Ryephile: I had this system on my car for a day: Your system looks like the Super 44 also. It was loud and "tinny" but the real problem was the drone. Unbelievably loud and annoying at exactly 3200rpm.
Here is what I ended up with, Dynomax Bullett 3" in/out 21" long. Still loud but not as annoying at higher revs. Will find out this weekend how loud it is at the races.
No, I used a Delta Force Race 40 series 8.5" body. Essentially no acoustic amplitude reduction over an open pipe. I'm guessing you had a big resonance at 3200 rpm because you had no center muffler to change the tuning frequency? Running a huge volume center muffler helps tons to quiet down the car [incidentally on both R53 and R56]. --->minispeedrcr: Good to see you were able to fit something in there, although it'll only take the edge off it might be enough to be tolerable.
No, I have a center resonator/muffler. It doesnt help. But the Helmholtz solved all the problems. It's an elegant solution with known parameters. Mufflers seem to be a "trial and error" solution--time consuming, expensive and with no mathematical model to consult to simplify the testing/experimental process. I've learned by talking to many of the people with straight exhausts on R53s that they have a much higher tolerance for droning than I do. Good on them, I say! As for the R56, the turbo seems to solve most, if not all, of the potential droning problems--I haven't heard one complaint of a drone on the R56?
It's possible to do a straight-back without batt box removal... Showing a G4, and the 2.25" G4 prototype. Adds between 12-15WHP, no foolin', and the "burble" causes folks to "duck and cover". Definitely want to look into the Heimholz though...
Wow... I've got scrapes on my battery box skid/protector plate... I'd hate to see what I would have done to that exhaust pipe over the past 6+ years on my car! It would be nice to get a little more clearance around the back pipe, though... On a drive across at MOTD in 2011, I got a stick jammed up there between the back pipe and the shifter housing... that sucker was smouldering after a 15 minute hard drive and it smelled like I had a campfire under my car.
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...
If you look at the Yellow Mini in the exhaust sound off thing from MOTD this year you will see and hear the exhaust I made. I lent it to my friend when his exhaust broke and he was low on funds. It makes power and is 2.25 under an un modified battery box on a lowered car. The yellow car with my exhaust:YouTube - Broadcast Yourself. See it, believe it, it can be done and sounds great on an R53. All cars in the sound off:MOTD 2012 Exhaust Sound Off - YouTube
Mine's actually the Checkmate in the Exhaust Sound Off thread... 2.25" under the batt box, including 2 inline louvered SS glasspacks and a corvette tip... and available commercially in stainless from G4 (see Mark's post, below...), it's also available in several versions, from mildly aggressive to "holy crap". [ame]http://www.youtube.com/watch?v=lSrcbA6B_eM[/ame]
You do not have to relocate the battery and delete the box. Our system is a simple install and adds between 13 to 17 hp depending on other mods. Look on our web site and contact me for further info and specs. Mark
Hi folks. I'm the new owner of Dr. Phil's Mini. I have to say the car is awesome. Except for the exhaust. It was left with the straight pipe exaust system pictured at the start of this thread. Removing this has become my top priority for the car. The reason: The 5 hour drive from Tacoma (where I bought it) to home in Spokane WA was probably the worst and best time I've ever had in a 'new to me' car. Best in that the car handled and drove very well. The worst because of the horrible drone at highway speeds. And 5 hours of it was damn near torture. Luckily I had the earplugs I carry with me for flights on Q400's. Otherwise I might have stopped and had the car towed! It was that bad. Now that I've had it home for a couple weeks, I've had a chance to do some research on different exhausts and found this thread. So, I'll be un-doing the straight through exhaust and replacing it with a dual muffler design (not decided on which one yet) and will be relocating the battery back to where it was. This means I'm going to fabricate a new battery box and in my mind, correcting a pretty bad mistake by the previous owner. The rest of the car though is, like I said earlier, AWSOME. I've got very little to do to make it what I need for autocrossing/HPDE & FATT.
Wow! Always wondered where his Mini went. Very cool that you now have it I remember his adventures with that exhaust :crazy: Don't see any need to try and put a battery box back in? Didn't he use a couple small batteries and lay them in the back? Also, a few people have had some success in using R56 straight exhausts on their R53, just a thought?
Hi Jim! Yeah, not sure what happened to the smaller batteries but when I bought the car it had a full size Optima yellow top and a carpeted box covering it. :confused5: It really doesn't go with the car so it's got to go. I'll check into the R56 exhaust. Thanks for the suggestion!
Yea, a couple of guys in our club with straight exhausts are using 2 small motorcycle type batteries with good results. They actually lay down, and end up being level with the seating area floor, if you know what I mean? Then they added a floor cover over the top to make it all level. Comes out really nice Think all those pics can still be found here, or hate to say, on NAM.
It's been proven many times you do not need to move your battery to have a straight exhaust on an R53. I have had one on my car and we put it on my friends yellow Mini for the Dragon last year. The link is in a post above. I have my Milltek on now but I think I will put the straight exhaust on again this year for the Dragon. I will also say you have lots of room for it under the battery box and I have NEVER scraped the exhaust and my car rides low.