mbquarts

iTrader: (10)

Incorrect. The stock uppipe does have a flex section. The flex section is not for movement it is for heat expansion. The exhaust manifold and uppipe will expand when in use. The flex section will flex when the uppipe gets hot in order to prevent the welds from cracking or the flanges from warping.

WRX Rush

iTrader: (7)

I have the STi Up-pipe from Japan, it has the same heatshield as stock, it has the same flex as stock, it has no egt bung.

I have never heard the theory of flex becoming a turbulent for exhaust. I will have to look into that. Even if the flex did add exhaust turbulence, the normal street driver would never feel that difference.

From the issues I have heard about a flex up-pipe is just re-assurance of no exhaust leaks, the no flex up-pipes, I have heard need to be machined, need to be double and sometimes triple gasketted in order for them to work the way they should.

I would say the best up-pipe for the money would either be the STi JDM up-pipe or the bosal, a copy of the JDM.

Cheers,
Austin

subabu05

+1 for STI uppipe.

meilers

As the other posters have pointed out, the STOCK PIPE has a flex joint itself; you just can't see it under the heat shield. Care to revise your statement?


Ah yes, the "buy a Honda" comment -- Study the thermal properties of cast iron vs. steel and get back to us. I think you'll find that a ceramic-coated rolled steel pipe is just about the same as a cast-iron pipe in terms of heat retention and prevention of hot spots.

meilers

The stock WRX and STI pipes both have a flex section, from the factory; I guess Subaru engineers have a few things to learn, according to you? Second, even though the flex is differently-shaped on the outside, the actual tubing diameter inside is consistent and smooth -- the flex is a change in the thickness and walls of the pipe, with a woven "basket" of steel mesh to prevent heat loss; it isn't as rough on the inside as it appears on the outside. See the pic of the APS pipe further up the thread, you can kinda see inside and the "woven steel" look is only on the outside.

EJ20Legacy

AAAHHHHH! OMG. I just wrote a very, very thorough like 2 page response to everything on here, and my cat stepped on the backspace key, the browser went 'back', and I lost it all. That just blows. So.... this is going to be short and to-the-point this time.

Engine mounts and only on asphalt: Manifold is connected to block, uppipe is connected to manifold, turbo is connected to uppipe and the block. The engine moves, it ALL moves. Together. Engine mounts, hard or soft, are completely inconsequential. The uppipe doesn't know the difference. And smooth roads? You've just totally lost me there. Who cares? I know the uppipe doesn't.

Coating = "who cares": Coating is NOT a "who cares." Coating does the above-stated things (lowers underhood temps, keeps heat away from cylinder #3... the failures of which, btw, have long-since [like 1993] been attributed or partially attributed to an uppipe curving around it and overheating it) and a whole lot more. It keeps the heat in the uppipe where it belongs. This means quicker spool and more power... which was proven in that header dyno comparison shootout deal, where coated/wrapped versions of identical headers spooled a couple/few hundred rpm sooner than their plain stainless counterparts, which needed a full throttle run or two to heat up before they began to spool about as early. It protects the metal from heat. This means less metal fatigue and less expansion. It protects the metal from the elements... the obvious things like water and underhood fluids, but also the less obvious corrosives that are in exhaust gas. A coated pipe should outlast your car. Surface temps are lower, which means less likelyhood of a fire should oil drip onto your exhaust, which does happen. It's far from a "who cares." The value is more than there.

Flex sections: Companies do this because it's cheaper than making a solid pipe that is properly made. The flex section allows major cost cutting in quality control. With a good solid pipe, it has to be PERFECT. After welding the flanges on--perfectly--they must be re-ground to ensure that they are at the exact correct angles and perfectly flat, and are the exact correct distance from eachother. Every single pipe has to be exact. The tolerances are very, very small. By putting a flex section in there, all this stuff goes out the window. Tolerances become very large in comparison, as any irregularities in the flange angles or distance can be bourne by the flex. Subaru's pipes have flex sections because they are mass produced and mass installed. They are NOT to the tolerances that a Crucial Pipe is. Cast iron, as it were, expands and contracts incredibly little with heat. This is not the reason the Subaru pipes have flex sections.

