High Flow Catalytic Converter Test Results

[Sean Roe]

Hi Everyone,
We had a chance to go on the dyno this past Sunday to test the higher flow catalytic converters we had been working on. The results were very good, as you will see by the dyno graph below. Not only did the Viper show the proper readings to pass an emissions test, but the power loss when compared to straight pipes with no cats was negligible.
When compared to the stock cats, the throttle reponse is improved and there is a gain of 12 to 14 HP at the rear wheels. We'll be placing a stock order for both 2.5" I.D. and 3" I.D. converters soon. The price will be $124.95 for each converter plus S&H. They have a 5 year manufacturers warranty.
You can also read more information on our Roe Racing Catalog

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Thanks for reading,

 

[BWoodbury]

Sean,

Can you post the graph for your high flow cats vs the stock ones? No cats is just not an option for me.

Also I am curious how much the 23 degree cooler air affected the results.

 

[Matt M PA]

Sean, seems like a good thing, a few questions though.
1. How much installation? Welding/Cutting?
2. How much do they affect the sound?
3. How will this affect the heat issue of the sills?
Thanks!

 

[Ulysses]

Looks as if there is no cutting/welding involved. I see the clamps on both sides of the cat. Should decrease sill temps considerably.

 

[Marv S]

Stock exhaust: you'll have to cut off the factory cat at the "in" end and unclamp it at the resonator (the "out" end.)

Then the new cat goes in with clamps at each end.

I have same questions as Bob & Matt.

Do they connect direct to the Borla header?

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<FONT COLOR="#ff0000" SIZE="1" FACE="Verdana, Arial">This message has been edited by Marv S on January 12, 2001 at 18:53</font>

 

[Ulysses]

You know what would be ideal, sell the section of flex? pipe that connects the stock header to the cat as well. That way it's one stop shop and we don't have to cut the stock setup or go have someone fabricate a section. I can just pull off the stock section and store it for when I want to bring it back to stock.

 

[Sean Roe]

Regarding the air temperature differences, there wasn't much I could do about that

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, but the dynojet software uses a correction factor to account for it. On the hot day, the correction factor added power ( multiplied measured power by 1.01), on the cooler day it reduced the measured power (multiplied by .97). On the cool day, it did make more measured power.

I cannot post a stock cat vs. high flow cat dyno graph on this car (my GTS). I never ran the Borla headers and cat back with stock cats, only straight pipes. So, the graph above compares straight pipes to the high flow cats. From other cars I've seen, removing the stock cats is worth as much as 18 rear wheel horspeower.

Regarding sound, they took out some noise compared to the straight pipes. So, I believe they will probably add a little more exhaust sound when compared to stock cats. The main benefit is the improved power and throttle response while meeting emissions requirements and not setting service engine codes. They should also run cooler than the stock cats as the substrate area is shorter and they are less restrictive.

In the installed picture, this was a temporary installation. As I didn't know how well this set was going to work out, I didn't want to make the installation very permamnent. I used 2.5" I.D. cats (the 3" have the same body dimensions) on my car for the Borla exhaust. The inlet into the resonator is 2.5" also, so there is a short piece of 2.5" O.D. tubing slipped into the resonator inlet and cat outlet, with the two butted up to each other with a single clamp between them. The inlet side of the cat and the Borla header outlet are both 2.5" I.D. also. So again I joined them with a single piece of 2.5" O.D. pipe with clamps at both ends. Now that I have finished testing and will be keeping this set in, I "may" weld one end and eliminate a clamp.
To replace the stock cats with these units, everything would be the same as how I did it on mine with the Borla exhaust, but the union pipe between the stock exhaust pipe and cat on the forward side would be an expanded piece, 2.5" I.D. inlet on one end with a 2.5" O.D. on the other end.

 

[Supercharged Vipermad]

Sound:
I used straight pipe for the 2000 Road Racing season, and trust me it was load (fitting for the hearing aid is next week...what? Huh? are you mumbling?). I ran the high flow cats (similar to Sean's) and the sound is much better, but still throaty, deep, but much more tollerable.

Well done Sean (I like the testing and comparision of posts like this).

 

[Anthony - 98 GTS]

I have an extra set of stock sections with the flex connection that I am willing to sell. This way you don't have to cut-up your system to install high-flow cats.

Let me know if your interested.

Anthony

 

[RockyTop]

Caution re exhaust clamps. I had one leak and set the insulation inside my passenger side side sill a smoulderin'. That was scary as I could not get under my lowered car to pull off the side sill at work. It finally quit smouldering. The culprit, a leaky band clamp. I had the forward joint welded after that.

P.S. I have Random Tech bullet-style 3" hi-flow cats. They reduced my side sill temps some, but forward of the cat it's still hot (due to proximity to header collector)! I did not do a baseline dyno so I do not know how much rwhp it added. The high flow cats and the Roe VEC together added about 10-14hp when compared to my old dyno sheets from a year ago. Not very scientific, but with only those two mods my rwhp went up 14.

 

[Craig 201 MPH]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by BSchillinger:
This must set the record for "oldest revived thread!"

<HR></BLOCKQUOTE>

No kidding!

That's funny, it's over a year old.

Craig