Stock Turbos

Tweedle335

Private
Dec 1, 2016
29
7
0
Illinois
Everywhere I read about n54 engines, everyone is going to either single turbo or new twin turbos. I know there are some options for upgrading stock turbos, but is it worth it to upgrade your stock turbos? I don't plan on buying new turbos or switching to a single turbo just because of the cost, but what's the cheapest route for upgrading stock turbos, and is it worth it?
 

[email protected]

Lieutenant
Nov 14, 2016
655
261
0
North Wilkesboro
Well.. Welcome to my boat.. I personally would love new turbos but, I don't have the funds for that right now. But... There is some hope!

Best options for stockers are:
Inlets/Outlets
High Flow Downpipes
FMIC + CP upgrade

All of those mods will increase flow and breathing ability of the turbos. so, you should have new limits after doing so.
 
  • Like
Reactions: Tweedle335

ATL-IS-N54

Sergeant
Nov 20, 2016
261
61
0
ATL ga
Everywhere I read about n54 engines, everyone is going to either single turbo or new twin turbos. I know there are some options for upgrading stock turbos, but is it worth it to upgrade your stock turbos? I don't plan on buying new turbos or switching to a single turbo just because of the cost, but what's the cheapest route for upgrading stock turbos, and is it worth it?
I never think the cheapest route is worth it... But that would probly be the ON3 kit
 

doublespaces

Administrator
Oct 18, 2016
9,276
4,281
0
AZ
Ride
2009 E93 335i
If you wanted the cheapest route to upgrade the turbos, as you said, then you would probably want to have a cheap log style manifold and piece the rest of it together used. Can't say its the best way in general, but that would likely end up having the potential for the lowest total cost while doing all your own installation work.

If you stop trying to force a square block into a round hole, plenty of power can be made on stock turbos. I think you should really assess what your goals are before you decide which modifications you want. Is this the fastest car you've owned?
 
  • Like
Reactions: ATL-IS-N54

Tweedle335

Private
Dec 1, 2016
29
7
0
Illinois
If you wanted the cheapest route to upgrade the turbos, as you said, then you would probably want to have a cheap log style manifold and piece the rest of it together used. Can't say its the best way in general, but that would likely end up having the potential for the lowest total cost while doing all your own installation work.

If you stop trying to force a square block into a round hole, plenty of power can be made on stock turbos. I think you should really assess what your goals are before you decide which modifications you want. Is this the fastest car you've owned?
Yes, this is the fastest car I've owned. My previous cars were a 1949 Chevy that only ran for a couple months before I started pulling parts out, and then a 4 cyl camry, so this is a lot faster and more powerful than either of those already.

That being said, I was hoping I could get it to somewhere around 450-500hp. I'm pretty young, so I don't have a ton of money to throw into it, which is why I can't buy new turbos.
 

ATL-IS-N54

Sergeant
Nov 20, 2016
261
61
0
ATL ga
Think about turbos last. There are plenty of fueling and chassis upgrades that are needed to take advantage of upgraded turbos. Research and get a game plan while your stockers are still spinning.
This is very true, power mods are not everything, and without the proper diff etc. you can't put it down anyway... I have 400 crank and 430 torque crank and it's honestly too much for a non LSD (limited slip differential) car to have. And why my next physical mod is no doubt going to be an LSD... MFactory LSD is what I've been eyeing... And you can make the car faster even just bY swapping the diff gears to higher ratio (lower gears)... Altho I'm good with the ratio 3.07, I just want the LS part :)
 

1and1

Specialist
Dec 28, 2016
61
34
0
Tally, FL
Hey ATL- Just curious what percentage you're using for DTL, and what transmission?

I'm 340/371 wheel, and was wondering about crank numbers the other day.

WHPWTQDTL %CHPCTQ
34037115%391427
34037118%401438
34037120%408445
34037122%415453
[TBODY] [/TBODY]

((WHP*DTL)+WHP) or insert wtq...
 
Last edited:

doublespaces

Administrator
Oct 18, 2016
9,276
4,281
0
AZ
Ride
2009 E93 335i
Hey ATL- Just curious what percentage you're using for DTL, and what transmission?

I'm 340/371 wheel, and was wondering about crank numbers the other day.

WHPWTQDTL %CHPCTQ
34037115%391427
34037118%401438
34037120%408445
34037122%415453
[TBODY] [/TBODY]

((WHP*DTL)+WHP) or insert wtq...

This is hard to tell I think, because BMW under rated the 335i from the factory with its 300hp rating. Only way to determine this would likely be comparing an engine dyno:

 

1and1

Specialist
Dec 28, 2016
61
34
0
Tally, FL
no biggie.
was probably figuring it wrong anyway, likely better to just divide whp by the dtl
whp/0.85 (340/.85=400, 340/.82=415 etc...)
 

doublespaces

Administrator
Oct 18, 2016
9,276
4,281
0
AZ
Ride
2009 E93 335i
no biggie.
was probably figuring it wrong anyway, likely better to just divide whp by the dtl
whp/0.85 (340/.85=400, 340/.82=415 etc...)

