N20 vs. N54 vs. N55 tuneability

Hey all. I have been intrigued by the new 328i and the power that it has. However, I have been reading a lot of posts stating that we can really come close to the 335i after the performance enhancements become available. I sense this may not be true, because of the fact that the turbo boost pressure in the N20 engine is already at 16 psi. Is that pretty much the high end of boost pressure for a turbo engine?

I have read that the N54 engine only supplied 7 psi of boost pressure, which made it very tunable as opposed to the N55 engine which was at 10 psi. This would be less tunable. As far as the N20, it seems to already be maxed out.

I am certainly no mechanic, and just looking for feedback to see if this makes sense.

Thanks!

As long as one doesn't plan to drive the car beyond 50,000 miles, boosting it into the 20's should be fine.

Originally Posted by jzcrna

Hey all. I have been intrigued by the new 328i and the power that it has. However, I have been reading a lot of posts stating that we can really come close to the 335i after the performance enhancements become available. I sense this may not be true, because of the fact that the turbo boost pressure in the N20 engine is already at 16 psi. Is that pretty much the high end of boost pressure for a turbo engine?

I have read that the N54 engine only supplied 7 psi of boost pressure, which made it very tunable as opposed to the N55 engine which was at 10 psi. This would be less tunable. As far as the N20, it seems to already be maxed out.

I am certainly no mechanic, and just looking for feedback to see if this makes sense.

Thanks!

I think it would take a qualified engineer to know for sure. Factors like cooling, bearing materials, compression ratio and others must be taken into account. We'll find out soon enough once the tuners get their hands on an F30 with the N20 engine.

Did you see this thread -

BMW N20 Power Upgrade from Kelleners Sport Bumps HP to almost 300, with 310ft-lbs

Seems to answer your question, right? As far as I understand it the N54 was the most tunable for insane power, the N55 is tunable, not as much as the N54 but probably more then the N20. That being said as the link above proves the N20 does have more power to give.

Tim

N20 is going to be a beast. With a little tune you are already at 335 numbers. 328 ftw

Originally Posted by tim330i

Did you see this thread -

BMW N20 Power Upgrade from Kelleners Sport Bumps HP to almost 300, with 310ft-lbs

Seems to answer your question, right? As far as I understand it the N54 was the most tunable for insane power, the N55 is tunable, not as much as the N54 but probably more then the N20. That being said as the link above proves the N20 does have more power to give.

Tim

I don't know if we can say the N55 (I understand the N54 is more tunable) is going to be more tunable than the N20. If both tunes can boost the power by a similar amount, the N20 would be more tunable from a percentage standpoint.

We also don't know the long term impact the above tune will have to the N20. Maybe to safely boost the power of the N20, other aftermarket hardware will be necessary.

i know in america u wont get the 320, but its the same CC 2.0 turbo.
but it would be hilarious if we could tune that to 300 hp!.. id gladly keep that 320 badge and kick some ASS!

Well the N20 will probably hit 335i numbers with a tune but if you want to tune your car you might as well buy the 335i. Pushing the N20 further would definitely damage it in the long run. I would imagine itd be a thirsty little f'er too. So far I don't like the N20 and N55 as much as the N54. They seem soft and unexciting in comparison

I'd get an Audi or VW if you want to get a lot of power out of a turbo 4, BMW uses aluminum blocks... but so does the Nissan GTR. The GTR also has plasma-sprayed cylinder liner bores, something I doubt any BMW motor has. All Audi/VW engines use iron blocks, heavier yes, but can take the abuse of more boost, etc.

Originally Posted by Spartan Eagle

So far I don't like the N20 and N55 as much as the N54. They seem soft and unexciting in comparison

I couldn't disagree more about the N55 vs N54. I was initially very skeptical on the N55, coming from having owned 2 N54s. But I'm sold on the N55, huge difference. It's smoother, revvy-er, sharper and more responsive and has less throttle and turbo lag. The engine just sings through the rev band like a NA I6, as opposed to the N54 which gets harsh in the upper RPM range. The N55 pushes me to WANT to rev it out, I love it. I'm even getting 2-3 MPG better while putting down more power with my Power Kit.

The N54 is not a bad engine by any stretch. But the N55 takes it a step further by bringing back the utter smoothness and response of a classic BMW inline-6.

Originally Posted by jwac

The N54 is not a bad engine by any stretch.

Tell that to all of us with HPFP issues...

Originally Posted by Spartan Eagle

Well the N20 will probably hit 335i numbers with a tune but if you want to tune your car you might as well buy the 335i. Pushing the N20 further would definitely damage it in the long run. I would imagine itd be a thirsty little f'er too. So far I don't like the N20 and N55 as much as the N54. They seem soft and unexciting in comparison

But with the 335i you get considerably more weight - not just from the engine but also a whole bunch of extra stuff on the car that only adds weight (power seats, moonroof). There's a big difference in how the e90 328i feels in corners v. the far heavier e90 335i. I'm betting the gap between the 328 and 335 F30 could be bigger.