--- install --- A flex section makes much more install idiot proof. Properly installing a solid uppipe is not trivial. You must do it correctly. Leaks on cars with solid uppipes are due to poor uppipes or a corner-cutting install. To properly install a solid uppipe you must completely loosen the turbo (banjos, turbo-to-block brackets, inlet hose, etc), attach uppipe to manifold, manifold to head, then uppipe to loose turbo, then bolt turbo down. A properly-installed, well-made, solid uppipe is less likely to leak over time than one with a flex section, because flex sections fail...

There are three types of flex sections that I see in Subaru parts. There's the banjo section that is in the OEM parts, the braided section like t3h Helix, and a cool slip section like PDE uses. The slip is sweet action. It's good stuff. The OEM-style causes a lot of turbulence. This is why a stock STI sees ~ 5+ whp from the addition of any aftermarket uppipe. The stocker is not a performance uppipe. Braided sections are prone to failure. The constant heat cycles fatigue the metal, the exhaust corrodes it, and the vibration and slight expansion/contraction put it over the edge. After a while, a braided flex section will fail. Especially one that gets as hot as the uppipe does. Less turbulent than the stock style, but it doesn't last like the stockers (which, btw, do crack in the flex section).



The Crucial piece cuts no corners. It is 321 stainless steel, not 304. 321 is a much better grade for high temp applications. The ceramic coating process is extremely intensive (see write-up on the CR site). It comes with embossed, copper gaskets. It comes with new studs. It comes with a resistor for your EGT probe removal. It comes with a lifetime warranty. All of that grinding and whatnot that I mentioned above is done. This is THE BEST UPPIPE ON THE MARKET. Factor in the value added by the studs, gaskets, coating, steel quality, lifetime warranty, and the $249 (with free shipping) price tag is a freaking steal!!!!!! No joke.



Well aren't we all just having fun pretending to have degrees in metalurgy and fluid dynamics . If a ceramic coated stainless pipe has the same heat retention properties of cast iron, I think you've just proven the Crucial point further! All the benefits plus more, none of the weight of freakin' iron. And I'm sure you have the graphs and data to back up your statments there guys, LOL. Yay let's all talk out of our asses!

You're talking about cosmetics. Who cares? Are you going to cut your hand on the laser-cut flange? Should Crucial attack it with a router before selling it?

As far as beveled entries and exits to the pipe, it's not important unless you've got a ported/extrude-honed manifold and a turbo with a larger exhaust housing inlet. The Crucial is designed to have the same inner diameter as the inlet to the stock and VF series turbos, and your manifold. Beveling those inner edges would have no effect. Having the proper diameter means higher velocity and more heat, which mean quicker spool. If you do get to a point where you have a turbo with a large inlet, you don't want a pipe with beveling anyway, you want a pipe that is the same diameter as the inlet the entire way through... and the manifold should be port matched to your heads' exhaust ports. Anyway, most of these setups wont be running your typical uppipes anyway so it's inconsequential...



In an attempt to help the thread starter: You do not need to buy an uppipe and downpipe from the same company. They don't touch eachother... they're separated by the turbo. So you don't have to get a "matching set" for fitment or synergy reasons or whatever. With that said, there is no reason to buy Invidia over Helix for the dp, IMHO. They are the same company, and the downpipes are identical or so close they might as well be. No sense spending the $$$ for the Invidia name when the Helix is the same product.

Hope this helps a bit. The Crucial uppipe is the best choice if you want the best quality, best performance, and best value. Choosing a GOOD uppipe is more important than the downpipe. If you're going to skimp on one side of the turbo or the other, it should be on the downpipe.

Jeremy

testes1010

excellent write-up Jeremy....BTW kill the cat....haha

misterx

Crucial has never had an complaint about an uppipe for any reason and we've sold hundreds of them. All of the users report remarkably quick spool-up.

