Wastegate ajustment for dummies

[custom8726]

Can someone explain in simple non technical english how to ajust the wastegate on My twins? I have a BD s300 with a s480 W/Race cover, from what I understand my small turbo should idealy make 50% of my total boost. I spent all day screwing around with the wastegate on the s300 and I can not get the 50/50 no matter were I ajust it.. I think something else must be wrong since I can max out the ajustment one way or the other and its only a 2-3lb boost differance. I tried pulling the wastegate hose off and running it and it also only increased the overall boost 3lb's.. According to my gauge my BD is only making around 30lb's give or take a couple LB's.. When I was running the BD as a single with Stock single CP it made over 40lb's According to my logs my converter is not locking untill 70MPH now and my rail pressure is dropping at the tail end of the 1/4.. Could the converter be my problem? I would assume if I am holding rail pressure through 4th I should still see bigger boost #'s untill the rail drops?? I went through the entire system this past weekend cleaning and checking all connections and hoses and clamps for leaks and can not find any.. I picked up a compression tester from Harbor Freight and that is my next step right now to try and figure out why this thing is not making the power/boost it was and should be making.. Any help or suggestions are appreciated, Thanks :hug:

 

[TrentNell]

Can someone explain in simple non technical english how to ajust the wastegate on My twins? I have a BD s300 with a s480 W/Race cover, from what I understand my small turbo should idealy make 50% of my total boost. I spent all day screwing around with the wastegate on the s300 and I can not get the 50/50 no matter were I ajust it.. I think something else must be wrong since I can max out the ajustment one way or the other and its only a 2-3lb boost differance. I tried pulling the wastegate hose off and running it and it also only increased the overall boost 3lb's.. According to my gauge my BD is only making around 30lb's give or take a couple LB's.. When I was running the BD as a single with Stock single CP it made over 40lb's According to my logs my converter is not locking untill 70MPH now and my rail pressure is dropping at the tail end of the 1/4.. Could the converter be my problem? I would assume if I am holding rail pressure through 4th I should still see bigger boost #'s untill the rail drops?? I went through the entire system this past weekend cleaning and checking all connections and hoses and clamps for leaks and can not find any.. I picked up a compression tester from Harbor Freight and that is my next step right now to try and figure out why this thing is not making the power/boost it was and should be making.. Any help or suggestions are appreciated, Thanks :hug:

In simple Terms you have 2 forces that open the waste gate on the S300 ,

1- Is boost going into the diaphram via the boost line and it pushes the diaphram open with what ever force total boost is; pushing the rod down and opening the gate, and works in conjunction with the rod adjustment (twisting in and out of the diaphram assembly to change the "spring" pressure inside the diaphram) .

2- Is the force of drive pressure pushing on the back side of the valves/pucks that the rod hooks too and atach's to the diaphram , if un plugging your boost feed chganges boost very little, drive pressure could be pushing the pucks open , if you have accsess to a dyno you can watch the rod under full load (with the boost feed removed) and see it that is the case , or try and rig something up to "lock" the rod in place , the rod pushes down when it opens the gate .


The next explanation is what happens when the gate opens , it diverts flow around the turbine of the S300 , that will lower the boost it puts out due to not as much exhaust flow driving the tubine , and in turn feeds the secondary the extra exhaust flow driving it harder , I usually loosen the gate all the way then start tightening it, I go as tight as i can with out dropping the amount of boost the second turbo is putting out , that way you are getting the most you can out of both turbo's , it will usually net the lowest EGT's, highest boost, and more HP .

Edit: Also if it was the coverter not locking I would expect to see the S480 be the one short on boostnot the S300. Could cause the higher EGT's you have been seeing, whats the difference when the converter locks on boost and EGT's ?

 

[ChevyDieselLLY]

What are you seeing for max boost? Not sure if that is important remember boost is only a number. You want volume.

 

[custom8726]

Overall boost is between 58 and 62lb's on my Race tune.. Boost does not change much when the converter locks or were I ajust the wastegate too Thank you guys for the insight so far, it's much appreciated :beer

 

[TrentNell]

Overall boost is between 58 and 62lb's on my Race tune.. Boost does not change much when the converter locks or were I ajust the wastegate too Thank you guys for the insight so far, it's much appreciated :beer

So total is 62 psi , what is the secondary making ? 32 ?

 

[maine04max]

I am trying to picture what my gate looks like so I understand how this adjusts . I have never adjusted it sense installing it or the twins .

 

[custom8726]

So total is 62 psi , what is the secondary making ? 32 ?

It's really hard to look at both gauges when WOT but I would say on average on my race tune WOT 58-60PSI overall is about average while the secondary stays around 30PSI consistantly.. I know that is close to the 50/50 I am looking for but when its easier to look at both gauges say at 50% throttle for instance, my secondary will read 6PSI while my overall is 20PSI Should I only be concerned with WOT? Also the truck made closer to 80PSI overall when I first finished the twins/dual fuelers.. IDK what changed but I can not find any boost leaks

 

[custom8726]

I am trying to picture what my gate looks like so I understand how this adjusts . I have never adjusted it sense installing it or the twins .

Me either and while I think its quite simple I just cant wrap my mind around it completly. If and when I figure it out I will gladly show you first hand how to ajust yours since I am completly frusterated trying to figure out mine

 

[custom8726]

I am trying to picture what my gate looks like so I understand how this adjusts . I have never adjusted it sense installing it or the twins .

What is your overall boost on average??

 

[JoshH]

It's really hard to look at both gauges when WOT but I would say on average on my race tune WOT 58-60PSI overall is about average while the secondary stays around 30PSI consistantly.. I know that is close to the 50/50 I am looking for but when its easier to look at both gauges say at 50% throttle for instance, my secondary will read 6PSI while my overall is 20PSI Should I only be concerned with WOT? Also the truck made closer to 80PSI overall when I first finished the twins/dual fuelers.. IDK what changed but I can not find any boost leaks

Yeah, you should only be concerned about it at WOT.

 

[TrentNell]

Yeah, you should only be concerned about it at WOT.

X2 no real way or need to regulate part throttle .

 

[maine04max]

wot boost , I see just over 60 overall and 32-34 on primary . my set of gauges are glow shift electric sensors with recall . that way I can hang the F on and look latter lmao

 

[custom8726]

wot boost , I see just over 60 overall and 32-34 on primary . my set of gauges are glow shift electric sensors with recall . that way I can hang the F on and look latter lmao

Interesting,, I still think I should and was making more then 60lbs of boost when I first put the truck together But since we have similar mods and it sounds like similar boost readings maybe I'm not that far off were I should be?

 

[custom8726]

Yeah, you should only be concerned about it at WOT.

X2 no real way or need to regulate part throttle .

Makes sense, Now I feel dumb for screwing around with the wastegates all day trying to get to 50/50 at half throttle:banghead:

Next Dumb question, Can I turn my DSP-5 down to say LVL 3 and make ajustments to get to the 50/50 balance or Do I need to do it all on my Race tune? If so I need to get some gauages like craig that remembers max boost:thumb: