sti emission test
 

what are the experiences here passing emissions test with an sti with modded exhaust. i.e.-catless downpipe and such. It looks like 96 and newer vehicles just get the obdII test so does that make it easier or harder to pass?

It's cake to pass as long as you have no CEL's and the ECU hasn't been reset in the last week or hundred miles (roughly).

Go to Fred's.

I'm asking becuase I am looking at an sti with a catless downpipe, and sti are catless upipes, so unless I am mistaken that only leaves a small one in the midpipe. So if I have the cobb set to stage 1 with no CEL codes showing I should be able to pass? I would hate to buy the car with the modded exhaust and not be able to pass it. :(

With a catless DP, you should run stage 2, and yes, as long as there is no CEL and the ECU is not "not ready" due to being reset recently, you'll pass. They don't do a sniffer test so you could be catless and still pass.

wow that's wonderfull news...thank you for the quick reply

it has a coated catless downpipe and borla hush on it currently. If I get this car and it doesn't pass I may have to kill you. :lol:

:eek: :P

Well, all I can tell you is that I have that exact setup (borla hush, coated catless DP as well as a catless coated UP) and I've passed every time (3 years now).

I guess the only thing that would suck is if the car had CEL's but somebody pulled the physical CEL to hide them or something. I'd get it checked out just in case. AutoZone can check for any CEL's for free or you may want to pay a mechanic to check it out for you and have them pull any codes...

wow, same setup... I know this is relative but how does it sound compared to stock. I imagine the dp adds a bit of growl.

Well, it comes with an AP and no codes so I imagine I can pass just like you.

The 2.5L might add some growl as compared to my 2.0L but it's surprisingly quiet...definitely louder than stock, but hardly audible on the freeway (Re: no drone). It's one of the quietest catbacks I've ever heard, but it's a true 3" all the way through. :cool:

It sounds perfect at sea level, but at this elevation, it's a bit on the quiet side.

looks like I am picking up an sti but it's all stock exhaust so I have some deciding to do. I have an invidia dp on my wrx right now and I like it (the invidia catless/tanabe back may be a tad bit to loud), I also was looking at a crucial ceramic coated dp. Maybe i'll just drive it around stock for awhile till I find a good deal.

If you didn't know, Crucial changed their DP slightly and now offers a complete CBE. See their site for details. It's still looks like a good DP.

I'll have to look into it. Most exhaust systems seem pretty similar power wise. Want to find one with good fitment and sound.

That's definitely true regarding CBE. You can find differing opinions regarding DP's though. :)

From what I have absorbed through research....The sti tends to experience some boost creep with open bellmouth design, so some people get the divorced wastegate style which crucial and invidia both make. Still deciding on getting one with a high-flow cat on it. Clean up the sound a little but it's like $200 more for the catted one, and then there is cat-back....

I believe that a DWG DP will also allow better boost response and tunability. The Crucial is also worth it for the high quality ceramic coating they use. I've had mine (older style obviously) for a few years and it's holding up perfect. I also have their old style high flow cat. Unfortunatley, it didn't seem to add much performance. I should have stuck with the stock 3rd cat, but oh well. Now I'm better set for any future turbo/motor upgrades.

What exactly is the benefit of ceramic coating after the turbo again?

Reducing IC heat soak...maintaining gas velocity.

I'm not sure how much heat soak a coated DP would stop... and if "maintaining gas velocity" were an issue in a DP, it'd be the same ~2" diameter that the UP is. Just seems like an awful expensive upgrade to a pipe for a pretty minimal gain.

You want the exhaust that causes boost creep, because it flows better. You should use proper engine management with any mods anyway.

EM alone isn't going to stop boost creep. It might help it by ramping up the WGDC faster than stock, but still, if the wastegate is 100% open and the boost is still building, no EM is going to open the wastegate more. The right answer is to port the wastegate housing on the turbo.

It doesn't solve the physical issue, but you can make it so that you don't get fuel cut.

...or it reduces the efficiency of the WG port by creating more backpressure...

No, it wouldn't.

DP's are large in diameter in order to allow a specific type of turbulence in a "collector" area as this actually spawns a cyclone effect that helps keep the velocity up. Unfortunately the WG gasses don't benefit from the turbulence and by bypassing that turbuland area of the DP, a DWG will increase the WG's efficiency.

And it does help with heat soak. Many bare DP people have wrapped their DP purely due to TMIC heat soak and engine bay heat.

http://www.crucialracing.com/products/turboblack.php

This one is looking pretty good. I want to try to find some people that have it to see if the fit/finish is good. Price looks pretty good.

This site has a lot of info as to what the coating does if anybody wants to check it out.

People are just starting to install the newly designed system. I'll let you know if I see any reviews up at WRXFanatics, but you might keep your eye on NASIOC for what would probably tend to be a less biased review. WRXF is owned by Jeremy who also owns Crucial Racing and we tend to sound like a bunch of fanboys over there.

lol, alright. Well, in the meantime let me know if you are able to get any discounts for me :)

LOLWUT?

Do a search on the venturi effect. Hell, just read this: http://en.wikipedia.org/wiki/Venturi_effect

If you want to "maintain gas velocity" like you said, you would use a smaller pipe... the transition from a smaller pipe (UP/turbo) to a larger one (DP) means lower gas velocity. My whole point was that you don't care about gas velocity in a downpipe, what you care about is getting as much gas out of the turbo as possible, i.e. volume not velocity. The ideal exhaust pipe shape is actually a trumpet bell right off the back of the turbo, anything else is a compromise, and while coating a pipe helps to keep exhaust energy (both heat and velocity) in the pipe (which is why you coat an UP, so you transfer as much exhaust energy into the turbo as possible) there is no real benefit to doing so in the DP that I can think of, except perhaps for under-hood temps... though a plain old proper heat shield should do a better job for a lot less cost than a fancy ceramic coating.

I can ask, but I kinda doubt it. You just want a catted DP?

I've never heard of a DP heat shield that fits aftermarket pipes. Please fill me in.

The ceramic coating may or may not reduce backpressure by maintaining gas velocity but it's worth it regardless as it definitely reduces underhood temps and TMIC heat soak.

Pretty much any turbo heat shield (even a cut stock one) covers the top of the DP, which is the only part of the DP that can heat soak a TMIC.

Edit: Also, I am arguing just for the sake of arguing... it's not like coating is really going to hurt anything, it just seems a rather expensive alternative to a $5 piece of metal.

The turbo heat shield might help keep some of the DP heat out of the engine bay and from radiating at the IC, but it's a turbo heat shield, not a DP heat shield. It's kinda like leaving the house wearing nothing but a hat. Sure, the hat helps keep some heat in, but you're still losing heat like like crazy through your naked skin.

Oh, I remember this argument. Remember the "$2 spring can't be as good as the stock solenoid" argument? :lol:

I would probably be looking for a catted turbo back depending on the sound. Still trying to find some videos as it looks like the one on the site isn't working.

I imagine that the coating does decrease underhood temps quite a bit and in additions to a cut-to-fit stock heatshield should be a huge decrease.

The ceramic coating or even heat wrap which is often used, maintains the heat inside the downpipe and increases gas velocity. The increase in velocity should create lower pressure around the turbo so exhaust gases exit more quickly and efficiently which is the point of a bigger dp to begin with. The coating just makes it that much more efficient. If none of this is true and I just created a bunch of bullshit in my head then there is still the fact that it does decrease underhood temperature which increases performance and reduces heatsoak, but the price of their exhaust really isn't that expensive so that benefit alone may be enough to justify it for me.

Cool, I shot Jeremy a PM for ya. I'll let you know. The Youtube vid on the page you linked to worked fine for me earlier today. Maybe Youtube is blocked for you if you're on at work or something?

