N20 /N26 Turbo Upgrade (Group Buy?) Interest

meltbox · 01-07-2020, 02:26 PM

Hey all. I have recently discovered my turbo has a chipped compressor blade and am looking into upgrades. I originally thought I would go with the MHI turbo but after looking into it I decided to try to go and build a custom copy to save a few hundred.

There are three options I have found and two require machining. Since setup is most of the cost for machining our turbos to accept larger compressor wheels it would definitely decrease cost if others were interested in these options.

Option 1:
Kinugawa CHRA with compressor housing machining. Kinugawa offers a CHRA for $680 which is balanced and warrantied for a year. All I would have to do is reach out to a shop to machine all the housings for whoever would want it and we could re-assemble with the Kinugawa CHRA and be set. I would guess CHRA and machining might be $780 or so plus a donor turbo for the housings.

Option 2:
Kinugawa/other 20T reverse rotation compressor wheel. I am confirming one is actually available separately since as of now I can only find 19T wheels for purchase separately. I would have to reach out to have all the CHRAs and the housings machined. This may be cheaper overall but carries no warranty. The CHRA would also have to re-balanced as a unit. My guess is total cost this way will be $550 plus a donor turbo to start with but this also includes doing a rebuild on the turbo (yourself) before you send it out to get balanced. Rebuild kits seem to run about $100 or a bit more.

Option 3:
Mamba offers a compressor housing + CHRA combo for about $970 or so if I remember correctly. Don't know if we could get a group buy out of them. Only reason I don't like this is because I wanted a 6+6 blade compressor wheel since I hear they work better over a larger RPM. Perhaps that is not even true but MHI is 6+6 so I would like to stick to 6+6 if possible. I also don't see what spec they balance to on their website so I will inquire. For example Kinugawa balances to under 1.5mg/125,000rpm which is good from what I have read.

Feel free to post questions and or PM me. I don't have a shop nailed down yet so price might be a bit slippery atm.

EDIT: Hahaha wow so I've been staring at the Kinugawa page for days and only now realized they give you a housing but it has a larger hot side which needs machining. Ooops. Well I will leave the option there although I'm not sure that I am interested in it anymore... Need to think more but I want to keep that instant spool.

EDIT2: Another option is buy the Kinugawa compressor housing and CHRA and swap in a regular turbine from the BMW TD04LR6 and have it rebalanced. Total cost of $780ish still but no machining needed. One downside is that voids the CHRA warranty for sure.

meltbox · 01-08-2020, 01:08 PM

As an update. I think the most sensible option seems to be to go with a kinugawa CHRA with matching compressor housing. Turns out they offer one. You would only need to swap the hot side housing over from your own turbo to use it and it comes with a 1 year warranty.

I think this means I will not be contacting any shops about custom machining for the time being. If anyone has any questions about the options above or any other mods to our turbos feel free to PM me or post here and I can do my best to help.

Cpatel · 01-08-2020, 01:21 PM

Are you going to upgrade your internals?

meltbox · 01-08-2020, 08:37 PM

Nope! Wish me luck

I'm trying to get the same boost/torque but higher up through the revs. This should do wonders for IATs and boost up high. Won't pull to redline (TD04L hot side is too small) but it will certainly not fall off as hard as the stock turbo.

If I were to do internals likely just the rod bolts.

I'm actually probably going to be the first upgraded turbo with stock intercooler and downpipe lol. I would get a downpipe if only there was a high flow one that guaranteed no CEL without stage 2.

Especially since I'm currently dealing with DME code 118602 which only shows up on long steady state drives. There's an SIB for it but the fix they suggested seems to not work for me. Don't want to add another variable to the mix yet.

BettyFkinCrocker · 01-09-2020, 07:47 AM

Quote:

Originally Posted by Cpatel

Are you going to upgrade your internals?

In theory, it's more necessary to upgrade internals on the stock turbo than a larger one.

meltbox · 01-10-2020, 09:49 PM

Quote:

Originally Posted by BettyFkinCrocker

In theory, it's more necessary to upgrade internals on the stock turbo than a larger one.

