Borla Hush is sweet
Thread Starter
VIP Member
iTrader: (2)
Joined: Nov 2002
Posts: 3,639
From: Longing for my ol' white '02 WRX :(
Car Info: 2016 Acura RDX ... meh. Um, nice subwoofer?
Borla Hush is sweet
Had mine installed today by MPJ/GB ( since it needed a new flange welded). Sounds very nice mated to me helix dp. Before, I was running stock dp and hks catback. Then I was was catless with the hks. And now catless with the Hush. This last combination reminds me of havin the HKS w/ a stock downpipe in terms of volume, no kidding.
Just from the buttdyno, I could swear I'm getting a little more backpressure. This might bother some of the pure top-end junkies, but it sure feels like a little better response down low.
jason
Just from the buttdyno, I could swear I'm getting a little more backpressure. This might bother some of the pure top-end junkies, but it sure feels like a little better response down low.
jason
backpressure is bad on any motor, n/a or f/i, the problem is if you go too big you'll lose exhaust velocity which you want to be as high as possible with minimum backpressure, n/a or f/i doesn't matter, f/i generally uses bigger exhaust piping because there's more exhaust gas flowing at a higher rate due to the turbo/blower
Im not claiming to know this but from what I've read here at i-club you only need pre turbo velocity for good spool. Post turbo you want the least amount of backpressure possible.
Thread Starter
VIP Member
iTrader: (2)
Joined: Nov 2002
Posts: 3,639
From: Longing for my ol' white '02 WRX :(
Car Info: 2016 Acura RDX ... meh. Um, nice subwoofer?
It really depends on who you ask. I've heard both sides of the argument, for NA and turbo before. And, both sides from reputable sources... including dyno plots. I think its just application specific. The only justification for what my buttdyno senses that I can think of is not a direct result of "less" air flow, but a byproduct of it. That is, heat. A constricted flow produces more heat. So while volume may be less, perhaps the flow is quicker. WTF do I know, eh?
jason
jason
iClub Silver Vendor
iTrader: (12)
Joined: Mar 2003
Posts: 8,228
From: 631 Railroad Ave. Fairfield, CA
Car Info: A Laptop
the ideal exhaust for a turbo is a big, smooth, horn on the end end of the turbo. You want the least amount of back pressure after the turbo while still keeping the flow somewhat smooth at the turbo's outlet. I have yet to see any data to prove that more back pressure makes more low end on a turbo engine. I've also yet to see any justifiable physics arguments to show this.
The fact of it is that a low compression, small displacement motor is not going to be making any significant torque without boost. The less restriction there is after the turbo, the quicker it will spool and make boost... period. I don't understand how people expect to get more low end with a more restrictive exhaust that slows down the spool of the turbo.
-- Ed
The fact of it is that a low compression, small displacement motor is not going to be making any significant torque without boost. The less restriction there is after the turbo, the quicker it will spool and make boost... period. I don't understand how people expect to get more low end with a more restrictive exhaust that slows down the spool of the turbo.
-- Ed
Thread Starter
VIP Member
iTrader: (2)
Joined: Nov 2002
Posts: 3,639
From: Longing for my ol' white '02 WRX :(
Car Info: 2016 Acura RDX ... meh. Um, nice subwoofer?
Originally Posted by vaus
I don't understand how people expect to get more low end with a more restrictive exhaust that slows down the spool of the turbo.
-- Ed
-- Ed
jason
[edit] p.s. remember, I said "faster flow" not "higher volume"
iClub Silver Vendor
iTrader: (12)
Joined: Mar 2003
Posts: 8,228
From: 631 Railroad Ave. Fairfield, CA
Car Info: A Laptop
Wrapping the exhaust post turbo doesn't have much of an effect on power or spool. Any effect that it does have comes from more heat being retained in the exhaust. Although the hotter gas takes up more volume, the velocity increase is more significant, so you're not actually increasing backpressure by retaining more heat.
-- Ed
-- Ed
Thread Starter
VIP Member
iTrader: (2)
Joined: Nov 2002
Posts: 3,639
From: Longing for my ol' white '02 WRX :(
Car Info: 2016 Acura RDX ... meh. Um, nice subwoofer?
Originally Posted by vaus
Wrapping the exhaust post turbo doesn't have much of an effect on power or spool. Any effect that it does have comes from more heat being retained in the exhaust. Although the hotter gas takes up more volume, the velocity increase is more significant, so you're not actually increasing backpressure by retaining more heat.
-- Ed
-- Ed
Hey remember everyone, if its on the Internet... ITS TRUE!
Registered User
Joined: Jun 2003
Posts: 273
From: Good Ol' LA
Car Info: 03' WRB
my buddy and i had identical turbo rx7s. i had a racing beat 3" exhaust and he was running stock with some glass packs. i had a more free flowing exhaust where he had a little more backpressure because of his more restrictive exhaust. he could always take me 1st threw low 3rd, but towrd the top of 3rd to 5th i was just walking him... we thought it might be the driver but we switched cars and it was the same result. i dont know i personally think that the best exhaust for a turbo car is no exhaust. but hey thats just my .02 centz
<
))><
<
))><
iClub Silver Vendor
iTrader: (12)
Joined: Mar 2003
Posts: 8,228
From: 631 Railroad Ave. Fairfield, CA
Car Info: A Laptop
Originally Posted by Christian
my buddy and i had identical turbo rx7s. i had a racing beat 3" exhaust and he was running stock with some glass packs. i had a more free flowing exhaust where he had a little more backpressure because of his more restrictive exhaust. he could always take me 1st threw low 3rd, but towrd the top of 3rd to 5th i was just walking him... we thought it might be the driver but we switched cars and it was the same result. i dont know i personally think that the best exhaust for a turbo car is no exhaust. but hey thats just my .02 centz
<))><
<
))><-- Ed
Thread
Thread Starter
Forum
Replies
Last Post
06scooby
Ongoing Projects
10
Oct 6, 2006 10:47 AM
Crisisback
NorCal Classifieds
6
Jul 20, 2004 08:25 PM