I think you just need to multiply the WHP by 1.15 to get CHP, assuming a 15% drive train loss
 

ATL-IS-N54

Sergeant
Nov 20, 2016
261
61
0
ATL ga
This is hard to tell I think, because BMW under rated the 335i from the factory with its 300hp rating. Only way to determine this would likely be comparing an engine dyno:

no biggie.
was probably figuring it wrong anyway, likely better to just divide whp by the dtl
whp/0.85 (340/.85=400, 340/.82=415 etc...)
It's really not as straight forward as a percentage drive train loss, it's different amounts at different power levels in different gears, and then all the different makes and models of trannys on top of that, I have a 6MT trans which is basically assumed to have 15% DTL but I wasn't using any of that when posting my crank numbers, and yes BMW heavily under ranks their numbers, I was quoting the Dinan numbers for the stage 3 Power package, which I have on my 335is, which comes from the factory substantially lighter and more powerful than a 335i, with the factory overboost function torque goes up to 370 factory and HP is probly right around there as well, altho the rated HP and Torque is 320 and 331...

Dinan, on their website, shows what BMW claims as stock, and what they actually measure, along with the gains their packages generate, and you can see many times BMW is rounding down, to say the least about factory numbers. This is also where I am getting my CHP numbers from. Stage 3 = 398BHP, 429LbFt... And more than any peak numbers the area under the curve is what counts not so much peak numbers...

Again I don't think DTL "%" is a proper way to look at it as it obviously has different power loss in different gears, RPMs, and many other conditions... But I think the general public accepts 18% for a classic single torque converter automatics, and 15% for a manual stick, and possibly some newer DCTs and even newer TC trannys. The number is just a loose average at best
 

ATL-IS-N54

Sergeant
Nov 20, 2016
261
61
0
ATL ga
I think you just need to multiply the WHP by 1.15 to get CHP, assuming a 15% drive train loss
Divide whp by 0.85 / 0.82 for 15 and 18% loss respectively... U don't multiply whp by 1.15, you have to work it backwards for the math to work right... I.e. 85 X 1.15 (115%) = 97.75, not 100 which is where you are trying to get... Aka 100% of the power produced

Like he said, divide WHP by (%DTL/100)
 
Last edited:

ATL-IS-N54

Sergeant
Nov 20, 2016
261
61
0
ATL ga
Holy shit I just wAtched that vid, wow!.... That shit is running HOT, makes me glad I ceramic coated the headers on my 540, (m62tu) all that surface area from 8 header pipes under the hood...

And that two step! blowing fire out the WG and shit on the engine dyno... Love it
 

mt_n54

Lurker
Dec 21, 2016
23
6
0
I made 440 whp FBO on stock turbos and stock inlets.. I wanted more power so bought a set of Pure Turbos and tuned with 3 different fuel setups before ultimately ending up with PI and a stage 3 LPFP, which I think is too much power for the streets...

550-575 whp is a good number for daily driven fun car..

If you upgrade turbos, then be ready to spend on fueling as well..
 
  • Like
Reactions: ATL-IS-N54

doublespaces

Administrator
Oct 18, 2016
9,276
4,281
0
AZ
Ride
2009 E93 335i
Divide whp by 0.85 / 0.82 for 15 and 18% loss respectively... U don't multiply whp by 1.15, you have to work it backwards for the math to work right... I.e. 85 X 1.15 (115%) = 97.75, not 100 which is where you are trying to get... Aka 100% of the power produced

Like he said, divide WHP by (%DTL/100)

Yes, I suppose if you're looking for the exact number you're right. I think the difference in my mind was always negligible, and it was early :)
 

ATL-IS-N54

Sergeant
Nov 20, 2016
261
61
0
ATL ga
Yes, I suppose if you're looking for the exact number you're right. I think the difference in my mind was always negligible, and it was early :)
Yeah, but let's say there was more, say 50% or 75% DTL, just for instance, 100 crank BHP would give you 25 wheel at 75% loss of course,. But dyno at 25 and multiply by 1.75 (25 X 1.75) = 43.75, no where close to the crank HP of 100... But if u put 25 / .25 = 100,... So mathematically there is no two ways about it,... Not tryin to be "that guy" and totally understand what it's like to not be awake yet lol ;)
 

1and1

Specialist
Dec 28, 2016
61
34
0
Tally, FL
Wow, kinda feel bad for dragging this so far off topic! Might be a good idea to clean up the OP's turbo thread and move all this DTL talk over to it's own thread so the data can be more easily seen by others with the same questions.

To the OP's actual topic, I agree with others that it's best to identify the end goal first, then work your way back to where you are now. That way any hardware changes you make will always be with that end goal in mind- no need to waste money doing things twice. Also, while I'm sure the OP is a great human and excellent driver, IMHO I would strongly encourage spending some time & effort on the Driver Mod before chasing raw power. For example look up your local SCCA chapter and go autocrossing. It's worth the time and very inexpensive.