i often hear stories about rx7 owners that want to shoot their turbo builders... i know one party that sent his new turbos back 3 times because they "SMOKED"



actually, a couple of weeks ago i was ready to call UPS after a summer of smoking up the wisconsin landscape.



i run 2 t04/t3 hybrids. i had started w .09 restrictors and had subsequently downsized to .07 w no improvement.



then i remembered Steve Kan telling me that t3s need .03 or they will smoke. i thought i would give it a try before shooting my good guy turbo builder Kevin Draper. i located a dremel drillset that had a .034 bit and.....



no smoke it has been 400 miles since and my turbos are spooling and smiling.



if you find yourself w a smokin' turbo SIZE does matter so make sure you have the correct restrictor.



BTW, since the area of a circle is radius squared times Pi... my restrictor area is now 27% of what it was at .07.



thanks Steve,



howard coleman

I want to know more about the concept of restrictor purpose after I get the 2nd new turbo. But why doesn't the turbo have that proper restrition built in its center section from Garrett (whoever) since they design them and know what is too much?

many turbos were designed to work with over the road diesel truck engines and require modification for use in the typical car. if, for example you had no restrictor in a Garrett t3 or t04 you would pump so much oil thru the turbo that your engine would lose almost all it's oil pressure.



newer GT turbos, as i understand, generally have built-in restrictors as they have been designed to work w cars...



howard coleman

Good info. Yeah if you don't restrict the oil pressure it likes to slip past the seals, causing that nasty smoke.

your turbo doesn't need all the pressure than the engine needs to get the oil where it needs to go. So when you restrict, you decrease the flow, less flow = less pressure. I'm sure there is a perfect pressure that the turbo likes to see, but I'm not sure what that is, and I don't know the math to knock the engines oil pressure down to that amount so I'm gonna call some people who do, and ask them. But that's the general concept.

Where can you even get restrictors?



I guess turbos don't normally ship with them...

That little bit would be a world of knowledge for lot of smoking turbos.

Also put that with the oil catch tank concept it should clean things up a lot.

if it's a kit for a particular setup, it will probably ship with it, but for a turbo by it'self there are just too many variables. I think I've heard of people using modified nitrous pills.

Yeah mine definitely didn't come with one, so I was just assuming I only needed what came with it. https://www.nopistons.com/forums/pub...IR#>/smile.png

you have to wonder how many turbos would have not had to be rebuilt if they had a card explaining the restrictor thing in the box with the turbo?

DO NOT DO THE .03 TURBO RESTRICTORS!!!!!!!!!!!!!!!!!!!!!!!!!



i just lost both turbo bearings after 165 miles w the .03 sized restrictors. JD was, in retrospect, right on the money as to them being too small. i will probably go w .05 after they have had a trip to Waco...



howard coleman

So what is the correct size for a T04R?

Yea I want to know that one too!

Any progress on this?

Anyone remember what the apexi turbo restriction size is? I remember it was tiny.

FWIW, ATPTurbo.com lists the T4 restrictor as .06:



Oil Restrictor

1.5mm or a hair under .06 is what I use on everything garret that needs a restrictor on a rotary and seems to be ideal. I have used up to 2.0mm without any big problems on your typical rotary, the only difference being that when the seals are close to being totally dead the turbo starts smoking earlier the bigger the restrictor.



HKaSs (garret) kits for rotaries come with a 1.5mm restrictor. HKaSs (garret) kits for piston engines come with a 1.8mm restrictor. Rotaries tend to run higher oil pressure than most piston motors.

I went ahead and ordered the .06, trusting that ATPTurbo knew what they were talking about. Hopefully I'll be okay!

i cant remember but it was small! and the only place i could get it was apexi japan. when i take my car apart next time i will measure it.