The need for engine modifications to support a turbo upgrade
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This is a discussion on The need for engine modifications to support a turbo upgrade within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; I've got a 2005 WRX that I am mid way through an engine swap on. I will be putting it ...

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    The need for engine modifications to support a turbo upgrade

    I've got a 2005 WRX that I am mid way through an engine swap on. I will be putting it together using a catless uppipe, turboback exhaust, potentially equal length headers, larger GrimSpeed TMI, K&N short ram, Mishomoto Radiator, ACT lightweight flywheel (14 lbs), and 255 lph Wahl fuel pump. I will also be getting the engine tuned when done. I bought the car with a blown motor from a dealer who could not provide me any information about why to motor went out, but I am discovering the answer as I take it apart. I noted the presence of a TDO (turbocharger) TD06H-20G ebay style aftermarket turbo, which I will be offloading and replacing. I'm trying to decide between getting a used stock turbo and then porting and polishing, or an aftermarket Blouch. I understand that if I get the Blouch, I will need to upgrade the injectors as well. The models I am looking at are:

    Blouch TD05H-16GXT 7cm^2 Turbo Billet Wheel Subaru Models (inc. 2002-2007 WRX / 2004-2014 STI)
    Blouch TD05H-16GXTR 8cm^2 Turbo Billet Wheel Subaru Models (inc. 2002-2007 WRX / 2004-2014 STI)

    This car will be a weekend rally racer, but a weekday DD, so I'm looking for a little faster spool, a little more power, but to keep things reasonable without necessitating an entire engine rebuild. I have three questions regarding the turbo:

    1. What size injectors are needed for this setup?
    2. Do I need to upgrade the pistons, cams, or other engine internals to accommodate these slightly larger turbos?
    3. Is it reasonable to tune this myself using a Cobb system, or do I need to take it in for a professional job using dynos, etc.? If I get it professionally tuned anyway, is there any reason for me to buy a Cobb Accessport?

    Thanks and let me know if I am missing information that will help with the answer.

    On a completely separate note... what the heck is this? Meth? Another component I found while taking the thing apart and I haven't found it in my service manual. The hose connects to the air intake.
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  3. #2
    Master Baiter EJ257's Avatar
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    There are a lot of things you can do at this point. In the end, it's up to you...

    I'm not sold on the 16G-XTR turbo. I don't think the 54mm turbine wheel is worth the premium on the 2.0L motor. With a larger motor, you're better off with a larger compressor turbo than the 16G, so I think the market space just isn't there on the Subaru platform. I feel you are better off with the traditional TD05 turbine wheel, and saving your money. The 16G is a fantastic turbo on the 2.0L motor; honestly, it's the turbo that should've come from the factory. The XT version is just that much better without any downsides other than cost (the regular/smaller 16G from Blouch used to be something like $650, but they no longer offer that option, due to the better compressor wheels they're putting out).

    Your parts list looks good, but I would add a few items to it:
    1) Turbo inlet. The OE plastic one has a tendency to crack/tear, and it isn't the best in terms of flow. A Perrin unit isn't all that expensive (~$200), and would be a good buy. While you're at it, since you're buying an intake as well, just finish off the intake tract and get a MAF hose (under $100), too. Be aware that the turbo in question may run into issues with pegging your MAFv, so you may need to consider a larger MAF diameter. KSTech offers some nice intakes that you can use at a pretty reasonable price; I'm a fan of their APS-style cold air intakes, as it keeps the filter behind the headlight, so the chance of water ingestion / hydro-lock is minimal (unless you're an idiot).
    2) TGV deletes. Since you already have the motor out of the vehicle, it's not like you'll be paying anything for installation of these. It's a PITA install, but well worth the effort. Grimmspeed offers a delete/P&P for around $200, and Zerolift offers composite units for about the same cost. Considering I'd recommend phenolic spacers to go with it, you're better off just getting the composite units and saving the hassle.
    3) Aftermarket boost control. The OE boost control solenoid is perfectly suitable for a typical StageII setup, but when you start swapping turbos, just spend the extra money and get an aftermarket unit. You can get the GM unit for ~$50 or so all said and done, but Grimmspeed offers a plug&play unit for ~$100 (vs splicing with the GM one).

    Onto your original question about injector size: at a minimum, you want 650cc injectors, but I prefer to go larger than smaller. 750cc injectors are typically no less expensive than 650cc, so why not give yourself some headroom? Injectors are very much a "tuner preference" item, so I urge you to speak to the person who will be mapping the vehicle. My standard suggestion for injector choice is the Injector Dynamics 1000cc units; they are arguably the best injector on the market, and aren't too large that you're giving up resolution in the mapping. Those should leave you enough headroom that you could run E85 down the road if you choose, but run pump gas perfectly well.

