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Old 11-23-2015, 12:35 AM   #1
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Default 2 quick questions about my turbo path

94 Miata


250+whp on pump gas

Already have installed:

Was planning on purchasing the following:
700cc DeatschWerks
Walbro 190 HP
used sr20 T25 w/ PTP blanket
FM Mani/DP/Outlet
CXRacing Intercooler kit + BOV
Devils own stage 2 WI
Heat Wrap for hoses
DEI Titanium Exhaust Wrap
+boost gauge
+oil/water feeds/returns
+turbo in/out flanges


1. Am I missing anything in my list?

2. I was told that I should replace engine internals at about 250whp, will this setup achieve that hp goal? If yes/no, should I even worry about internals?

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Old 11-23-2015, 03:01 PM   #2
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Get FlowForce injectors instead of the DW injectors. The SR20 T25 will not make 250whp no matter how high you spin it. You will top out around 225whp with it.

Rods bend somewhere between 215-250ft/lbs of torque. I have seen SR20 T25 kill stock motors at around 12psi, I have seen other stock motors run 18psi on a 2560 for years without blowing. Luck is really the deciding factor on that.

Skip the FM/SR20 route, save up money, buy MKTurbo in the spring. PROFIT.
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Old 11-23-2015, 03:09 PM   #3
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Originally Posted by shuiend View Post
Luck mechanical emphathy is really the deciding factor on that.
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Old 11-23-2015, 08:38 PM   #4
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-Tap & die for oil drain
-Catch can, GTX pcv valve
-Lower heat range plugs
-some form of boost control
-6 speed
-wideband w/ AFR gauge
-bigger exhaust...probably

-and a spare engine to build before you pop yours...
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Old 01-01-2016, 07:41 PM   #5
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As always, your mileage may vary, but with my very slow buildup, i got the stock rods to hold on for quite a lot of abuse (with the plan always being to rebuild the bottom anyway). I started building by getting an AEM computer to run the engine stock, spent a couple years working from that (COP with AEM C2Di, RX7 injectors, rerouting coolant, Fidanza flywheel, lotsa head work, all the little stuff before major engine surgery).

My 94 1.8 stock rods stood up to 25lbs of boost, which included the tuning process (started at 9lbs I think).
I'm using a rather large turbo and it spools kinda late, so there's a bit of protection (I suppose) in that regard. It's more than adequately intercooled and I was (and still am) very conservative with the timing.
When the rods finally failed, it wasn't catastrophic, #4 bent enough to contact the block and make a slight knock (at all engine speeds). #3 was visibly deformed but not contacting the block. I think this goes a long ways towards illustrating the term "soft" rods.
As far as how long they lasted, this is my 5th car (full garage syndrome is setting in), so it only is driven for fun, when the weather is nice, I think the rods lasted for about 5k miles of "fun". Pretty much every time I was in the car it was full boost and 7k shifts.
I'm building the bottom end right now, as a matter of fact in the morning I start putting the new bottom end together (it's been apart for a little while ....).
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Old 01-01-2016, 10:52 PM   #6
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I asploded my 56k mi motor at less than 250whp lol.

Run E85 if it's available.
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Old 01-02-2016, 01:43 AM   #7
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I blew a 5 speed at 200ft/lbs.

Mechanical empathy makes the difference
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Old 01-06-2016, 07:48 AM   #8
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I would urge you delete the heat wrap. Ductile iron will get hot enough to flake off in small bits and after a year it will become about two pounds lighter.

There is no performance gain available, even if it seems so.

Insulate the items that can be hurt by radiated heat. Brake master, water lines.......

There is no danger to the hood, either, but tack some reflective mat there anyway.

Pay some more attention to the compressor inlet. Just a filter is not a good answer. Look into "ideal" air inlet shapes and a little cool air. Don't go hog wild on cool air inlets, they are only small help ( about 6F in the manifold at around 10 psi) if you have a proper intercooler.... 90%+.

Go for it, have fun, and develop slowly.

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Old 01-06-2016, 09:05 AM   #9
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I'd skip the water injection personally, it's just added complication and more stuff to go wrong.

On a streetcar I'd leave the motor and transmission stock for those power goals, the cost to upgrade (6 speed or built motor) way outweighs both the risk of blowing the stock stuff or the cost of replacing them.
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