What works better? I need some ideas

[86BGN]

Using a needle valve as a restriction between the compressor and the waste gate?

OR

Using a needle valve as a bleeder between the waste gate and the compressor?

Will either spike or be erratic in some way? I am not worried about spool up, only stable boost. Just trying to figure out who has had good luck with what. I am currently running a RJC valve, stock adjustable waste gate actuator with a TA-49 turbo and a THDP. With the stock turbo the boost was right on the money 22psi through all gears, now with the TA-49 I am struggling to even get a consistent 17-18psi and it gets lower with each gear. It just goes all over the place....

Thanks for any help or ideas

 

[turbocody]

hey, thats my old turbo!! i sold it to ttafreak and he decided he did not want the tuning headache......i dont blam him.lol anyway, i think the problem is with the actuator, puck not sealing or the wastegate is trash.....try just hooking a line straight from the wastegate to the compressor and see if it's better, it will spool slow but it should give you stable boost. do that and tell me what it does. HTH btw.....thats a strong running turbo, i went 7.46@91 in humid air with a stock longblock!

 

[ijames]

Even if you use a needle valve to replace the fixed orifice in the stock y fitting, you will still need to have one leg venting to atmosphere and the other connected to the wastegate. That vent is going to have to have some kind of restrictor, either a solenoid or a fixed orifice. Then, the more boost you want to run the more you will be closing down the needle valve and thus the less flow into the wastegate and so I think it would be more and more prone to boost spikes as you raise the boost. Just my morning pre-Diet Coke thoughts .

 

[86BGN]

I just do not understand why the stock turbo was fine? Could it be a restriction with the stock intercooler, since the TA-49 flows more volume?

 

[86BGN]

Even if you use a needle valve to replace the fixed orifice in the stock y fitting, you will still need to have one leg venting to atmosphere and the other connected to the wastegate. That vent is going to have to have some kind of restrictor, either a solenoid or a fixed orifice. Then, the more boost you want to run the more you will be closing down the needle valve and thus the less flow into the wastegate and so I think it would be more and more prone to boost spikes as you raise the boost. Just my morning pre-Diet Coke thoughts .

So you think that it would be more accurate to use the valve as a bleeder and not a restriction?

Thanks

 

[2QUIK6]

I think you need to check the WG puck alignment to the WG hole on the exhaust housing.

 

[86BGN]

I think you need to check the WG puck alignment to the WG hole on the exhaust housing.

Thanks for the reply, what if the puck hole was ported too much? How would I correct that? I have read allot about guys not able to keep the boost from creeping up and then they port it. I don't have a creep problem just consistency and holding boost......

 

[2QUIK6]

Thanks for the reply, what if the puck hole was ported too much? How would I correct that? I have read allot about guys not able to keep the boost from creeping up and then they port it. I don't have a creep problem just consistency and holding boost......

What type of DP do you have?
If its THDP or other aftermarket DP, chances are it has a 1-1/8 to 1-3/8 puck in it which should be plenty big for a TA49, but may not line up as all DPs are created unequal and off-center...
If its the stocker, then you very well may have too big of WG hole in the exhaust port if it was ported....either get a new DP, or a new exhaust housing if it does not match up.

To check to see if the puck aligns, remove the DP, coat the puck with a thin layer of grease...
Bolt the DP back up being very careful to keep the puck/arm in the open position (tape it up is best)....once the DP is on, untape the puck arm and close it manually a few times, then tape it back open.
Remove the DP , keeping the puck open, and look at the grease print on the exhaust housing to make sure it has good coverage of the WG hole.

 

[86BGN]

It is a Terry Houston

 

[ijames]

If you've put any miles on it at all you can usually see a black ring on the puck so it's easy to tell if it is sealing. Just take off the wastegate rod, pull the four socket head cap screws holding the THDP to the turbo, and pull the dp away from the turbo so you can see the puck and the turbo flange where the puck seats. Yes, I think it would be much easier to control boost using a needle valve as a bleeder than as the restrictor, but I really like the stock setup with the solenoid valve as the bleeder. The problem with a needle valve bleeder is that you have no idea how much the valve is open and no idea how many psi boost a small change in valve setting equals. Does the puck move freely when the wastegate actuator rod is off? Shouldn't be able to feel any resistance at all. Did you also change chips when you got the new turbo? Maybe the new tune is too rich and the egt's are now much lower than before, killing the boost? If you connect the wastegate "tuner style", with a hose directly from the compressor to the wastegate, and set the rod about 2-3 turns tighter than where it just slips on the puck elbow, you should get 12-14 psi boost and it should be rock steady after the initial spoolup. That would eliminate the stock solenoid and y and hoses as the source of the problem (the solenoid could be going bad; that gives erratic boost).

 

[86BGN]

Thanks everyone, I appreciate the help and will look over everything. I didn’t think about simply moving the waste gate lever and checking for smooth operation. Maybe it is getting hung up. Any other advice on different boost control set ups would be welcome