Trouble lowering boost with Tial 38mm

[87NAT]

I am trying to bring my boost down to around 19 psi with my new headgaskets to start a basic tune. I have a Tail 38mm External gate with the large blue spring(14psi) installed and an air regulator run closed loop to the top port of my gate. Even with the regulator closed and no manifold pressure being routed to the top port I am building 23-24 psi. Is my gate to small with my turbo(6776dbb) to drop the boost? I have the turbine hole ported out on the turbo to match the downpipe. Would a smaller spring say a 10 or 12 psi spring help this situation or could I have another culprit that I am missing making the boost rise. It is insta spool at half throttle to max boost. At least I dont have any lag issues

Any input would be appreciated.

 

[slimtastic]

what the hell is an air regulator in reference to a wastegate?

id just make sure that the port on the top side of the diaphram is open to atmosphere and the port under the diaphram is going to the boost reference on the turbo...

past that if the "wastegate path" has any harsh 90' degree angles, and your turbo is really efficient, then the path of least resistance would be through the turbo.... high speed air hates to turn hard

 

[JayC]

The problem is the hole in the turbo. I dont care how big you make it, you still have to coax the exhaust to go through it and the newer turbos flow so well that the exhaust doesnt want to make the turn, just wants to keep spinning that wheel. As such, not enough exhaust is going through your wastegate to make the difference.

If you move it coming off the header, you'll have better results. I think the Tial 38mm is maybe a little small but should work. Thats one reason we use the TurboSmart stuff. It just plain works.

 

[JayC]

what the hell is an air regulator in reference to a wastegate?

You use them to control the boost manually with external gates. The ones you buy at the hardware store have a lot of spring pressure (Well over 100 PSI), I prefer the ones that top out at 50 PSI but you cant just walk into Home Depot and buy one.

 

[87NAT]

The problem is the hole in the turbo. I dont care how big you make it, you still have to coax the exhaust to go through it and the newer turbos flow so well that the exhaust doesnt want to make the turn, just wants to keep spinning that wheel. As such, not enough exhaust is going through your wastegate to make the difference.

If you move it coming off the header, you'll have better results. I think the Tial 38mm is maybe a little small but should work. Thats one reason we use the TurboSmart stuff. It just plain works.

My hole is matched to the DP dimensions and I have never wanted to bring the boost down before...therefore I never realized I had a problem. All this being said if thats the way its going to be I will just keep it tuned to my current boost levels.

Thanks for answering about the air regulator.

 

[pacecarta]

as mentioned you need to allow atmosphere to the top , if the hose is there and the regulator closed youve trapped the air in the top of the gate (gate cant lift to lower boost unless it compresses the air above the gate )

run a hose direct from turbo to the bottom of the wastegate and leave the top port open

if that doesnt work order a lighter spring like an 11 or an 8

after that if still too high the only fix would be a bigger gate as jay mentioned the new turbos need less air to make boost so more air needs to be diverted away and a 38mm gate (especially when run of the puck port) might not cut it when trying to lower the boost to pump gas levels

 

[TR Custom Parts]

Try the lower spring first 7-8 lbs, helped on mine. Ported the crap out of the exhaust hole in the exhaust housing AND the inside of the dp and laid back the entrance to the exhaust port of the housing. Using the Turbonetics air regulator boost controller. Tried their billet one that only goes to the bottom of the wastegate (open loop) but that didn't work too well.

Like Jay said, the newer turbos move a lot of air so the header deal it probably the best way to go. I am running a 6262 bb myself and might eventually go the header route.

 

[87NAT]

I have always read that by removing the top hose you would have irregular boost or fluctuations..but I will try that before doing anything else. That is by far the easiest solution.

Makes sense about the trap air not allowing the diaphragm to rise and raise the valve.

Thanks guys.