Orfice before boost controller (y fitting)

[Wahoo]

So my y fitting has been broken for awhile, I just removed it completely.

It's been running fine, doesn't seem to spool really fast but I really don't know how fast it should spool (hot air TA33 turbo), and I do have exhaust leaks pre turbo.

Just curious if an orfice or a y-fitting would be beneficial to use?

I heard it makes the turbo spool faster and it's supposed to be before the wastegate I believe?

This is on my old hot air setup, I'm actually building a separate motor that's going to be intercooled in which I imagine the orfice/y fitting should also be installed on.

Thx

 

[Anthony P]

the y-fitting with the orifice restrictor is necessary.

the orifice restrictor is located in the first half of the straight section of the y-fitting. the angled fitting to the back half is unrestricted.

the restrictor is just a metal insert secured internally to reduce the inside diameter of the fitting to slow the flow rate. I don't recall the id specs off hand.

the purpose of the restrictor is to ease the buildup of pressure to the wastegate actuator and to the wastegate solenoid and to slow the release of pressure from the actuator when coming off of boost.

the actuator is controlled by a spring loaded rubber diaphragm. linear buildup and bleed off of boost pressure is the desired way to go. if using an unrestricted y-fitting, the action of the wastegate actuator would be too quick. it's not supposed to react as instantly as a solenoid valve.

I'm sure someone here has one available.

 

[Wahoo]

the y-fitting with the orifice restrictor is necessary.

the orifice restrictor is located in the first half of the straight section of the y-fitting. the angled fitting to the back half is unrestricted.

the restrictor is just a metal insert secured internally to reduce the inside diameter of the fitting to slow the flow rate. I don't recall the id specs off hand.

the purpose of the restrictor is to ease the buildup of pressure to the wastegate actuator and to the wastegate solenoid and to slow the release of pressure from the actuator when coming off of boost.

the actuator is controlled by a spring loaded rubber diaphragm. linear buildup and bleed off of boost pressure is the desired way to go. if using an unrestricted y-fitting, the action of the wastegate actuator would be too quick. it's not supposed to react as instantly as a solenoid valve.

I'm sure someone here has one available.

Thanks for your reply.

So without it will cause boost to build a little slower because the pressure builds too quick against the wastegate diaphragm and maybe the wastegate puck starts to flutter?


Is the boust solenoid used when you have a TT chip, because most people run more boost so wouldn't it be not needed?

Could I just put an orfice of similar size tee'd into the vacuum line to the wastegate if I don't find another y fitting?

I feel currently if I set my boost to 18 psi and go WOT it spools and huts 22psi and drops down to setpoint, is that normal?

Thx

 

[Anthony P]

yes...boost problems will occur. on a stock type non-adjustable wastegate actuator, boost pressure starts to overcome the spring's pushback force at about 9psig. unrestricted boost pressure to the actuator causes it to move too quickly, opening the wastegate puck and loosing boost while the engine controls are trying to build boost. the system fights itself. similar when you lift from the throttle. if you let off instantly and completely, throttle blade closes, turbo is still spinning at 140K rpm making boost that can't go anywhere. so the restrictor aids in slowing the release of pressure from the actuator, slowing the closure of the wastegate puck. while it's not needed for stock turbos performing at stock boost levels about 15psig, you've seen up pipes to the throttle body incorporating a blow off valve. higher capacity turbos have gas porting in the inlet to alleviate the pressure buildup when coming off boost.

boost solenoid, y-fitting are needed when using a chip. the chip has different boost settings, fuel curve parameters, etc to allow the ECM to manage the engine performance to that specific boost level. TT street is 16-18 psig.

I'm sure someone has a spare y-fitting. Kirban sells a replacement. http://www.kirbanperformance.com/product/44330/REPLACEMENT+BOOST+LINE+VACUUM+T+#7704.html

yes, you could use a 50-cent y-fitting from an autoparts store and with some roll pins fabricate your own restrictor. I don't believe I would spend $30 on this replacement fitting, I would enjoy making one myself and have the satisfaction that I did.

boost should build linearly to the desired level and maintain that level for as long as your foot is to the floor. It definitely should not bounce, spike, overshoot or anything like that.

I'll measure the restrictor and post since it looks like you want to make your own.

 

[Anthony P]

vacuum line hose is 7/32. the restrictor orifice opening is 0.0465 in. use a # 56 drill bit or use a 3/64 bit which is 0.0469.

the original restrictor is a brass plug that was 2-stepped drilled. once to 0.140 then to 0.0465. the larger hole in the plug would be like a sleeve for the tool used to insert the restrictor into the y-fitting.

the restrictor itself is not very long, maybe 1/8 or 3/16. certainly not half the run length of the of the y. it is located about halfway down the first half of the run length, before the y branch connects.

 

[Wahoo]

vacuum line hose is 7/32. the restrictor orifice opening is 0.0465 in. use a # 56 drill bit or use a 3/64 bit which is 0.0469.

the original restrictor is a brass plug that was 2-stepped drilled. once to 0.140 then to 0.0465. the larger hole in the plug would be like a sleeve for the tool used to insert the restrictor into the y-fitting.

the restrictor itself is not very long, maybe 1/8 or 3/16. certainly not half the run length of the of the y. it is located about halfway down the first half of the run length, before the y branch connects.

I have a stock style adjustable wastegate, but I think i need to redo my boost gauge hose, I think it has a leak, if I go over 20 psi the gauge flutters. It did this with another gauge as well so I know the hose must have a leak.

 

[Wahoo]

I forgot to say I have a manual boost controller between turbo boost reference to Watergate diaphragm so the office probably isn't needed any more @Anthony P ?

 

[Anthony P]

well, that makes a big difference. I was expecting you were using the stock setup and control solenoid on the driver's side valve cover, letting the ECM control boost and that you were having boost control issues from eliminating the y fitting.

cockpit mounted manual boost control negates all the stock stuff.

 

[Anthony P]

just to clarify....I(we) don't know the exact components of your manual boost controller.

if you have eliminated ECM control of boost altogether, I would expect a self-contained, under the hood regulator would have some sort if internal restrictor built-in to control surge during buildup of boost pressure and also to control the venting of the boost pressure.

the cockpit or dash mounted electronic controller I noted above was a reference to the unit sold by Poston's years ago when they were in business. it had a switch to override ECM control of boost and a dial to adjust boost setting. it also had a secondary boost control circuit that could be wired to the brake switch for staging or to the 3rd gear switch or a low alky light to limit boost in those circumstances.

someone else may need to chime in here...