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Old 03-27-2005, 09:04 PM   #1
komm.zu.mir
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Question Scoobysport exhausts for NA.. Confusion abounds.

Okay, I'm confuzzled. I'm looking to get a Scoobysport sooner or later, but while looking at the site (rallyperformance), it seemed that most of the exhaust components offerred are ideally for the WRX and STi, not the N/A cars (despite the fact that I chose the N/A "section").

Which of their exhaust solutions would you N/A owners suggest?

Also, when I see a post mentioning the "Hayward & Scott" ver., are the posters writing in reference to the "Rallye" style (as RallyPerf mentions H&S as well when describing the Rallye)?

Thanks in advance, all.
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Last edited by komm.zu.mir; 03-27-2005 at 09:05 PM. Reason: "exhaustus" ^.^
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Old 03-27-2005, 09:37 PM   #2
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I've got a H&S scoobysport, it's bolted up to a stromung midpipe. No modification of the flanges needed, I just used smaller bolts.

Since an exhaust with a 2.25 ID is ideal for our cars, you'll want to stay as close to taht as you can. Unless you're seriously modded (heads, cams, etc...) you won't realize any gains from going to a full 2.5 ID exhaust.

IMHO why would any company spend time and money researching how to make parts for a N/A suby when turbo cars are much easier to "open up".

As for your question about the rallye? I dunno.
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Old 03-28-2005, 07:19 PM   #3
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I had one of these on my last RS.
Here's what I liked about my ScoobySport axle-back:

It sounded pretty good under throttle.

Here's what I didn't like:

It took more than 8 weeks to get here.
It was a WRX axle-back(3") with a reducer flange welded to it so it would mate with the RS mid-pipe.
It fit like crap.
It cost more than my current cat-back, and didn't sound, or perform as well.

The problem is that the axle-back they make, is for a European WRX, read: turbo. It is 3", and is simply too big for the N/A RS, I lost backpressure, and therefore, low-end torque, and it sounded like crap everywhere except full throttle, because with the 3" you lose exhaust velocity, and ended up sounding like a fartcan. There is ALOT of hype with the H&S Scoobysport exhaust, it's really not worth it.

Yes, it was a brand-new, Hayward and Scott made Scoobysport axleback.
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Old 03-28-2005, 07:34 PM   #4
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Hayward and Scott = Scooby Sport, based in the UK, made all the orig scooby sport exhausts.

Scooby Sport USA exhausts are now made by janspeed (i think) to scooby sport specs.

If you talk to anyone who has seen the two the quality of the H&S scoobysport far exeeds its janspeed counter part.

Do yourself a favor, if your going to get one, contact hayward and scott in the UK tell them what you want and they will make it for you. Its gonna cost alot more but the quality is worth it.

They quoted me around 700 for 3' axle back for my project. I use to own a H&S scoobysport mated to a stromung midpipe and borla headers, best exhaust ever.

Jay
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Old 03-28-2005, 07:35 PM   #5
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Quote:
Originally Posted by deuce.five
I had one of these on my last RS.
...I lost backpressure, and therefore, low-end torque...
backpressure is bad. Losing it is good. You did however, lose escape velocity, as you mentioned.

.02

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Old 03-28-2005, 09:49 PM   #6
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Quote:
Originally Posted by gtwagon941
backpressure is bad. Losing it is good. You did however, lose escape velocity, as you mentioned.

.02

Jared
No, a certain amount of backpressure is good. Some racecars use mufflers, and not just because of sound requirements.

Last edited by deuce.five; 03-28-2005 at 09:59 PM.
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Old 03-28-2005, 09:56 PM   #7
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Quote:
Originally Posted by McDade
Hayward and Scott = Scooby Sport, based in the UK, made all the orig scooby sport exhausts.

Scooby Sport USA exhausts are now made by janspeed (i think) to scooby sport specs.

If you talk to anyone who has seen the two the quality of the H&S scoobysport far exeeds its janspeed counter part.

Do yourself a favor, if your going to get one, contact hayward and scott in the UK tell them what you want and they will make it for you. Its gonna cost alot more but the quality is worth it.

They quoted me around 700 for 3' axle back for my project. I use to own a H&S scoobysport mated to a stromung midpipe and borla headers, best exhaust ever.

Jay
This info is correct. However, They are all still made by H&S, infact, when you e-mail H&S, they'll steer you to Rally Performance, the Scooby Sport USA distributor. This is exactly what I did, infact I e-mailed H&S again, and said I wanted to deal ONLY with them, but they couldn't/wouldn't. Take my word for it.
Best exhaust ever?? That would be my lightweight race muffler purchased from Coastal Fabrication, hand-tig-welded to 2.25" stanless~all custom, best sounding Scoob ever. (and that's not just my opinion).
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Old 03-28-2005, 10:22 PM   #8
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Quote:
Originally Posted by deuce.five
No, a certain amount of backpressure is good. Some racecars use mufflers, and not just because of sound requirements.
Interesting. How can this be? Links, proof? The physics of exhaust gases leaving the engine and then the exhaust system doesn't support your theory.

sorry for the hijack.

