Exhaust Question

#1

I’m currently running the stock exhaust system on my (still) street-legal SPEC car. I wouldn’t mind keeping it street legal for now, so long as it continues to pass NY smog inspection, but wouldn’t mind ditching the stock muffler for something a bit lighter and less restrictive. What options do I have?
The usual aftermarket cat-back systems (SuperSprint/Tri-Flo/Borla) seem a bit pricey for a few HP and shiny tips. Any suggestions?
Thanks,
Rob

#2

Over to you on what you want to end up with, but I wouldn’t spend too much $$ on a Muffler and definitely would not drop alot on shiny system that will not make any real power gains.

For street…I’d just go with the least expensive most durable option avialible. There is almost no HP to be found aft of the cat on these cars, so it’s foolish to spend much.

If you have to buy something to replace a worn out stock muffler, go with something like a Flowmaster Super 40. Costs about $80 and will last forever. Not too loud for the street but you get better flow.

For a full-on race application, I recommend having the muffler shop cut the pipes just forward of the cat (i.e. get rid of it) and weld up twin 2in tubes each with its own glass pack. Good sound, good flow, decent HP increase and very inexpensive.

hope this helps

#3

…not sure of rules and whats allowed but Borla, magnaflow, and as mentioned…Flowmaster, make straight thru ss muffler cans that are inexpensive.

RJME…I needed some exhaust work so Im having a full system built incl hi flow cat into single 2.5 " system…will come by if u r interested. JoelK.

#4

…not sure of rules and whats allowed but Borla, magnaflow, and as mentioned…Flowmaster, make straight thru ss muffler cans that are inexpensive.

RJME…I needed some exhaust work so Im having a full system built incl hi flow cat into single 2.5 " system…will come by if u r interested. JoelK.

#5

If you are planning on running the car as a Spec E30…the exhaust configuration must remain stock. For example, an i car needs twin pipes all the way back.

#6

nasaregistrar wrote:

thanks…will go back to dual oe set up when I go spec racing…

#7

nasaregistrar wrote:

Good comment Sean.

I had straight pipes and got called-in while leading KP during a BMW CCA enduro, for being over-loud. I had a local muffler shop install a couple of cherry bomb straight-through mufflers and it’s fine. Still loud but under the regs of the tracks.

They were $50.00 each and he installed them for free…actually, I gave him a bottle of our best heavy-duty handcleaner.

Carter

#8

Just curious- If the "stock configuration" for an i car must be followed, wouldn’t you be limited to one dual entry-twin tip muffler. On my car I just cut the cat off and welded a single pipe to a single muffler. Simple and effective. I just don’t see why it even matters. If it passes sound regs, hp differences would be minimal. Just my two cents.
Ryan

#9

Ryan:

We are allowing a muffler in each pipe because that’s how many of the drivers did it from the start.

And we require the twin pipes because that’s how the cars came from the factory, and at this point, we’re not going to change the rules. In performance, it probably doesn’t matter but we’re going to keep it consistant.

And once it’s done, you won’t have to change it to try to figure out which is better, which makes more performance, etc. If we allow different pipe number designs, drivers will be testing different setups and that’s not what Spec E30 is about.

Spec E30 is about building the car to the Rules and coming out to race. We constantly hear questions from potential drivers who want to change certain items, add this or that, etc. After they build the car and come race, that goes away. At the track, no one has ever said, "If we could have a single pipe exhaust, the racing would be much better and I’d be having a lot more fun." or "I really miss that additional $75.00 that it cost to have two pipes installed instead of one."

But more important than any of this is the fact that our drivers know that the Rules will remain consistant and that they can rest easy knowing that they won’t have to spend a lot of money to get the latest "go-faster" part, once their cars are built.

Carter

#10

Do you allow a factory muffler with holes in it??

#11

Good seeing you guys this weekend!

9.3.4 of the rules says it all. Anything from the cat & back can be "replaced". Now, "replaced" is spelled out in 8.5. Glasspacks and 2+" tubing hardly fit the "replaced" definition.

So, it can be easily argued that all the front runners are illegal. Looking at the cars @ SP this weekend, only Steve K, Vic, and Han have a legal exhaust (because they are the stock pipes, cat removed, and muffler in the stock location). That is unless the rules change "replaced" with "modified".

Im new to all this but its unfair if someone built a car to the letter of the rules, showed up at the track, and saw what was running.

That said it makes sense to change the rules. No one will argue the extra 10+ hp over the stock exhaust is a bad thing. Glasspacks are cheaper too. A win-win in my book.

Jut playing the devil’s advocate,
SMD

#12

smdubovsky wrote:

[quote]Good seeing you guys this weekend!

9.3.4 of the rules says it all. Anything from the cat & back can be "replaced". Now, "replaced" is spelled out in 8.5. Glasspacks and 2+" tubing hardly fit the "replaced" definition.

So, it can be easily argued that all the front runners are illegal. Looking at the cars @ SP this weekend, only Steve K, Vic, and Han have a legal exhaust (because they are the stock pipes, cat removed, and muffler in the stock location). That is unless the rules change "replaced" with "modified".

Im new to all this but its unfair if someone built a car to the letter of the rules, showed up at the track, and saw what was running.

