While doing some research on high flow cats, I came to puzzling scenario described below:

I have spoken to both SP Motorsports and Racing Beat regarding high flow cats and visited Rotary Performance website. Here is what I have learned/been promised:

SP: Says that there is going to be about 8-10hp increase with just the highflow cat. This stems from the fact that, the stock catalytic is really restrictive. Thus their unit is quite an improvement, yielding a relatively significant increase.

RB: "We do not really believe in high flow cats for this car, since a high flow cat is still a cat and is thus still restrictive, Mazda has done a good job on their catalytic so an upgrade would be a waste of money”. Thus they don't even have one under development. They did give me a hypothetical estimate of a 2hp increase, while politely suggesting I should get their cat back system.

RP seems to side with SP on this issue, as their website shows a dyno charts with about 9hp increase at 8400rpms.

So as you can see there is a clear difference in philosophies.

[Note: All of the numbers motioned are solely for the highflow catalytic converter and do not include any other mods.]

As you can see there is a disagreement on numbers or facts between RP & SP and RB (not opinions since they are proven by dyno results).

Who is right? How can there be such a blatant disagreement on facts, after all the products are dyno tested?

I am still inclined to get a high flow catalytic, the question is which one? Or is this a pointless (at least in terms of not getting the results that I am promised) thing to do like RB suggest?

Being in Toronto I am having a hard time locating local shops that have any kind of experience with RX-8 tuning in this department, this doesn’t help me choose since I am far removed from being an expert in car tuning.

If you got any experience with the above mentioned tuners, products or any useful knowledge and ideas, your help is greatly appreciated.

 

Racing Beat has actually published that they got about a 7 hp increase from completely removing the cat.

 

Chris Buddy...it is SR Motorsports...not SP

 

I've read the same... But, he brings up a good point; how are two different (and hopefully reputable) companies posting results like this? One saying removing EVERYTHING gives you 7hp, and shows the dyno... The other saying you'll get that and 3-5 more hp, and shows you their chart?

 

Jaguar_MBA buddy ... my bad

 

It's going to be hard to answer the question directly as to which one is correct. After all you get a fairly wide range of dyno readings on these cars from vehicle to vehicle. Because of this alone it would be logical to assume that depending on the car, the results for gains may also vary.

 

Seeing as how the RX-8 cat endures some brutal temps, would anyone be worried about the durability of aftermarket replacements? I.e., does the OEM have special construction to deal with the heat?

 

RB: "We do not really believe in high flow cats for this car, since a high flow cat is still a cat and is thus still restrictive, Mazda has done a good job on their catalytic so an upgrade would be a waste of money”. Thus they don't even have one under development. They did give me a hypothetical estimate of a 2hp increase, while politely suggesting I should get their cat back system

In my opinion I would go with what RB says, if you want their CAT back system that is another issue.

Are there any members who can tell you their actual experience with 'High Flow Cats" on their 8 or rotaries. Can't see the value.

 

well, the TurboXS exhaust seems to be disproving RB's precious numbers.....

 

Take 10 stock cars, in good mechanical condition (the oil is changed, the cat is not coughed up ...), that are broken in (one can just shift at 4.5rpm all the time), with about 10.000 km
Flash them with the proper program.
Dyno them. Make sure they are at peak performance.
Take the cars that are at their peak. Put the high flow cat on.
Dyno them. Take the best result and post it. This would be the “max” a car can get with this mod.

(Do all this in the same day, same conditions, gas …)

This is in my "non expert" opinion, how it should be done. If one goes about it in this manner, statistical abnormalities should be eliminated, although there should still be some slight difference in results.

The fact that RB claims that the highflow cat is relatively useless for the RX-8 or (about 2hp increase), claiming that 8HP is the max they got with a straight pipe. While SR Motorsports claims they got 8-10hp with a high flow cat unit. In my opinion means that one of the positions is false.
I suppose that both companies have done extended research in this department and have dynoyed more than one car. They are professionals and should know how to measure and be responsible for results.

The argument by Rotarygod:

“It's going to be hard to answer the question directly as to which one is correct. After all you get a fairly wide range of dyno readings on these cars from vehicle to vehicle. Because of this alone it would be logical to assume that depending on the car, the results for gains may also vary.”

Assumes, if I can borrow a line from the “brilliant” Walter Sobchak (The Big Lebowski) “we are dealing with a bunch of amateurs”

(and I don’t think either RB or SR fall into this category)

It is either this or the fact that one of the companies position is clearly not correct.
We are dealing with physical facts here and although there can be some discrepancies there cannot be a direct disagreement.

And for anyone who has not seen “The Big Lebowski”, watch it.

 

Who's trying to sell you a product...and who's not

"Follow the money" usually smokes out a large # of these issues........

RB has been know to be uber-conservative in the past....others....well, maybe not so

 

dannorbe:

what do you mean by "follow the money"? If you mean that I should follow whatever other people have done - Then my question is why? What does this solve or prove? You are assuming that those people have done extensive research and came to a definite conclusion.

