Most liked posts in thread: Straight exhausts on R53

Not really but I was able to dissolve any kidney stones with the ultrasonic vibrations.

 

G4 has worked HARD to bring noise levels down on the R53 straight-back, but the little R53 popcorn poppers are TOUGH to quiet down. After more than 13 attempts (no foolin'!) at a "subtle" prototype, G4 has called it quits on the "subtle" system and resigned themselves that the G4 R53 exhaust will only be offered in "aggressive" and "race" versions.

The length of the R53 exhaust, combined with both the interior volume and the resonant frequencies of the bodyshell seem to create a convergence

G4 has found 12-15 HP - which is certainly noticeable - and the exhaust tone is rather good, so if you want an aggressive, powerful system with Corvette tips, G4's got that covered! But... subtle it's not.

 

I understand, but I've been running versions of that exhaust for 2 years - the installation can be done successfully, but takes a lil' effort (not a simple bolt-on), need to add a muffler hanger on the battbox.

G4 ran dyno tests on the 2.5" system and it absolutely frees 10+hp, dyno'd at 14+ gain over OE (2 cars more, 2 less), simply because the OE system has at least seven 90 degree bends in it, restrictive mufflers, and at least two flow restrictions where pipes change diameter. Even the other split systems (Borla, JCW, Strat, Milltek, etc.) have 4 bends on each leg plus that "split" which does cause some exhaust turbulence. That's still MUCH better than OE, but not straight thru.

This one is essentially straight-thru. The 2.25" system hasn't been dynoed, but has had a good stopwatch on it (same car, same driver, same gas, same weather conditions, same long uphill straight, comparing stock, the 2.5" G4, the 2.25" G4, and the Borla Race). I admit to not having the spreadsheet anymore (don't ask :cryin: ), but the results were as expected: 2.5" fastest, followed by 2.25", Borla, and OE lagged significantly. The noise level was the inverse order.

We've even seen a difference running an open oval tip vs. the split "corvette" style tips, just due to that split disrupting airflow - there's also a noticeable difference in sound (the open oval is quieter in the car).

Aaron, your car is dropped pretty low! I can't imagine scraping my batt box - and have no scrapes on the exhaust - but I run my R53 at stock height. I've also got a diffuser that hangs some 3/8" lower than the exhaust pipe, and I admit to having scraped the diffuser running 205/50/15's, but that was on a fairly decent bump with 3 people in the car on a VERY crowned city road - and only a small scrape. Mark from G4 runs lowering springs but he's only 0.75" lower than stock and doesn't scrape with the 2.5" system.

Hope that helps...

 

G4's got the drone thing about licked. No straight-back is going to be 'subtle', but minimal drone at highway speeds. You CAN hear it clearly, but it's not that brain-busting drone of the early systems. They continue efforts on "subtle", but there's a clear tradeoff between big HP numbers and sound...

 

:cornut: "Hey! DaveO's peeing sand everybody!":wink::eek6::lol::lol:

Jason

 

Huh. What does the smaller device to the right do?

 

I vote for an audio sample

 

Is this the thread you were referring to?

 

You do know for every link to "that other site" from here you need to place 2 on there back to here.... :ihih:

 

sounds like a fair deal to me :lol:

 

Now I know where I have seen that before.....

That's a shark exhaust and a sucker fish ?

 

I believe you that it works (OEM intakes typically use Helmholtz resonators too).

It appears that they terminated the resonator pipe with a capped-off glass-pack, perhaps to knock down the Q of the resonator.

 

I have two versions of the straight through I did on MM2, one being a scavenger box Flowmaster during the supercharged setup and the latter being a shot while fabbing the exhaust for the turbo project. I cut out the battery box and relocated a small battery beneath the drivers' seat for tighter polar inertia. Yes, I used the factory aluminum aero pan as a heat-shield, it worked fantastic!

 

yes....I was just about to mention the intake application

 

Straight pipe on Race Car

So I have a Mini I race with USTCC and at the first race I had a muffler failure.
http://www.flickr.com/photos/26328383@N06/3489141656/

Any recommendation on what muffler would be a good replacement since you guys seem to have a little experience at this. Main issue is the sound limit is a 103 decibels at the tracks here in Northern California. I went out with just a straight 3" pipe and the sound was over 107 db at thunderhill. I'm running a Webb custom header in 3" that goes into a reonator just past the header then straight out the back. the current setup does have an annoying reonance at about 5000 rpm.

Vince Parker
USTCC #96 Mini

 

Hi Vince, your posted image doesn't seem to work.

Any, I defer to the other guys on exhausts. I just have a standard-issue Magnaflow (which I love) but I don't think that's what you are looking for.

 

Sorry I can't seem to make the picture thing work. suggestions?

 

Here ya go...

Instead of copying the URL right click on the image and select copy image location or something to that effect depending on the browser.