That said it makes sense to change the rules. No one will argue the extra 10+ hp over the stock exhaust is a bad thing. Glasspacks are cheaper too. A win-win in my book.

Jut playing the devil’s advocate,
SMD[/quote]

Steve,

I respectfully disagree with your assertions above.

8.5 states:
"Replaced" means that the item may be replaced with items meeting or exceeding OEM specifications.

9.3.4 states:
9.3.4.1. Any part of the exhaust system beginning with and including, the catalytic converter may be replaced, unless a replacement system is specified in these regulations, provided:
9.3.4.1.1. Replacement system retains original configuration, (e.g. single or dual, etc).
9.3.4.1.2. The system exits from beneath the body in the same approximate location(s) as the original system.
9.3.4.1.3. Catalytic converter may be removed.

Given the two sections you quoted, 2+ inch pipes and glass packs would meet or exceed OEM specifications. They would only be considered modifications if:

  1. They were switched from single to dual or vice versa;
  2. They exit the body of the car in a different location as stock.

A replacement system has not been specified in the regulations, so it looks like the front runners are still legal.

-Steve

P.S. I would also be illegal since I have 2+ inch pipes going to a sport muffler.

#13

Steve, you need to be VERY carefull here. I don’t think a 100db muffler meets OEM specs (it surely doesn’t since it would fail the european and US noise limits). A stainless muffler and pipes of the same size, type, and location would fit the "replaced" definition better.

By your definition one could read into other rules (doing a quick pdf search on "replaced"):
9.3.1.2.3. Rings may be replaced. (Do you think one can run low pressure or even missing oil control rings for less friction? The factory probably only specs thickness & end gap)

9.3.1.2.5. Valve guides may be replaced. (Can one use a cut down or tapered aftermarket guide to improve flow? The factory probably only specs ID and wear limits. What if an aftermarket guide just happens to be 2mm shorter?)

Now, of course Im taking all this to a silly extreme. Im used to writing (and reading) specs. All Im really saying is that there IS an ambiguity in the specs that the original poster brought up. No one wants a 400 page spec, but changing a word or two is pretty painless.

SMD

#14

Guys.
More rules is certainly not what I’m in favor of. Simplified rules yes. If rules are rules than two mufflers are in fact illegal. Why don’t the rules state two mufflers are allowed? Why not just say exhuast from the cat back is open? If somebody w/ more time and money than sense wants to put gold plated pipes on, who cares. What is attractive about spec E30 is good close racing and seemingly simple rules. Splitting hairs over non issues is a turn off. If I have to change my exhaust to "stock configuration" I will.
Thanks, Ryan

So you know- I’m not trying to cause trouble, especially as a future racer. Just saying its free for all existing systems and potentially the cheapest for any future racers

Post edited by: rshand325, at: 2005/10/19 20:13

#15

OK - I’m convinced that adding a new exhaust to my winter projects list may have some benefits. In interest of appeasing the neighbors (during loading & unloading of the car) I’m thinking of going with a Flowmaster 40 series Delta Force Race muffler. I would imagine this would have minimal backpressure, yet keep the noise level within reason. The only problem is that on their site it doesn’t look like they sell and mufflers with multiple-inlets.

So, before proceeding, I thought I’d ask if running dual 2" pipes from the H-pipe to a 2-1 Y-pipe attached to a single-in / single-out flowmaster would be legal? I guess I would think it would be, since it still retains the dual pipe configuration (at least to within 8" of the muffler), but I thought I’d check.

Also, if I remember right the stock pipes are 2" apiece, which would give a total pipe cross-area of 2x(Pi x r^2) = 2x(3.14 x 1^2) = 6.28". In order to at least match this area, the inlet to the muffler would need to be 3", which would have a cross area of 3.14 x 1.5^2 = 7.1". I assume that this would be the best inlet diameter to use?

Thanks much for any thoughts on this. I’m no engineer - I just play one on the weekends!

Steve

#16

…stock pipes are 45mm(@1 3/4")…I belive…

#17

Joel’s correct. The stock pipes have a 1.75" diameter.

I think there was a discussion that ended saying that "i" cars with single-out exhausts were ILLEGAL.

I think the cheapest, legal, best performing solution is the following:

  • After your x-pipes, go to 2" piping.
  • Run both 2" pipes all the way back to glasspacks, or a really high-flow muffler
  • Keep the 2 pipe output intact
#18

Thanks for the quick replies!

Flowmaster does make a dual outlet 40-series muffler. That may be the answer.

#19

I didn’t read any official comment on whether 2" pipes and glasspacks were, in fact, legal … or whether the word "replaced" would be changed to "modified".
thanks,
bruce

victorhall wrote:

[quote]Joel’s correct. The stock pipes have a 1.75" diameter.

I think there was a discussion that ended saying that "i" cars with single-out exhausts were ILLEGAL.

I think the cheapest, legal, best performing solution is the following:

  • After your x-pipes, go to 2" piping.
  • Run both 2" pipes all the way back to glasspacks, or a really high-flow muffler
  • Keep the 2 pipe output intact[/quote]

    Post edited by: leggwork, at: 2005/11/18 14:43
#20

Still wondering about a factory muffler with holes in it…