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Everything up until now has been my own work but alas when it comes to welding I must rely on a fabricator to help me out. On my list of things I needed welded: Two vacuum nipples on the compressor discharge elbow, welding the piping legs together for the compressor discharge elbow to IC inlet, welding the BOV flange to that IC pipe, and welding a vacuum nipple for the oil injector vacuum and a hose bung for the airpump inlet pipe to the air filter/turbo intake connector pipe. I spent the time cutting the pipe legs to length, marking the vacuum nipple and BOV flange locations, and mocking up the intake pipes. The IC pipe was made from a single 90deg 2.75" aluminum elbow. As they always say measure twice cut once because I needed every inch of that raw 2.75" 90deg pipe bend.

Mockup of three pipe legs for IC pipe. Markings for BOV flange location.

Now particular attention must be paid to the clearance between the compressor outlet elbow and the strut tower bar. Depending on how you have clocked the compressor housing this may or may not be an issue but since mine it clocked so the discharge is essentially pointed vertically (to accomodate the airpump discharge pipe), as suspected the cast 90deg elbow hit the strut bar bracket. Nothing significant but over time the strut tower bar could potentially wear a hole in the pipe and also make a nasty vibration noise during operation. So with some judicious grinding of the offending underside portion of the strut tower bar, cutting about 1/4" off the elbow pipe to lower it, and adding some custom fabricated spacers to the strut tower bar mounting locations I was able to generate about 1/4" to 3/8" clearance between the elbow and the strut tower bar.

1/4" strut bar spacers. I used the strut bar bracket as a template.

Clearance between strut bar and compressor discharge elbow. Box of aluminum pipes and parts to be welded.

So with parts and raw materials in hand off to Mitch Piper of Piper Motorsports I went. The result is I had a complete “kit” and could finish up with the install. So with the pipes completed I could hook up all the various vacuum lines listed above. The TiAL 50mm BOV is installed on the IC pipe as instructed using the O-ring and V-band flange. Be very careful not to pinch the O-ring during the install. Of note, however, is that the spring that came with the BOV, as purchased, is too heavy for use on a rotary engine that has such low normal engine vacuum (relative to a piston engine). I returned the spring to TiAL and they replaced it “no-charge” other than a $5 shipping cost. The BOV I purchased came with the standard 11lb spring (liftoff at 26inHg which is too high for a rotary). I replaced it with the softest spring TiAL offers - 7lb (liftoff at 18inHg).

Finished pipes with all necessary fittings. -4AN weld on fittings used for vacuum lines. Large 4" pipe is for the intake. BOV connection flange. Don't pinch that O-ring!

Test fit the new pipes. Thank goodness all the pipes fit perfectly. In dire need of some polishing though!


The last big obstacle, and it's a big one for most of us, is what to do about tuning. Both for the PFC and the boost controller. The boost controller should be fairly straightforward but the PFC... Switching to a single turbo is going to take you far from the tuning you once had with the old twin turbo setup. And then there is the consideration of other components of your setup. For example, what size injectors used, what size IC, what kind of exhaust system is installed, MP or high flow cat, etc. All these and more will play a role. Lucky for me another friend of mine has travelled much the same road as I have. We share the same size injectors, have stock unported engines, use large/race sized stock mounted IC’s, have 3" full flow exhaust systems, and most importantly bought identical turbo kits from A-Spec. In short, since we had been conversing for well over a year about the conversions we both undertook he was kind enough to share with me his maps for the PFC to get me started. His car has been tuned on a dyno and from here is where I began. A few keystrokes on the Datalogit and with the new tuning installed I will test drive, with a local tuning buddy, logging data from my wideband as I explored the fuel maps.....

6 weeks later...the fruits of my labor.

A bit of spit and polish here and there for appearances sake of course.


As complete as the kit from A-Spec was there are quite a few other items that are, in my opinion, needed in order to complete the installation and should be considered when undertaking this project, not only from a preparation standpoint (I hate getting halfway into a project and then having to stop for a week while I await parts) but from a financial standpoint also. There are, of course, a whole bunch of other items that are potentially “required” to run a single turbo and to make big power, that can substantially increase the cost of doing the conversion, but since I had most of these items no expense was incurred by me at this time. I’ll just throw out a short list of other things I have already installed on my car that could be necessary:
Larger IC - to take full advantage of the extra boost
Programmable ECU - more power means more fuel...that the stock ECU can’t handle
Larger radiator - more power means more heat although switching to a single turbo will in some respects reduce the heat load on the cooling system inherent in the design of the stock sequential twin turbos
Bigger fuel injectors - more power requires more fuel and the stock 550cc primary and 850cc secondary injectors are more than likely going to be undersized for hp numbers approaching 400rwhp.
Plus things like silicone couplers and T-bar clamps from my previous setup I reused.

