We have tested a Renesis 6-port engine on the dyno with MANY different exhaust configurations. We have run several different types of headers, with cats/without cats, and at least 10 different prototype mufflers in an attempt to uncover the potential for performance improvement in the exhaust system. We have read with amusement of some of the rather wild numbers being thrown around with regards to some of the HP claims being made about some of the exhaust systems currently on the market.

The “open” exhaust tests were conducted with a larger RB connecting pipe behind the stock exhaust manifold and cat section. The muffler section was simply removed from this connecting pipe. (Running the stock connecting pipe during testing was impractical due to the “slip-joint” that Mazda incorporated into this tube. The RB pipe was fitted with a flange that could be bolted up to each aftermarket system and our prototypes.)

The best results were found without any cats, but even running two presilencers and a muffler, the exhaust note was extremely loud! This might work for the hardcore guys, but the average person would soon become tired of this racket.

We will post an in-dept article on our findings in the near future. I am working with Jim Mederer as we organize and format the data that has been collected.

Jim Langer
Racing Beat

 

thanks for the update

 

I've been a big fan of the RB exhaust systems for quite awhile. Awesome build quality, and wonderfull tone. When the time comes (wife approval) I'm going to go with a RB unit. CJ

 

Jim/Racing Beat, have you considered (a) trying the exhausts with a high-flow catalytic converter, and (b)Header plus exhaust port work (and cat+muffler, of course)? I hear the stock ports are cut such that a header alone won't help much, as it usually does with most engines.

 

Although we are familiar with the term “high flow” cat, what exactly does this mean? I have yet to see ANY documentation with any of these units comparing any type of exhaust flow data to the stock unit, right?

We tend to stay away from the rather touchy issue of replacement cats for street use. In California, the Air Resources Board does not look lightly upon the replacement of cats with any type of “high performance” unit. As long as I have been working with CARB, it is my understanding that moving, relocating, and/or “upgrading” the cat is not permissible. A cat can technically only be replaced if it has failed, and even then CARB would want to know why a cat has failed so early on such a new car.

It would be hard to claim a “high flow” unit is a “race” component since not too many cars use cats on a track. I am certain that there will be these types of units offered by some vendors in the future, I will let them assume the increasing risk of getting busted by CARB or the EPA.

We are in the process of developing a both a downpipe and header for the RX-8, but these will clearly be intended for racing applications and not intended for street use.

Jim Mederer will be undertaking porting research in the near future. Currently, stock engines are very limited and we are undertaking baseline readings before the engine is disassembled. Once we modify the engine, making comparisons against a stock engine is not possible.

Jim Langer
Racing Beat

 

Great Jim, thanks for the well thought out, complete response.

As for the high-flow cat, Random Technologies has a unit that they claim adds 8 to 15 HP and Lbs of torque (depending on the application) due to reduced exhaust restriction. Check their website for more info: http://www.randomtechnology.com/ . They're pretty clear on their claims.

I can understand your concerns about offering a kit that includes a replacement cat... but it might be worth doing the research so that you can at least discuss that option with your customers if they ask... then whatever they do, they do at their own risk. Besides, there are 48 states that don't have the same stringent emmissions standards as California does. Just a thought.

Also, I'll be VERY interested in hearing about your port work.

 

The biggest HP gains that we have measured on the Renesis have been without any cat on the car, but we haven't seen any gains of up to 15HP through our exhaust program.

There are indeed other states that have adopted the CA emsissions standards. The Feds didn't want to have 50 different sets of emsission laws on the books, so they offered either the FED or CA standards to the states. At least five other states have adopted our CA standards (NY, NJ, NH, ???... correct me if I am wrong.) Many states now have programs that require tailpipe emissions tests, making "cheaping" more difficult.

My main point is that this is a VERY sensitive issue and the more prudent aftermarket manufacturers are paying close attention to the potential negative legal ramifications.

Jim Langer
Racing Beat

 

When you dyno the car with different exhaust combination, did you datalog the a/f ratio? Any a/f ratio changing from different combination?

rx7.com has info on their midpipe and greddy cat-back exhaust system. They claime a 21 rwhp gain with the midpipe and cat-back exhaust and they claim the exhaust tone to be mild. what's your thought of that?

Another vendor offers ECU tuning that is supposed to gain 20-25 rwhp with complete stock system and with a midpipe, it will gain about 30-35 rwhp. What's your thought of that? Do you think it's safe to tune the renesis motor with a 13.2 a/f on 91 pump gas?

I trust your company more than anyone else. Your black 235 mph rx7 is simply amazing!!

