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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Aftermarket turbo owners: Genuine thoughts on low RPM performance?



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      03-15-2016, 05:58 AM   #1
bradsm87
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Aftermarket turbo owners: Genuine thoughts on low RPM performance?

Can anyone with RB/VTT/Hexon turbos share their honest thoughts/findings with performance below 3000rpm, or more specifically, below 2500rpm?

Thanks in advance!
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      03-15-2016, 07:24 AM   #2
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Ok, I have RBs with inlets and RB outlets running straight 99 RON fuel with a custom wedge tune. Below 2500 there is practically nothing, once I hit 2500 you can really feel the power start to build, looking at my logs I hit peak boost (23psi) by about 2800-2900 rpm then it just pulls hard all the way to redline! I'm sure adding e85 or meth would affect low down power in a good way.

I should also add that I'm only on the revision 3 map so there's a few more revisions to come before its all dialled in properly so spool may get better once finished.
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      03-15-2016, 07:29 AM   #3
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Its all in the tuning. Even my relatively mid size turbo has no lag due to vanos tuning.
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      03-15-2016, 07:47 AM   #4
Flex68
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I'm also interested In this as I'm far from concerned about max power but more so response and torque and useable power and reliability
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      03-15-2016, 08:55 PM   #5
bradsm87
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Quote:
Originally Posted by blisstik View Post
Its all in the tuning. Even my relatively mid size turbo has no lag due to vanos tuning.
I agree that tuning helps a lot but this is the type of response I don't need. "No lag" is physically impossible. "It still feels pretty responsive" would be better. Boost pressure achievable at 2000, 2500 and 3000rpm would be even better.

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      03-15-2016, 08:58 PM   #6
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Quote:
Originally Posted by Flex68 View Post
I'm also interested In this as I'm far from concerned about max power but more so response and torque and useable power and reliability
I'm leaning towards a custom Hexon that's smaller than RR600s but still noticeably bigger than stock at this stage unless I get some promising numbers from somebody about performance around the 2500rpm mark (with proof) of Stage 2 turbos.
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      03-15-2016, 09:37 PM   #7
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Quote:
Originally Posted by bradsm87 View Post
I'm leaning towards a custom Hexon that's smaller than RR600s but still noticeably bigger than stock at this stage unless I get some promising numbers from somebody about performance around the 2500rpm mark (with proof) of Stage 2 turbos.


Please keep me posted as I'd be keen
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      03-15-2016, 09:53 PM   #8
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I have a set of VTT 2+ and while boost does not get "on target" until the 2800-2900 rpm mentioned above....its unfair to say there is nothing. There is something, and by looking at the logs you will see that you are boosting, just not at your target.
Think about it... if you target 20 psi at 3k rpm are gonna hit it?

When running aftermarket turbos you will naturally be running higher boost, and targets are expected to be higher. But remember the turbo needs to spool up...point blank, and the user needs to understand that.

Keeping that in mind, the "lag" in my turbos is imo unnoticeable running inlets, outlets and adequate tuning to make that shit go!
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      03-15-2016, 10:44 PM   #9
bradsm87
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Quote:
Originally Posted by big_ed View Post
I have a set of VTT 2+ and while boost does not get "on target" until the 2800-2900 rpm mentioned above....its unfair to say there is nothing. There is something, and by looking at the logs you will see that you are boosting, just not at your target.
Think about it... if you target 20 psi at 3k rpm are gonna hit it?
With stock turbos, probably yes. The area where I'm trying to compare is while the turbo is building boost from low RPM anyway.

Quote:
Originally Posted by big_ed View Post
When running aftermarket turbos you will naturally be running higher boost, and targets are expected to be higher. But remember the turbo needs to spool up...point blank, and the user needs to understand that.
I don't plan to change my low-mid RPM boost target with bigger turbos. The only change with boost target will be to hold boost flat to redline. I'm wanting to compare the highest achievable boost between stock and Stage 2 turbos at fixed RPM points below 3000rpm.
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      03-15-2016, 11:02 PM   #10
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Also reliability and longevity
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