There were some items in the "kit" that although may be acceptable, I found it necesssary to upgrade from what was supplied. Installing a single turbo will cost a lot more than just the “kit!” Note that some of these items were bought in quantities more than what is needed but at least in my case I was able to split the cost and product with a friend who was installing his kit at the same time I was. I shall start with the kit:
GT35R single Turbo kit - A-Spec to which one might add:

1) TiAL 50mm Blow Off Valve w/Aluminum flange, Silver - [new] (eBay - $218.00 shipped
2)Thermo-Tec Heat shielding all from (the “kit” only came with one small 12" square of adhesive backed Al sheet)
- Heat Barrier FIber Reinforced Adhesive Back aluminum sheets (12" x 24") [pn 13575] (2 boxes) $32.70
- Thermo-Flex Aluminum cool tube (5/8" x 36") [pn 17062] (2 boxes) $21.38 - small wiring harnesses and turbo coolant hoses small wiring harnesses and turbo coolant hoses
- Thermo-Flex Aluminum cool tube (1" x “36") [pn 17100] (2 boxes) $29.50 - heater hose and AC hard line
- Thermo-Sleeve (5/8" x 36") [pn 14010] (1 box) $13.32 - various heater hose and larger wiring harnesses
- Thermo-Sleeve (1/4" to ½" x 36") [pn 14005] (2 boxes) $20.04 - vacuum lines
3) Turbo turbine discharge to DP gasket (1) (pn GRT-GSK-003) (ATP Turbo) $8.95
4) Oil feed line restrictor w/0.035" inlet hole (pn ATP-OIL-021) (ATP Turbo) $12.00
5) Turbo compressor discharge 2.5" to 2.75" silicone reducer (1) (pn ATP-SIL-057) (ATP Turbo) $17.50
6) IC pipe silicone connector 2.75" straight (1) (pn ATP-SIL-042) (ATP Turbo) $6.00
7) IC pipe silicone hump connectors 2.75" (2) (pn ATP-SIL-049) (ATP Turbo) $24.00
8) T-bar clamp 2.5" for compressor discharge (1) SS Breeze clamp: $2.37 from
9) T-bar clamp 2.75" for compressor to IC piping (1) SS Breeze clamp $2.40 from
10) -4 AN aluminum weld on vacuum line bungs [I used XRP 6061-T6 fittings] (3) $15.00 from Livermore Performance
11) -4 AN vacuum line hose barb fittings [I used XRP Hose End, Push -On, Straight -4 AN Female fittings] (3) $10.00 from Livermore Performance
12) 4" flexible intake hose (pn 53145 K67) [Santoprene: General purpose polypro/rubber duct hose, Black 4" ID 4-9/32" OD, 5' length (McMaster-Carr) $23.35 This was split with a friend - my expense $17.00
13) 4" worm gear clamps for intake hose (3) (Home Depot) $5.00
14) Tube of antiseize $3.00 (Pep Boys)
15) GReddy Profec B Type II Boost controller [new] (eBay) $285.00 shipped from [ domian name has since expired so I don't know who these folks are now - search eBay]
16) Bag of small zip ties $2.00 (Home Depot)
17) Proper spec turbo coolant line and oil drain lines. Parker Push-Lok oil line hose 2' and Parker Push-Lok 3/8" x 3' coolant hose $11.54. These were sourced locally.
18) Hardware - 5/16" internal tooth star lock washers for wastegate flange fasteners $2.00 (NAPA autoparts)
19) Hardware - SS shouldered nuts for turbo to manifold connection. (kit supplied with jam nuts) 4x $1.50 ea: total $6.00 McMaster-Carr (P/N 93776A471) [18-8 Stainless Steel Hex Serrated-Flange Nut, 3/8"-24 Screw Size, 9/16" W, 11/32" O'All Height]
20) 4" aluminum tube for filter to intake tube connection ( 4" x 0.125" x 3.75" x 12" (12" minimum order) $15.00 ($10 shipping) This was split with a friend. You will only need about 4"
21) 2.75" T6061 aluminum tube 90deg elbow (Burns Stainless) 6" x 12", [pn LB-275-40-16-6061] $75.11
22) GReddy 90 deg cast elbow for compressor discharge. This was actually given to me and as far as I know was part of a GReddy 2 piece IC hard pipe kit. The GReddy kit goes for about $185. But the piece in question is essentially a tight radius bend 2.75" diameter *cast* AL elbow or something like this from EIP tuning (although this is only a 2.5") elbow image 1 or here elbow image 2
22) 6 mm vacuum line (15ft) ( Hose Techniques) $29.25
23) Exhaust manifold to block gaskets - Racing Beat (pn 16302, ENG-TO-HEAD GASKET 74-75 ALL) (Mazda Pn1757-13-889B) (2) $8.00
24) Pack of small vacuum caps for unused vacuum nipples $2.50 (Pep Boys)