Back on track to Scoobysports and BUMP>

Jared
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Old 03-28-2005, 10:54 PM   #9
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Quote:
Originally Posted by McDade
I use to own a H&S scoobysport mated to a stromung midpipe and borla headers, best exhaust ever.

Jay
That's basically my setup, except for a revolution motorsports header. Stock cat, sounds awesome.

Gotta love the 25 year warranty

I found mine in the classifieds, yeah it's a little more than you'd pay for anything else except a JIC full ti system, but it'll be the last muffler you'll have ti buy.
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Old 03-29-2005, 01:44 AM   #10
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[quote=gtwagon941]Interesting. How can this be? Links, proof? The physics of exhaust gases leaving the engine and then the exhaust system doesn't support your theory.

sorry for the hijack.

Back on track to Scoobysports and BUMP>

Jared[/QUOTE

It is fact. Do some research. I don't feel like teaching tonight. Try some muffler websites. We're talking N/A, not turbo, therefore SOME backpressure is good. If it wasn't, we'd all want 4" exhaust.
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Old 03-29-2005, 01:50 AM   #11
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NO. The 4" exhaust is not bad because there is no backpressure, it is because it is so large that the exhaust can't exit the system as quickly and efficiently as possible. read this thread: http://spda-online.ca/modules/newbb/..._id=57&forum=9

believe what you will, but when you tell it to other members, the vicious cycle continues of misinformation.

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Old 03-29-2005, 02:09 AM   #12
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so if backpressure is bad why do we even have exhaust pipes then? why not just put on headers and leave it? ok headers and then a really big mufler.
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Old 03-29-2005, 02:13 AM   #13
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because it is louder than you could probably stand on a daily basis (not to mention the cops that would be all over you) and there are environmental restrictions that some people are at least partially concerned with. Also, unless you want side exhaust pipes, it has to get out the back some how, unless you just dump it straight out of the header.

Jared
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Old 03-29-2005, 10:24 AM   #14
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You guys are driving me nuts. You're almost saying the same thing, but refuse to accept it. You'd rather argue. Back pressure is only good in that it increases the velocity of the gases. If you remove back pressure, then the gases slow down and you lose all the benefits of scavenging the exhaust. The key is to keep the gases somewhere around 300 ft/sec. Oddly enough, the speed is pretty much constant no matter what engine you are talking about. The whole theory goes in the toilet when you are talking turbo however.
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Old 03-29-2005, 10:36 AM   #15
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ok, if you say so. I don't see how we are talking about the same thing, but if you say so, then great. We are both on it.

Jared
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Old 03-29-2005, 06:51 PM   #16
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Quote:
Originally Posted by OneOBS
You guys are driving me nuts. You're almost saying the same thing, but refuse to accept it. You'd rather argue. Back pressure is only good in that it increases the velocity of the gases. If you remove back pressure, then the gases slow down and you lose all the benefits of scavenging the exhaust. The key is to keep the gases somewhere around 300 ft/sec. Oddly enough, the speed is pretty much constant no matter what engine you are talking about. The whole theory goes in the toilet when you are talking turbo however.
Thanks, I was TRYING to avoid an argument.
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Old 03-29-2005, 07:42 PM   #17
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The exhaust size/backpressure/etc. debate is a very heated and opinionated one, so... you're going to get some pretty heated arguments if you start one. I'm afraid you may have opened a can of worms, even if no intentions to do so.

What I do know is that H&S does indeed make US-spec "Scoobysport" exhausts. The exhaust is actually an H&S exhaust, it's just called "Scoobysport" because that's the UK company which originally ordered them to spec, and made them wildly popular. Scoobysport UK was shut down and bought out, and is now under entirely different management. Rallyperformance, the US branch, is still the same.

As far as I'm aware, the UK exhausts were transferred to Janspeed instead of H&S, not long before the buyout/changeover, in fact. (If there's any correlation/reasoning involved there, it's all speculative.) But the US exhausts are still all produced by H&S, yes.

I'm fairly certain that most come in 2.5" IDs, but can be ordered in 3" spec. I've never heard of a 3" version being "standard issue," but I suppose I could be wrong. Try Emailing another vendor for another educated opinion, such as Rich at www.daddysscp.com in Leominster, MA.
(As a former, lifelong New Hampshirite, that's pronounced "Leh-min-STAH" in New England-ese. )

Indeed a 2.25" is best for N/A cars, but perhaps using a 2.25" midpipe with a 2.5" H&S exhaust would work nearly as well.

