I've been receiving lots of requests for information regarding this. So, I'm creating this thread to clear up any confusion regarding this type of conversion and to pool information because some threads lack important info. If you have anything to add, please by all means do so, just keep it civil and of pure logical importance.
The following is information i gathered before and after doing my 1/2na-t. This is how i did it, the mistakes i made, and better ways to do things. Don't assume this is the "best" way to perform the 1/2na-t, this is simply my experience with it.
First and Foremost, i think its necessary to let people know that this is not an easy project. If may look easy, but don't let the conversion checklist fool you. This could ultimately make or break your car. Half-assing will not be tolerated by your engine. If you are to do this conversion, you must take your time. This sort of thing can't be rushed. You must also have a good undestanding of what you are doing. I would suggest you read "Maximum Boost" by Corky Bell. This book will really help you understand turbochargers. Then i would suggest you rent the book "Vehicle and Engine Technology" by Heinz Heisler. Thats about an $85 book with almost 780 pages. Written by a professor from london, its very very helpful in learning about tuning and engine theory. Just touch a few chapters in that book, he beats a few topics to death. Again, i would like to stess the fact that i researched and read for almost a year before doing this conversion to my car. Its important to know what you are doing and that lefty is loosey and righty is tighty.
Another topic that often comes up in discussion is cost. heh, cost... Most supra owners will tell you NEVER EVER add up receipts, well... i did. The 1/2na-t cost me $1239 total. But... I got the following items for free; 440 injectors, fuel regulator, exhaust manifold, HKS downpipe, stock bov, stock tubing. I also got insane deals on a rebuilt ct-26 (175), safc (150), and intercooler (60). Also one thing that i forget to budget for this project is mistakes.. Heh, mistakes cost me at least 50 total. Just for broken bolts, nuts, new gaskets, silicone, hose clamps... over time it all adds up. I would say, a safe budget would be at 1500-1750. Its always better to have too much money for a project than too little.
Okay, here is the 1/2na-t Parts list that i worked off of. I collaborated this list 4 monthes before i did the project and then modified it after i did it. Its fairly accurate.
The ½ NA-T Conversion
Performed on a 1986.5 mk3 Toyota Supra
Parts Needed From Mk3 Turbo
-CT26 turbocharger
-Stock Piping
-Exhaust manifold
-Down-pipe
-440 injectors (better get them now)
-Blow off valve w/ tube assembly
-Oil inlet and outlet lines
-Coolant in/out lines
-Fuel Pressure Regulator
Optional Parts from Mk3 Turbo
-Stock BOV (probably easier to put aftermarket on)
After market necessities
Items marked with * can be optional but just make life easier
-Boost Gauge
-Fuel Pressure Gauge*
-Air/Fuel ratio Gauge
-New free flowing exhaust*
-A’PEXi Super ACF fuel controller (SAFC)(HIGHLY RECOMMENDED)
-2mm Metal head gasket (MHG) Tighten your stock to 72 ft/lb. and you should be good*
-Fuel Pressure regulator of some kind! Generally a rising rate fuel pressure regulator (RRFPR)*
-Oil Cooler*
-Aftermarket Downpipe*
-Aftermarket Blow Off Valve (BOV)*
-¾” rubber hoses for oil outlet*
-Turbo NGK Spark Plugs gapped at 29
-MSD ignition Boost Timing Master (BTM), this will eliminate detonation and take the guesswork out of retarding the timing on the car.*
Tips and N/A modifications to ensure the proper operation
-Tighten your AFM so the turbo doesn’t constantly suck it open
-Retard timing 2-5 degrees if no MSD BTM is used
-Re-Route PCV hoses and plug up where they enter the throttle body, if this isn’t done you’re car will smoke like no tomorrow
-For the Oil, take oil from the pressure sender unit, just screw in a T and get your oil feed from there. For the oil drain, you can either; a) remove the block plate for the oil cooler return and use that, which is easier but may not flow as well, or you can b) remove the oil pan (PITA) and insert your own drain fitting
-Start out with a stock boost pressure and get the car running for a while before you crank the boost.
-Cranking the boost is not recommended
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Alright, if you have any questions regarding information on this list, it can most likely be found in SF, so just search. If it doesn't appear in the search, ask me, and i'll add it to the list if i think its important.
Okay, next i'll include the installation checklist i used during my 1/2na-t. Its not very specific because most of the stuff i had in my head, but it'll get you started in the right direction.
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½ NA-T Conversion Checklist
-Check Compression, using TSRM, if not good... Do NOT proceed
-Remove all NA intake and exhaust manifold, throttle, ect.
-Clean engine
-Remove valve covers
-re-torque HG (get instructions for this)
-Clean throttle, intake Y-pipe, and manifold (carb cleaner, just get carbon out)
-Install RRFPR and injectors (make sure to put the rubber washers on the bottom of the injectors)
-punch hole for oil drain or use existing oil drain (easier and safer to remove oil pan for this)
-Install oil feed T-coupler into oil pressure sender
-install intercooler and oil cooler
-install EGT probe and other probes/gauges
-Gap and install spark plugs (autolites, NGK, but NO BOSCH!!!!!)
-install ex. manifold, turbo, elbow, DP (may need new bolts, nuts, and gaskets)
-install Intake manifold, y-pipe, and throttle
-install hoses, BOV
-Adjust AFM
-Add Octane booster (toluene, xylene, ect)
-Adjust timing
-tune, and get to idle
-check oil pressure for turbo
-grace tuning
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The following are mistake i made along the way and how to correct them....
1) Oil feed... i used an oil filter reloation kit to feed oil to my turbo. That proved too much oil too soon, and it forced oil past the seals, into the intake. bad idea. I now have oil coming from a feed installed in the oil pressure sender. much better
2) Oil drain... I punched a hole with a punch into the side of my oil pan then jammed a fitting in there. I'm a little embarrassed by this, because it's probably the dumbest thing i've ever done. Oil leaked everywhere and my GOBS of silicone glue didn't aid the problem at all... I removed the oil pan and now have a nice, clean, secure fitting in there. It doesn't leak a drop.
3) dyno.... this was rushing in its purest form. I completed the 1/2na-t in a week and set a dyno appointment for the end of the week. It sucked. The car ran poorly because i tightened the last bolt 5 minutes for the dyno. A huge manifold leak and throttle blockage caused miserable, embarrassing, and depressing numbers. To fix this... simply take your time.
4) BOV... I vented a stock BOV to open air.. enough said... that caused nice vac leaks and inconsistant boost. To fix this... get an aftermarket or plumb the stocker into the intake.
5) I didn't search... I pestered the heck out of people from SF, over AIM and on the phone. I was a real PITA, asking dumb questions. This made a lot of people uncomfortable with talking to me, and kinda annoyed with me. To fix this problem... just search, read, and learn because that will answer most questions. If you need pics, search SF, i've posted quite a few. Have fun with this and be careful!
