[FenixMike]

Originally Posted by mike@x-ph.com

N55 is maxed out from the factory ? What ?? !!!
Here is a dyno with the same engine. You can see stock power, versus map1 on a stock car versus map 2 with a car running catless DP versus map 7 on a car running catless DP and E85

Apparently you fail to see how no matter what you do, it hits 5,500 rpm and ends at the same place... unless you have another suggestion why it can't make any more power up top?

[FenixMike]

Originally Posted by Jayphil

Mike, how would you compare power of a F30 vs F10 N55 (same transmission let say 8spd) do you believe we are able to achieve similar dyno results.

For some reasons 335I or 435I N55 dyno always show much higher number vs the F10 where we rarely see anything above 310whp.

Also from what I see from the dyno you posted is that once you have a tune nothing will be added past 6k rpm but you are still gaining peak HP but at much lower RPM vs stock curve (between 4.7K to 5.5K RPMs).

Thats because the turbo is out of air... hence what I've been saying. Im sure Mike would love to sell you more parts, but simple fact is, they only add power down low, which doesn't do you much good unless your goal is just to do a ton of smokey burnouts.

Once you get out of first gear, your car wont ever drop below 5500-6000 rpm again (depending on 6 speed or 8 speed trans) unless you're manually shifting it at a lower RPM, so basically you're investing more money into it when all you're doing is spinning the turbo harder down low, and once you hit about 5500, its out of air. This is why people are getting HUGE gains off aftermarket turbos on these cars, and why you don't see any N55 535s picking up much from stock. If you want to count the under the curve gains, sure you can make a bunch of power... but honestly what good is that unless you just want the car to "feel" fast, or blow the tires off.

I don't get offended one way or another if you dump a bunch of money into those engines and feed off the hype of "40-80 horsepower gains" when the power only comes on in a specific area of the curve. BMW did a great job at perfectly matching that turbo to the inline 6, which is why it spools up fast for a single turbo as opposed to using a larger turbo that may yield larger gains for aftermarket stuff but suffer on spool time. The downside is with that perfectly matched turbo, there just isn't any room for improvement except the areas where the turbo isn't on full demand, such as the mid range and lower RPMs.

[///M5Driver]

Originally Posted by FenixMike

Apparently you fail to see how no matter what you do, it hits 5,500 rpm and ends at the same place... unless you have another suggestion why it can't make any more power up top?

It tapers off torque just like a BMS N54 tune does. I'd imagine there has to be some sort of conservative approach to a nationwide tune. I'm sure if you lean on it with a custom tune you could probably increase duty cycles up top to help.

[mike@x-ph.com]

If your engine hits max HP at 4500-5000 rpm, what are you shifting at redline ?
I would shift at 6000 rpm so car is always in the power range between 4000 - 6000 rpm.
Thats what all the N54 guys do.

[FenixMike]

Originally Posted by mike@x-ph.com

If your engine hits max HP at 4500-5000 rpm, what are you shifting at redline ?
I would shift at 6000 rpm so car is always in the power range between 4000 - 6000 rpm.
Thats what all the N54 guys do.

Call me crazy, but I guess I bought an automatic car so I don't have to shift...

[mike@x-ph.com]

Originally Posted by FenixMike

Call me crazy, but I guess I bought an automatic car so I don't have to shift...

But you said that Catless DP do not provide any benefit because engine is maxed out. You should have said Catless Downpipes do not add any gains because im too lazy to shift at 6000 rpm

[FenixMike]

Originally Posted by e46beater

It tapers off torque just like a BMS N54 tune does. I'd imagine there has to be some sort of conservative approach to a nationwide tune. I'm sure if you lean on it with a custom tune you could probably increase duty cycles up top to help.

There are issues associated with over spinning a turbocharger... first and foremost is heat (especially for us warm weather guys). Skyrocketing IAT temps will end up causing the computer to pull timing out which will likely cause the car to make less power than the boost increase might have added. This will get progressively worse with each run, so if you're trying to do a 1/4 mile pass or multiple races in a row, you're in for a real treat if you aren't running good fuel and/or methanol. In addition turbo life is dramatically reduced when you have it just spinning wide open at all times. Having a custom tune dump in fuel and compensate with timing may help a small amount, but you're really just chasing a problem that can be easily fixed by using a correctly sized turbo for the power output you want. Running race fuel and increasing timing INSTEAD of trying to max out your turbo will help more, but unfortunately once the timing is in, you will have to run better fuel at all times (unless someone makes a multiple flash setup).

