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Saku Saku is offline
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Default 11-30-2010, 11:00 AM

Quote:
Originally Posted by DBFIU
im 90% sure youll pick up power...
Agree. Turbo and open exhaust, even if boost is the same at any rpm point, ex manifold pressure may be less. This causes higher tq/hp.

Possible reasons not to would be:
-knock sensor picking up false sounds caused by open exhaust noise or reconanses.
-ecu to go limp home mode or such for some unknown reason.

On other turbo cars, exhaust mod may *feel* slower. Driver feels the sudden tq rise=boost rise. Boost build starts sooner and boost (=tq) is higher at any rpm point. For N54 this might affect rpms around 800-2000, not higher.

Very interesting to see the dyno numbers.
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Default 11-30-2010, 12:07 PM

Not to start a tuner war, cause im not sure how the inner working like Vanos work in this car, but on my previous car, exhaust design could only go so far without the proper tuning.

What I mean by that is, my last car had the ability to adjust cam angles, some of you might be familar with cam gears on older b series hondas or something.

Same concept except it was adjustable electronically... anyway, finding the right combination of those cam angles, would bring back that lost torque or what have you that may have felt to be lost when switching exhaust.

My point being, and i truly just dont know, are these tunes taking FULL advantage of these exhaust changes?

Does Vanos play a role? Can it be altered? Is it supposed to be altered? Things like that.

So to say, a 3inch dump lost power, well, was it the exhaust dump that lost power, or are the tunes not taking advantage of it?
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Default 11-30-2010, 12:18 PM

that's pretty much what I see doing. Of course a little further forward. I was wondering if the cutout was mounted 90 degrees from the flow of exhaust it would still eliminate back pressure but I'm sure it would be a little off as far as flow. Anyone tried something like this? Oh and as far as the knock sensors.. Yeah when they feel knock they disable EVERYTHING wastegates wide open 0 boost. it's pretty much a slow 128i till the knock goes away. Ever want to try it just unplug your sensor and drive around for a sec. Don't ask me how I figured this out.

Last edited by KC_skyrider; 11-30-2010 at 12:35 PM..
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Default 11-30-2010, 01:28 PM

I got N/A Mode on the procede. Its quite amusing with 0 boost. LOL. I actually daily drive like this now.
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Default 11-30-2010, 01:46 PM

Quote:
Originally Posted by dzenno
+1 but its waaay too loud on my AE ******* exhaust literally scares neighbours...my poor neighbours, sometimes I feel so sorry for them listening to my beast wake up in the morning...
Stock exhaust crew here.... its simply perfect.

I was going to buy a catback exhaust for its simplicity in comparison to a ******** install just to wake up this car a little on the noise side, but after N/A mode, it just saved me a good $1000+ cause I no longer need one

Its quite loud on cold start....
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Bowser330 Bowser330 is offline
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Default 11-30-2010, 05:13 PM

What is the benefit to driving in NA mode? Do you feel you get better mpg? Is the resting of the turbos good for them?
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Default 11-30-2010, 05:41 PM

Feelings are for your GF , I havnt logged any MPG differences simply because most of my driving is half racing, half crusing, but a few friends told me there were good improvements for daily commutes.

Boost tables even for 1-4 PSI boost transitions use a lot more fuel then loading up N/A in the RPM range, so its obvious it would save gas since your not swinging in and out of boost on low throttle inputs during acceleration and cruising on the highway.

I would imagine not spinning up the turbo's 10's of thousands of RPM would be a benefit as its less abusive over the long term.

But besides both of those benefits, it just sounds badass, sounds like inlike 6 again with the classic e36/e46 sound. Which some people love or hate.

I love it.
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onefastman onefastman is offline
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Default 12-02-2010, 09:13 AM

Just picked up strait ***** for the mids on the e92m and will run it with a stock muffler.

I think I will do something like what is shown above so I can run compleately open *****
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Default 12-02-2010, 09:58 PM

KC any updates?