    You are very much able to map out your ECU with the Cobb AP; they offer their AccessTUNER Race software which allows you to manipulate the tables. There is no canned tune for the turbos in question, so you would need to have something customized regardless. Whether you feel confident enough with knowledge of internal combustion engines and electronic fuel injection to DIY is something only you can decide. The debate of OpenECU vs Cobb AP is common, and you would need to weigh the costs/benefits of said devices, as well as know whether or not your tuner (if you choose not to DIY) is willing to tune either option.

    As for the motor, that is entirely up to you. Since the motor is out of the vehicle, I would urge you to replace some of the components with better pieces (for longevity). Personally, I wouldn't go with a 2.0L displacement, but that's your prerogative; I would look into the 2.1L stroker build (which uses 2.0L pistons/rods and a 2.5L crank). The cost for those better internals will run you in the $2K range (not all that much more than forged 2.0L parts), but you get a far more desirable powerband, and since you're replacing components already, may as well "upgrade" while you're there. For the turbos that you're considering, I wouldn't bother with headwork (other than clean-up) or cams; the parts I would recommend are likely to price you out of your budget (although, you didn't state what that was), and I think you'd be happy with the setup I described. If you can swing another $1500-2000, then there's something to talk about, but otherwise, K.I.S.S.

    The picture you included is an oil catch can.

    Good luck...
    Last edited by EJ257; 12-16-2013 at 07:47 PM.
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    Thanks for the great advice.

    Im leaning toward the TD05h-16gxt due to cost, since I'd rather put the money elsewhere, which is what you were saying I think.

    Thanks for the tumbler input as well. I was considering going with phenolic spacers anyway, so the deletes may be a good option. Have you heard of any problems connecting the zerolift delete with the stock metal intake? Does the composite have any durability issues as compared to the port and polished grimspeed version? I've also heard of potential space constraints when using phenolic spacers and a tmic, which is why I was undecided with the mod.

    Lastly, I'm hearing estimates for about 300-320 hp for this turbo and this type of setup, does that sound about right? I'm willing to build the motor up if necessary, but would prefer to save cash. 300 to 325 is my target hp range. Can I get away with stock internals or will that severely limit my longevity? I'm not looking to blow the motor like the last guy...
    Last edited by SubuRyan; 12-16-2013 at 08:53 PM.

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by SubuRyan
    Thanks for the great advice.

    Im leaning toward the TD05h-16gxt due to cost, since I'd rather put the money elsewhere, which is what you were saying I think.

    Thanks for the tumbler input as well. I was considering going with phenolic spacers anyway, so the deletes may be a good option. Have you heard of any problems connecting the zerolift delete with the stock metal intake? Does the composite have any durability issues as compared to the port and polished grimspeed version? I've also heard of potential space constraints when using phenolic spacers and a tmic, which is why I was undecided with the mod.

    Lastly, I'm hearing estimates for about 300-320 hp for this turbo and this type of setup, does that sound about right? I'm willing to build the motor up if necessary, but would prefer to save cash. 300 to 325 is my target hp range. Can I get away with stock internals or will that severely limit my longevity? I'm not looking to blow the motor like the last guy...
    A proper tune with a 2.0L/16G combination shouldn't require forged internals, but if the motor is already out of the car, you may as well upgrade it while you're there. Again, your budget wasn't stated, so it could be out of the question.

    The TGVs have required some work with some metal intakes, however I believe the majority of those issues are with the side-feed injectors / STI intake manifold. That would be a question for the manufacturer, as they would be supporting the units. As for durability issues, I can't see why not; essentially, instead of a composite spacer, the entire unit is made of the composite material (which is why I recommend just going that route from the beginning).

    Your power goals are extremely dependent on bhp or whp values. If whp values, which the turbo in question is certainly capable of, I would say since the motor is out, just get better internals. If bhp, then you shouldn't need anything more than a stock TD04 turbo and skip the extra goodies.
    2005 WRX STi (Mods | Virtual Dyno)

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    I have seen reports of the composite TGV deletes warping over time.. I would just go the traditional route of deleting the buttterflys and gasket matching the ones that you already have.

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    Thanks guys, I got the intake manifold off today, so it is time for me to reflect on my budget a bit and call the shot, I will keep you posted. By the way, with the TGV deletes, does that create challenges with passing emissions?

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by SubuRyan
    Thanks guys, I got the intake manifold off today, so it is time for me to reflect on my budget a bit and call the shot, I will keep you posted. By the way, with the TGV deletes, does that create challenges with passing emissions?
    As long as there aren't any DTCs associated with it, there shouldn't be an issue.
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