I'm not quite sure I understand the point of this thread. It seem a some "expert" has tried our pipe and found it lacking. Please, provide some basis for the complaint and I'll be pleased to respond. Since the pipe comes with a lifetime warranty, if you have a pipe that didn't fit or is leaking because it's faulty, send a note to Crucial and we'll fix it, no questions asked.

meilers

I don't buy your argument against a flex section. You are only talking about the engine-to-turbo sement of the engine, which convinently ignores the fact that the other side of that turbo is connected to the actual exhaust, which can be up to 60 pounds of mass and which is mounted (purposely) in a loose fashion on the car. Try this: get a friend to gun the engine while you're outside looking at the tailpipe, and you'll see it wiggle. That movement starts all the way at the engine block and moves back, transferring the physical force through the entire system. If the design tolerances are as tight on the Crucial as advertised, that would start me worrying about all the possible variences in the OTHER parts of the exhaust system, turbo and mounting mechanisms! Having a little slack to fall back on is good. Do the WRC cars have a flex up-pipe? That would certainly be the ultimate test of up-pipe fittment.

Considering EGTs on a properly tuned car rarely get over 1480 F, I don't think you can make an argument about a heat-based failure on any pipe, steel or iron; a pipe that had been so fatigued would connect to a car that had taken even more of a beating, meaning that some other component (such as the turbo) would be likely to fail first. The exception to this of course would be a catted up-pipe, which do have documented failures and decomposition of the catalyst. As a friend of mine put it, "damn pipe turned my turbo into a garbage disposal!"

I think the Crucial part is an excellent pipe and a lot of work goes into it, but I don't see a definitive argument as to it being the only workable approach or only logical choice. The Helix Flex and APS pipes certainly have plenty of positive customer reviews, and -- to be frank -- I don't think anyone on this board (or 99% of the WRX or STI drivers out there) will ever stress their cars enough to provoke an up-pipe failure of even the stock part, nor would they notice the incremental performance gains from one pipe to the next. 100rpm of faster spool-up goes by pretty quick, even if you are timing your quarter-mile by the milisecond. I'd pass on the Crucial pipe for the reasons I've stated; a tiny amount of HP or RPM gain doesn't (for me) balance out against an extra safety margin for long-term durability of the entire exhaust system. If you've got the time, money and/or skills to fit and employ a part as precision as the Crucial pipe claims to be, go for it -- that's why we have a free market and so many wonderful choices.

EJ20Legacy

Is that what you call that solid metal bracket that connects the downpipe to the transmission? It all moves together, son. An uppipe WILL NOT be induced to flex when the engine moves. The turbo is solidly bolted to the block with two very thick, non-moveable brackets. The turbo goes up and down with the block, as does the downpipe because it is bolted solidly to the transmission. The uppipe goes for the ride. The turbo cannot move up and down on its own, pushing or pulling on the uppipe. Try again.

Again, you are talking completely out of your ***. You have no idea how heat fatigues a metal, you are just making statements that you cannot back up. It is heat cycles that fatigue parts like an uppipe... going from hot to cool over and over again. It is not maximum temperature-related, although it could be... but other things would go down the toilet first, as you mentioned. The ceramic coating helps prevent this, btw, by shielding the metal from some of the heat and slowing the heating and cooling of the pipe. As mentioned, 321 stainless is significantly more resistant to heat-induced stress than 304. It is a much higher grade of steel.

Hey, Adrian (who actually knows what he's talking about, wrote the following to me:

"Thermal Conductivity:

Cast Gray Iron: 44-52 W/m-K (watts/meter-Kelvin)

AISI 321 Stainless annealed sheet: 16.1 W/m-K (watts/meter-Kelvin)


Cast Iron would have to be nearly 3 times thicker than bare 321 stainless to have the same thermal insulating properties ... then there's the coating. B) The only reason people think cast iron is a good insulator is because it is usually cast very thick. The thickness of any metal affects how quickly heat flows through it.

Information courtesy of Modern Casting Dot Com and Aerospace Specification Metals Inc.



Adrian~"

So there's the data you were looking for. Doesn't look like it helped your case. Too bad you had no idea what you were talking about, again.


Uhoh!!! Looks like you don't know what you're talking about again. Let me educate you (courtest of Adrian, again, who actually does possess an education in fluid dynamics.

"Dynamic pressure increases proportionally, but Static pressure decreases. Total pressure (static + dynamic) remains the same. One goes up, one goes down, that's how the turbo works. Not that the guy who said that on i-club knew the difference."