IF someone did make a neat E85 tune for that car where it could reliably and correctly run 100% E85 and not a mix, you could get a lot more timing out of it before inducing knock retard, but unfortunately on 91 or even 93, the correct answer isn't just keep adding boost until you run out of turbo, and then keep trying to add more. The other manufacturers have been playing that game for decades now and none of it ended well for the owners that tried it. I guess on the upside, it may give you the unexpected opportunity to put a forged rotating assembly and correct turbo in after whats left of your engine comes out

[FenixMike]

Originally Posted by mike@x-ph.com

But you said that Catless DP do not provide any benefit because engine is maxed out. You should have said Catless Downpipes do not add any gains because im too lazy to shift at 6000 rpm

[Jayphil]

FenixMike I do get your point and to some it is less than ideal to have to manually shift at 6000rpm and it would be nice to be able to flash the tcu to change the shift point.

In my case I am most of the time doing city driving and added torque add to driving enjoyment. Also I am not that often full throttle so I am not much worried about premature turbo wear, I am also not tracking my car.

The few times I am doing spirited driving, I am already using the paddle shifter. Still if you do not shift at 6000 rpm there is still some gain up top vs stock with a tune (adding anything else do not add past 6000rpm though).

All your comments are informative to help people decide if those mod are for them or not but to me a 1200$ including installation (JB4 and downpipe) to gain around 15% peak hp on 94 pump gas we have here in Canada is a no brainer. Adding anything more on top of that (excluding turbo upgrade) will be considered as mostly a waste of money.

By the way I am coming from an Audi A4 2.0t (7 years of fun) with a tiny turbo with all bolt on so I am already used to that type of feeling "Diesel" like since you have a lot of torque but need to shift in lower RPM. Also the turbo was still running strong after 100k miles.

[///M5Driver]

Originally Posted by FenixMike

There are issues associated with over spinning a turbocharger... first and foremost is heat (especially for us warm weather guys). Skyrocketing IAT temps will end up causing the computer to pull timing out which will likely cause the car to make less power than the boost increase might have added. This will get progressively worse with each run, so if you're trying to do a 1/4 mile pass or multiple races in a row, you're in for a real treat if you aren't running good fuel and/or methanol. In addition turbo life is dramatically reduced when you have it just spinning wide open at all times. Having a custom tune dump in fuel and compensate with timing may help a small amount, but you're really just chasing a problem that can be easily fixed by using a correctly sized turbo for the power output you want. Running race fuel and increasing timing INSTEAD of trying to max out your turbo will help more, but unfortunately once the timing is in, you will have to run better fuel at all times (unless someone makes a multiple flash setup).

IF someone did make a neat E85 tune for that car where it could reliably and correctly run 100% E85 and not a mix, you could get a lot more timing out of it before inducing knock retard, but unfortunately on 91 or even 93, the correct answer isn't just keep adding boost until you run out of turbo, and then keep trying to add more. The other manufacturers have been playing that game for decades now and none of it ended well for the owners that tried it. I guess on the upside, it may give you the unexpected opportunity to put a forged rotating assembly and correct turbo in after whats left of your engine comes out

Thank you for explaining tuning to me.. I've been doing it for years lol. I'm just stating they more or less took a conservative approach to a nationwide applicable tune. Leaning on a newer platform especially unaware of most customer's modifications is a little risky for any tuning company offering off the shelf power solutions. There maybe other factory limiting factors with higher boost like the bypass valve leaking, charge pipes cracking. I highly doubt the stock turbo is out of breath at 14-15 PSI.. but hey I could be wrong

[FenixMike]

Originally Posted by e46beater

Thank you for explaining tuning to me.. I've been doing it for years lol. I'm just stating they more or less took a conservative approach to a nationwide applicable tune. Leaning on a newer platform especially unaware of most customer's modifications is a little risky for any tuning company offering off the shelf power solutions. There maybe other factory limiting factors with higher boost like the bypass valve leaking, charge pipes cracking. I highly doubt the stock turbo is out of breath at 14-15 PSI.. but hey I could be wrong

I wont get into an internet war with you, but I will share some simple information about turbochargers... Boost is nothing more than a reference of restriction, basically telling you how much air it is having to "force" in where the engine naturally cannot take anymore by vacuum alone. Saying a turbo is "out of breath at 14-15 PSI" really doesn't tell you anything, reference anything, nor allow you to really judge anything about power levels. The more efficient your engine becomes (adding a down pipe, intake, exhaust etc) the less boost you will naturally make at the same setting because the turbo is no longer having to force as much air in. Turbochargers are able to compensate for this as long as they have the ability to flow more air by adjusting the wastegate to increase exhaust flow, which spins the intake wheel faster. In this case, as well as EVERY newer vehicle, they do not have as much left on the table as they are properly matched to the engine to provide the most efficient power with the least amount of lag. GM does it, Ford does it... pretty much every manufacturer because their goals arent the aftermarket world. Ive tuned MANY Ford Ecoboost and GM Turbo cars with the same results, which is they pick up a ton of low end where the engine demand for air is much lower and you get a 3-4 lb increase of boost, and once the engine gets cooking and needs the air flow, the turbo becomes "maxed out" with the inability to efficiently flow more air and your boost drops back to near stock levels as it can no longer sustain the higher airflow. That being said, by making the engine more efficient with the addition of intake, downpipe etc, you are making more power without the turbo (the engine is becoming more efficient allowing for more natural flow of air), which in effect gives you bit of a bump in horsepower, even while dropping boost (remember, boost is only a measure of restriction of airflow, not an indicator of horsepower, so it is possible to make more power on less boost merely because your engine is getting more airflow than before without having it forced into the engine). Once you pass the efficiency range of the turbo, the gains are typically heavily offset by negatives such as heat, knock retard, and reduced engine/turbo life.

