I don't understand cat by-pass pipes
 

Hello everyone,

I was just about to place an order for a bypass pipe thinking it would give me a somewhat significant power boost. I decided to do a search and found that most people say it will barely produce any more power and change the sound slightly. This confuses me.

I have a euro spec 3.2 engine, should put out 231 hp, but a cat was installed to pass my CA smog test :( so I thought that going to a by-pass would bring me up to 231 again, as I thought I was at about 217 with the cat. Will this be the case and was I just reading about US spec cars? Or did all euro cars have the euro pre muffler?

The exhaust has been something I haven't been able to understand quite yet :rolleyes:

Thanks for any help in advance SmileWavy

You need to put in on a Dynometer to really see if there is HP difference.

But your butt dyno will tell you, your current low end torque may be lost to give way to the higher end torque at the wheels.

Sound is definitely more throaty and you may experience back fires/gurgles on decel.

My experiences,

Jim

Not sure how much you will gain without dyno comparison, but it's definitely a lot lighter. Not producing heat at the area like the cat.
If you are interested in a used one, I have it available.

I believe euro-spec 3.2 engines have higher compression, around +10:1. That's the main difference in torque/HP.

Thus, it's not just the addition or deletion of a converter.

Sherwood

Removed the stock cat and installed a sweet looking stainless bypass. (Yeah, could of punched out it out but then I'd just have a corroded hollow piece of steel that looked like crap.) Removed the O2 sensor. Steve W remapped my chip and the butt dyno says, BAM! Nice job. Feels like a new car. Pulls much better.

Most of the ROW are 9.5 not the 10.3 as believed because you cant get gas for 10.3 all around the world.
Bruce

Isn't there also a basic difference between a cat bypass and a pre-muffler?

I thought a cat bypass was essentially just a straight pipe while a pre-muffler included some baffling--changing the flow and sound profile.

There are cats, and then there are cats. Is your cat a factory unit designed for the car, or some after market piece? If your engine is a true RoW 930/20 unit, it did have 231 DIN hp (170kW) at one point. If your engine was converted to M 298 specs, it will have only 204 DIN hp (150kW). If it was converted by slick willy's conversion shop, using a modified ECU and a junk cat, it might only make 180-190 DIN hp (I've driven some converted 231 hp cars that were complete dogs!).

A test pipe might help, but it might do little more than making the car noisier. It all depends what else was done during EPA certification, you might not even have the ECU that was with the engine originally. A Euro pre-muffler is your best bet regarding the exhaust, but more info is needed regarding the ECU. I'll let the electronics gurus work on that with you.

Maybe I'm missing something here, but you also don't want to upset the car enough to fail future bi-annual tests.

Baffles? interesting I would like to know?

From what I know the engine should be almost completely stock. It is a 930/20 and I figured it would not have been changed at all especially since it only ha 23,000 original miles when it came to me. Would the PO have had to change the compression ratio or anything like that?

Also I have a SW chip programmed for the euro spec version. If I do upgrade the exhaust, how much will the chip hold back until I can have him remap it?

'78 chip? Is your car a 3.2 with a DME?

Sorry, the car is a 78 but the engine is 84 carrera 3.2 euro spec

Oh I see, then should be possible was the oil tank also updated to a 3.2 oil tank?

m 499
 

my 84 euro is the german version [m499] 10.3 comp which calls for ron 98 unleaded..i have the euro premuffler, no 0,2,a b&b 1in 2out, this is my second 84 911 euro . when retured to thier german configuration they become like a race car as it says on SW,s website. ive owned 87 and 89 3.2s and a 97 993 and for raw power you can beat a euro 3.2 for imho http://forums.pelicanparts.com/uploa...1310691593.jpg

Damn to be a Euro, Hmmmm, but to obtain pure 98 octain unmolested by eth is impossible here in People Republic of Kalifornia

I think the tank has actually been updated
What I really want to know is what that "german configuration" is

He actually said ron 98. Our 93 (mon+ron/2) works just fine with 10.3:1.

