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      05-30-2011, 02:36 PM   #1
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Meth with stock downpipes?

I'm trying to figure out if its safe to run meth and 16psi at full flow with stock downpipes. Will the added cooler IATs and turbo efficiency make up for the increase turbo strain due to the downpipe restriction? I'm keeping my car for a long time so longevity is the most important thing for me. I do not want downpipes due to noise. Even race catted are to loud for my taste. I'm very interested in meth because it will keep my intake valve cleaning intervals down, improve fuel efficiency, lower oil temps slightly, decrease knock and make my turbos run cooler but can I increase boost?

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      05-30-2011, 03:12 PM   #2
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Ok, Listen to just catless downpipes with stock exhaust. Sounds gross IMO. Im looking for a way to safely increase PSI using meth. I understand the cats are a major restriction but will a more efficient combustion mitigate the use of downpipes?
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      05-30-2011, 03:13 PM   #3
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Stock DPs represent the worst restriction in the whole n54 setup..n if u r running that much boost AND meth i would not keeps stock DPs..go for catless DPs to optimize the longetivity of ur turbos

I am full catless.believe its not that loud...sound is more a function of the exhaust n mufflers u run. Not so much DPs
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      05-30-2011, 04:40 PM   #4
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Ok i think u r comparing apples and oranges. More effcient combustion, reduced air intake temps and increase octane are all benefits of using meth, but what you need to be concerned about are exhaust gas temps which are at issues especially at 16psi.. By going catless DPs you drop those significantly.

I understand you are looking for a way to safely increase PSI using meth and that you dont like the "sound" of DPs w the stock exhaust which is why i said looking into another exhaust setup s/b ur focus.

You can not consistently boost 16psi safely w stock DPs regardless of meth use or not..and especially if you are concerned with longetivity of your turbos..

Simply put you cant have it all.
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      05-30-2011, 06:13 PM   #5
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I think hotrod182 ran meth with a completely stock exhaust.
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      05-30-2011, 07:18 PM   #6
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16spi stock compared to DPs is less cfm, so turbos working less... but less power of course due to VE.

EGT is efficiency of combustion and cylinder pressures. DPs would most likely result in higher EGTs at similar boost.
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      05-30-2011, 07:27 PM   #7
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Quote:
Originally Posted by Joshboody View Post
16spi stock compared to DPs is less cfm, so turbos working less... but less power of course due to VE.

EGT is efficiency of combustion and cylinder pressures. DPs would most likely result in higher EGTs at similar boost.
So are you saying with Catless downpipes the turbos will work harder thus reaching higher temps? Doesn't the turbo compressor wheel have to work harder to fight the back pressure of the cats to reach target PSI? Thanks for any info. Still learning here.
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      05-30-2011, 07:34 PM   #8
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Originally Posted by tibra1 View Post
Ok i think u r comparing apples and oranges. More effcient combustion, reduced air intake temps and increase octane are all benefits of using meth, but what you need to be concerned about are exhaust gas temps which are at issues especially at 16psi.. By going catless DPs you drop those significantly.

I understand you are looking for a way to safely increase PSI using meth and that you dont like the "sound" of DPs w the stock exhaust which is why i said looking into another exhaust setup s/b ur focus.

You can not consistently boost 16psi safely w stock DPs regardless of meth use or not..and especially if you are concerned with longetivity of your turbos..

Simply put you cant have it all.
I run meth and all 4 cats. I run at 16.5 boost all day. EGTs are in fact lower when spraying meth. The only thing I could see is the higher octane causing the cat to fail earlier than normal but that's way down the road. The higher octane will make the cats work harder to add oxygen to the exhaust stream and will expel the precious metal faster. I'll replace stock DPs when my warranty is up in a few years.
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      05-30-2011, 07:41 PM   #9
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Quote:
Originally Posted by (-(ellblazer420 View Post
I run meth and all 4 cats. I run at 16.5 boost all day. EGTs are in fact lower when spraying meth. The only thing I could see is the higher octane causing the cat to fail earlier than normal but that's way down the road. The higher octane will make the cats work harder to add oxygen to the exhaust stream and will expel the precious metal faster. I'll replace stock DPs when my warranty is up in a few years.
Great to learn of a downside to meth.I guess I can get new cats welded in later down the road. How much meth do you flow? How ofter do you have to fill your tank? What size tank and and injector do you use?
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      05-30-2011, 07:42 PM   #10
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Quote:
Originally Posted by 335i 07 View Post
Ok, Listen to just catless downpipes with stock exhaust. Sounds gross IMO. Im looking for a way to safely increase PSI using meth. I understand the cats are a major restriction but will a more efficient combustion mitigate the use of downpipes?

quick question, what tail lights r those? off topic i know
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      05-30-2011, 07:54 PM   #11
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Originally Posted by 335i 07 View Post
Great to learn of a downside to meth.I guess I can get new cats welded in later down the road. How much meth do you flow? How ofter do you have to fill your tank? What size tank and and injector do you use?