If there is anyone here who has done a before and after dyno with a highflow cat, I would like to hear from you

 

last time i checked anyone producing a consumer good is trying to sell them...

lets talk about exhausts... RB claims 5hp is the max gain possible and thats why they only gain 3hp. They also provide no dyno's. Borla has a dyno showing 8whp gain. TurboXS has a dyno showing 12hp gain. Rotary Performance has a dyno showing 10hp gain. Sr motorsports and JIC also with similar numbers to show this... they are all out to sell you something, but there only seems to be 1 that doesn't agree with the others...

hmmm

 

I will say that most companies out there do a dyno run or 2 on a chassis dyno, make their change and then go back and dyno it again to post gains. Nothing wrong with this. This is how most do it out there. We do know that the baseline dyno readings on these cars can vary by as much as 20 rwhp so I don't think anyone being an amatuer has anything to do with it. I do know that Racing Beat uses an engine dyno and has done hundreds of dyno runs on these engines and constantly do so on a regular basis. They use the same engine for back to back testing and they do it over and over again many times over many days and then take an average over the course of each session. That's pretty thorough. Since they know that an average means you may get more or less than what they state, they publish a slightly lower number just to be conservative. If your car gets the advertised amount, it's what you expected. If your car gets more, you are even more happy. Racing Beat did test several other systems out there and found similar average gains to their system. Is it possible that their engine responds diferent to gains than some others? Maybe. The Formula Mazda racing series would disagree with this though as they state that all engines are extremely consistent. This must mean that ecu differences are causing issues in readings. We see all sorts of issues with this ecu so it's possible.

I'm not here to say that only Racing Beat is reputable and that all other claims are wrong. Not at all. What I am saying is that everyone should take all claims with a grain of salt, even those with dyno charts. Differences in each car, differences in each dyno, and differences in testing methods will definitely cause a variation on this car. Can there be some user error? It's possible. We've seen 10+ hp differences just based on engine temperature at the time of the dyno. Even back to back ones or ones that have waited a while between runs. It isn't too hard to see how numbers can be different. I still stand by my opinion that there is no one system out there that does much better than another and that they are all still farily comparable. I guarantee that no one system is faster than any other simply based on power gains. Factor in other things such as sound, looks, and possibly even weight, but don't buy one solely based on it's power claim.

 

Rotarygod:

Your discussion although insightful misses the point:



The fact that RB claims that the highflow cat is relatively useless for the RX-8 or (about 2hp increase), claiming that 8HP is the max they got with a straight pipe. While SR Motorsports claims they got 8-10hp with a high flow cat unit. In my opinion means that one of the positions is false.


We are dealing with physical facts here and although there can be some discrepancies there cannot be a direct disagreement.

You are right:
“I don't think anyone being an amatuer has anything to do with it.”

 

I don't think it misses the point. I think it explained it accurately and you are trying to over analyze it. Racing Beat only did get about 2 hp on their motor and SR motorsports got about 8 hp on theirs. They can both be correct and still get different numbers. They didn't use the same dynos, engines, or testing methods so it is very possible that both of them are correct according to their individual findings. That's the whole point. If I dyno an RX-8 at 172 hp and another forum member dynos theirs with an identical setup on a completey different dyno somewhere else and get 195 hp (we've seen this happen several times btw), who's to say either of us are wrong? Take all claims with a grain of salt instead of trying to determine who is wrong. Maybe no one is and that's just what they got when they tested it.

 

What is the inter- and intra-assay %CV on dynapack, dynojet and mustang dynos anyway?

 

Rotarygod:

SR and RB cannot both be right. I stand by my original post. SR quoted me about 10hp with the highflow cat and RB tells us 8hp is max with the straight pipe. They cannot both be right. RB says that the highflow cat is useless and that the stock cat cannot be effectively be upgraded on, overall they are not going to develop a highflow cat. SR claims it to be an effective mod and a solid upgrade over the stock cat.

Your argument still rest on the car being variable, different dynos, conditions ….

What if the difference in claims was: 2hp and the other 15hp. Would you still claim that they can both be right? If so at what point shall we draw the line?

Further more BR claims that having tested other companies's exhausts, they found the advertised figures to be false and that some of the systems actually lost power.
Does that mean that both companies are still probably right but one claims say 12hp and the other says that the system looses 2hp. Are they still both right?

Overall I have outlined a hypothetical (not that easily done but possible) procedure that should help determine the truth. Let examine another hypothetical scenario (until I win 30mil and actually conduct this kind of test), let suppose that we took 50 cars with 10.000 km on them, driven and serviced at the exact same manner. We flash them, inspect the engine, change the oil, etc… Dyno them, take the 20 cars that all within the 5 hp difference on the dyno (statistical abnormalities are taken out). We then put on the highflow cat from SR and get the dyno results, (20 dyno machines, same time same day same weather conditions…) we see that on the average those 20 “normal cars” gave us an increase of 2.5 hp. We then put on the RB midpipe and get an average increase of 9.2hp. Are both companies still right?

