[Phocused]

Has anyone tried running a single muffler on the S? I'm looking at the fake dual setup, and I know that the faux dual exhaust does not benefit 4-cylinders (as opposed to true duals on a V8 for example). I'm curious to see if anyone has just run a straight pipe with one muffler...and if so, what kind of dyno numbers is the car putting down?

Alan

[Grinder]

Welcome to the board!

It does seem to me that i read about someone putting a straight pipe on their MINI, but i dont remember who. Try running a search and you'll probably find it. If not i can do some hunting.

[Phocused]

I did a search and came up empty handed. Maybe I'm insane, but it just makes sense to have the exhaust travel a single route instead of the funky y-pipe. Seems weird how the aftermarket hasn't caught onto this yet. If there isn't a single exhaust alternative out by the time I get my S (shooting for Feb-Mar), then it looks like I'll have to have my own fabricated.

[jlm]

garfield pioneered the single exhaust using the supertrapp muffler and claimed a substantial weight decrease and hp increase; I'm pretty sure he did it on an S

[Grinder]

http://mini2.com/forum/showthread.php?s=&threadid=17326

I'm not sure if this is what you're looking for at all...

[Garfield]

That link is for a Cooper with a straight pipe, which may work. But the Cooper S needs back-pressure, which is why I did the Supertrapp. Also, I was trying to loose weight and make room for the hitch to pull my tire trailer. Do a search on Supertrapp and you'll find plenty of pics and stats.

Brian

[benggolf]

Here is another single pipe exhaust system for the MCS from Rogue Engineering.It weighs only 28 lbs.

MCS Single Exhaust System

[helix13]

We have prototyped a single muffler, center exit exhaust for the MCS (we're up to our 3rd version). Sounds good, looks good, problem is: It doesn't make power. We're going to play with the muffler baffling to adjust back pressure. Join our mailing list for updates at helix13.com.

[podger]

The exhaust in the centre is restrictive anyway, I want to tow a motorcycle trailer , and at present I can't , because I can't get a decent tow hitch in the UK

[macncheese]

Quote:

Originally posted by Phocused
Has anyone tried running a single muffler on the S? I'm looking at the fake dual setup, and I know that the faux dual exhaust does not benefit 4-cylinders (as opposed to true duals on a V8 for example). I'm curious to see if anyone has just run a straight pipe with one muffler...and if so, what kind of dyno numbers is the car putting down?

Alan

The factory S setup is a single muffler setup, no? I've never seen the innards of the factory system but I'd imagine that one is a resonator and the other is the muffler. The exhaust tubing is in series so all exhaust is flowing through both "boxes"


--
Dave
æ

[CurtP]

Quote:

Originally posted by Garfield
But the Cooper S needs back-pressure, which is why I did the Supertrapp.

Artificial atmosphere engines (i.e., turbo and superchaged) do not like or need backpressure. You've got that mixed up with naturally aspirated engines, which (if done correctly) can produce more HP and torque in the low to midrange RPM area with a bit of backpressure to help scavanging of the exhaust gasses from the cylinders. The positive pressure in the intake on a turbo/supercharged car force the exhaust gasses out of the cylinders during valve overlap, so any exhaust restriction would only be detrimental. However, this is more noticable on a turbocharged vehicle, since backpressure affects the turbocharger RPM.

[benggolf]

Curt P, I quite agree with your statement that super-charged and turbo-charged engines will benefit from eliminating exhaust restriction unlike naturally aspirated engines which need a certain amount of back-pressure to conserve torque at low to midrange RPM.

From what I have read from MCS owners that have swapped out their OEM exhaust, the aftermarket exhaust systems so far have not improved the perfomance of their car enough to support claims on HP gains by these manufacturers.

Have you done any independent testing with your MCS on this regard? TIA.

[macncheese]

You're saying some things correct but I dont think we're on the same page.

Positive exhaust pressure doesn't help scavenging. Scavenging is created by tuning the lengths of the exhaust runners in a manner in which the pulses from each cylinder never hit each other. You actually get a vacuum of sorts that pulls the other pulses along (and pulls in more intake charge during overlap). Less backpressure, less pumping loss, more power. No arguements.

Backpressure is never a "good" thing but some people think its sometimes necessary depending on the cam design. Its believed that if you have alot of valve overlap, the high pressure in the intake will force the charge right out the exhaust port without ever getting lit. You need backpressure to keep your charge in the cylinder and help close the exhaust valve. This may be true for some RPM ranges but will never make maximum power in an engine. The extra torque it creates is in exchange for top end power.

