[MNBart]

Anyone know what our turbo produces in lbs? I came from a GTI where the APR tune doubled the turbo's output but I am wondering what our BMW's produce stock. I haven't found anything on the topic using search so i apologize if it's out there

thanks!

[mikew2069]

Strange I haven't seen any threads on this either. What's the stock psi?

[utenigma]

Stock ECU on the N55 boost peaks at ~10psi

[mikew2069]

Wow that's pretty low. Lots of room to INCREASE!

[tojo_m]

Not sure where I read it but it was something like 8.6 psi

[shivaswrath]

Originally Posted by mikew2069

Wow that's pretty low. Lots of room to INCREASE!

i don't think the stock block can handle insane amounts of more boost...12-14psi MAX, and that's probably meth.

[mikew2069]

Originally Posted by shivaswrath

i don't think the stock block can handle insane amounts of more boost...12-14psi MAX, and that's probably meth.

The new Kia Optima 2.0T runs 17.5psi stock....

[buildbright]

Originally Posted by shivaswrath

i don't think the stock block can handle insane amounts of more boost...12-14psi MAX, and that's probably meth.

Around 15 psi on pump gas no meth. with meth 16+

[shivaswrath]

Originally Posted by mikew2069

The new Kia Optima 2.0T runs 17.5psi stock....

this ain't a KIA, lol.

[mikew2069]

Exactly. I don't have much experience with turbos but why would the Kia 4 banger block be able to handle twice the boost as the Bimmer block?

[utenigma]

Originally Posted by mikew2069

Exactly. I don't have much experience with turbos but why would the Kia 4 banger block be able to handle twice the boost as the Bimmer block?

Didnt research the kia, but off the top of my head they probably run less engine compression

[verbs]

Originally Posted by mikew2069

I don't have much experience with turbos but

which is why you shouldn't jump to all kinds of assumptions that the 335i has tons of room to increase boost.

[mikew2069]

Originally Posted by verbs

which is why you shouldn't jump to all kinds of assumptions that the 335i has tons of room to increase boost.

I am having fun and talking about what could be. Get out of here hall monitor.

[PeterM]

Originally Posted by shivaswrath

i don't think the stock block can handle insane amounts of more boost...12-14psi MAX, and that's probably meth.

Boost will not matter that much its how much power it makes at that boost. Back to my 1.8T days i ran 24psi on stock turbo and 24psi on upgraded GT35R turbo the power difference is nigh and day and i ran the risk of blowing the motor. So are you saying increasing the boost by 4-5psi on a stock turbo N55 motor it will blow? Aren't the N54 guys pushing close to 500hp on stock engines.

[shivaswrath]

I was taking into consideration the turbo sizes and strength of the block.

I ran 23psi peak boost on my 4G63 block, but had a nice taper. The solid, iron block on an Evo VIII with its strong stock internals could take it, and the twin scroll turbo was a champ.

The N55 twin scroll turbo is significantly smaller...

[RPM90]

Originally Posted by mikew2069

The new Kia Optima 2.0T runs 17.5psi stock....

BMW N20 18.9 psi.

Smaller displacement engines have to have very high stock boost pressure to achieve that type of power, as they have 33% less displacement compared to the N55's 3.0 liters.
The N55 can run lower boost pressure as it makes more displacement power.
1.0 liters more and 2 more pistons.

In simplest terms adding appx 15psi (normal atmosphere is 14.7 psi) of boost is like doubling the engines combustion chamber volume. For example, a 2.0 liter with 15psi of boost is like a 4.0 NA engine.
N20 2.0 at 19psi is like a let's call it 4.5.
N55 3.0 at 15psi is like a 6.0 NA.
But, the N55 has average boost a bit over 10psi, not quite double, 2/3's, or 2.0 liters more. 5.0 NA.

Even with a modest 5psi increase over stock, the N55 would then have 15psi of boost, doubling NA displacement to 6.0

The N20 would need 30psi total boost to make it like a 6.0 NA.
N55 with 30psi would be a 9.0!

That's why a larger displacement engine can run with less boost and create more power.
It also shows why the N20 is as powerful as it is compared to the N55.
This simple example shows a 4.5 vs 5.0 NA power.

This is just for fun, I'm not promoting this as exact as there are many variables.
The N54 is also a 3.0 running close to 9psi yet developed the same power as the N55.
But, that's a twin turbo vs a single twin scroll. It's one of those variables.

[RambleJ]

Originally Posted by mikew2069

Exactly. I don't have much experience with turbos but why would the Kia 4 banger block be able to handle twice the boost as the Bimmer block?

Please go off of that assumption and let us know at what psi your engine goes boom.

Unfortunately engines are made differently, so simple assumption like that doesn't hold any value.

[mikew2069]

Originally Posted by RambleJ

Please go off of that assumption and let us know at what psi your engine goes boom.

Unfortunately engines are made differently, so simple assumption like that doesn't hold any value.

Originally Posted by mikew2069

I am having fun and talking about what could be. Get out of here hall monitor.

Once again, another hall monitor with a comment with absolutely ZERO value. See my comment about having fun talking about what 'could' be. Get out of here with YOUR assumptions that I actually want to just increase boost by 200% without accounting for other variables.

[RambleJ]

Originally Posted by mikew2069

Once again, another hall monitor with a comment with absolutely ZERO value. See my comment about having fun talking about what 'could' be. Get out of here with YOUR assumptions that I actually want to just increase boost by 200% without accounting for other variables.

my assumptions... Who pissed in your cheerios this morning kiddo.
Yes its pure speculation on my end seeing that this is my 4th turbo charged BMW.
It may seem like we are raining on your parade, but just giving insight from EXPERIENCE.
The n54 engine was able to handle double the boost with higher octane and FBO, but the n55 is not the same unfortunately.

[RambleJ]

Originally Posted by PeterM

Boost will not matter that much its how much power it makes at that boost. Back to my 1.8T days i ran 24psi on stock turbo and 24psi on upgraded GT35R turbo the power difference is nigh and day and i ran the risk of blowing the motor. So are you saying increasing the boost by 4-5psi on a stock turbo N55 motor it will blow? Aren't the N54 guys pushing close to 500hp on stock engines.

Unfortunately the differences between the n54 and the n55 are way more than just a different turbo set up and valvetronic. The n55 swapped out some internals to save some weight.