Dyno results: High-flow cats from PartsRack

[ntmatter]

A few months ago, I installed the nice metal substrate Random Tech cats from PartsRack. (JonB gave me a heck of a deal, BTW) I bought them primarily to keep my side-sills cool, though I noticed that the exhaust sounds nicer. Today on the dyno, I discovered that the 3" cat (using adapters for 2.25" header & exhaust) added 20 HP and 30 ft/lbs of torque:

3/23/02 Dyno:
HP: 432.2 TQ: 470.5

3/8/03 Dyno:
HP: 451.1 TQ: 501.1

This is a pretty solid result for cat-only performance improvement; this is the only HP mod I've done in the last year, it was the same dyno, and the weather was approximately the same a year ago as today. So, I'm very happy with these cats for the heat reduction, the better exhaust note, and now for a considerable amount of power.

 

[motor602]

WHOA MAMA! AWESOME NUMBERS! congrats man, you make me want a pair of cats now!

 

[Hoosier Daddy]

Nice #'s. I can't remember do you have the snake oyl rear assembly also? This should put those creampuffs out your rear view mirror for certain. I tell ya these 96-98 wake up with the exhaust mods.

 

[HOGDEALER]

Very Cool!!! What pipes do you have from the cats back?

 

[ntmatter]

I believe that I just have the snake oyl rear subassembly - they were put on by the previous owner but this is what they were identified as at Viper Days. The headers are stock. This is pretty much everything for engine mods, except for filters & tubes. So, with a .85 driveline loss ratio, I figure that filters, tubes, cats, and rear subassembly get me 530 HP and 590 ft/lbs of torque at the crank.

 

[SoCal Rebell]

A few months ago, I installed the nice metal substrate Random Tech cats from PartsRack. (JonB gave me a heck of a deal, BTW) I bought them primarily to keep my side-sills cool, though I noticed that the exhaust sounds nicer. Today on the dyno, I discovered that the 3" cat (using adapters for 2.25" header & exhaust) added 20 HP and 30 ft/lbs of torque:

3/23/02 Dyno:
HP: 432.2 TQ: 470.5

3/8/03 Dyno:
HP: 451.1 TQ: 501.1

This is a pretty solid result for cat-only performance improvement; this is the only HP mod I've done in the last year, it was the same dyno, and the weather was approximately the same a year ago as today. So, I'm very happy with these cats for the heat reduction, the better exhaust note, and now for a considerable amount of power.

Sorry Andy, that's real hard for me to believe :confused . Were they both done at the same dyno? Were they both SAE #s? I only ask because when I dynoed my '00 at my shop I got a baseline then put in Bellanger headers, Bellanger 3" catbacks and Random Tech cats (3" in and 3" out) and "only" gained 30 RWHP and 41 RWTQ.

 

[Snake Bitten]

Sorry Andy, that's real hard for me to believe :confused . Were they both done at the same dyno? Were they both SAE #s? I only ask because when I dynoed my '00 at my shop I got a baseline then put in Bellanger headers, Bellanger 3" catbacks and Random Tech cats (3" in and 3" out) and "only" gained 30 RWHP and 41 RWTQ.

I have long believed that the stock SS shorty headers that came out in 1998 flow just fine unless you have SUBSTANTIAL power adders...

Problem is: 99% of the people that do these exhaust mods, do them all at once...Headers, High Flows or Catless, and catback...then off to the dyno, and chalk the 30 hp gains up to the headers and catback, and not the MASSIVE FREAKIN RESTRICTION THAT IS THE STOCK CAT!!!

How does one know which exhaust component helped the system "flow" better?!?

Hold a 24" 5lb (estimate, but very close!) stock cat right up to a light and try to see through it....YOU CAN BARELY SEE ANY LIGHT! It's like you have 24" of Fiberglass clogging up your exhaust under each sidesill...