Anyway, you could prove yourself wrong all day and that would be fun for me an all, but I've only got two things to say:

1) Misterx pointed out that he has not had a single pipe returned to him ever. They have a lifetime warranty... had there been fitment, leakage, or any sort of problem, he would have had one returned.

2) The pipe is the best value on the market, hands down. Good steel, ceramic coating, studs, copper gaskets, egt fix, lifetime warranty... it is soooooo inexpensive for what you get!!!!

Jeremy

btw -- I have personally seen and have also read about (on here and NASIOC) plenty of Helix pipes w/ cracked flex sections. Braided will not last.

WRX Rush

iTrader: (7)

It still remains that factory straight from subaru, the up-pipe has a flex,

So without a flex there must be some kind of driveability problem. Well maybe not because that is the USDM catted version...

Oh! But the catless JDM STi up-pipes still do have flexes.

Getting an up-pipe without a flex is just asking for problems, be on the safe side and get a flex up-pipe.

Rush

testes1010

i've on been using a Crucial Uppipe for almost a year and no leaks, no problems....

..|., fok the flex...........

the 'well-engineered' flexed Subaru WRX uppipe has a cat in it....so much for engineering...they must had lost their conductor's hat....

EJ20Legacy

Are you joking? This is a STUPID argument! Please don't take offense, I'm not trying to be a jackass here but you people need to think about what you're saying.

First, had you read my first post in its entirety--and I understand why most people wont (it's a freaking novel!)--you would know where I stand on the factory flex section and why [I believe] it's there. Like I said, it allows the company to produce parts to a much lower tolerance and save A LOT of money. This is how car companies work. Engineering must work around a budget set by the company. If they didn't, the WRX wouldn't come on RE92's, it would have Inconel exhaust parts, titanium valves, kevlar clutches, magnesium wheels. Saving $2.00 on a car part means millions in savings to a company like Subaru that produces hundreds of thousands of these parts. There is a reason that '05 JDM STI seats bolt right into my 1998 Legacy, why WRX brakes bolt right on, why the suspensions are swappable, etc. Subaru is wonderful at cost cutting. They do not change things unless they have very good reason to. I'm sure you don't think the stock WRX transmission is a wonderful transmission. Talk about cost cutting! I know you know that OEM isn't the best quality that you can buy.

I know you know this because we ALL modify our cars. The [insert little girl voice] "oh but the factory uppipe has a flex so it must be the best solution" argument is total crap. If OEM was the best, we would NEVER replace parts on our cars. But we do. We replace pretty much everything. Why are all good aftermarket intercoolers bar and plate while the factory ones are tube and fin? Tube and fin is cheaper, bar and plate performs better. There would be hundreds of examples of this same kind of thing. You cannot argue something that you, yourself, do not believe in.

Going from flex to solid IS AN UPGRADE!!!!! OEM = cost cutting. You = modify your car. If you actually thought OEM was "the light" = you would never modify your car.

...oh and I almost forgot... you're talking about the same Subaru that put a catalytic converter before the turbo, right? Cuz that's a freaking genius idea! You bash the loss of the flex, so why don't you think aftermarket pipes should have a cat in them. I mean, the OEM one does! Do you see how your argument falls flat on its face because of what you, yourself, have said and done?


....and further example of how much everyone has NO CLUE what they are talking about and they are simply spitting out arguments that they read from somebody else or heard from some kid on the street and they feel like being asshats and saying "flex is better" because they have one on their car and would now feel stupid to know that they made the WRONG decision, so they have to slam solid ones with absolutely no basis for it in order to preserve the size of their quickly-shrinking *****'.... anyway...

WTF have all of your posts been ?!?!?!?! Hahahaha. You've talked about all sorts of crap, including thermodynamic properties of metal and exhaust gas pressure relating to velocity and other things and not only didn't back ANY of it up, but you were WRONG on almost all of it. Hahahaha. You should have followed up ^^ that ^^ statement with "my name is meilers but you can call me Pot. I will call all of you guys Kettle. P.S. -- you're all black."

Jeremy

Warning: Light at end of tunnel may be a train.