N54 turbos

hdzpablo03

New Member
Oct 8, 2023
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So i have an 08 335i and have a wastegate rattle that i tried to fix but came back again, wanted to upgrade the turbos. i do daily the car, i have looked up on the forums as well that upgraded twins are better for daily driving (was looking at 17t’s) than single, but wanted to see what if anyone has ran a 5862 turbo (smaller singe turbo setup.) ive seen on a forum that you keep low end torque with a 5862 unlike big turbo setups, just wanted to see if anyone has ran a turbo that size and still debating on upgraded twins or single turbo just wanted other peoples opinion. i know single will make more power. thanks for any help
 

rev210

Corporal
Feb 24, 2019
235
138
50
Ride
335i - 08 Coupe .
Consider that too much low end torque (something of an N54 strength) is a problem on an unbuilt motor (rods) and also precipitates the need for decent investment in tyres/chassis mods. Even stock turbos torque causes traction issues if you aren't on top of either tyres/chassis.

If you were to get a bigger turbo than the one suggested, it will make power easier and the slightly slower onset of power/torque in the rpm range makes it easier to put to the ground. You can easily limit the tune to keep it safe. The turbo will ideally not be working hard. Keep in mind ,some decent sized big turbos will still make rod breaking/uncontrollable wheelspin levels of torque.

You can tune down the power /torque in any case. Something you should ask the tuner and get to know the boost by gear MHD options to help you tweak optimal traction too.

Twins will likely be cheaper short term but, in the world of new MHD O2 sensor options/Reflex+ the single is probably easier (also to fix) ,lower cost long term potentially and more reliable.
 
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jzx_andy

Corporal
May 22, 2019
137
191
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Perth, Western Australia
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2008 E92 335i 6MT
A lot of it is in the tune as well. A conservative tune on an unopened motor will inevitably ramp torque down a little with upgraded turbos, unless the turbo setup is inherently laggy. And yes it is possible to have a laggy twin setup.

From all the logs and dyno graphs I've seen over the years, the 5862/gtx3576r "sized" single turbo setups in twin scroll configuration and with a decently sized TS rear housing (0.83 - 1.0x) will make a tad more power and spool a couple hundred rpm or so later than 17t's, all else being equal. They're definitely not laggy in the grand scheme of things but are nowhere near the level of responsiveness of stock turbos or 17t's - expect around 16 psi just over 3,000rpm on e85 with an ST setup like the one I've described.

If you truly want a single turbo setup that's comparable to 17t's, you'd need to go with something sized similar to a gtx3071r, or a borg warner efr turbo that is just a tad larger. But understand that going smaller will shift the torque curve further to the left, and if it's on e85 and an unopened motor, you likely won't be able to use all the potential torque (even if you can put it down to the pavement).
 
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aferguson30

New Member
Oct 11, 2023
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I have 17t and they pull like a freight train on a good tune. After doing a motor swap I'm less worried about the expense of blowing the motor as I am adding more power to rear differential. Stock is not safe for more power than the 17t can deliver, but that's just my opinion. You open a can of worms when you start adding more than 650whp on this car and becomes very unsafe without doing the proper work.
 

ShocknAwe

Captain
Jan 24, 2018
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Charleston, SC
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N54/3 1er ///Mutt
Big twins with a ported head and cams makes it possible to have a medium speed spool and max out around 600-650 on pump 93 with higher redline which I feel is the sweet spot.

Nothing wrong with single, but I feel the platform was designed to operate with twins, stick with them.
 
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