[FenixMike]

Originally Posted by Jayphil

FenixMike I do get your point and to some it is less than ideal to have to manually shift at 6000rpm and it would be nice to be able to flash the tcu to change the shift point.

In my case I am most of the time doing city driving and added torque add to driving enjoyment. Also I am not that often full throttle so I am not much worried about premature turbo wear, I am also not tracking my car.

The few times I am doing spirited driving, I am already using the paddle shifter. Still if you do not shift at 6000 rpm there is still some gain up top vs stock with a tune (adding anything else do not add past 6000rpm though).

All your comments are informative to help people decide if those mod are for them or not but to me a 1200$ including installation (JB4 and downpipe) to gain around 15% peak hp on 94 pump gas we have here in Canada is a no brainer. Adding anything more on top of that (excluding turbo upgrade) will be considered as mostly a waste of money.

By the way I am coming from an Audi A4 2.0t (7 years of fun) with a tiny turbo with all bolt on so I am already used to that type of feeling "Diesel" like since you have a lot of torque but need to shift in lower RPM. Also the turbo was still running strong after 100k miles.

I do agree my N55 car felt much more fun with the AFE Scorcher on it, it just really wasnt any faster up top. Removing it made the vehicle quite boring around town, but before diving in with lots of mods, I went through all the options and decided for me, that the costs weren't worth the benefits. For the price you're getting on your stuff, that sounds like a really good deal on a small investment, which will likely pay off... when I priced out the JB4, intake, downpipe, building a nice custom and quiet exhaust (the benefits of being a fabricator for 12 years), then realizing the problems people were having due to these mods (charge pipe failure, heat, high IATs etc) that I would also need a new charge pipe, methanol injection system and to correctly set it up, a larger intercooler since I live in Arizona. Calculating the costs of all these, and even doing all the labor myself, I just couldn't justify that cost for the low gains and once in a while track visit. I instead invested that money into a down payment on the more mod friendly 550, but I understand not everyone has that option.

Im just hoping people will go through the true costs of what it will cost THEM to do these mods before whipping out a credit card and spending the next few months paying it off with disappointment. Im glad I did my research, but many others may see its ok for them and be perfectly content... as I said, doesn't matter to me one bit what anyone does, I'm just trying to provide insight to my research.

[ssgm1x]

Originally Posted by paul223

Get the cat less downpipe. I have one. It will make a big difference in performance coupled with jb4 2. Some posts are simply not true here. lol

I know this post is 3 years old but i have a question. I have a F10 535i and wanna know if a Catless downpipe with stock exhaust will be loud inside the car.....and what it sounds like outside the car...anybody care to comment?

[paul223]

Originally Posted by ssgm1x

I know this post is 3 years old but i have a question. I have a F10 535i and wanna know if a Catless downpipe with stock exhaust will be loud inside the car.....and what it sounds like outside the car...anybody care to comment?

Not much difference in sound at all after engine is warmed up. Cold start is loud for about 10 seconds.

[ssgm1x]

Originally Posted by paul223

Not much difference in sound at all after engine is warmed up. Cold start is loud for about 10 seconds.

Originally Posted by paul223

Not much difference in sound at all after engine is warmed up. Cold start is loud for about 10 seconds.

Thank you Paul. I'm debating if I Should put a catless downpipe on my car with the stock exhaust but I do not want it to too be loud. I want it to sound close to stock. Will I be happy if this is what I'm looking for? Just a minor difference?

[paul223]

Originally Posted by ssgm1x

Thank you Paul. I'm debating if I Should put a catless downpipe on my car with the stock exhaust but I do not want it to too be loud. I want it to sound close to stock. Will I be happy if this is what I'm looking for? Just a minor difference?

You will be happy. Do it. Do it. Do it.

[ssgm1x]

Originally Posted by paul223

You will be happy. Do it. Do it. Do it.

Done!!!!
Thank you for the advice Paul