the catalytic question with Nameless 's 3 inch downpipe

[OrbitalEllipses]

^ Subaru engines don't have particularly high VE like the F20C.
@Sportsguy83 we're not talking about replacing a bendy, shitty, stock exhaust with 2 cats. We're talking about the difference between two high performance exhausts where one includes a high flow cat and the other has the same diameter/routing, but lacks the cat. It's NOT a big deal. It won't make significantly more power. Will it pick up 10-15whp? Probably.


And yes, I haz degree. Listen to me, peasants!

[DeliciousTuning]

Originally Posted by OrbitalEllipses

^ Subaru engines don't have particularly high VE like the F20C.
@Sportsguy83 we're not talking about replacing a bendy, shitty, stock exhaust with 2 cats. We're talking about the difference between two high performance exhausts where one includes a high flow cat and the other has the same diameter/routing, but lacks the cat. It's NOT a big deal. It won't make significantly more power. Will it pick up 10-15whp? Probably.


And yes, I haz degree. Listen to me, peasants!

That is an all encompassing answer. So you are saying even at 750whp a 200 cell cat will not restrict power? I just do not agree...

Ok, that might be a little extreme but at what point do you say having a high flow catalytic converter will work? It is definitely air flow defendant and below a certain threshold it will work fine, but once you hit that threshold you will definitely be limited.

What is that limit? Well that is up to the professional tuner who might have a degree or two themselves and what they have experienced from tuning easily 1000+ Subaru engines over say a 15+ years or longer.

Cheers,
William Knose

[CSG Mike]

I like this post.

Less restriction is less restriction, period.

[King Tut]

Originally Posted by DeliciousTuning

What is that limit? Well that is up to the professional tuner who might have a degree or two themselves and what they have experienced from tuning easily 1000+ Subaru engines over say a 15+ years or longer.

Cheers,
William Knose

Listen to this guy. He haz a couple degrees.

[CSG Mike]

Originally Posted by DeliciousTuning

That is an all encompassing answer. So you are saying even at 750whp a 200 cell cat will not restrict power? I just do not agree...

Ok, that might be a little extreme but at what point do you say having a high flow catalytic converter will work? It is definitely air flow defendant and below a certain threshold it will work fine, but once you hit that threshold you will definitely be limited.

What is that limit? Well that is up to the professional tuner who might have a degree or two themselves and what they have experienced from tuning easily 1000+ Subaru engines over say a 15+ years or longer.

Cheers,
William Knose

That would depend on the actual diameter of the cats...

I've seen cats that are 10+ feet wide in diameter in testing cells, and these engines were making 750+ whp. Those cats were a 600 cell too

[OrbitalEllipses]

Originally Posted by DeliciousTuning

That is an all encompassing answer. So you are saying even at 750whp a 200 cell cat will not restrict power? I just do not agree...

Ok, that might be a little extreme but at what point do you say having a high flow catalytic converter will work? It is definitely air flow defendant and below a certain threshold it will work fine, but once you hit that threshold you will definitely be limited.

What is that limit? Well that is up to the professional tuner who might have a degree or two themselves and what they have experienced from tuning easily 1000+ Subaru engines over say a 15+ years or longer.

Cheers,
William Knose

I'm not disagreeing with you - I think it's a minimal gain for the trade-off, especially given the street-driven nature of the car and the power goals. I don't think what I said is unreasonable, but I acknowledge you're also correct.

My opinion is that a street car should have at least one cat and the pursuit of power in a street car shouldn't eliminate every cat, that's all. Let's just amicably agree to disagree; it's the OP's and tuner's choice anyhow.

Originally Posted by King Tut

Listen to this guy. He haz a couple degrees.

But is he superior???

[Jesse@JDLAutodesign]

What effect does the cats positioning to the turbo effect things? Being in the front pipe its quite a distance from the turbine outlet on most setups. I think this helps compared to some cars that place a cat directly after the turbo.

[DeliciousTuning]

Originally Posted by OrbitalEllipses

I'm not disagreeing with you - I think it's a minimal gain for the trade-off, especially given the street-driven nature of the car and the power goals. I don't think what I said is unreasonable, but I acknowledge you're also correct.

My opinion is that a street car should have at least one cat and the pursuit of power in a street car shouldn't eliminate every cat, that's all. Let's just amicably agree to disagree; it's the OP's and tuner's choice anyhow.



But is he superior???

I would agree with you that a daily driver of sorts; having at least one catalytic converter is definitely worth while. Most customers will want it, for a multitude of reasons.



Cheers,
William Knose

[DeliciousTuning]

Originally Posted by CSG Mike

That would depend on the actual diameter of the cats...