Yeah it worked for me like an hour ago and now it doesn't, another one on youtube from them is down also. On nasioc they said they would be trying to get more video out of the warehouse so I am anxiously waiting. Hoping to see some video of the catted tbe just to see the difference

How does heat from the part of the DP under the car radiate onto the TMIC? Your hat analogy is correct, when you consider that your head is the only thing outside.

And I'd still run a stock boost controller if I was running a stock ECU. The MBC is just a simpler option because I'm running a Hydra on a race car. It's just one less thing to have to tune. But none of that matters, because we're talking about coating DPs, not MBCs. And even if I was a hypocrite about MBCs, hypocrisy isn't grounds for invalidating an argument anyway.

How about we settle this scientifically: show me the dyno of a car run back to back with a coated and uncoated DP of the same design and we'll see just how much benefit there is from reduced underhood temps and "exhaust velocity" gains. I'm sure Crucial has all this data, no? They are the stalwart of the industry when it comes to backing up their claims, after all. :P I'm not doubting that there probably are some gains (at least from the lower temps, but I'm dubious on the whole flow aspect of it)... I'm just wondering whether or not the gains are worth the $200 a decent thermal coating costs, especially if a piece of sheet metal over the top of the DP works just as well.

There's like a foot and a half of DP that runs up along the firewall...and it's the hottest part of the DP. I'd ventrue to say that most of the heat that escapes through the DP's body, finds it's way into the engine bay. A piece of sheet metal around the DP might help, but sitting on top of the turbo, it's not going to do the best job at keeping the heat in the pipe. The Crucial is a great buy when you consider the lack of issues people have with them, the forever warranty, and the great design.

When Ed tuned my car the first time, he was uber impressed with the boost response. The first thing he asked was what DP I was running. When I told him, he said something to the effect that it apparently lives up to the hype. He found tuning my boost easier and that my car recovered boost faster than normal. This is when I was on the stock solenoid. My power levels ended up being about what you'd expect for my setup. Most of my CBE is totally overkill, but I'm just a turbo, TMIC and injectors away from an upgraded turbo if I ever choose to upgrade.

With airflow from the hoodscoop, the only heat from the DP that can heatsoak the TMIC is radiant heat, i.e. line-of-sight between the DP and the IC, which is just the top of the DP that's normally covered with a heat shield. Is not like there's a mass of warm air from the DP limiting the effectiveness of the intercooler... the IC gets fresh air.

I'm still not sold that keeping the heat in the DP does anything for performance of the DP. Keeping the heat out of the intercooler, sure! But I don't know that there's any real benefit to exhaust flow.

sperry -- you're a little bit mistaken on some of those points. Most importantly, just the huge and extremely dramatic drop in underhood and intercooler temperatures a WRX sees with a thermal coated or heat wrapped downpipe vs. a bare one. There is a heck of a lot of exposed downpipe metal that is still inside of the engine bay and there is a lot of surface area for it to radiate heat from. It does, of course, get very hot. Your turbo heat shield does cover an inch of the downpipe, but that doesn't prevent the other ~ 18 inches under the hood from radiating heat like crazy and, as we know, heat tends to go upwards and upwards is where you keep your intercooler. You'll notice that when you come to a stop, you can literally see hot air shooting out of your hood scoop. That hot air is going up through your intercooler and out your scoop, and a whole lot of that is thanks to your downpipe. While a heat shield does an okay at blocking direct radiant heat, it doesn't block conducted heat or hot air flow very well at all and once that heat shield gets hot, which it does!, it starts radiating its own heat into the air as well. However, if you coat the downpipe or wrap the downpipe, you're actually preventing heat from leaving it in the first place... radiant or conductive. In fact, because we coat outside AND inside, we're preventing the exhaust heat from soaking into the metal to begin with.

