I am referring to a ser 4 turbo here. I tried the simple port it method and it helped a bit, but not enough(still creeped). The next restriction is the size of the flapper door, As you can only port it to the diameter of this( still not big enough for full exhaust, intake, etc.

Tools you will need:

Socket and wrench to remove the turbo
Open wrenches
Die grider bit(which can fit to a power drill or air tool)
Angle grinder
Accesss to a mig welder or welding shop
Exhaust valve from a Honda( or any sufficiently circumfranced valve)
So to solve then next issue is to enlarge the flapper door, to cover the soon to be much larger WG hole.
I used a exhaust valve from a Honda motor, as they are easy to come by at a Honda perf. shop. Also they will withstand high temps.

1. Remove the turbine backplate to expose the wwg hole and arm. Use a angle grinder to grind off the old "door" leaving the arm intact

2. Using your die grinder bit port the WG hole about 2x the original size. from pinkie size to an easy thumb size. Keeping within the dimensions of the new door.

3. now take your valve and cut the stem off it til its about .5" long and taper it a bit. Now shape the valve base to the necesarry circumfrance.

4. bring it to a welder and have him weld the stem up through the hole in the arm, mking sure it leveled correctly. With a healthy beed. be surethat the valve wil open and close cleanly with no rubing on the any of the walls around it.
5 Reinstall and ejoy rock solid boost! I have done this procces and can hold 5.5lbs(If I wanted to!) with 3" turbo back, TID, intake, ported TB, and 11-13 lbs

Total cost:
Exhaust valve free from a shitty Honda head, my labor of grinding/installing, and 50$ to my welder. Total cost 50$!, and took total around 3 hours. Why isnt this more common? My pinky use to baarely fit in that hole, now I can wiggle my thumb in it! Good flow!

 

sounds good! looks like a mod ill be doing as soon as i get the car back from the rebuild. how much did the valve cost you?

 

You beat me to it!
I have an exhaust housing from the Hitachi HT18S-BM that used to be on the 12AT in my old HB Cosmo. I had to replace when I rebuilt the turbo it because it's extensively cracked. In another example of strange Mazda engineering, these turbos have huge wastgates compared to the 13BT, even though the exhuast housing is mush smaller. The diameter of the port is 25mm, the flap is 35mm. The 13BT's wastegate port is only about 15mm, so the 12AT's one is nearly three times bigger! I haven't had a chance to put the housings side-by-side to see if this will fit, but I'm going to try to swap the 12AT flap onto the 13BT arm, then port the wastegate as big as will fit.
Hopefully my results will be as good as yours.

 

maybe i should have read this more carefully.

 

This is a much better sticky than that Newbie FAQ that other guy wrote.



Few more and page 1 will be all stickies

 

Damn I thought this thread would be of more intrest. This is THE cost effective solution to boost creep(IMO), which is one of the worst inherent flaws of T2's.

 

Up

 

boost, check your pm's man!

 

boosted, what do you have on your car in terms of fuel? i currently have the 550s in, with an HKS F-CON to help with the fuel. are you still running on the ecu or do you have a S-AFC to control your injectors? also do you have larger injectors? im very interested in your setup as it seems to be similar to what i plan to go with.

 

I have a rewired Walbro 255lph pump, RC Engineering 800cc secondaries, FCD, and SAFC. Plenty of fuel for a stock turbo. I run around 11-12lbs boost

 

sounds interesting....I'd love to see some pics ....

 

Yeah, Pics, im a lil lost when it comes to the welding parts. Thanks and nice write up

 

why do you say the honda exhaust valve can withstand higher temps? What is it made of and what are other exhaust valves normally made of? Just curious

 

I think that comment was referring to the fact that it was an exhaust valve, not that it was made by Honda. Any suitably sized exhaust valve should work fine, because they were designed to handle exhaust temps.

 

I'm half way through this and are using a flapper off a Garrett T2 which fits perfectly, no need to resize it.

 

boost, wanna come down to connecticut and help me do that? *big grin*

 

Not really but you can come up to NH!

 

Dude, I totally will if you can help me with it.

 

I did a similar mod to my turbo when it was getting high flowed.

With the wastegate disconnected I drilled out the wastegate hole in the turbine housing to the biggest possible without the risk of it leaking.

But I also drilled through the split pulse housing as the original only vents one side.

My car on the dyno would spike 12 psi at 4000 Rpm and come back down to 10 Psi at 5K.

After doing this I did not get a spike and once it came on boost it would hold all the way to 7500 Rpm.

What I should have done is used a 32mm flap (from a similar sized Garret turbo) and used the T04 shaft, bored out housing to suit and back cut the blades- but I wanted the turbo back in the car that week, so I went the easier option with a bigger compressor wheel.

If you want to stay with the STD turbo I would highly suggest doing the above but with a bigger compressor cover and a custom manifold (STD is crap!) and you notice the difference straight away AND have lower intake temps at the same boost levels.