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How To Turbo Your Non-Turbo 626 Or Mx6* (Parts And Install)

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****Disclaimer Part 1****

I am not a certified mechanic, or an automotive expert. I am simpy someone that has ONLY owned an F2 or F2T engine car, and because of that, I happen to know a lot about it, and how to mess with it. Everything I have done is an experiment, a guess or an outcome of hours sometimes days or weeks or months of research. Multiply this by 6 years and I start to think I'm pretty good at it. I could always be wrong, forget something, or need to be corrected.

****Disclaimer Part 2***

If you question the health of your engine (leaks, drips, shakes, shimmys, bumps, knocks, pings, pongs, creaks, squeaks, squeals, rattles, taps, ticks, tocks, dings, dongs, unexplained smells or smoke DO NOT TURBO, FIX IT FIRST DUMMY!!!


So you have a non-turbo 88-92 Mazda 626, MX-6, or ford Probe, and want to swap the turbo parts from a GT to make your car faster and cooler.

Lets begin with what a GT F2T comes with that makes it a GT, (not necessarily what you NEED, but simply what makes it different than the F2)

-Engine block (same shape and design only difference is extra nipples near the turbo for oil and coolant feeds/returns and different piston compression ratio)

-Oil dipstick

-Cylinder head (exhaust valves are heat treated, that's it)

-Turbo, exhaust manifold, EGR pipe, intake pipes, charge pipes, intercooler

-GT injectors (square plug for 88-89, oval plug for 90-92)

-GT ECU (computer unit), that means the engine harness is different as well

-Distributor, ignition system

-Knock sensor (back of block)

-Oil cooler, has coolant lines running to a sandwich plate the oil filter screws onto

-Flywheel, clutch, c/v axles, transmission (all different from a non-turbo) and that includes engine and transmission mounts

-Front wheel hubs (to support the different spline count on the GT c/v axles

-Oil line that feeds the turbo (comes from back of the block, to the right of the oil filter) *two pieces*

-Hard coolant pipe (wraps around front of block), has an extra nipple for turbo coolant hoses.

On top of all that, the F2T has lower compression pistons than the F2, to allow for safer boosting and makes it literally fool proof (or very close)

"But doesn't that mean if I turbo swap my non-turbo, I will make more HP than the F2T?" YES, much more. I will get to that soon.

Ok, so your probably saying "wow, that's a huge parts list." Yes it is, BUT remember I said this is just what makes a GT, a GT. Not necessarily what you NEED to turbo swap your F2.

"I'm not made of money, what's the bare minimum I need to turbo swap?"

Hey, you're preaching to the priest on that one, I turbo swapped my F2 over night, with the absolute bare minimum, with a final cost of a little over $100 (the turbo was $90, so you probably see where I'm coming from lol)

Minimum GT parts to make your non-turbo F2 Mazda into a F2-T:

-Manifold, turbo, O2 housing, EGR pipe, exhaust downpipe

-All intake pipes and clamps, including intercooler and OEM bypass valve unit

-Metal oil line feed line (two pieces) from back of block, including the banjo bolt with the hole in it, and crush washer

-**Injectors (higher flow rate than the non-turbo)**

-Oil dipstick

-Vacuum/boost gauge

-Wideband tuning kit for reading air/fuel ration, and allowing you to PROPERLY tune your engine

(I'm probably forgetting something, so I'll fix this if I remember or get corrected)

-Extra vacuum line, coolant line, vacuum T's, fittings, clamps, and other stuff too probably


Turbo, manifold, and O2 housing:


GT injectors:


Charge pipes:


Throttlebody boot, and other charge pipes:




Where does the oil feed go????? There's a sensor in the way!!!!!

Check it out:



Dont forget the banjo bolt!

Banjo bolt, BPV (Bypass Valve), GT dipstick and turbo support bracket:


Problems with doing the bare minimum:

1. Because you swapped in the GT injectors, it will run super, super rich at idle and cruise, making it almost un-drivable (I will explain this)

2. You will not have coolant feed or drain for the turbo

3. There will not be a nipple for you to run the turbo oil drain line to

4. Your clutch cannot, and probably will not, hold the power you will now be making

5. There is a unit on the turbo called the boost solenoid, this controls boost levels. Because you don't have the GT ECU and harness, it will be unplugged, you can even remove it completely.

Solutions for these problems:

1. **Important** (See below these steps)

2. If you tap into the coolant lines near the non-turbo distributor area, you can make a system that feeds the turbo (You will need extra hose, and T fittings)

3. If you JB weld (or equivalent), a barb fitting into the oil pan under the turbo near the drain pipe on the turbo, you can make a DIY drain hose into the oil pan



4. Buy an reputable, (NOT EBAY), clutch kit that can handle the power. (Southbend non-turbo stage 2 kit for example)

5. Run a vacuum line dirrectly from the compressor nipple on the turbo, to the nipple on the wastegate. You should have between 7psi and 10psi of boost before the wastegate opens.