Sport Compact Car or RX magazine can definitely do some kind of test. (obviously not the one described above)

What you are telling me is that I should not compare claims about HP increases between RB and SR because of the many variables involved (variable cars, different conditions, different dynos…)
This leaves the posed claims to be somewhat irrelevant, since they cannot be compared, what use do I have for them? Perhaps you are right, and the whole process is not extensive enough to pass to be “statistical ethics”.

Unfortunately what I do understand is that if I do order the SP highflow cat, it is going to be a trial and error kind of procedure.

I got exam the next 2 days so I will be off the forum. Thanx for the help.

 

FWIW, you will never get a large group of people here to admit the RB is anything except a tuning god not matter what proof you show them

 

So what you are saying is that if RB tested and only got 2 hp on their setup and that SR tested and got 10 hp on their setup that one of them are wrong? How? As I said, if they are telling you what THEY got on THEIR testing, how is that wrong? Furthermore, why do you believe one over the other? I stand by supreme logic and understanding in that you can have 2 different results and both be correct based on your individual tests. I'm not saying that only Racing Beat is correct and everyone else is wrong. I'm trying to get the point across that there are so many different readings that happen on these cars that it is very possible to see different gains published depending on who did the testing.

You didn't seem to respond to another thing I said that is just as relevant. You can't rebut it so I guess it would be easy to ignore. What if someone dynos their car at 174 hp and I dyno one at 195 hp and we had the same mods and used the same types of dynos? Who's wrong? More importantly are either of us wrong? You assume that dynos are accurate trustworthy devices. They aren't. They are tools good for establishing gains from a baseline on the same machine. That's it' If dynos were accurate, every dyno out there regardless of type would all dyno the same. They don't. Keep in mind that we do see dynos with this wide of a variation so who's wrong? Stranger yet, why would you believe one over the other? It is possible for us to both be correct. What you are having such a hard time comprehending is itself hard to comprehend. It's so simple. Open your eyes and figure it out. Maybe no one is wrong. They are each publishing their test results. You can't call that wrong.

 

Chris,

A +10 whp difference is easily attributed to dyno variance. When your testing exhaust mod's, you have to unstrap the car to change out the midpipes. If you restrap the car slightly differently, it can result in different gains.

There are a variety of articles on this subject. Here's two short ones to give you an idea of the incredible variance on one car, that is doing nothing but getting redyno'd continuously over a day. The variance is about +30 whp depending on what dyno is used, and how the car is setup on the dyno.

First off is an article comparing a 4 wheel dyno to a 2 wheel dyno.
http://www.sportcompactcarweb.com/ed...ble/index.html

Second is an article taking a 350Z (same car) to 7 different dynos.
http://www.turbomagazine.com/tech/03...ash/index.html

In case you choose to ignore the links. Here's the variance on the same stock car, on the same day.

Dyno HP TQ
Dynapack 249.4 242.8
DTS 257.6 556.5*
Dynojet (Win) 235.8 227.8
Dynojet (DOS) 243.7 237.2
Clayton 265.7 240.6
Super Flow 228.9 226.6

The key rule of dyno's...

1) The numbers aren't very important, the curves are.
2) Always use the same dyno, every single time, if your trying to tune your car.
3) Peak power increase is not as important as a smaller, but wider increase across the rev range.

As to who is right? I'd tend to side with racing beat. They err on the side of the average gain they recieved, instead of the maximum gain. Its very easy to quickly throw up the worst stock dyno next to the best modded dyno, and then claim a large power gain. (See every single pulley comparison thread)

Racing beat most likely either uses the average gains of the stock runs vs the modded runs, or the highest runs of each when comparing.

Turbo XS also seems to be following a similar system to racing beat, and I'm incredibly impressed with their dedication to "dyno" prove their product. Not only are they taking a conservative approach, but they've also dyno'd multiple 8's. Mad props to those guys.

Here's a quick example of what I'm talking about.

Stock Runs
180
185
190

Modded runs
190
195
200

Some manufacturers will take the 180 vs the 200, and say the product produces 20 whp gains. Since you are never shown all the dyno's, you never find out how much actual power the product produces till owners start dyno'ing.

 

and there are some people, no matter what RB does, will not give them the credit and respect the should

 

Rotarygod:

You have not read my previous post and have not responded to my questions, instead you have chosen to single out one concept and concentrate on it: this is classic example of a straw argument. Frankly I have nothing to add to my previous post, thanks for the help overall.

Overall however, I am going to wait and see how Mazda is going to squeeze our more HP out of the car (Car and Driver 10best link below)... And then decide to the mod that I am going to do.

http://www.caranddriver.com/article....ticle_id=10363

 

no need to wait - read the 2006 sticky in the discussions forum. hehhehee C&D heard it from us

 

Chris_Bangle, this is BRealistic from C&D- but I am blocked from that site due to very crappy forum software and absolutely NO support.


Anyways- if you want to make measurable more power, you have to increase intake breathing at the same time you increase exhaust breathing. Engines are air pumps.

So my concern with the exhaust mod is the intake mod. If my memory serves me- the bolt on intake mods screw up the flow across the MAF which messes up the idle.


Honestly- I would look at a piggyback chip controller first. That seems to return the best performance gains for the money.