It is the Vishnu PWM meth kit. It uses dual 1.0 mm nozzles. The flow depends on load conditions and throttle percent so the kit conserves a lot of meth. The tank is the stock windshield reservoir so it's 1.5 gallons and has lasted me about 3 weeks of normal driving.

Here is the link to the kit.
http://www.procedetuning.com/BMW/n54.../methanol.html

Here is the link to my dyno.
http://www.e90post.com/forums/showthread.php?t=527169
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      05-30-2011, 08:24 PM   #12
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Quote:
Originally Posted by (-(ellblazer420 View Post
I run meth and all 4 cats. I run at 16.5 boost all day. EGTs are in fact lower when spraying meth. The only thing I could see is the higher octane causing the cat to fail earlier than normal but that's way down the road. The higher octane will make the cats work harder to add oxygen to the exhaust stream and will expel the precious metal faster. I'll replace stock DPs when my warranty is up in a few years.
You could run that level of boost w all cats and meth if u choose..but the OP said his big concern is the longetivity of the turbos and I dont agree that this setup would promote that longetivity..

The turbos will see serious duty cycles well above levels that are safe for extended time due to restriction of the stock DPs, so failed cats would be the least of his concerns..at the end of the day its up to you OP whether u wanna run the risk..

I understand the warranty issue w the DPs but this is the reason I waited until after my warranty was up to mod..
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      05-30-2011, 09:56 PM   #13
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Turbo speed and reliability are related. Speed is related to boost. Boost and VE are related. Lower VE, lower turbo speed to reach boost. DC is related to turbo speed but is not linear of course. DC will only be very high if you are targeting higher flow then the turbo can handle... beyond it's efficiency range. 16psi catted or not is well within this range. the difference between catted and not catted is VE, flow... you get more cylinder fill at same boost without cats. Turbo at 16psi catted is working less than non-cats.

Bottom line is DPs create more power due to increased flow, but stock will not adversly effect reliability, EGT, etc.

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      05-30-2011, 10:08 PM   #14
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Have absolutely had great results with stock dps and meth. In fact in the 117mph trap area...the DCI were more of an improvement than the DPs. And I have logged traps before putting them on..talking them off...and the installing them on the sedan. Biggest improvement is on the spoolup in everyday driving..but that wont necessarily translate to much in a qtr mile run.

Also..do you have a coupe or sedan? The coupe is much louder compared to the sedan.
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      05-31-2011, 08:25 AM   #15
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Quote:
Originally Posted by Joshboody View Post
Turbo speed and reliability are related. Speed is related to boost. Boost and VE are related. Lower VE, lower turbo speed to reach boost. DC is related to turbo speed but is not linear of course. DC will only be very high if you are targeting higher flow then the turbo can handle... beyond it's efficiency range. 16psi catted or not is well within this range. the difference between catted and not catted is VE, flow... you get more cylinder fill at same boost without cats. Turbo at 16psi catted is working less than non-cats.

Bottom line is DPs create more power due to increased flow, but stock will not adversly effect reliability, EGT, etc.
Great post, but wouldn't higher (ie., greater) volumetric efficiency -- not lower -- result in slower turbo speed needed to reach a given level of boost?

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      05-31-2011, 10:06 AM   #16
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i recently put cattless AR dp's out and honestly its not loud at all.. gives you a tad more bass to your exhaust and a rewarding little gurgle gurgle when letting off the throttle. its just enough, very subtle. get dp's ..
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      05-31-2011, 12:57 PM   #17
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Quote:
Originally Posted by MDORPHN View Post
Great post, but wouldn't higher (ie., greater) volumetric efficiency -- not lower -- result in slower turbo speed needed to reach a given level of boost?

Neil
NO, cause the turbo is pushing more air. Pressure/boost is a result of restrictions... less restriction, less pressure at the same volume of air, OR same pressure, more volume.
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      05-31-2011, 01:11 PM   #18
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Quote:
Originally Posted by (-(ellblazer420 View Post
I run meth and all 4 cats. I run at 16.5 boost all day. EGTs are in fact lower when spraying meth. The only thing I could see is the higher octane causing the cat to fail earlier than normal but that's way down the road. The higher octane will make the cats work harder to add oxygen to the exhaust stream and will expel the precious metal faster. I'll replace stock DPs when my warranty is up in a few years.
FYI catts dont work like this at all. Catalysts by definition are not consumed during the chemical reaction, but they assist or expedite the process. Nor do they add o2 to make the exhaust "cleaner".
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      05-31-2011, 01:16 PM   #19
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Originally Posted by Joshboody View Post
NO, cause the turbo is pushing more air. Pressure/boost is a result of restrictions... less restriction, less pressure at the same volume of air, OR same pressure, more volume.
Got it. Thanks.

