Considering going back to twins...

Jan 31, 2017
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www.hydraperformance.com
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2010 135i 6MT
You'd be more apt to answering this than I would, but I'm curious about the tradeoffs in heat and weight between running two turbos vs one. Your points about the coolant inlet are totally valid, but what about IATs and actual heat generation with two smaller turbos vs one? And I see you've just released your own line of turbos, which is awesome, but call my crazy, I have a huge fear of running anyone's twins on track because of all the horror stories, not to mention the pain in the ass install. A single is way easier to service, and backed by a company like Garrett, BW, etc..

IATs are primarily a function of boost, compressor (adiabatic) efficiency, and intercooler effectiveness, and have nothing to do with the whole single vs twin debate, and everything to do with having the compressor wheel(s) properly sized for your application. You are confusing IATs with in-cyl temp rise caused by high residual gas fraction from running a EMP/TIP (high backpressure/boost) ratio - an issue with older TT offerings using stock turbine housings, and certainly not applicable to mine. I understand your reliability fears given all the horror stories out there, but I'm hoping that my use of OEM TD04 turbine wheels + good QC/attention to detail should make this a non-issue. Time will be the ultimate judge I guess, although in the final analysis everything fails eventually. I have an Evo X customer here who is on his 3rd GTX3071R... Finally, I don't see why a bottom mount single turbo would be "way easier to service", sure you have 4 less oil/water line connections to worry about, but accessibility is still hindered no?
 

berns

Corporal
Jan 15, 2018
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'09 135i
IATs are primarily a function of boost, compressor (adiabatic) efficiency, and intercooler effectiveness, and have nothing to do with the whole single vs twin debate, and everything to do with having the compressor wheel(s) properly sized for your application. You are confusing IATs with in-cyl temp rise caused by high residual gas fraction from running a EMP/TIP (high backpressure/boost) ratio - an issue with older TT offerings using stock turbine housings, and certainly not applicable to mine. I understand your reliability fears given all the horror stories out there, but I'm hoping that my use of OEM TD04 turbine wheels + good QC/attention to detail should make this a non-issue. Time will be the ultimate judge I guess, although in the final analysis everything fails eventually. I have an Evo X customer here who is on his 3rd GTX3071R... Finally, I don't see why a bottom mount single turbo would be "way easier to service", sure you have 4 less oil/water line connections to worry about, but accessibility is still hindered no?

A proper v-band bottom mount turbo would be way easier to remove/replace than removing both exhaust manifolds, etc...
Looking forward to hearing about more of your turbos getting punished. I'd be stoked if they were the end-all application for my type of driving and build.

Here's a lap at a track I frequent. Still fighting understeer issues, but more power is not something I actively need. More topend would be nice for sure, and with more efficient turbos I'd hope temps would improve. In >80*f ambient, I can run full 15 minute sessions without issue. 90+, however, and it's just a matter of time.

 

The Convert

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Jun 4, 2017
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Personally, I hate the v-band connection on my ST. However, I’ve not had a 4 bolt flanged kit to compare ease of install/removal to.
 

berns

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Jan 15, 2018
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'09 135i
Personally, I hate the v-band connection on my ST. However, I’ve not had a 4 bolt flanged kit to compare ease of install/removal to.

4 bolt is fine when it's easily accessible but still annoying to deal with gaskets, loctite, etc.. v-band should be nice when it's in a good spot.
Anyway, just going to throw an S54 in the 1 and call it a day haha.
 
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The Convert

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Jun 4, 2017
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@doublespaces can you pull all of the suspension posts out of here and start a suspension thread with them. There’s a lot of good info and would be easier for people to access if it was in a thread that made sense for it. Thanks.
 

fmorelli

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Aug 11, 2017
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