DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Abandoned build

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Old 01-05-2016, 09:34 PM
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Default Abandoned build

Once upon a time a customer stiffed me on a rear end swapp. (Its a 95 with 77k, swapped rear from a 99 with 36k). So 2 years later im a proud owner of an na8 miata. But I feel as if it is underpowered, so I dynoed it and scored a 105.9 at the wheels. I know curb weight is around 2300 and I feel like 10lbs/hp is a good number so I came up with a formula that looks good on paper but before i go dumping money i would like a little feedback from seasoned veterans. Heres what it looks like:
6 puck cluch and light weight flywheel from a trans shop up the street
Aluminum underdrive pulleys
T3t4 turbo (leftover from a golf build someone abandoned, probably chinese but it is free)
Cxracing manifold
Rx8 fuel injectors
95 lph walbro fuel pump
MegaSquirtPNP2 engine management system

Any insight is appreciated
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Old 01-05-2016, 09:57 PM
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No underdrive pulley. Nothing to be gained there.
No cxracing manifold. Get a decent manifold. Flying Miata, Begi & MK Turbo make reasonably priced ones. Or if you can weld, buy some weld-els and make a simple side mount manifold.

Everything else is par for the course for budget builds. Maybe skip the 6puck for a full disk if this will be a street car.
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Old 01-06-2016, 12:20 AM
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Not only are the potential gains from an aluminum underdrive pulley minuscule (bordering on immeasurable), but the installation of same entails removal of the crankshaft harmonic dampener. Miata oil pumps are somewhat fragile to begin with, and doubling the HP while simultaneously depriving the crankshaft of damping is a well-documented recipe for failure.

The stock fuel pump is adequate for your HP goals. RX8 injectors are also adequate, though opinions here vary more than those concerning beauty in art. At least one person will counsel you to consider Injector Dynamics.

Money spent on cheaply-made welded tubular manifolds is money wasted, unless you own a TIG welder and really enjoy using it on a regular basis.

And welcome aboard.
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Old 01-06-2016, 07:07 AM
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puck clutches are dumb.
underdrive pulleys are a gaurenteed way to blow your motor.
a t3/t4 is too big.
cxracing is junk
rX8 injectors are fine for low boost
you dont need a fuel pump
MSPNP2 is great.

1-2 for 7 ain't bad.
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Old 01-06-2016, 11:22 AM
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You can probably find a decent manifold by being patient and checking the for sale section. What about down pipe, exhaust etc?
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Old 01-06-2016, 11:33 AM
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Op so dumb he picks cxacing over ebay cast, even pays more for the privilege. Shiny parts are shiny, go fast. Vroom.
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Old 01-06-2016, 11:41 AM
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Downpipe and exhaust are going to be done at the tuning/dyno/custom exhaust shop
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Old 01-06-2016, 11:49 AM
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Yes, like I said. Soooo dumb.
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Old 01-06-2016, 11:53 AM
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Originally Posted by Pretending2koolz
Downpipe and exhaust are going to be done at the tuning/dyno/custom exhaust shop
Then have them build the damn manifold. It isn't hard to build a log one.

Last edited by shuiend; 01-06-2016 at 01:28 PM.
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Old 01-06-2016, 11:57 AM
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Originally Posted by Pretending2koolz
Downpipe and exhaust are going to be done at the tuning/dyno/custom exhaust shop
That being said, find a source for a decent cast-iron manifold which will fit that sketchy mystery turbo of unknown pedigree that you're basing your whole build around.

Seriously. The propensity of those cheap, potato-shaped manifolds made from thin formed-steel tubing and sold by cxracing and similar fly-by-nite vendors to crack in a short period of time is so great that it's become sort of a running joke; the punchline to a joke no one told.
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Old 01-06-2016, 12:50 PM
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What's your intended use, by the way?

Sounds like a nice pickup . . . really low miles.
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Old 01-06-2016, 02:07 PM
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Originally Posted by Joe Perez
Seriously. The propensity of those cheap, potato-shaped manifolds made from thin formed-steel tubing and sold by cxracing and similar fly-by-nite vendors to crack in a short period of time is so great that it's become sort of a running joke; the punchline to a joke no one told.
I started a joke, which started the whole mt.net crying...
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Old 01-06-2016, 02:28 PM
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Originally Posted by Braineack
I started a joke, which started the whole mt.net crying...
Brainey, we talked about this before. "All negroes are the tool of the corrupt and tyrannical Jew oppressor, and they must be destroyed" isn't really a "joke" by most reasonable definitions of the word.
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Old 01-06-2016, 09:18 PM
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Alright, after input from the wise ones, here is the re-evaluated plan:

6 puck clutch and light weight flywheel. (I do a lot of business with the guy so he is cutting me a deal, I think, $125 for an 11.4 lb flywheel and $140 for the clutch set)
NO Aluminum underdrive pulleys....Probobly the dumbest thing I ever read/heard/said, Not only for the fore mentioned reasons, but I also discovered the one I was eyeing doesn't even have a timing mark. If I get brave I'll get an ATI dampener
T3t4 internal wastegate turbo (Which even though I am having severe second thoughts about I figure, build it with this, upgrade the turbo later.)
Rx8 fuel injectors
95 lph walbro fuel pump not so much, if people are doing good with the stock(for the power range im shooting for), no need to change it
Talked to the guy at the muffler shop, showed him the turbo, said he can make one better than one I would buy. He said it would still be shiny.(2.5" turbo back no muffler)
MegaSquirtPNP2 engine management system

Intended use:

Not really a daily, weekend warrior, Saturday night special, Midlife crisis, just a fast Miata
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Old 01-06-2016, 09:21 PM
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3" exhaust > 2.5"

Don't use the T3T4.

Do it once, do it right.
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Old 02-14-2016, 10:51 PM
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Spool on a t3/t4 with a 2.5 exhaust is going to be terrible. consider a smaller turbo that will fit your goals.
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Old 02-15-2016, 06:26 PM
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Attached Thumbnails Abandoned build-80-spool_c4d53f71346e4fe744be266d7681f257348e4ffe.gif  
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Old 02-15-2016, 08:26 PM
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I don't need a citation for real world experience. Just thought OP might consider advise from someone that is still feeling the lag from a bad decision. Didn't mean to plagiarize. Please don't send me to the principals office. I only have 3 months left of school.
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Old 02-16-2016, 12:03 PM
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I'll fix this:

Spool on a t3/t4 with any sized exhaust is terrible.
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Old 02-16-2016, 12:06 PM
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This just in,

Spool on a t3/t4 with any sized exhaust is terrible.

...more at 6pm
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