[Garfield]

First of all, yes, the Supertrapp DID net some significant gains. Right now, 911ETR has the sheets that I scanned last night for proof.

Second, if the NA's like back pressure, and the FI's don't, then why do the FI's loose torque the more you open them up and the NA gain by opening them up?

Am I missing the definition of back pressure? Isn't it essentially clogging the system, on purpose?

The Celica GTS want nearly NO discs or completely Open. Same with the MR2 Spyder.

It may be because I want more torque from my MCS. But when I dynoed mine many times at 4 discs, 6, 8, 10, and completely Open (22 discs), it was the 8 that worked best and at 10 I started to loose the lower end with slight gains at the top end.
Keep in mind, the more discs, the more open, the less back pressure. Or is that wrong?

I don't profess to be an expert, I just know what my experience has been.

[Targa]

Garfield helped me out with info on the Supertrap system for my Rally car. We are running a Digi Tech mod on the ECU with a smaller pully on the Supercharger (12psi max boost).

On the Dyno we had best power with 18 discs but more torque with 12. We went for the torque for the rally. The power increas was a couple of HP but the torque was about 10 ft/lbs.

We ran the exhaust out through the original centre hole (we dont need a trailer hitch) and it all worked well and sounded sporty. (too sporty for road use!)

You can see the set up in my gallery photos

[Mugami]

im going to chime in with m2cw.. if im wrong fine im wrong. on an FI machine supercharged one.. the supercharger make perssure according to the crank.. there for at low rpm its not really boosting the power. 1-3psi if i remember. so in essents its like a NA machine for low end and back pressure is needed just the same. But as the pressure increases to the 8-12 or more you would get better hp from a less restrictive exhaust. As for a Turbo FI since the turbo needs exhaust speed to spin the turbo quicker. then a less restictive exhaust will cause the pressure increase in a turbo to happen faster giving the turbo less lagg and more power all the way around. Just a thought for those making an exhaust for the S. PWC's use a Rav valve for the exhaust along with most of the two stroke bikes now a day. The Idea behind this is simple the machine needs more back pressure for torq at low rpms for better pulling power. so the valve is closing part of the exhaust up to create this backpressure yet at higher rpms it will open up to create a free flow non-restrictive exhaust for better scavenging and top end power. Could this idea be adapted to a Superchared machine to give it the benifits of better low end and yet still retain better topend power?? Im not an engineer so I dont know if its worth while or even possible. But this sounds like it would work according to the tests Garfield and the others did with the supertrap.

[Grinder]

Now I'm really curious about that as well. I think you should post that question on a new thread, as it will probably get lost at the back of this one.

[Mugami]

might do that.. but since some of the guys like garfield will most likely be reading it. I hope they will bring it up. Also on the PWC and most bikes.. the area that these systems are used are well protected. unlike a car where the exhaust Is more exposed to the dangers of the road. then you also have where these machines are driven longer and more constant. therefore is it worth while to have another part that could quit working without you knowing it at anytime. where a standard exhaust is a set it and forget it type. But not to worry I have Tons of ideas that sound great on paper but Suck in the Real world. But if I remember correctly I think Supertrap did come out with a Vairable exhaust pipe that looked like it had a spring loaded plunger in the end of the pipe. This was many many years ago and was discontinued cause the plunger would get stuck causing bikes to have to much back pessure and mess them up.

[Garfield]

I'm 30, been into car information and stats since I was 10. But, I've never been much of a mechanic or engineer. If I didn't have a wife and two kids, I'd probably be quite the gearhead.

But, if you want my opinion, sounds like a GREAT idea! I don't remember that Supertrapp setup myself.

Brian

[Mugami]

Not to worry Brian as I said the exhaust came out for only one production year if that before it was abandoned and was for a bike. this was about 1 year maybe 2 before the vairable exhaust came out on dirt bikes. some where in 1985 I think. the idea on cars are already out there.. ever heard of a Vtec engine . they allow a short duration openings at low rpms for increased torq. the open up more at high rpms for better top end. only thing is i havent seen is this being done for a car exhaust. I mention you in my posts cause I respect you for what you have said on the boards and since you do the autocross this is something you may want to persue where as I just love a great sound and Oddballish ideas. Hopefully soon I will be going after my replacement Mini S which will be as basic as I can get since im already changing just about everything already. Well have fun, be safe, and Keep motoring