Neil
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      05-31-2011, 01:46 PM   #20
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Originally Posted by zsapphire7 View Post
FYI catts dont work like this at all. Catalysts by definition are not consumed during the chemical reaction, but they assist or expedite the process. Nor do they add o2 to make the exhaust "cleaner".
Perhaps its time to do some reading.

The three way cat uses precious metals to oxidate the exhaust stream. It starts by reducing nitrogen oxides to nitrogen and oxygen. This oxygen is stored in the cat to be used as an oxidizer. The cat will then add then oxygen to the hydrocarbons to break it down into carbon dioxide and water. It will then oxidate carbon monoxide into carbon dioxide. This is how emissions are reduced. The higher octane will poison the precious metals and coat them causing them to be less efficient. I went to school for this stuff man I'm well aware of what a cat does. It is also my profession and it is how I make a living. It is you that needs to do some learning before cutting me down. I pasted the wiki link because that is the easiest way to show you. Please read it.

Three-way
Since 1981, three-way catalytic converters have been used in vehicle emission control systems in North America and many other countries on road-going vehicles. A three-way catalytic converter has three simultaneous tasks:
Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2
Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2
Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O

http://en.wikipedia.org/wiki/Catalytic_converter

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      05-31-2011, 01:57 PM   #21
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Quote:
Originally Posted by 335i 07 View Post
I'm trying to figure out if its safe to run meth and 16psi at full flow with stock downpipes. Will the added cooler IATs and turbo efficiency make up for the increase turbo strain due to the downpipe restriction? I'm keeping my car for a long time so longevity is the most important thing for me. I do not want downpipes due to noise. Even race catted are to loud for my taste. I'm very interested in meth because it will keep my intake valve cleaning intervals down, improve fuel efficiency, lower oil temps slightly, decrease knock and make my turbos run cooler but can I increase boost?

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I think you may have a few misconceptions but I would be happy to clear some up for you.

First and foremost me as well as many others can and do run methanol with stock downpipes.

However here are a few things to note.

The only way to improve efficiency of your turbo's is via intercooler or downpipes.

Methanol will actually not improve efficiency of the turbo's themselves but have them work harder cause you are increasing boost.

Methanol wont improve your gas mileage, reduce oil temps, or make your turbo's run cooler. (unless you spray methanol onto the turbo's themselves but that will greatly reduce longevity of the turbo's even more so). Thats a little past the scope of this thread though.

****

The whole idea of methanol injection is simply this:

With a full bolt on pump gas car you would find about 15 PSI is a safe area of boost. Methanol injection regardless of modifications can run 17 even 18 PSI no problem.

Its not that it improves turbo efficiency, in fact none whatsoever.

All it simply does is cool down the intake charge right before the motor, and increase effective octane which in turn allows you to run more boost.

Hope this helps clear up some confusion.
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      05-31-2011, 02:06 PM   #22
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Quote:
Originally Posted by (-(ellblazer420 View Post
Perhaps its time to do some reading.

The three way cat uses precious metals to oxidate the exhaust stream. It starts by reducing nitrogen oxides to nitrogen and oxygen. This oxygen is stored in the cat to be used as an oxidizer. The cat will then add then oxygen to the hydrocarbons to break it down into carbon dioxide and water. It will then oxidate carbon monoxide into carbon dioxide. This is how emissions are reduced. The higher octane will poison the precious metals and coat them causing them to be less efficient. I went to school for this stuff man I'm well aware of what a cat does. It is also my profession and it is how I make a living. It is you that needs to do some learning before cutting me down. I pasted the wiki link because that is the easiest way to show you. Please read it.

Three-way
Since 1981, three-way catalytic converters have been used in vehicle emission control systems in North America and many other countries on road-going vehicles. A three-way catalytic converter has three simultaneous tasks:
Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2
Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2
Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O

http://en.wikipedia.org/wiki/Catalytic_converter
I didnt mean to cut u down at all. I also studied this stuff btw..

I think we are saying the same thing. I interpreted your previous statement incorrectly. If you look at it it can be interpreted as the catt ADDS o2 to the exhaust kinda like an injection system where it eventually runs out. However, if you read the wiki post, catalytic systems can store the o2 that it "breaks down" from the original exhaust gases, specifically from NOx to N2 and O2, then "releases" it later.

In otherwords, I thought u were saying that catts will run out of o2 to inject... rather than they "can" store the o2 that is broken down from NOx and release it later.
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