any real benefit on
mainly stock cars to take the piece out. Maybe down the
line with major mods it's a point of restriction.
I really wish Subaru had just run a snorkle right to the air
box to begin with and then we wouldn't have this debate!
Please don't get me wrong, I know I sound sarcastic, but
let's face it, big power comes from big mods. It's wishful
thinking to believe little stuff like this is worth a squat.
Afterall our favorite monster, the STi makes 300 h.p. with
stock filter and silencer in place.
I admit, the induction noise is noticable. Although I can't
even hear the difference with my windows down. My
cat-back pretty much drowns out what little change in
noise there is.
And you are right, the battle rages on over this piece of
plastic. I just don't believe there is any real benefit on
mainly stock cars to take the piece out. Maybe down the
line with major mods it's a point of restriction.
I really wish Subaru had just run a snorkle right to the air
box to begin with and then we wouldn't have this debate!
08-31-2003, 04:56 PM
#14
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
The whole of any car is the sum of the parts. There is no one simple mod (turbo or supercharger but that's not simple) that's gonna make any car noticeably faster on it's own. It's all the little things combined that make a car fast and to me part of the fun. Every little bit helps is all, I never said it would make a rocket ship out of the car.