JB4 //MMP Stage 3 turbos//Custom Exhaust/BMS DCI//FMIC/KW suspension//Pi & Fuel it stage 4/MHD
BEF /CP&TIAL/ OCC.
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Default 12-03-2010, 11:46 AM

Nope. My custom exhaust welding budget just went to a set of twin snails I picked up from ebay to go on the shelf till I'm ready for RB upgrade. Once I decide to go with Auto hobby shop on base or Schafer clubsport in town I'll have another paycheck to get this back on track. Don't worry I will update when I'm done.
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Default 12-03-2010, 08:33 PM

Quote:
Originally Posted by JPSlick
Not to start a tuner war, cause im not sure how the inner working like Vanos work in this car, but on my previous car, exhaust design could only go so far without the proper tuning.

What I mean by that is, my last car had the ability to adjust cam angles, some of you might be familar with cam gears on older b series hondas or something.

Same concept except it was adjustable electronically... anyway, finding the right combination of those cam angles, would bring back that lost torque or what have you that may have felt to be lost when switching exhaust.

My point being, and i truly just dont know, are these tunes taking FULL advantage of these exhaust changes?

Does Vanos play a role? Can it be altered? Is it supposed to be altered? Things like that.

So to say, a 3inch dump lost power, well, was it the exhaust dump that lost power, or are the tunes not taking advantage of it?
I have to agree.

I had a Peugeot 406 coupe V6 when I was younger. It was the first car I ever drove which would red line in top gear (160+) but when I had a straight through exhaust made, it never made that 160 again.

I think that's what you're saying, it's not just flow or pressure etc, it's a combination.


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Default 12-04-2010, 11:38 AM

Quote:
Originally Posted by DeadEye
I have to agree.
I had a Peugeot 406 coupe V6 when I was younger. It was the first car I ever drove which would red line in top gear (160+) but when I had a straight through exhaust made, it never made that 160 again.

I think that's what you're saying, it's not just flow or pressure etc, it's a combination.
Is the 406 N/A if so it would be a poor example. Not many N/A engines made can gain power with 0 back pressure. Normally some is simply required. Hence a "tuned" exhaust giving the better gains, and meaning the lose of power in your Peugeot should be expected with a straight exhaust. Turbo cars do not require the back pressure and it's been a proven practice that 0 back pressure after the turbo = greater response and power without additional tuning in turbo cars of all kinds of makes and models. Ours can be the exception however comparisons with naturally aspirated cars will not easily support theories as to why.
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Default 12-04-2010, 12:36 PM

Quote:
Originally Posted by DeadEye
I have to agree.

I had a Peugeot 406 coupe V6 when I was younger. It was the first car I ever drove which would red line in top gear (160+) but when I had a straight through exhaust made, it never made that 160 again.

I think that's what you're saying, it's not just flow or pressure etc, it's a combination.
Well what im really saying is, what I said, "are the tunes available not taking advantage of the exhaust". From my understanding, tunes are only concentrating in one fashion or another on Ignition Fuel and Boost.

What about vanos? Can that be changed? There is a reason the car stock has variable valve timing more or less, so maybe it needs to be adjusted if possible to tune for extra boost and more flow in the exhaust.

Maybe cams are needed? Who knows. Just thinking out loud here.

Its most common practice that N/A engines require a tuned exhaust that has a scavenging effect and Turbo cars simply need to get the exhaust out with the most flow as possible.

Last edited by JPSlick; 12-04-2010 at 01:51 PM..
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Default 12-04-2010, 12:40 PM

Quote:
Originally Posted by DeadEye
I have to agree.

I had a Peugeot 406 coupe V6 when I was younger. It was the first car I ever drove which would red line in top gear (160+) but when I had a straight through exhaust made, it never made that 160 again.

I think that's what you're saying, it's not just flow or pressure etc, it's a combination.
turbocharged engine??
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Default 12-04-2010, 12:49 PM

strange people here.... someone spends $1500 on a bigger exhaust.... open exhaust and it is a good idea, but if someone spends $300 on a device that opens the exhaust when he wants to.... the strange people says... its not going to work!!
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Default 12-04-2010, 12:55 PM

Quote:
Originally Posted by sti917
strange people here.... someone spends $1500 on a bigger exhaust.... open exhaust and it is a good idea, but if someone spends $300 on a device that opens the exhaust when he wants to.... the strange people says... its not going to work!!
The so called strange people you speak of only deny it works cause they claimed they tried it and "FELT" a power loss.

