DDP vs Elbow + DP vs DP w/ Elbow

[Grandavi]

I am not running a cat because

a. I dont need one legally
b. I dont need one environmentally

There is a good argument for both sides of the fence, but remember.. this is a car that sees about 3000 km of road per year. That equals about 4-8 tanks of fuel if I'm lucky.
If it was a daily driver.. sure.. I would run the cat. But for what the car is, not running one has nothing to do with making people's eyes bleed. Definitely not going cheaply... and definitely not a dick (of course.. others may disagree with me).

If I were to put this car on the road as a daily driver, I would run a highflow cat, but it's not going to happen right now because its just not worth it.

Should add... I agree with catalytic converters in large urban centers simply because it changes the exhaust so there are different gases being expelled. Less acid rain, but more CO2 or NO2... (well.. not more... because it doesnt add to the exhaust, it just alters its chemical makeup). NO2 is like 300 times more damaging to the environment if your concerned about global warming than NOx...

So... like I said... 2 arguments.. both good. Im okay without running the cat.

 

[Orion ZyGarian]

Another comparison. I dont know who thought this was a good idea...

 

[Dan_Gyoba]

When I was looking at exhaust setups, I was told that removing my completely nonfunctional cat was fine, but that I could not install a different, non-factory one. If I were to retain a catalytic converter at all, I had to install both factory ones, or else it would qualify as "tampering with factory emissions." No cats at all is removing nonfunctional ones, which was legal.

Not that it's happened in the past decade (or two), but I used to get an inordinate number of equipment inspections. As it stood, no cat, perfectly legal, no ticket. Aftermarket cat, illegal, potential big ticket and order to remove.

I've since found a sane person who has told me that the aftermarket one wouldn't get me a ticket, so I don't have to install factory ones, but now, I own the RT "racing" downpipe, and I'm not all that interested in buying another one in order to spend a bunch of money on a cat for a weekend driver.

As with Grandavi, it's not a daily driver (Neither will the 1990 I just bought) and in fact I didn't even burn the entire tank of fuel that I put in the car in April. Not feeling a strong desire to spend a couple hundred dollars on that. So maybe yeah, I'm being a little cheap, but in closed loop mode, my Supra still produces less HC and NOx than my friend's 2009 pickup truck completely stock.

 

[Nick M]

I am not running a cat because

a. I dont need one legally
b. I dont need one environmentally

The law is never to be used on a public road. So if you burn up to 8 tanks of fuel on the road, you are in fact violating the clean air act, and could be fined heavily. Not that I am going to do it. I have nothing to do with the EPA. If you live in an area that does not have a high enough population density, then the clean air act does not have to be enforced. And you would not be fined (big fine) for removing emission control devices.

That assumes you drive south across the border.

 

[Poodles]

I am not running a cat because

a. I dont need one legally
b. I dont need one environmentally

There is a good argument for both sides of the fence, but remember.. this is a car that sees about 3000 km of road per year. That equals about 4-8 tanks of fuel if I'm lucky.
If it was a daily driver.. sure.. I would run the cat. But for what the car is, not running one has nothing to do with making people's eyes bleed. Definitely not going cheaply... and definitely not a dick (of course.. others may disagree with me).

If I were to put this car on the road as a daily driver, I would run a highflow cat, but it's not going to happen right now because its just not worth it.

Should add... I agree with catalytic converters in large urban centers simply because it changes the exhaust so there are different gases being expelled. Less acid rain, but more CO2 or NO2... (well.. not more... because it doesnt add to the exhaust, it just alters its chemical makeup). NO2 is like 300 times more damaging to the environment if your concerned about global warming than NOx...

So... like I said... 2 arguments.. both good. Im okay without running the cat.

Follow a car without a cat with your windows down and see if your eyes burn. Also, NOx is far more harmful than CO2 to the environment and to people.

Might want to study up on how a catalytic converter works and why they're used. Also, how the car is tuned for them and without it, it's actually doing more damage than usual.

When I was looking at exhaust setups, I was told that removing my completely nonfunctional cat was fine, but that I could not install a different, non-factory one. If I were to retain a catalytic converter at all, I had to install both factory ones, or else it would qualify as "tampering with factory emissions." No cats at all is removing nonfunctional ones, which was legal.

Not that it's happened in the past decade (or two), but I used to get an inordinate number of equipment inspections. As it stood, no cat, perfectly legal, no ticket. Aftermarket cat, illegal, potential big ticket and order to remove.

I've since found a sane person who has told me that the aftermarket one wouldn't get me a ticket, so I don't have to install factory ones, but now, I own the RT "racing" downpipe, and I'm not all that interested in buying another one in order to spend a bunch of money on a cat for a weekend driver.