I was hoping I could drop IATs at higher boost with the upgraded turbo too. That is the one benefit I could see. The hot side is the same so I think it won't help with exhaust temp/pressure at all.

kahnfucious · 01-11-2020, 05:05 AM

I'm just going to challenge on why you would want to go through all this R&D personally if the MHI is readily available - and for just a few hundred more? It doesn't seem like you are going for any substantially different objectives.

Not criticizing - just want to understand it a bit more.

meltbox · 01-14-2020, 01:15 AM

So. You make a very valid point. Part of it is I like the whole build your own approach to a lot of things and it wouldn't hurt to learn what it takes to have a custom turbo fabricated.

A bit of cost savings was also the initial idea. I also thought it would be simpler to source "good" parts for reasonable prices. It turns out all this is not so easy. That and our turbo is reverse rotation so good luck.

Now I will be going with the Kinugawa compressor housing + CHRA which makes it a 20T. Only thing that befuddles me is they claim its only good for 300hp. I'm thinking this is because they are used to old subaru/volvo engines which just make less power off the same pressure/flow. I was hoping this would bump up the top end and push over to 350ish hp if I ever wanted to push it there.

Saves me about $700 instead of the MHI turbo so I can basically have a turbo and downpipe for the price of the MHI. Now I may regret this but hey someone has got to be the guinea pig right? (I'm not counting the price of the turbo I bought salvage since I can resell a good turbo after the swap from my housings and the salvage CHRA)

Although...
Honestly the more I read the more it seems like the hot side is choked on these turbos and nothing short of upgrading it to TD04HL or bigger hot side will really help hold boost to redline. I am a bit worried what this turbo will do to EGTs. I would imagine if MHI decided to do it it should be okayish.

