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Old 07-24-2014, 03:53 AM   #1
WTFJayJay
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Member#: 198725
Join Date: Dec 2008
Chapter/Region: South East
Location: Kennesaw, GA
Vehicle:
2004 WRX Hybrid 18g
PSM

Default APS DR725 too big for my 18g?

Figured this was as good a spot to post as any. Call me a parts whore but at the moment I have a Turbo XS front mount that I had planned on using for my build with my Dead Bolt 18g. Well recently I ended up picking up an APS DR725 through some trading with thoughts of going with a much larger turbo..

The larger turbo funds really need to be going towards getting the damn thing running again and I know ill be happy with the power from the 18g anyway. Sooo ive been trying to decide weather or not to keep the APS! Only thing im trying to wrap my head around is the whole pressure drop thing. I've done a bunch of searching and reading and still don't completely understand it as most of the threads just turned into arguing matches and never seemed to get anywhere as usual..


So all you "Flow Guru's" time to chime in. Keep your "go back to top mount" comments to your self lol bumpers already cut anyway .



-According to the Subaru Turbo List Sticky, the DB 18g's specs are 590cfm, 39 lb/min.


-The Turbo XS does not have posted turbo size recommendations, but people seem to run them on anything from OE VF STi turbos to large rotated set ups with good results.
-Core size not including end tanks: 25" x 9.25" x 3.5"


-The APS DR725 is designed around larger turbo's utilizing 50 - 75 lb/min
-Core size not including end tanks: 28" x 9.5" x 4.5"
-Has larger end tanks than the TXS
-End tanks also have 45* turn into the piping as well as the over all piping flow seems to be laid out better with less sharp turns than the TXS piping.

I'm leaning towards the APS. I like the over all quality of the whole thing better. LETS JUST ASSUME that cores where identical, the APS set up would be a no brainer with the better pipe lay out. (Just for ****s and giggles ill measure the over all length of both systems pipes when i get a chance). Even though the ratings on the DR725 do seem to have minimal pressure drop, im still concerned weather or not the core is indeed too large for the DB 18g.

Also the minimal drop from the APS may out weigh the performance gain from better flow in the piping and possibly better cooling with a larger core. Not to mention I don't even know what possible pressure drop the TXS would yield..




By the way this will be on a hybrid motor with 272 cams, 225lpr fuel pump, 1000cc injectors with custom fuel rails and regulator, and the DB 18g with 38mm ewg. Will be running 50/50 meth in the future.

Plan on staying around 17-19 psi


I understand that larger IC's tend to have more pressure drop that can add to lag and throttle response, Im just wanting to choose the one of the two I have that would give the best results.
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Last edited by WTFJayJay; 07-24-2014 at 01:28 PM.
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Old 07-25-2014, 09:15 PM   #2
jaxscuby
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Chapter/Region: South East
Location: S Ga / Hell Rock
Vehicle:
2002 USDM WRX
WRB

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your assumptions are correct that the APS DR725 is too much fmic for 18G.
now if you had a 20G you would at the lower limit of that ginormous fmic.

the turboxs fmic would be a better fit for your setup.

ran this fmic on several gt35 turbo cars in the past before APS came out with the 725.

abit overkill on injectors unless you plan to run E85.
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Old 07-25-2014, 09:32 PM   #3
WTFJayJay
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Join Date: Dec 2008
Chapter/Region: South East
Location: Kennesaw, GA
Vehicle:
2004 WRX Hybrid 18g
PSM

Default

Ok thanks. Pretty much just need people to talk me out of it a guess lol.

I knew better consodering i actually got it from a guy who was running a 20g as well and he wanted to go with a smaller ic too.

And my injectors are only that big because a friend of mine has them made on the dl and they where very cheap. Figure when ever I do go with a bigger turbo one day ill already have more fuel and dont habe to worry about maxing them out

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Old 07-25-2014, 09:35 PM   #4
WTFJayJay
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Member#: 198725
Join Date: Dec 2008
Chapter/Region: South East
Location: Kennesaw, GA
Vehicle:
2004 WRX Hybrid 18g
PSM

Default

And id love to go e85, but this will be my dd once its done. Dont really want to have to search for gas stations when I might be in a pinch as they are few and far between around Atlanta for now anway

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Old 07-26-2014, 07:19 AM   #5
A-man07
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You'd be even happier with a TMIC but yes, the APS 725, as nice as it is, is waaayyy too big for an 18G and will only induce driveability problems.
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Old 07-30-2014, 02:19 AM   #6
Weemus
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02 WRX+1.5XTR+E85=
WRBwhatothercoloristhere?

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I just ran the APS 725 on a Blouch 18G (44#/min). I only did it because I knew I was stepping up to a Dom 1.5 for now and likely a Dom3 or more in the end. Anyway, its too big for the 18G (add 500-800rpm). A nice TMIC is the best way to go for keeping that snappy boost threshold. I would ditch the meth if you have access to E85 its like crack for turbo cars, I never want to go back to 91!

I would sell both FMICs, the FP18G, and keep the 1000cc injectors. Take the funds and buy a nice big TMIC and a newer/updated ball bearing turbo and run E85...
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Old 08-02-2014, 04:47 AM   #7
WTFJayJay
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Member#: 198725
Join Date: Dec 2008
Chapter/Region: South East
Location: Kennesaw, GA
Vehicle:
2004 WRX Hybrid 18g
PSM

Default

Well looks like I may be picking up a Dom 3.0

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