With a cat bypass you will not be cooking the left exhaust valve cover and tire when parked..it gets hot under there!

I just like to pollute the environment.....kidding. I def. noticed a difference w/ the bypass, muffler and chip. The bypass gives the car more of a hollow muscle sound.

Best bang for the buck, without doing major changes, is cat-bypass with a SW Chip. better all around performance, and MPG's too! The OEM muffler actually flows fairly well, but a significant improvement can be had with the bypass!

The oem cat is very restrictive. I run a sport cat with modern design. It and my sport muffler work great and is no different in the seat dyno w/o the combo.

what you really want are dual sport cats - one on each bank

P AG went to that design with the Boxster and IIRC the 996 or 997


also, CARB has deployed mobile sniffer units - if you get caught and they do a quick look under the car, you will be made very very unhappy very quickly

CARB, is that a Oregon thing?

CARB - California Air Resource Board. It's a California thing. ;)

Damn Ba$turds, well my M&K looks like a cat :P

http://forums.pelicanparts.com/suppo...eys/paddel.gif ROFLMAO...

What are the penalties of being cought without a cat here in CA?

Do you guys prefer the euro pre mufflers or the bypass?
The premuffer should get just a few more ponies right?

Air Board: GHG Sniffers for Research, Not Enforcement
February 8, 2010 | 4:09 PM | By Craig Miller

FILED UNDER: Government & Business, Air, California Air Resources Board, Emissions, methane, Policy, Technology

Scientists in California have begun setting up a statewide network of monitors to track California's greenhouse gas emissions. Similar equipment has been in place for years as part of a continental network established by the National Oceanic & Atmospheric Administration (NOAA). But officials at the California Air Resources Board (CARB) say this new system will be the first of its kind.

"The unique thing about this is that we're actually looking at the local emissions, rather than the global average, says Jorn Herner, who heads the Greenhouse Gas Technology & Field Testing Section of CARB's research arm. "Nobody has done that before."

Scientists have been systematically tracking atmospheric CO2 on a broad scale since 1958. California's network of GHG sniffers will be capable of tracking CO2, nitrous oxides and other known greenhouse gases, and will initially focus on methane.

But CARB officials say the network is not part of a "Big Brother" strategy for emissions compliance. "This is initially a research project," said Herner. He says the new network will provide a "second data point" to augment the state's current method of estimating GHG emissions. Currently California's current climate law, AB-32, relies on a "bottom-up" system of estimating emissions from individual sources, then adding them up to arrive at total emissions for the state.

"The modeling won't tell you each individual source but what you'd be able to do is develop a gridded inventory. So you'll be able to say in this square mile of land over here, it looks like emissions are much higher than in this square mile next to it."

The Air Board has purchased seven "next-generation" analyzers from Picarro Instruments in Sunnyvale. Five will go to fixed locations, such as a tower on Mt. Wilson, above the Los Angeles Basin. The two others will be on "mobile platforms;" electric vehicles that can roam the state taking ground-level readings. The units cost about $50,000 apiece but Picarro executives say they are self-adjusting and require far less human intervention than previous models, which will ultimately make them more cost-effective.

Picarro's CEO, Michael Woelk, says a nationwide network of 500-to-700 detectors could yield a comprehensive GHG map of the US with resolution down to ten kilometers (a little more than six miles).

If California regulators are successful at putting in place a statewide or regional cap-and-trade system for greenhouse gases, industrial emitters will have to pay fees for the carbon they pump into the air. Horn agrees that at that point, some kind of check on the current system of self-reporting will "probably" be needed, but, he says, "that's not the goal of this monitoring network at this time."

"The science is really young," he explained. "We’re really just trying to find out the potential of what we can do with this network. How it’s used in the future is still up in the air."

…so to speak.


Air Board: GHG Sniffers for Research, Not Enforcement | KQED's Climate Watch

This was just over a year ago. How long will it be before they pull up to your car in a parking lot, hook it up and transport it to a crusher?

uh huh - and the US Navy is putting scientific research buoys all over the pirate parts of the Indina Ocean just for research; it is only to help out scientists...