I think you'd be shocked at the difference. Without even measuring, it is just painfully obvious when you open the hood after a drive. You wont feel a rush of hot air on your face. You'll be able to press your hand on the intercooler to find it at ambient temperature. It takes a lot longer to see hot air coming out of your hood scoop and the intercooler stays cool to the touch much, much longer after you come to a stop. In fact, we see a DROP in underhood temperatures and intercooler temps with our uppipe and downpipe vs the OEM parts with all of their heat shields. That drop isn't huge, but it's big enough that many many customers have mentioned it in their reviews and some even took the time to verify with measurements. The difference between coated and a bare aftermarket pipe.... MASSIVE.

If you're running a short ram intake, you get direct HP benefits from sucking in colder air thanks to your cooler engine bay. If you're running a TMIC, you get benefits of a higher knock threshold thanks to the lower intercooler temps and you're much less likely to knock if you drive hard immediately after coming to a stop for a little while (like after sitting at a traffic light or staging at the track before you get to race), as the rate at which the intercooler heat soaks is slowed way, way, way down.

While it's very easy to assume that if you're moving, the air flow is going to outweigh the heat coming off of the downpipe, it's typically not true. First of all, there aren't many situations where you never stop :lol:... BUT... there simply is not enough airflow and pressure through the intercooler and the grill (and, btw, after the air goes through the radiator it's not cool when it comes out the other side) to push all of that heat out the back of the engine bay and under the car. There is a difference in underhood temps while driving. Less than the difference after you come to a stop, yes, because of that air flow, but it is NOT sufficient to make up for all of that scorching hot, bare metal under the hood.


....we do a lot of custom coatings for people, btw. It's typically $85 for a shorty downpipe and $105 for a full-length downpipe... It's worth the price, unquestionably. If you don't want to spend that sort of $$$, spend the $50 and heat wrap it (which, although it also works very well in the end result of dropping underhood temps and we do have a good account with DEI, is not our preference because it tends to cause metal fatigue and the wrap is very tough on whatever is underneath it... eating into the metal and causing pretty nasty surface rust).


For what it's worth, the WRC Subaru ceramic coats its ENTIRE exhaust, in-and-out, from cylinder heads to muffler tip.


Jeremy

I'm okay with that. I'll let you know if I ever come across any relevant "hard evidence", but I do recall at least two instances where I have heard people in hot climates complain about their car running shitty and after it's suggested that they heat wrap the DP, and reset the ECU, the problem goes away.

uhh.. yeah what he said lol...

since the crucial guy had a comprehensive answer there, I would only add that while the air from the scoop is cooling the intercooler core (only while moving btw) the bellows keep the air blowing straight through the middle. The radiant heat coming from the dp is only inches away and there isn't much stopping it from heating the intercooler from the outside in.

I haven't looked, but I don't have any offhand proof that the coating has any benefit on top of what he mentioned. But for things like exhaust that are a pretty important piece of the engine performance as a whole, I don't mind spending that little bit extra for what are essentially the proven tangible benefits of coating outlined by senor crucial.

oh and my catless 04 wrx just passed emissions which makes me happy. sti here I come :banana:

If they're so huge and dramatic, it would be a cinch for you to quantify them, no? So how much is this temperature drop?

Now there are a lot of assumptions... first, my head shield does in fact cover the turbo and DP all the way to the firewall... that is, when I'm running it... since I never really noticed a difference, what with my FMIC and all. So, personally, I'm not having any sort issues with "hot air shooting out my hoodscoop". And I'm not sure that a ceramic coating is going to make this massive difference you're implying... by the time the exhaust is past the turbo, it's what around 600F? So the pipe is maybe 300F instead of 325F due to the coating? We're not talking about dealing with 1600F exhaust right off the headers... so we're talking about a delta of maybe 50F, which means very little in terms of how fast a TMIC is going to heatsoak due to radiant heat from the pipe... again, some real data on the effectiveness of this coating would be useful. But I'm just making these numbers up... I don't have a coated DP to point my IR gun at... hell, I don't even have a running car right now if I wanted to test it. :(

Once again, if I were selling something and touting the underhood temp reduction as a selling point, I'd be very interested in providing actual temperature data, what with the whole "truth in advertising" ethical responsibility thing.