As with Grandavi, it's not a daily driver (Neither will the 1990 I just bought) and in fact I didn't even burn the entire tank of fuel that I put in the car in April. Not feeling a strong desire to spend a couple hundred dollars on that. So maybe yeah, I'm being a little cheap, but in closed loop mode, my Supra still produces less HC and NOx than my friend's 2009 pickup truck completely stock.

Yeah, sounds like you guys have screwed up laws up there about cats or people that don't know how to interpret them.

Out of all the emissions equipment on the car, the cat is the single one that has zero side effect to power or maintenance (i.e. it doesn't get dirt and need cleaning). It's also the main one that removes deadly toxins from the exhaust...

 

[peytoncoyote]

well considering he used KM as a refrence says that he is not in the U.S. for one, two yeah cats don't get dirty and need to be cleaned but the collect allot of CO2 that eventually will cause the cat to be replaced but it takes allot of miles and years to do that. People have there own opinion, but if I remember correctly the originial thread was about Down Pipes not Cats. On that note keep the cat, you do need it and getting a high flow will help the performance but it won't be that much of a gain with or without.

 

[Dan_Gyoba]

@paytoncoyote: You need to read up on catalytic converters. They don't collect stuff, they act as a catalyst on the exhaust gasses to ensure complete combustion. All of the atoms that go into it come out, but rearranged, so that they're less harmful.

@Nick: I agree on screwed up laws, and those interpreting them.

So tell me how you'd react. I read the legislation, and it states clearly that a functional catalytic converter cannot be removed. Okay, I get that. A nonfunctional one, or one that is over a certain age (At which time it can be presumed nonfunctional) can be removed. Okay, I get that, too. For installing one, it is stated that you must replace with the same number and size as was provided OEM. I called for clarification. I specified that my car is a 1989 (Making it 19 years old at the time I asked, which was more than old enough - 15 - for removing the factory cats regardless.) The person I spoke to informed me that I was perfectly free to buy or build an exhaust system with no catalytic converters whatsoever, but if I were to install a non-factory converter, that would be an offence. This didn't make sense, since I don't need one at all, how could a non factory one be an offence? I asked if there are "approved" aftermarket ones. I was told that only the OEM catalytic converters, or direct OEM replacements could be used, and that aftermarket would be subject to a fine of $xxx (Don't remember what the total was) and an order to remove if I was caught with it. The only "good" news from this conversation was that I wouldn't need both, since the downpipe cat could be deemed "removed at greater than 15 years age."

So for me, my reaction was to remove the catalytic converter from my online shopping basket, and add a test pipe. Then I removed the downpipe and test pipe, and substituted the "racing" downpipe, which was some $45 cheaper than the combination.

2 years later, I was inquiring about a different car, and was informed that what I was told was still a possible interpretation, but that the current definitions of "direct OEM replacement" included a number of larger high flow converters, and so long as it was installed in the same location as one of the factory devices, I'd be okay.

 

[Enraged]

I might put a cat back into my system simply to quiet it down. I've got a dump and electric cutout if I want to be insanely loud.

 

[Grandavi]

I grew up with cars without cats.. it was when they introduced cats that I noticed the smell... and for some reason.. it was mostly from Fords... I believe it was odoriferous hydrogen sulfide and ammonia being created. Not sure if this has been addressed because I have only smelled it once in the past 10 years. You could definitely smell the rotten eggs throughout the early 80's... lol.

I also grew up with lead in my gasoline... and gas was mega cheap.. lol.

I dont run a cat because I dont need one, nor will anyone notice.

oh.. adding this... if you have a coolant leak (and I have never had this happen) that is going into your piston chamber.. I believe long term, that can coat the inside of the cat and cause issues..

Anyway... like I said.. good arguments for both sides. My car will not have a cat, will be tuned for not having a cat (or an EGR btw), I dont run it at the track and am not concerned about it at all. Luckily, of all the provinces in Canada, I live in the one that actually has the most freedom.

As a final comment, if I hadn't done all the work I just finished I would have actually put on a high flow cat, just because I like staying as close to the stock setup as I can. Its a 1988 Supra. No cat.. I think people wont mind.

Back to the topic though, I am a fan of DDP vs Elbow + DP. If your "building your own", the elbow + DP gives you a lot more flexibility and may actually be cheaper, but having gone down this path already.. I am happy with my DDP. (no constructive comment about performance to toss in... I think the difference between the two is minimal, but not sure)

 

[Nick M]

You can not remove a nonfunctioning converter unless it is replaced with a like unit. Just to get technical on our clean air act...

 

[Emeraldage]

LOL, you guys talk a lot. Sorry for waking up a dead thread but we were able to get an elbow, but it was cracked and all that so we'll have to get a refund. A guy is coming sometime soon to buy a lot of parts off my parts car so I'll have a little bit of money hopefully.