IDK if any of those strange people have actually dynod the loss or have tuned for max potential though.

Its likely with the Jb3 crowd they might need to map up cause if they stick on the same map prior to the change they might be making less boost or something. IDK

Last edited by JPSlick; 12-04-2010 at 01:09 PM..
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Default 12-04-2010, 01:01 PM

On N/a engine is you put too much exhaust on the engine (big *****, big head exhaust valves, etc) you get a lot of reversion which kills low end torque./power There were/are some old school tricks like using stepped headers and even header ***** with obstructions (a lip) welded on the floor of the exhaust port to stop airflow from going back up the pipe towards the head/exhaust port. I saw this first on several v8 engines back in the day.

On a turbo engine, once the turbine starts spinning you're not going to get any reversion from the exhaust system post-turbine so you can run as large an exhaust as you like and it will always be good for power in a theoretical sense (P1/P2 etc). The problem on a car with modern electronic engine controls is the DME/ECU. If you play with the exhaust you could end up putting in ***** that are too big or leaky and they will pull in more fresh air, the O2 sensors will see it and throw off the tune. That's likely how you could lose a lot of power.

I've seen and even worked on few fast turbo cars from 10+ years ago (mustangs), and they had only one O2 sensor up by the head. AFAIK they only made more power with larger exhaust up to open exhaust because the O2 sensor was close to the engine and the ECU controls were very basic. N54 has four O2 sensors I believe, 2 of which are in the middle of the exhaust with the other 2 in the *********.


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Default 12-04-2010, 01:11 PM

Quote:
Originally Posted by BavarianBullet
On N/a engine is you put too much exhaust on the engine (big *****, big head exhaust valves, etc) you get a lot of reversion which kills low end torque./power There were/are some old school tricks like using stepped headers and even header ***** with obstructions (a lip) welded on the floor of the exhaust port to stop airflow from going back up the pipe towards the head/exhaust port. I saw this first on several v8 engines back in the day.

On a turbo engine, once the turbine starts spinning you're not going to get any reversion from the exhaust system post-turbine so you can run as large an exhaust as you like and it will always be good for power in a theoretical sense (P1/P2 etc). The problem on a car with modern electronic engine controls is the DME/ECU. If you play with the exhaust you could end up putting in ***** that are too big or leaky and they will pull in more fresh air, the O2 sensors will see it and throw off the tune. That's likely how you could lose a lot of power.

I've seen and even worked on few fast turbo cars from 10+ years ago (mustangs), and they had only one O2 sensor up by the head. AFAIK they only made more power with larger exhaust up to open exhaust because the O2 sensor was close to the engine and the ECU controls were very basic. N54 has four O2 sensors I believe, 2 of which are in the middle of the exhaust with the other 2 in the *********.
Ah, good points about o2 sensors and a false lean condition reading.
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Default 12-04-2010, 01:30 PM

Quote:
Originally Posted by onefastman
I was flabergasted when I felt a SIGNIFICANT loss of power (40hp at least).

I was on vk dp's, ets fmic, 100% meth (m5), map9 18ohm.


I understand where jpslick is coming from but in such a mod I would be skeptical of gains as they would be small and thus hard to tell if it is true but when you feel a huge loss of power with no changes to conditions other than removing the exhaust I can say with confidence that it hurt performance.
skeptical of gains??? let me see...
stock exhaustt is : 2--- 2.25 exhaust ***** = 7.952 square inches area

a single 3 inches exhaust pipe is................. 7.06 square inches area

when a exhaust company replaces the stock exhaust with a single 3 inches exhaust, call it performance exhaust and charges $1300 or $1400 for it you dont get skeptical???? if there is any horsepower gain is ion the high flow mufflers, meaning people are paying $1300 for two high flow mufflers, cause the pipe is smaller than the factory... and you're not skeptical about this???
what say you?
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Default 12-05-2010, 08:58 AM

All 4 O2 sensors are in the ******** itself. 2 pre first set of cats and 2 immediatly after and before the ******** flange. To fit these I will be mounting in the mid pipe somewhere forward of the 2nd set of cats to eliminate any additional resistance. This will give more than 24" of 2.5" pipe between the nearest O2 sensor and dump. I'm not good at fluid dynamics but I feel confident that the massive amount of pressure exiting these ***** would restrict air at atmospheric pressure from entering the pipe during running. I understand that if this did happen it would cause a false LEAN indication and cause a lose of power. To bad everyone running open ********* already have their aft sensor disabled. I also doubt outside air is getting to the sensor mounted within inches of the turbo.