I'm not running either a short ram or a top mount. I went to a CAI when I measured 170F intake temperatures on the dyno w/ a short ram.

So you're saying that the air around the DP is heating so fast that the air rises faster than the flow of air through the hoodscoop? :lol: Unless you're running a full undertray on the car, the negative pressure of the airflow under the body of the car is going to suck the air that entered the engine bay through the radiator and hoodscoop down and out along the firewall. It may not be a ton of airflow, but it's certainly more air than the DP heats up and rises into the TMIC when you're stopped. And if these underhood reductions are only when you're stopped... well who cares, unless you're a drag racer who needs the IC to be as cold as possible the instant you leave the line... the rest of us will have reasonable cooling again withing seconds of moving.

If I were running a car that regularly sees water crossings, perpetual gravel spray, snow, etc, and if I had a WRC team budget, I'd coat my entire exhaust too regardless of any possible temperature gains. :lol:

Either way, what I'm not seeing here is any claim that this coating makes horsepower. For the sake of argument, I'll concede there may be an underhood temperature decrease, but even that doesn't make additional power on a car that's got a proper intake and intercooler setup... things that do make real measurable differences in intake charge temps. And the biggest point here that I was disputing is this idea that coating the DP makes the exhaust somehow flow better, something that you didn't even mention.

I'm not trying to say that coating the DP is bad... I just don't see that there's any massive benefit to it, at least not when compared to the cost. Now if you want to do it 'cause it looks sweet, by all means. My radiator and FMIC are both anodized black... which according to the industry is only good for like a 4% cooling effectiveness gain... not worth the cost for performance reasons, but I did it because my radiator and IC were getting pretty old-n-busted looking, and they look a crap-load better blacked out. Same goes with the IC piping that I had powdercoated... looks nice, does basically nothing for performance.

I dont understand why you would buy another dp when you have a perfectly good one already. I really doubt that the difference is going to big enough to even notice it. No offense to crucial, but it kinda sounds like a waste of money to me.

was that directed towards me?

I have...in 30 min it will be HAD an 04 wrx with a catless downpipe and a tanabe racing medallion catback. I just sold that car ( already miss it)

I am now buying an 05 sti and the exhaust is still stock so I am researching for the best tbe for me.

On a car running a CAI and a FMIC I probably wouldn't suggest somebody send their downpipe to us to be thermal coated. I'd tell them that the results probably would not justify the expense for them. While the post-turbo exhaust under boost happens to be a heck of a lot higher than 600 degrees (and there are plenty of guys running EGT probes post-turbo who have posted results all over the Subaru forums), I also don't think having a coated or wrapped downpipe is going to matter enough for exhaust gas velocity reasons to really justify doing it. However, of course, everybody's budget is different and the possibility of seeing gains plus having a nice, black downpipe is more than enough justification for a lot of people with a larger wallet than I.

With a short ram and/or a TMIC the coating or wrapping is ABSOLUTELY worth the time and expense. Most people purchasing their first downpipe are going to have a top mount intercooler on the car for quite some time, possibly for the rest of their ownership of the car. There are many, many more cars running TMIC's with turboback exhausts than cars where the owner spends the cash to upgrade to a fmic setup. Most cars with mild turbo upgrades up through 20G or so in size don't even do fmic. AND.... most FMIC setups end up running short rams anyway (although the intercooler is a more pressing issue when it comes to engine bay heat and obviously direct heat from the dp).

Anyway, on pre-turbo exhaust parts, we have seen repeated spool-up and response benefits to our coating. Maintaining the heat and energy inside of the exhaust gas going through the headers (especially with aftermarket steel ones!!!) and the uppipe absolutely translates into a measurable spool increase of up to ~300 rpm. It is regularly seen that with a non-coated stainless header, your spool-up gets quicker after a couple of pulls... this is due to the exhaust heat soaking into the header. We don't see that with coated headers so you get the quickest possible spool right off the bat. ....oh and the coating we do on turbine housings in conjunction with the P&P is also very effective at quickening spool-up and increasing response. Usually they'll hold boost towards redline better as well....