1. To solve the issue of running super duper rich, I took off the top plastic cover from my VAF unit to tighten the air metering door spring, and I also drilled out the idle mixture control plug, to adjust idle richness. I knew exactly what I was doing, and what the VAF does, I was able to have an absolutely perfect tune @10psi and over 25MPG.


The VAF unit is very sensitive, and once you change the OEM setting (unless you mark it) you can never go back. You might be asking, ok then, so can I use the non-turbo injectors?

I never tried using the non-turbo injectors while boosting, I assumed that because of the lower flow rate, it would run too lean and be too risky.

So I understand I told you to run the GT injectors AND not to touch the VAF....this is very contradictory and leaves a huge blank spot in the how-to. I cannot just simply tell you how to tune the VAF for GT injectors, I can only tell you what I did, and that I do not recommend the average Mazda owner to open it up and try to duplicate my results.

What I did to lean my tune, to support the use of GT injectors on a non-turbo:

Inside the VAF, under the plastic cover, is a wound up spring that controls the stiffness of the airdoor. How far this door opens, is how much fuel your injectors let out.

Once you put in GT injectors, this door does not need to open as much, or as easily, since the new injectors dump in a lot more fuel.

"Ok, I guess I understand...so I need to tighten the spring?"

Yes, it is a 'click' setup. Turn the gear clockwise, and each click is a little leaner. Turn the gear counter-clockwise and it richens.

Example: (This is inside the VAF, under the plastic cover, the arrow is pointing to the locking 'thingie' that stops the gear)


The big black plastic block is controlled by the spring, and attatched to the door inside. The metal arm on this black unit, rides along a track and in turn tells the ECU how much air is pulling the door open.

"Interesting, so how many clicks?"

I can't really answer that, ever motor is different. For me, it was anywhere from 5 to 10 clicks clockwise, or more. And I was constantly adjusting this to account for further engine modifications, or tune-ups.

For example, if you start up your car with GT injectors directly after the swap, you will notice how poorly it idles (if it even starts), and if you try to drive around, it will perform horrible, but probably boost.

With the VAF cover off, you will see that the sensor arm is kind of bobbing around or at a steady location, the air the engine is sucking in, is pulling the door open, thusly telling the ECU how much fuel to dump in. Understand?

You can use you finger the see how the arm inside the VAF controls the tune, gently push the arm so the door is less open, and it will get leaner, and maybe start running better, since it will be too rich to begin with. Push the arm so the door opens more, and the engine will probably stop running, because it will be too rich.

Lets assume you've done what I have recommended you should not, and have gotten your cruise air/fuel ratio to a point that allows the car to drive and boost without blowing up or bogging down from too much fuel. There is a likely chance it will be too lean at idle (if you make it too lean), and either over heat, or want to stall. You shouldnt have to lean too much after the injector install, to the point where you need to richen the idle tune, but in case you do, and need to know how:

Remember that idle air/fuel plug I mentioned?

Here it is:


There is an alluminum plug on the VAF that hides a brass adjustment screw, you can drill out the plug to get to the screw. BE CAREFUL, drill too far and you're screwed (haha, get it?.......)

Turning it clockwise, allows less air to bypass the door, meaning it makes it as rich as possible at idle, counter clockwise, allows more air to bypass the door making the idle tune leaner.

I used a universal narrowband air/fuel ration gauge and a volt meter hooked up to my O2 sensor, to get as good of a tune as I possibly could, at idle, cruis, and while boosting. Lot's of research, practice and a watchful eye on my spark plugs kept me from being too lean, and detonating while in boost (exploding my engine internals.)


Any mechanic, engine builder, shop or profesional will tell you that any change in air/fuel ratio or attempt to, should be made with a proper tuning device, and by someone who knows exactly what they are doing. NOT an of the shelf narrowband, since they have a less than a 1/4 of the ability of a wideband.

Meaning, a wideband oxygen sensor and gauge is MANDATORY for tuning your air/fuel ratio, you should not even attempt to tune you car by sight/sound/feel alone.

"Wait, but that's what you did...and that's basically what you're telling me to do"

OK maybe, but I'm also saying do it at your own risk, and I'm not responsible if you blow up your motor, ok?

Everything from ignition timing to tuning air/fuel ratio, I've done by sight/sound/smell/feel, and it's been close to perfect every time. Am I god? No, just really carefull, and have had lots of practice, for better or worse.

If you expect your engine to last at all, properly setting your ignition timing along with constant maintence/inspection is a must.

**This how-to is a work in progress, I need to spell check it, error check it, and make sure I didn't leave something huge out. Suggestions, corrections and constructive critisism is welcomed**

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  • 3 months later...
  • 2 months later...

Not necessary, but it is a good upgrade versus the lower end 70a.


Keep an eye out when you go to the junk yard. I found an automatic 626 with a brand new alternator once, 90a if I'm not mistaken.