Sorry to contribute to the confusion, if in fact that's what I've done.

=S2=
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Old 03-31-2005, 02:40 PM   #18
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With exhaust manifolds like the stock one on NA imprezas, momentum is needed to help drqw teh exhaust out of the engine. The longer the dump pipe, them larger the gas colume, and more momentum to keep moving while exhaust valves are closed to produce a small vacuum in the manifold so the engine isn't always pushing.
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Old 03-31-2005, 02:51 PM   #19
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Quote:
Originally Posted by deuce.five
No, a certain amount of backpressure is good. Some racecars use mufflers, and not just because of sound requirements.
Back pressure is a direct result of flow impedence. It could be a necking in the exhaust (causing higher pressure that forces exhaust gas faster through it), an obstruction, or a twisted path with lots of flow area change.

There is always going to be a certain ammout of back pressure due to friction of the gas in the pipe (laminar flow blah blah blah). Engines don't like back pressure, hence the exhaust that causes it are not effective. Header design has alot to do with the neccesity of exhaust velocity. Not all manifolds/headers are created equally.

Alot of race mufflers are collector designs. The design of a collector on the header has a significent effect on performance. If you replace a poor collector with a highly engineered race muffler/collector (see www.burnsstainless.com ) you will gain out put. Do not believe for a second that putting a muffler on a previously uninterupted pipe is going to gain anything. You might not lose anything, but anyone claiming a gain should be suspect.
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Old 03-31-2005, 02:53 PM   #20
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Quote:
Originally Posted by OneOBS
You guys are driving me nuts. You're almost saying the same thing, but refuse to accept it. You'd rather argue. Back pressure is only good in that it increases the velocity of the gases. If you remove back pressure, then the gases slow down and you lose all the benefits of scavenging the exhaust. The key is to keep the gases somewhere around 300 ft/sec. Oddly enough, the speed is pretty much constant no matter what engine you are talking about. The whole theory goes in the toilet when you are talking turbo however.
Welcome to my world. I walk over this land mine as a course of habit.
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Old 03-31-2005, 04:30 PM   #21
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Quote:
Originally Posted by Section 8
Engines don't like back pressure, hence the exhaust that causes it are not effective.
How can we (myself and deuce.five) be saying the same thing if what is quoted above by Section 8 is correct. That is the same thing I said.

Section 8, where you agreeing with OneOBS? How can what you say (same as me) be the same as deuce.five saying that backpressure is good? I'm not trying to start a war over who is right or wrong, just trying to gain knowledge.

Jared
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Old 03-31-2005, 06:09 PM   #22
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Old 03-31-2005, 10:40 PM   #23
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Quote:
Originally Posted by gtwagon941
How can we (myself and deuce.five) be saying the same thing if what is quoted above by Section 8 is correct. That is the same thing I said.

Section 8, where you agreeing with OneOBS? How can what you say (same as me) be the same as deuce.five saying that backpressure is good? I'm not trying to start a war over who is right or wrong, just trying to gain knowledge.

Jared
I'm not agreeing with anyone. Backpressure is a RESULT. You don't add back presure, it is a RESULT of many different conditions. Assume we measured two exhausts, and they had equilivent pressures. It sounds like you both would assume that they would be equlivent as far as power production. THat would not be the correct assumption. THey COULD be equlivent, but likely they would not. Or just think of it as not all back pressure is the same.

To boil it down, there is going to be little difference between 2.25 and 2.5 inch pipes when it comes to flowing a gas. Peak flow will be different (the 2.5 will have diffaculty reaching any where near capasity), but the increase in pressure in the smaller pipe will not be much, because there are other factors that the engine depends on that varies with what exhaust manifold/header is on the car. It isn't a one size fits all, and heads/cams do not make that big of a difference for mid pipe selection. Its a system. All the parts work together, with smaller systems there is more inherent back pressure, but it is not significent when looking just at pipe diameter, your choice of muffler will have more effect on it. Keeping in mind all back pressure is not the same, once again, the restrictive muffler creating more back pressure on the larger pipe will perform worse than the small pipe with out a pressure raising muffler, because it is not about the back pressure it is about th exhaust velocity, and momentum of the gas colum. If you neglect back pressure all together when theorizing about your exhaust you will do fine. THe only time you need to think about it is when you are worrying about it being excessive.
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Old 03-31-2005, 10:45 PM   #24
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Oh yea. You are saying the same thing because back pressure is a side effect of velocity. The idea is the same, its just that you two are at excessive polar ends. You don't understand the REASON behind it, and Duece is taking it a little to fanatically. THere are other reasons why an exhaust works or doesn't, not just gasous flow charectoristics.
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Old 03-31-2005, 10:55 PM   #25
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thanks Section 8. I do however understand the reason. College physics is good for something. Just not necessarily willing to describe it well enough in my posts.

Jared
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