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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 12-22-2008, 05:13 AM   #1
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Red face My DIY "Budget" Turbo Build

My turbo installing process has began. I began this thread in hopes of answers to any future roadblocks that i might encounter. Also, I hope it might help some people that are planning of undergoing this journey. My kit took exactly 198 days between purchasing my first part part for my kit to the day of the installation. It seems that it is the season to install kits as i see more and more people installing them recently.

Model - 1994 Mazda Miata 1.8 M-Edition with power steering, air conditioning and cruise control.
The goal was to make a 200+ whp car while staying with a somewhat low budget. Mainly, i wanted to spend less than the Begi S kit while making more power than their Stage 3 system.

I decided to install a 5-6 PSI style kit first before installing an intercooler and clutch and runner more boost. This will lower the downtime of my car and also lets me save a little more money before the large purchase.

Here is my current part list. I tried to include everything needed for a complete kit.

With miata mods and Harness

EBC + AIT Harness + GM Boost sensor + AIT Kit

Ebay, S14 BB Garrett 2560.

Turbo Manifold
Used Begi with EGR. From

460 PnP Turbo RX7 Injectors, from RX7 Classifieds + Cleaning

Made for NB. Old style FM. From Ebay

Inlet/outlet adapters
To attach silicon hoses to turbo. Ebay

MS “boomslang”
Ordered 3 sets to met min order, sold off 2 sets.

Turbo Fittings
Includes all fittings/lines minus inlet and outlet

Oil Pan fitting
3/8 NPT to 5/8 Barb

Oil drain
Used from From a t3, must mill to fit t28.

Oil inlet
With restrictor for Ball Bearing turbos

LC1 with Gauge
Used from

Tap and Die

Oil + Filter + extra oil for flushing out metal bits from drilling

3” 90 degree elbow

3” to 2.5 reducer
Total so far - $1485

I've had the following items to begin with: Blow off valve with attached pipe, 90 degree 2.5" silicon hose, universal 3" air filter.

Prior to the installation of the turbo i had both a megasquirt and LC1 wideband hooked up and running. I highly recommend doing this unless you are already familiar with the MegaSquirt. It will take a little learning and troubleshooting to successfully install a MS. Unless you buy a PnP.

Week one -
Me and my friend began the installation. Everything was going smoothly until we began drilling and tapping the pan. I thought that having the AC and PS that thing were going to be a little harder, Surprisingly, it was not. We ziptied the 2 hoses that were in the way and removed the front driver side tire for extra room. We first decided to drill a "guiding" hole which helped guide the larger 35/64 drill bit. (The 9/16, which is technically the correct size for a 3/8 NPT tap is 7 dollars more. The 35/64 is only 0.0156" smaller.) Once we began to to screw in the fitting we noticed that we could not get it to thread. the solution was to tap a little further so the initial hole was slightly larger.

Our second problem came upon us when we tried to attach the 5/8 high temperature hose. The drain hose was made from silicon and was fairly thick. We ended up drilling the hole a little to high to the PS bracket. (Or AC, which ever one is on the bottom.) After a little thinking, we decided to shave the top part of the hose so it thinner. Worked like a charm, until we found out the hose was ~1.5" to small. I'm thinking of just using a 5/8 heater hose. Ill deal it a little later.
The manifold went one nice and smooth. I was able to do a test on the bolts using PB blaster and this "Freezing" spray. (The forget the name of it, will check later.) Surprisingly, the PB blaster was outperformed by this freezing spray.

My turbo had to reclocked on both the cold and hot compressors. The cold size was very easy but the hot side decided to give me some trouble. I tried nearly every opinion that i read on the forums but only one worked. I baked the turbo at 250 degrees for about 20-30 minutes. Expect other people to joke about "salt and peppering" it. Once it was nice a toasty, a few hits from a $1 rubber mallet from Big Lots got that sucker to move.

The downpipe that i have was made for a 1999 NB miata. This is an older FM 2 piece downpipe. It has a small "bellmouth" style top piece that leaves at about 2" then turns into a 2.25". Once the second part of the downpipe is connected it turns to a 2.5" to the cat. My budget downpipe had the end flange cut off leaving about 3" to 5" space to the cat. I was expecting to use just the top part and clamping on a universal, flexible exhausting piping all the way to the cat. I decided to try to mount the 2nd part of the downpipe just to see the fitment. Regardless of what others say about the NB downpipe on a NA, mine seems to fit. Although It is not fully bolted in yet, it seems to be a perfect fit once we remove the transmission exhaust bracket.

The piping portion of my kit has given us the most headache. The cruise control unit had to be relocated to right in front of the driver's side firewall. Once the back side bracket of the unit is removed, a pre-existing hole from the stock intake system can be used to mount the unit.

To make the air filter section i had to use a 2.5" to 3" reducer. This was connected to a very cheap 3" 90 degree elbow. Both of these were bought at a local parts store and was branded "spectre" These are very cheap and flimsy products, The Elbow was painted aluminum but was made from plastic. The reducer was a single layer rubber compound. The elbow had to be trimmed on both ends to make the connections shorter. This allowed the air filter to sit slightly lower and allow more room for the pipe from the compressor to pass though.

Because of a mistake prior to ordering my silicon hose connectors, i had to slightly "force" a 45 degree bend and a 90 degree bend to fit onto the turbo's inlet. I will soon order the proper connectors and hopefully make it fit a little better.

Still need to do list: Connect the hose under the throttle body to intake pipe. Connect AIT sensor into intake pipe. Make room and connect all water lines to the turbo. Assemble the stainless steel lines for the oil inlet. Figure out a way to make the drain hose work. Figure out exhaust.

Sorry for the lack of pictures, i will get more as time permits.

Last edited by jobambo; 12-22-2008 at 04:03 PM.
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Old 12-22-2008, 02:12 PM   #2
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not sure if ur gonna get 200 rwhp without an intercooler safely but so far the install looks good. snap more pics! and keep up the good work
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Old 12-22-2008, 02:15 PM   #3
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Space bar and enter key. Make that **** readable.
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Old 12-22-2008, 08:07 PM   #4
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Originally Posted by sbkcocker499 View Post
not sure if ur gonna get 200 rwhp without an intercooler safely but so far the install looks good. snap more pics! and keep up the good work
No way will i try to get 200 without a intercooler. My final setup will include it.

fine Pat, ill add some extra spaces.
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