The autos and GTs come with much better alternators. You can tell the difference by looking at the front (pulley side), if you see a triangle formation of 3 bolts, it's the low end type. If it's a square 4 bolt pattern, it's the 80a or 90a.

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Good to know. I need to replace my alternator and I remembered the turbos are 80 amps unlike mine that's a 70 amp. If I were to get the 80 amp alternator, would I even be able to fit it into a non-turbo model? That's my concern, getting the damn thing and not being able to mount it in...


By the way, you have one kick ass 626! That spoiler is the poop!

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Hah, thanks. I have way too many mx-6 spoilers lying around, so it was just a matter of time before I slapped one on.



Anyway, any alternator from 88-92 GD will drop right in, the plugs on the back change but any of them *should* plug it. I could be wrong, but I've used 90-92 alternator in my 89.

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  • 1 month later...

quick question for you. since the injectors were causing such a rich condition, couldnt you have simply used a FMU to add extra fuel during boost? im just curious because my buddy is looking at maybe boosting his 90' 626 , but doesnt want to deal with the rich condition.


You dont run into any fuel cut ? did you upgrade the fuel pump at all?



other question i have is what is the stock PSI for this turbo? i can mod the actuator rod to lower the boost if need be. i just know my buddy doesnt want to push the limits of the stock internals


sorry for all the questions, you just seem to be the only person i can find online that has any sort of guide for how to do this.

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Why no FMU?:

I wanted to keep the fuel system as close to stock as possible (as far as after the fuel filter). Also, I did the "turbo swap" overnight in my garage, it took me a week or two to figure out I could control the idle and cruise A/F with the VAF. An FMU could have done the same thing, but it would have complicated the situation I think. The issue was solved using the tools Mazda gave me, that's how I see it.

About fuel cut:

The N/A model was not intended to see boost, so the N/A ECU will not cut fuel. This gives you a large and dangerous sandbox to play in. On my application, I had already upgraded the fuel pump long before I actually turbo'd it. Walbro 190lph.

The GT model will limit boost to around 12PIS, after the VAF hits a limit sensor and cuts fuel. People with GT models use a chip to alter ignition timing and remove that fuel cut. For example, I'm using a probinator chip in my GT, I run 20PSI.

Stock PSI:

GT? 7-9PSI, the turbo is "capable" of running 12-16PSI, and some even push it to 20PSI. Consider the turbos 'redline' to be around 16PSI. I am running a hybrid turbo, and even then, 20PSI is nearing redline.

A bone stock, well maintained F2T can see over 20PSI without blinking. However, it's the tune that matters the most, the bottom end is essentially bullet proof stock. The F2T uses softer pistons, prone to cracking during detonation.

The F2 has slightly higher compression, so tread very lightly. At the same time, the pistons are much more resistant to 'accidents'.

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Ah i see. i appreciate the quick answers by the way! i love friendly car communities.

ill have to see what FMU he should be using then as that should be a little less hastle to hook up for him. my car (95 eclipse) uses a 12:1 FMU, but no idea on these cars.

i have a tiny side moint intercooler that was given to me, looks like 2" inlet and outlet. that should be plenty enough for 7-9 psi yeah?


one more question for the moment . I noticed the turbo flange on the manifold looks like a t25 flange. is that correct? if so, this may make things even easier for him, as i have a td05 turbo with a t25 flange on its way, but decided i wanted a t3 flange for my car (to avoid using an adapter).

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  • 1 year later...

Out of curiosity Leev, how was engine reliability when you did a turbo swap on a nonturbo?


I've been debating it still lately and I'm iffy about it because if there are genuine special differences between the GT and non-GT engines that make it so the GT can last as long as a non-turbo... I dunno know...

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It ran 12 Psi for 3 years, then I ran out of money to replace critical seals. Starting leaking oil from obvious places.

Keep in mind, I checked my plugs weekly, and tuned it by hand. Then I eventually got a wideband and found out my A/F during boost was perfect.

It's a commitment, but on a healthy n/a block, you'll make scary power on stock boost levels.

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  • 3 months later...

Hey Leev!

Just wanted to let you know that I used your write up to turbo my B2200 a couple of years back. It worked great! Everything you said also applied to the truck, except that the stock RHB5 o2 sensor housing interfered with the driver's side engine mount. I should mention that I ran 626 ECU/harness/AFM in place of the truck's stock Mitsubishi parts. With Denso 315cc green-top injectors off a 7M-GE engine, 5 clicks tighter at the AFM had me in the ballpark.

Anyways, I'm putting together a second B2200, this time with an F2T bottom end. I'm looking forward to running more boost this time around. I'll keep you posted!

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I'm super glad this helped someone. I reread it myself just now and noticed many spelling mistakes and formatting that needs to be touched up, but I reeally don't feel like it, haha.

Really glad it helped. Thank you.

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  • 1 year later...

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