My baseline with the STOCK CATS was 433 rwhp and 470...I have since installed High Flow Cats and basically the EXACT same mods as Andy, only different brand of High Flows, and I did "rear muffler delete" as opposed to the Snake Oyl rear assembly........and will be dynoing again as soon as this white crap melts...I will save this post and report back!!

Oh, I am also bolting on a 150 shot, so those numbers should be a little more impressive, but I will make some pulls "all natural"...

Has anyone:

Removed the mufflers or installed a catback...then dyno'd
Removed the cats or installed high flows...then dyno'd
Installed aftermarket headers...then dyno'd

Somebody donate a set of headers to Andy...to confirm substantial gains over these SS shorty header!

 

[treynor]

I dyno'd my '01 before and after high flows, with the following result

Stock: 408 RWHP, 442 RWTQ
Add tubes & K&Ns: 415 RWHP, 448 RWTQ
Add belanger headers & exhaust: 431 RWHP, 475 RWTQ
Add 3" high-flow cats: 438 RWHP, 485 RWTQ

 

[Daffy Duck Viper]

I dyno'd my '01 before and after high flows, with the following result

Stock: 408 RWHP, 442 RWTQ
Add tubes & K&Ns: 415 RWHP, 448 RWTQ
Add belanger headers & exhaust: 431 RWHP, 475 RWTQ
Add 3" high-flow cats: 438 RWHP, 485 RWTQ

Hey, nice research. Thanks for the informative breakdown.
-Daffy

 

[ntmatter]

The cats are the only engine mod that I've done since my previous dyno. The dyno is almost exactly 1 year later, the weather to my recollection was very similar (grey skies, a little rain), and it was the same dyno at the same shop. They gave me a separate print out of this pull vs. a year ago, this scan is posted below. (My memory was slightly off on the exact numbers, but they're basically the same as above).

Since I have stock-diameter exhaust and headers, I figured that this result would best show the advantage of the improved flow in the cat itself, rather than improvements in going to a 3" system.

You must be registered for see images

 

[Russ M]

Another great dyno jet facility .

Sorry but the chances of picking up that much power from just cats is about 0 percent. I am not even going to get on the subject of a gen 2 viper making 450rwhp and 500 torque from just cats and exhaust.

 

[MES]

It's actual HP not SAE corrected, do you have corrected?

 

[ntmatter]

Well, I'm awfully sorry that you don't believe me, but here is exactly all of the engine mods done to the car:

K&N Filters
Smooth Tubes
Snake Oyl rear sub (stock mufflers).
'99 cooling fan
Randomtech High-flow metal substrate cats

That's it for the engine, I've also done some brake and suspension work, rollbar, harnesses, but as I understand it this only adds HP on yellow Vipers.

The only one of these mods that have been done since my last dyno run are the cats. On both ends I had to use adapters for the smaller header and exhaust size. As for correcting to an SAE figure, I'll try to call the dyno facility and ask. Both now and a year ago, temps were in the mid-40's (long sleeve shirt weather), drizzling rain, and normal Seattle-area humidity. This may knock off a point or two, but since it would do that consistently for both before and after I think I will stand by the 20/30 gain.

 

[Ron]

I'll try to verify Andy's numbers later in the spring. Currently stock exhaust contemplating the same cats Andy purchased. Worse, I have the OEM cast iron manifolds rather than Andy's tubular shorties!

Dyno'd last year at 435 RWHP SAE corrected with K&N's and smooth tubes so we're starting off pretty close.

Will post when I get around to doing the install.

 

[Fast Viper Dan]

I hope your coming down for Viper Days Andy. I would like to here the difference in sound with your high flow cats. I,m thinking of doing this also.

 

[BigCarrot]

Every car I've ever had dynoed different on different days! I'm sure his car did make 30 more the second time! I'd probably only attribute 10, maybe 15 to the cats though, which is good!