01-07-2020, 02:26 PM	#1
meltbox Private First Class 43 Rep 170 Posts Drives: 2014 328xi GT (F34/N20) Join Date: Sep 2018 Location: Michigan iTrader: (0)	N20 /N26 Turbo Upgrade (Group Buy?) Interest Hey all. I have recently discovered my turbo has a chipped compressor blade and am looking into upgrades. I originally thought I would go with the MHI turbo but after looking into it I decided to try to go and build a custom copy to save a few hundred. There are three options I have found and two require machining. Since setup is most of the cost for machining our turbos to accept larger compressor wheels it would definitely decrease cost if others were interested in these options. Option 1: Kinugawa CHRA with compressor housing machining. Kinugawa offers a CHRA for $680 which is balanced and warrantied for a year. All I would have to do is reach out to a shop to machine all the housings for whoever would want it and we could re-assemble with the Kinugawa CHRA and be set. I would guess CHRA and machining might be $780 or so plus a donor turbo for the housings. Option 2: Kinugawa/other 20T reverse rotation compressor wheel. I am confirming one is actually available separately since as of now I can only find 19T wheels for purchase separately. I would have to reach out to have all the CHRAs and the housings machined. This may be cheaper overall but carries no warranty. The CHRA would also have to re-balanced as a unit. My guess is total cost this way will be $550 plus a donor turbo to start with but this also includes doing a rebuild on the turbo (yourself) before you send it out to get balanced. Rebuild kits seem to run about $100 or a bit more. Option 3: Mamba offers a compressor housing + CHRA combo for about $970 or so if I remember correctly. Don't know if we could get a group buy out of them. Only reason I don't like this is because I wanted a 6+6 blade compressor wheel since I hear they work better over a larger RPM. Perhaps that is not even true but MHI is 6+6 so I would like to stick to 6+6 if possible. I also don't see what spec they balance to on their website so I will inquire. For example Kinugawa balances to under 1.5mg/125,000rpm which is good from what I have read. Feel free to post questions and or PM me. I don't have a shop nailed down yet so price might be a bit slippery atm. EDIT: Hahaha wow so I've been staring at the Kinugawa page for days and only now realized they give you a housing but it has a larger hot side which needs machining. Ooops. Well I will leave the option there although I'm not sure that I am interested in it anymore... Need to think more but I want to keep that instant spool. EDIT2: Another option is buy the Kinugawa compressor housing and CHRA and swap in a regular turbine from the BMW TD04LR6 and have it rebalanced. Total cost of $780ish still but no machining needed. One downside is that voids the CHRA warranty for sure. Last edited by meltbox; 01-07-2020 at 03:15 PM..
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01-08-2020, 01:08 PM	#2
meltbox Private First Class 43 Rep 170 Posts Drives: 2014 328xi GT (F34/N20) Join Date: Sep 2018 Location: Michigan iTrader: (0)	As an update. I think the most sensible option seems to be to go with a kinugawa CHRA with matching compressor housing. Turns out they offer one. You would only need to swap the hot side housing over from your own turbo to use it and it comes with a 1 year warranty. I think this means I will not be contacting any shops about custom machining for the time being. If anyone has any questions about the options above or any other mods to our turbos feel free to PM me or post here and I can do my best to help.
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01-08-2020, 01:21 PM	#3
Cpatel Private First Class 40 Rep 178 Posts Drives: N26 328i Join Date: Oct 2018 Location: USA iTrader: (0)	Are you going to upgrade your internals?
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01-08-2020, 08:37 PM	#4
meltbox Private First Class 43 Rep 170 Posts Drives: 2014 328xi GT (F34/N20) Join Date: Sep 2018 Location: Michigan iTrader: (0)	Nope! Wish me luck I'm trying to get the same boost/torque but higher up through the revs. This should do wonders for IATs and boost up high. Won't pull to redline (TD04L hot side is too small) but it will certainly not fall off as hard as the stock turbo. If I were to do internals likely just the rod bolts. I'm actually probably going to be the first upgraded turbo with stock intercooler and downpipe lol. I would get a downpipe if only there was a high flow one that guaranteed no CEL without stage 2. Especially since I'm currently dealing with DME code 118602 which only shows up on long steady state drives. There's an SIB for it but the fix they suggested seems to not work for me. Don't want to add another variable to the mix yet.
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01-11-2020, 05:05 AM	#7
kahnfucious Private 32 Rep 54 Posts Drives: 2016 BMW 328i - M Sport Join Date: Nov 2019 Location: Northern NJ iTrader: (0)	I'm just going to challenge on why you would want to go through all this R&D personally if the MHI is readily available - and for just a few hundred more? It doesn't seem like you are going for any substantially different objectives. Not criticizing - just want to understand it a bit more.
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01-14-2020, 01:15 AM	#8
meltbox Private First Class 43 Rep 170 Posts Drives: 2014 328xi GT (F34/N20) Join Date: Sep 2018 Location: Michigan iTrader: (0)	So. You make a very valid point. Part of it is I like the whole build your own approach to a lot of things and it wouldn't hurt to learn what it takes to have a custom turbo fabricated. A bit of cost savings was also the initial idea. I also thought it would be simpler to source "good" parts for reasonable prices. It turns out all this is not so easy. That and our turbo is reverse rotation so good luck. Now I will be going with the Kinugawa compressor housing + CHRA which makes it a 20T. Only thing that befuddles me is they claim its only good for 300hp. I'm thinking this is because they are used to old subaru/volvo engines which just make less power off the same pressure/flow. I was hoping this would bump up the top end and push over to 350ish hp if I ever wanted to push it there. Saves me about $700 instead of the MHI turbo so I can basically have a turbo and downpipe for the price of the MHI. Now I may regret this but hey someone has got to be the guinea pig right? (I'm not counting the price of the turbo I bought salvage since I can resell a good turbo after the swap from my housings and the salvage CHRA) Although... Honestly the more I read the more it seems like the hot side is choked on these turbos and nothing short of upgrading it to TD04HL or bigger hot side will really help hold boost to redline. I am a bit worried what this turbo will do to EGTs. I would imagine if MHI decided to do it it should be okayish.
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