There are literally dozens of posts from different customers online with before-and-after measurements of underhood temperatures. Most people can't do this though because they weren't running an aftermarket downpipe prior to purchasing ours... few people swap between parts so there aren't that many opportunities to actually do non-coated vs coated temperatures. For most, the extremely obvious difference before-and-after kills their motivation to do scientific testing. Just with your face and your hands when you open the hood, it's as obvious as opening the fridge and opening the [hot] oven. The difference is not something small, it is HUGE. We're talking underhood temps going from a couple hundred degrees down to only a little above ambient. It is blatantly apparent, and there's plenty of non-biased commentary online to back that up. It has been years since we were actually asked to show numbers and I don't have data anymore. We do, however, have an STI in the shop with our downpipe uncoated on it so that's a good opportunity for us to get some fresh numbers on underhood temps and intercooler temps in various situations (while driving at different speeds and different amounts of full throttle time, after idling for 2 minutes, 5 minutes, 10 minutes, etc). Truly, I'm not super motivated to take the time and effort to do that though. We haven't seen a direct request for this sort of information for years. Again, it's SUCH a big, night-and-day difference that it isn't even a question in most peoples' minds.




btw -- there's a thermal dispersant coating that we do for anything metal that you want to radiate heat as efficiently as possible, and it's pretty trick stuff. Can increase the efficiency of an intercooler or radiator by up to 20%. Race teams also use it on brake calipers, oil pans, cylinder heads, transmission cases, oil coolers, intake manifolds, etc... as long as there's good ambient air flow over the part, it will shed head faster than uncoated. We've shown on FMIC cars (one local GT30 STI in particular) that it really does work shockingly well. Post-intercooler air temps were actually getting down to exactly ambient, which was never the case before the coating.



So I wouldn't claim it's for everyone. sperry, if you asked me if you should coat your downpipe I'd say it's probably not worth the time and effort to take it off and ship it back and forth to us plus the cost of the coating because of your setup. If you were running a TMIC, I'd tell you to do it. Either way, it's obviously up to you because whether the $100 is a lot or a little isn't something I can decide ;)


Jeremy

Well hell, I like the fact that you took the time to type all that shit out. The upipe things scares me a little more because if any of the coating comes off it's bye bye turbo. I appreciate the honest assesment. Crucial is on my top 3 choices when I decide to get everything.

I was making an ass out of myself and assuming that you were reverting to stock and then selling the car. my bad.

I've never heard of a problem with the ceramic coating inside (or outside) any Crucial pipe peeling off. It's not that Jet Hot Bullshit. Getting the stock cat and EGT probe out of the UP should be #1 on any 2L WRX mod list for safety and performance though. Going to a Crucial UP was a slam dunk for me.

I see what you did there :lol:

Cody, since I sold my wrx I have to decide on parts for my new sti. I know the upipe is catless stock so I have to decide if a coated upipe is worth the PITA it is to put it in.

This thread started out as one thing and turned into another. I think I confused the shit out of everybody :oops:

Either way i'm learning a ton and narrowing down my choices. The only drawback I see from the crucial tbe is the sound. It's hard to tell from the video but I am looking for something that is slightly quieter then my old wrx with a catless dp and tanabe hyper racing medallion catback.

You can always get their DP and whatever 3" flange CBE you want. The new Crucial DP system bolts right up to any 3" flange CBE you want. I run a Borla Hush with the optional 3" flange adapter, and while I don't think it's all that pretty or light...it's quiet as it gets, 3" all the way, and doesn't draw attention like the "sportier" axle backs will.

And Jeremy doesn't even usually recommend replacing the stock STi UP due to the PITA install and cost with only minimal gains when compared to the stock catless UP.

Up pipes are easy you all are just babies, it just takes some rough love.

I dont think that an aftermarket up thats coated and/or wrapped would make a noticable difference over the stock one with its heat shields though.