Just looking at bic 3" DP vs Bic 3" DDP. As it sits the only mods it will have is exhaust, and 57 trim rebuild in the future. Is there a big of a difference getting that DDP or should I save myself 100$+ and just get the standard one? What is the power difference? From what I'm reading a screamer pipe will get super annoying after a month or so.

 

[Grandavi]

Seriously don't think there's much of a difference at all. The only difference would be in flow. There is turbulence built up if the waste gate dumps into a "wall" like it does on the stock set up, but its nothing to be overly concerned with in my opinion.
I am just removing my raptor racing DDP and loved it. Wasn't overly loud, had the elbow integrated with a divider to prevent turbulence and was just a quality build overall.

I would be more concerned with properly porting a head before I got hung up too much on the elbow.

 

[Emeraldage]

Had the head tanked and redone didn't have it ported or anything have no where near enough money for that haha.. DDP have much difference in sound than the standard? I saw this one video I loved it it sounded like a diesel truck at low RPM without the obnoxious high compression pinging sounds and then it sounded like a normal supra on the gas. But it was open exhaust which mine will not have.

 

[Grandavi]

Stock exhaust my car sounded like a vacuum cleaner... No rumble... Very quiet... But the engine sounded... Well... Like a vacuum cleaner.
Add the DDP I have and a 3" HKS catback twin tipped muffler, and now I have a quiet car but with that deep growl. No fartcan sound. It's a bit loud at WOT, very deep tone when torquing under load, but quiet when cruising.

No idea what it will sound like with the t4 setup and the wastegate dumping to atmosphere. But looking forward to finding out.

 

[Dan_Gyoba]

DDP should really only change the sound when you're at the boost pressure that your wastegate is open. At that point, it's definitely going to get louder (Unless your DDP is recirculated, in which case... Probably zero difference.)

A larger DP than stock will help with flow through the turbo, which means faster spooling. That may change some of the intake sound, but there are other things that will affect it more.

Most of the sound from your exhaust really is determined by the catback. In that case, it can be reasonably quiet (I really like my Tanabe Hyper Medallion for that) to obnoxiously loud (3" straight pipes anyone?) but with a turbocharger, even straight pipes aren't going to be as loud as my old V8 was.

In the process of my turbo swap, I had to move the car with no exhaust at all, just the turbo elbow.

 

[Nick M]

Another comparison. I dont know who thought this was a good idea...

What is funny is Toyota has a CT26 elbow that is open. Just not for the 7MGTE.

 

[Poodles]

LOL, you guys talk a lot. Sorry for waking up a dead thread but we were able to get an elbow, but it was cracked and all that so we'll have to get a refund. A guy is coming sometime soon to buy a lot of parts off my parts car so I'll have a little bit of money hopefully.

Just looking at bic 3" DP vs Bic 3" DDP. As it sits the only mods it will have is exhaust, and 57 trim rebuild in the future. Is there a big of a difference getting that DDP or should I save myself 100$+ and just get the standard one? What is the power difference? From what I'm reading a screamer pipe will get super annoying after a month or so.

The difference is very noticeable. IIRC BIC did a back to back dyno run with them and gained quite a lot of power with the DDP.

 

[jetjock]

. I agree with catalytic converters in large urban centers simply because it changes the exhaust so there are different gases being expelled. Less acid rain, but more CO2 or NO2... (well.. not more... because it doesnt add to the exhaust, it just alters its chemical makeup). NO2 is like 300 times more damaging to the environment if your concerned about global warming than NOx....

Not that it really matters because it's been 6 months but that's some serious ignorance right there. You clearly have NFI about emissions or how catalysts work. No wonder you refuse to use one.

 

[Grandavi]

Not that it really matters because it's been 6 months but that's some serious ignorance right there. You clearly have NFI about emissions or how catalysts work. No wonder you refuse to use one.

Seriously?

I burn four cat less gas tanks a year and its going to hurt someone?

I'm not a city... I'm one car. One very rarely driven car...

You should holler at the 64-65-66 crowd... Wonder how many of them have cats.

Why not discuss the toxic effect making millions of catalytic converters has on the environment...

Regardless, I run without... Not by choice... Solely because that's how it worked out.

 

[Emeraldage]

Aha.. I don't have a cat either. I'm a cheapo I have a mk3 not a mk4

Also performance difference versus the DPP versus standard Bic DP. Is it worth the extra 150$? I'd have to get it recirculated.

I wish my car could sound like this http://www.youtube.com/watch?v=l0Xu1YSzL9Y... Sounds like a big truck diesel engine low revs it's awesome. And normal supra at higher RPM. But yeah It's my daily driver I'd rather have it quiet anyways.