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12a PP, turbo sizing

Old 03-06-2008, 01:40 PM
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Hey guys, long time lurker here. Tons of free time at works lets me search and read up on the forums for a few hours a day. Anyways, to my point.



I am in the midst of building a 12aPP, with aspirations to go turbo after broken in. Here is what I plan on doing. I do not want this engine to rev high (looking at 8000, maybe 8300 max) as I am looking to keep it inexpensive (no ceramics) but turbo soon (no carbons), and I want it to be somewhat streetable. Idle has to be below 2000, looking for about 1500 and below.



Weber 47/50 DCOE (easier in general for my turbo app)

Housing holes 1.5" Diameter

No clearanceing

Standard Mazda rebuild (steel apex)

Shim regulator, have atleast 100psi

Clean up oil passageways

S4 Water Pump

S4 Rad

3rd gen corner seal springs

84-85 12a Rotors



That is just off the top of my head, I have everything written down at work.



Now, question is, if I want to keep the powerband somewhat streetable, would the GT35 be a good turbo? Or will it run out of breath at higher RPMS? Also I am at a loss about the Trim levels and whatnot still. I have Maximum Boost and another Turbocharging book available with me that I read up from time to time.



Any help would be great!
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Old 03-06-2008, 02:56 PM
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I haven't done it before, but I would almost guarantee it would not work. Turbine selection is just too restrictive for a PP. We do however sell a hybrid 35R that would work.
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Old 03-06-2008, 04:48 PM
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Originally Posted by 1Revvin7' post='896004' date='Mar 6 2008, 03:56 PM
I haven't done it before, but I would almost guarantee it would not work. Turbine selection is just too restrictive for a PP. We do however sell a hybrid 35R that would work.




Thanks for the quick reply. I am assuming you are talking about the GT35R/Ptrim? How much do those typically run, if you do not mind me asking? Also what other turbos could I look at? I am not shooting for over 400hp. If I got 300 at the fly, I will be more than happy.



I am also looking at the exhaust porting, I am thinking of going down about 1.5mm with a rounded square shape, and going up to the sleeve so it will look like a D. Any comments?



Quick edit: Beveling the housings a little for longer apex life also, from what I have been reading.
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Old 03-07-2008, 03:42 PM
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Gt35/40 + 1.06 Rear Housing. Will work very well.

Get rid of the Mazda Steel Apex seals.



Put some SCR or PTS seals in it. Mazda Seals and PP are never a good combo.



For your rev limits it will be fine.



Any chance you get rid of the webber and put injection on it?

It will make it so much more drivable. Considering how low your rev limit is, with the webber your usable power band is going to be 5-8000rpm. With the injection it will be much earilier. Unless of course you can get the webber running mint.
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Old 03-07-2008, 06:07 PM
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I am trying to keep this on somewhat of a budget. The steel mazda apex I will go with because they are dependable and can hold to boost, plus cheap. I do not know what the SCR or PTS seals are, and the search function will not search 3 letter words (believe me, it was hard enough finding something for 12a's).



The weber I would like because it is cheaper than going complete EFI. I would love to go EFI, but getting throttle bodies and an ECU will cost more than my weber and manifold. 5000-8000 is where the sweet part of the rev band will be, but I do not want to have to shift at 6k+ RPM just to "drive down the street".
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Old 03-09-2008, 05:02 AM
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www.southcoastrotary.com.au if you want to read about SCR seals.



They actually cost the same as Mazda Set of 3mm Seals.



As for your budget.



IDA 50mm+microtech+fuel system ecu is around $2600 bucks.



Your saying in your above post that you want the car drivable. I dont see how good its going to be with a webber. Even with a N/A PP drivability is pretty average, and with turbo its just going to be worse.



Beauty of using the 35/40 is of course that your main power band is 5000-8000 but you will have plenty of toruq from 2500rpm. I mean HEAPS.



With the injection you could drive it like a normal car and the only let down would be the high lumpy idle.



Also with your 12a rotors. Id go 12a turbo Low comp rotors. The High comp rotors are much more annoying to tune with. It can be done. Youll just have an easier time with the low comp rotors.



Oh and by the way. If your looking for a Well priced turbo kit for your 12a i can do one. Pm me and ill go into further detail on pricing etc.



But just remember this. Do things once and do it properly. If you can stretch your budget alittle it will pay it self off later on like you wouldnt believe.
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Old 03-11-2008, 09:11 PM
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i wish you all the luck man i do but....the words pp turbo and budget are not even in the same paragraph in my book. KNow if your budget is 10-12 grand than thats a diffrent story!
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Old 03-13-2008, 08:14 AM
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Originally Posted by yetterben' post='896377' date='Mar 11 2008, 09:11 PM
i wish you all the luck man i do but....the words pp turbo and budget are not even in the same paragraph in my book. KNow if your budget is 10-12 grand than thats a diffrent story!




This is a budget PP motor. If I were to build an all-out motor then yes, it would be over 6 grand to build. I do not want to see 10k+RPM, so that eliminates TONS of dollars off hand.



But thanks for the luck! Will keep it updated!
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Old 03-20-2008, 10:59 AM
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Hmm, Would that turbo take well to a W/A intercooler? I will be using my spare tire tub as a water res so to speak. Could I use an AC Radiator from a First Gen for the turbo radiator? I am piecing together a W/A intercooler as we speak.
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Old 03-25-2008, 08:39 PM
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Can I ask why you want to go PP w/ a goal of 300bhp and rev limit of 8000? I would think with those goals a healthy turbo would do you just fine.
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