 

How close are you guys to finishing the catback.. I would realy like to have it my xmas..

 

If I remember it correctly you cannot change your cat converter until you have 5 years or 50K miles per EPA standard. I think RandomTech website says that too.

The only exception is that the cat fails. How a brand new cat can fail is beyond my imagination. I live in CA and I care a lot about CARB certification.

So, when is RacingBeat going to release its catback exhaust?

 

I have a call in with my CARB rep, I will let you know their position on cat replacement for CA. What CARB doesn’t want to hear is that a cat has prematurely failed. If a cat has failed, they will look at the causes of the failure and potentially require that the manufacturer issue a recall if there is a widespread problem.

This in part plays into the “lost power” issue with the RX-8. Mazda’s engineers have programmed the car to run “rich” at higher RPM’s in order to keep the exhaust gas temperatures down. Running a leaner mixture at these higher RPM’s may overheat and prematurely damage the cat, risking that dreaded word to every car maker….. recall!

We are certainly working on the exhaust, but the man-in-charge is currently in Japan and I must wait a couple more days for an update. My guess is that we are still several weeks away, sorry.

Jim Langer
Racing Beat

 

Just got off the phone with our CARB contact, here’s what I know. The following information only applies to CA, the Federal standards may be different.

Let’s only talk about a 2004 RX-8. If your car has been involved in an accident, you must replace the unit with an OEM replacement. Depending on the new vehicle emissions certification for that particular vehicle, a cat has been designated to last a specified time period by the car manufacturer. This might be 50,000, 100,000 or even 120,000 miles depending on that particular car. If the cat has PROVEN to have failed during this mileage period, the cat can be replaced with an OEM unit under the emissions warranty for that vehicle.

Can you place a “high flow” cat on your car and be “legal”. Legally, no. The cat cannot be replaced, moved, or repositioned and still be emissions legal. Can you still get your car smog checked during a tail-pipe emissions test with a “high flow” unit on your car? Not legally, but your car may slip through the system unnoticed. Much depends on the testing facility.

It is also possible that a less efficient “high flow” cat, may alert the trailing O2 sensor of a “failing cat” and trigger a check engine light or register a trouble code.

What if you really wanted to play by the rules and replace the cat with a legal aftermarket unit? Since the car is certified to ODB II standards, the cat must be a ODB II certified unit. According to our CARB contact, there are only a very few units that have received this approval, and they are only for select domestic applications.

Jim Langer
Racing Beat, Inc.

 

Good info Jim!

Any idea what Federal department writes the laws for things like this? (Read, outside of cali )

 

Thanks Jim.

 

My understanding is that the EPA writes the laws for the Federal standards.

 

Solution: move to Texas, and in particular a county that does not perform emissions testing. Not that I favor polluting the environment, I just like all the cheap HP I can get...

:D

 

We could move the RB shop to Texas, but our morning commute would be a real lon-distance pain!!! If we could bring the So Cal beaches and weather with us, and we might consider moving.

Don't think you are out of the woods when it comes to emissions, things will only become tougher for ALL states in the future.

Jim

 

In Colorado, new cars are emissions testing exempt for 4 years. :D

 

Guys,

Educate me about emissions testing in YOUR state.

1. What state and city is your car registered in?

2. Are you required to pass a tailpipe emissions test?

3. How often is testing required?

4. Is there a "visual test" that is performed prior to the tailpipe test to verify that the required emissions components are in place?

5. If you purchase a new car, how many years is your car exempt before the first emissions test is required?

Let me know any other details that you think are relavant.

Jim Langer
Racing Beat

 

Miami, FL. No emissions testing anymore. Got canned a couple years back since it was unecesary and besides, all the damn lazy latins just paid on the side to pass anyways. Yes, I am a lazy latin but I didnt pay. My neon was the bizomb. It passed on it's own.

See, you can have the beaches and sun (more of it actually), AND no emissions to worry about.

plus it's way cheaper than Cali.

And the hoochie mama's over here are plentiful and easy too! :D

 

1. Ohio, Montgomery County (Dayton)
2. Yes.
3. Alternating years. (odd years for odd year cars)
4. Yes.
5. Exempt for first 4 years.

I believe we are the only (or one of only) counties in Ohio with emissions tests.

 

In Wisconsin, Milw County and others on the east side may have something, but nothing on the west side of the state.
Tom

 

RacingBeat has updated their product page for the cat-back exhaust.. check it out!!! Some new photos.

Click ME!!!!!!

 

I want that exhaust!!!!!!!

 

that looks great but will them ever MAKE it