I've seen cats that are 10+ feet wide in diameter in testing cells, and these engines were making 750+ whp. Those cats were a 600 cell too

Completely on point. Here is something we came up with at HG Motorsports for a Subaru STI running a GTX30R rotated turbo kit. He really wanted to stay clean but make power and we found on one high flow 200 cell cat it was just too restrictive, so we put in two. By doing this we were able to add another 50whp and 50wtq.



Also the further the catalytic converter is placed away from heat, the better it will flow. Because as air cools, the molecules slow and can flow a lot easier through small holes.

Cheers,
William Knose

[SmsAlSuwaidi]

Did some research and realized something with the 2 cars @PrimeMotoring

Here is a list of mods:

P&L Stage 1 Turbo Kit
ACT Heavy Duty Street Clutch Kit
Prime Motoring Flex Fuel
Tomei Expreme 80mm Cat-back
P&L Overpipe
ID 1000cc Injectors
DW65c Fuel Pump


Feel free to ask any questions if you have any.

P&L Stage 1 Turbo Kit
ACT Heavy Duty Race Clutch Kit
Prime Motoring Flex Fuel Kit
Ultimate Racing 2.75" Exhaust System w/HFC
ID 1000cc Injectors
DW65c Fuel Pump
Crawford AOS

@PrimeMotoring care to chime in ?
Because the only difference i realize is the exhaust system with the two cars ! Is it all from the HFC ? or was the driver of the second car asking for less power ?

[PrimeMotoring]

Originally Posted by SmsAlSuwaidi

Did some research and realized something with the 2 cars @PrimeMotoring




@PrimeMotoring care to chime in ?
Because the only difference i realize is the exhaust system with the two cars ! Is it all from the HFC ? or was the driver of the second car asking for less power ?

The exhaust system and HFC definitely had an effect on the numbers because we did get the catless car up to 480 at one point and it could have made more if we pushed but limited it down for drivetrain's sake. Also the ethanol content in the e85 slightly varied from each car so that would account for a bit of power as well.

[Michaeljp92]

I own the second Prime turbo FRS posted above (424whp). The first turbo one that made 480whp was running e66 fuel last I checked and he was catless. I was running e55 fuel and have a high flow cat (Ultimate Racing Exhaust). I could not afford to go catless being as in the town I live in and the surrounding towns, you simply cannot get away with catless anymore. They have "sniffer vans" that do on-spot inspections and it's a $5,000 fine PER CAT that is missing, but that fine is only issued if the vehicle is COMPLETELY catless, so my car is still legal. I'm going to ask my next set of questions to help you figure out if it worth it or not to actually put the time into removing that cat in your exhaust...

What are your power goals?
What kit are you running?
Is this a street driven car?
Can you easily get away with catless where you live?

I can tell you right now, my tuner told me that if I were able to have dumped actual e80~ series content in the tank, I could've broke over 500whp, same goes for the other car too, e66 still is not ideal for making a ton of power. Both of our cars were stock motor, stock trans builds, so neither of us wanted to go over 500whp because you're gonna risk blowing it to pieces. At the end of the day, a cat will rob you of horsepower, no argument there. What I'm trying to get at is, are you shooting for a mild 400whp street build? If so, then a cat really isn't going to affect you. Are you trying to build a 700whp+ build? Then you may want to go catless just to squeeze out the extra available horsepower.

- Mike

[SmsAlSuwaidi]

Originally Posted by Michaeljp92

What are your power goals?
What kit are you running?
Is this a street driven car?
Can you easily get away with catless where you live?


- Mike

Thank you very much for the reply mike !

Power goals are sub 500whp for sure i will be very very happy with 450whp

I will be running @MAPerformance 's new kit with a gtx3076

Yes/no, i dont drive it every single day even though its my only car i sometimes ride a bike to school

I no, California laws are strict as hell and could get me screwed over if i get caught but hey what ever


Sent from my IBrick

[Michaeljp92]

Originally Posted by SmsAlSuwaidi

Thank you very much for the reply mike !

Power goals are sub 500whp for sure i will be very very happy with 450whp

I will be running @MAPerformance 's new kit with a gtx3076

Yes/no, i dont drive it every single day even though its my only car i sometimes ride a bike to school

I no, California laws are strict as hell and could get me screwed over if i get caught but hey what ever


Sent from my IBrick

For your goals then, I would just leave the cat in there, you'll be completely fine, also keep in mind the dyno numbers posted above are Mustang Dyno numbers, reads a lot lower than Dynojet. You're gonna love the gtx3076 by the way, that thing punches HARD and you'll easily clear 450whp with that thing catted or not lol. Also being as you're in Cali, I would stay catless as they have the same sniffer vans and even more severe punishment if you violate the smog laws. To me the $10,000 total fine wasn't worth another few horsepower, that I couldn't use anyways because I'm on a stock motor. Enjoy the car though and make sure you post up a build thread for it, I'd love to see the outcome!