Power output in a turbo engine is not simply a matter of PSI (that's a 20+ year old mindset that went back to manual boost controllers being literally turned up by the owner). So you can't look at one engine making 7 PSI and another making 10 and say "the 10 PSI engine makes more power"

It comes down to a huge number of factors, but here's one: the volumetric efficiency of a turbo. The n54 had two small turbos that were most efficient (turning volume of air movement into usable compressed volume) at overall lower PSI rates than the N55, whose single turbo was larger and had better efficiency at somewhat higher PSI rates.

A well designed larger engine will always have more power potential than a similarly well designed smaller engine. An engine a simply an air pump - the more air you pump, the more torque you can get, given similar levels of efficiency. The more torque you can put out, and the higher you can rev safely, the more horsepower you'll get.

End of story. This is why the 3.0 liter n54/n55, which has 50% more combustion chamber volume than the n20, will be able to put out more power. Now you can get into all sorts of things like which one has better built pistons/rings/rods/bearings/fueling system....But that's for another day

...

Re the individual who stated VW & Audi use iron engines so that's the better bet for more boost....this is wrong. For example, the new S4 uses an aluminum block. There is nothing wrong with tuning aluminum blocks to high power levels (if you disagree, please talk to any STi owner, current EVO owner, etc.). They are simply more sensitive to being poorly tuned and running hot.

Originally Posted by JoeFromPA

Power output in a turbo engine is not simply a matter of PSI (that's a 20+ year old mindset that went back to manual boost controllers being literally turned up by the owner). So you can't look at one engine making 7 PSI and another making 10 and say "the 10 PSI engine makes more power"

It comes down to a huge number of factors, but here's one: the volumetric efficiency of a turbo. The n54 had two small turbos that were most efficient (turning volume of air movement into usable compressed volume) at overall lower PSI rates than the N55, whose single turbo was larger and had better efficiency at somewhat higher PSI rates.

A well designed larger engine will always have more power potential than a similarly well designed smaller engine. An engine a simply an air pump - the more air you pump, the more torque you can get, given similar levels of efficiency. The more torque you can put out, and the higher you can rev safely, the more horsepower you'll get.

End of story. This is why the 3.0 liter n54/n55, which has 50% more combustion chamber volume than the n20, will be able to put out more power. Now you can get into all sorts of things like which one has better built pistons/rings/rods/bearings/fueling system....But that's for another day

...

Re the individual who stated VW & Audi use iron engines so that's the better bet for more boost....this is wrong. For example, the new S4 uses an aluminum block. There is nothing wrong with tuning aluminum blocks to high power levels (if you disagree, please talk to any STi owner, current EVO owner, etc.). They are simply more sensitive to being poorly tuned and running hot.

great post, very informative

Originally Posted by blueguydotcom

But with the 335i you get considerably more weight - not just from the engine but also a whole bunch of extra stuff on the car that only adds weight (power seats, moonroof). There's a big difference in how the e90 328i feels in corners v. the far heavier e90 335i. I'm betting the gap between the 328 and 335 F30 could be bigger.

The gap between the F30 335i and F30 328i is smaller. The new 335i loses more weight than the new 328i.

Unfortunately power seats and moonroof are always a must have for the other half.

Originally Posted by JoeFromPA

Power output in a turbo engine is not simply a matter of PSI (that's a 20+ year old mindset that went back to manual boost controllers being literally turned up by the owner). So you can't look at one engine making 7 PSI and another making 10 and say "the 10 PSI engine makes more power"

It comes down to a huge number of factors, but here's one: the volumetric efficiency of a turbo. The n54 had two small turbos that were most efficient (turning volume of air movement into usable compressed volume) at overall lower PSI rates than the N55, whose single turbo was larger and had better efficiency at somewhat higher PSI rates.

A well designed larger engine will always have more power potential than a similarly well designed smaller engine. An engine a simply an air pump - the more air you pump, the more torque you can get, given similar levels of efficiency. The more torque you can put out, and the higher you can rev safely, the more horsepower you'll get.

End of story. This is why the 3.0 liter n54/n55, which has 50% more combustion chamber volume than the n20, will be able to put out more power. Now you can get into all sorts of things like which one has better built pistons/rings/rods/bearings/fueling system....But that's for another day

...

Re the individual who stated VW & Audi use iron engines so that's the better bet for more boost....this is wrong. For example, the new S4 uses an aluminum block. There is nothing wrong with tuning aluminum blocks to high power levels (if you disagree, please talk to any STi owner, current EVO owner, etc.). They are simply more sensitive to being poorly tuned and running hot.

Very good info. I guess one of my main concerns was if a tune would tax an N20 motor more than the N55. Thanks so much for the education.

Hmm, good info.

Maybe BMW intentionally made the N55 less tunable so they are not bombarded by warranty repairs and disputes because people tune the crap out of their turbos.