 

[ntmatter]

There's a club dyno day coming up on soon, so I'll take it back and re-dyno it and see if I'm getting a consistent number. I ran 3 pulls last weekend within about 1.5 HP of one another, so it was a fairly consistent result. I actually ran 4 pulls - the first was 440.6 HP with a colder engine, then 3 sequential runs at 450-451. If I get the same number in a week or two then I'll stand by it.

As to Viper Days, I cannot unfortunately make it down for these events this year - too busy paying for last year. I'm definitely planning on a full season next year in Modified or Super Modified, however.

A

 

[LTHL VPR]

The main point people are bringing up is that your DYNO has ACTUAL HORSEPOWER, NOT CORRECTED HORSEPOWER. This is a VERY valid point. You can not compare dyno runs with ACTUAL HORSEPOWER. Ask them to print out your SAE CORRECTED dyno sheets for an accurate comparison. Very easy for them to do. All they need to do is choose SAE before printing; all of this information is already stored.
-W

 

[jimandela]

I will be calling Jon B before adding my B&B cat back!!!

 

[ElDiablo Viper]

The main point people are bringing up is that your DYNO has ACTUAL HORSEPOWER, NOT CORRECTED HORSEPOWER. This is a VERY valid point. You can not compare dyno runs with ACTUAL HORSEPOWER. Ask them to print out your SAE CORRECTED dyno sheets for an accurate comparison. Very easy for them to do. All they need to do is choose SAE before printing; all of this information is already stored.
-W

I agree, those numbers don't mean anything. My car dynoed 430RWHP 467RWTQ with coras and K&N, when I took the cats off I dynoed 437RWTQ and 480RWTQ.

 

[sbkim]

Just a follow up - does anyone else have high flow cats (3" RT) with stock headers and exahust (muffler delete)? I am curious whether there is a noticeable improvement in sound and power.

Thanks

 

[Sam 01 RT10]

I have Roe's high flow 2 1/2 cats w/ no mufflers whatsoever.
I love the sound, and felt a slight increase in power. Haven't dyno'd the car yet though.

Love the MGW knob, BTW!

 

[cruser]

When & where is this dyno day occuring?

 

[ViperJoe]

I wonder if there is a difference in HP and sound between RT metal substrates and RT hi-flows?

 

[KenH]

Just a follow up - does anyone else have high flow cats (3" RT) with stock headers and exahust (muffler delete)? I am curious whether there is a noticeable improvement in sound and power.

Thanks

When I added 3" ceramic RT cats to my stock headers/Corsa catback it increased the sound volume significantly over the catback alone and changed the overall sound quality of the system. Don't know about performance changes as I also went to 3.55 gears at the same time, though most that have dyno'd seem to state about a 5-7hp increase. Metal substrate cats are louder than the ceramic ones from my understanding.

--- Ken

 

[H8TOW8]

2000 RT/10 (creampuffs? No.) Dyno -

ALL SAE CORRECTED (RWHP/RWTQ)

Stock (xcept K&N, Tubes) - 405/444
Add 3" corsa, RT Hi-Flow Cats - 432/469
Add Arrow 1.7 Rockers - 452/492

So, even SAE corrected, not too far off 'ntmatters' numbers...and creampuff to boot!

Curve:

 

[Bob K]

Cruser,
I am in charge of planning the dyno day and don't have it scheduled yet. It will be some time in late March. Keep an eye on the WA VCA calendar for details.

Bob K

 

[JonB]

As claimed above, Many, Many of our customers report +12 ~ +20 HP, and attribute it to RandomTech HF cats....but the motive is always "less heat, better sound, deeper tone"

We promise 10HP ceramic, 15HP metal honeycomb but THE YEAR MATTERS!

 

[ggc]

How much does the year matter in results? I assume you are comparing the 96 - 99 with the 2000 - 2002 cam differences? or does the cast iron vs 98 on header manifold make a difference as well?

 

[garolittle]

Oh man. I just bought the Random Tech ceramics and a pair of spinner mufflers from Jon B (great deal, by the way) and I can't wait to have them installed. This post is making me anxious!