Shipping costs for all these bits and pieces. Est. $75.00

And some of the extras I purchased for my install:
25) Brass fittings for Oil pan vent line $6.00
26) Air pump 3/4" vent line “T” $1.00

And don’t forget to add to this the cost of having new IC and intake piping fabricated. $90.00
So if you want to be honest with yourself, installing one of these kits **YOURSELF** will cost you probably over $1000.00 more than the price of just the kit itself depending on the quality of the parts you purchase and what you had previously installed on your car. Note, however, that about $500 of this additional cost was for the BOV and the Profec B boost controller.


So it was that with much trepidation I headed out to try out my new steed. Three weeks of street driving yielded nothing but cheesy grins and exuberent cheers of joy. The car was a rocket...certainly much faster than my old setup. Several weeks of datalogging and testing and tuning to tweak the fuel maps and PFC settings ensued. The car is far from well tuned still but it is "safe." And that I can live with until a time when I can focus more energy on extracting the full potential of the setup. Driving on the street was fine but the true test would come when pushing it HARD while on the track. A tuning hiccup prompted me to do a compression test of my motor (boy was that ever a scare!) Hard starting and a really lumpy idle led me to believe I'd lost a rotor seal, and this only days before a track weekend. False alarm - compression numbers on all rotor chambers were low to mid 8's. So off to the track I went. With boost set at 10psi (Profec controller turned off) I hit the track. Note: I replaced the supplied 7psi (little blue) wastegate spring with a 10psi (big red) spring.
"Big Red" (10psi) and "Little Blue" (7psi) TiAL wastegate springs.

Day 1 went fine. And then there was day 2 when the excitment started. First session of the day started fine so I decided to flip on the controller and try 12psi of boost. Well things weren't all roses and some nasty sounds began eminating from the exhaust system and boost begin to wane shortly thereafter. Turns out the wastegate inlet flange connection had shed two of the retailing bolts (simply gone) and the other two were rattling around in their holes they were so loose, resulting in the metal/fiber gasket being completely blown out. Two hours under the car during the lunch break and I managed to find replacement hardware, reused the other gasket from the exhaust side of the wastegate, and hit the track again. BAH! Same problem. The hardware and gaskets just didn't seem up to the task. I return home and with the help of some friends, all with the same GT35R kit and all experiencing the same problem on the track, there are 3 of us, we agreed that copper gaskets and some fancy new locking hardware, the flanged connection would stand some chance of holding up the heat of a hardworking wastegate at track temperatures. I replaced the bolts with a stud and nut arrangement and used a great SS locking washer called Nordlocks. The copper gaskets were hand cut from 0.025" thick copper sheet. I replaced both the inlet and discharge gaskets. The hardware was longer (30mm vs. the supplied 25mm) SHCS on the inlet side (8.8grade - M8x30mm) and studs and SS nuts on the discharge side. (8.8grade - M8x25)(SS M8 nuts) All mounted using Nordlock washers (NL8mm SS) The hardware was all bought from See pictures below. The result was that at the next track weekend I successfully ran 12psi all weekend with no wastegate issues to speak of and all the hardware remained tight.

The remains of the blown out gasket. New copper gaskets and hardware. The valve seat, thankfully, remained undamaged.

Single Turbo Installation: Page 1
Single Turbo Installation: Page 2
Single Turbo Installation: Page 3



This page last updated December 21, 2005

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