At this point it's all debate and plenty of people are offering valid theories. However till we get a car on a dyno that's all any of it is. If someone is very curious then it's gonna cost you $300 to find out. Otherwise just be patient and I'll put this one to rest in due time. Even if I lose power, oh well, it means I have an exhaust to scare people I pass on the autobahn, and with a flick of a switch I'm back to a quiet sleeper with all it's power. It's worth $300 just to have that feature and I get to find out if I can also gain power. So for me it's win win.
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onefastman onefastman is offline
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Default 12-05-2010, 11:21 AM

Quote:
Originally Posted by sti917
strange people here.... someone spends $1500 on a bigger exhaust.... open exhaust and it is a good idea, but if someone spends $300 on a device that opens the exhaust when he wants to.... the strange people says... its not going to work!!
Umm no


1. I paid $600 for my turbo back exhaust so I am not a fan boy of expensive *****
2. I agree that these cars have too much restriction
3. I have tested this with stock exhaust, stock dp's with mid and muffler, ******* dp's and ******* exhaust, open dp's, open dp's with ******* mid w/o muffler, and back to full ******* with muffler.
4. I drag my car often (had top 20 n54 time for a while) so I think I would notice a huge drop in power.
5. When I ran open dp's I felt a massive loss in power on map9 with meth
6. When I put the mid pipe back on I felt a significant gain in power from open dp's but still a over all loss from full exhaust.
7. When I put the muffler back on (took it off to spray it) I felt a further gain back to where it was.

Its not like I am saying I felt a 5hp increase. I felt a loss of torque in the 50lb ft range or more. The loss was massive.
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Default 12-05-2010, 09:57 PM

Quote:
Originally Posted by onefastman
Umm no


1. I paid $600 for my turbo back exhaust so I am not a fan boy of expensive *****
2. I agree that these cars have too much restriction
3. I have tested this with stock exhaust, stock dp's with mid and muffler, ******* dp's and ******* exhaust, open dp's, open dp's with ******* mid w/o muffler, and back to full ******* with muffler.
4. I drag my car often (had top 20 n54 time for a while) so I think I would notice a huge drop in power.
5. When I ran open dp's I felt a massive loss in power on map9 with meth
6. When I put the mid pipe back on I felt a significant gain in power from open dp's but still a over all loss from full exhaust.
7. When I put the muffler back on (took it off to spray it) I felt a further gain back to where it was.

Its not like I am saying I felt a 5hp increase. I felt a loss of torque in the 50lb ft range or more. The loss was massive.
Something is wrong with the car IMHO. Im not doubting what you felt, but a huge gain like that on a FI car makes no sense.
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onefastman onefastman is offline
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Default 12-05-2010, 10:01 PM

Quote:
Originally Posted by DBFIU
Something is wrong with the car IMHO. Im not doubting what you felt, but a huge gain like that on a FI car makes no sense.
I dont think so. I was going to go to the track to test open dp's but felt such a loss I put the exhaust back on after 15 min of testing. That night I went to the track and ran a 12.20 @119.5 with a 6mt on run flats so I think the car is running just fine
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Default 12-05-2010, 10:04 PM

Quote:
Originally Posted by onefastman
I dont think so. I was going to go to the track to test open dp's but felt such a loss I put the exhaust back on after 15 min of testing. That night I went to the track and ran a 12.20 @119.5 with a 6mt on run flats so I think the car is running just fine
its running fine with the exhaust restriction? I dont understand.
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Default 12-05-2010, 10:12 PM

Neither do i but it felt really off
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