Twins tunning help!! Please!!

9

96strokerwg

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Sep 27, 2008
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well after some hard work i got the twins installed, but it runs like crap. To start i tried messing with the wastegate i adjusted it both ways and it didnt seem to hel[ either way i went. The truck is pretty laggy when i really get on it i can hit maybe 20 or so psi of boost I have a gauge in the cold pipe and it wont even move till the overall boost is about 15 or so then it goes along with the over all boost. What can i try doing any advice would be awsome!!!
 
For starters set the wastegate on your top charger so the linkage just starts to get loose with about 25-28psi of regulated air on the actuator. Then look for leaks in your piping.
 
RonA said:
For starters set the wastegate on your top charger so the linkage just starts to get loose with about 25-28psi of regulated air on the actuator. Then look for leaks in your piping.
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How do i do this what can i use to set it at that exactly?
 
96strokerwg said:
How do i do this what can i use to set it at that exactly?
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A regulated air source to hook to the actuator. Hook it to the actuator and slowly raise the pressure while holding the linkage. Once you see where it starts to just get slightly loose, adjust the arm accordingly. Shorten the rod to raise the pressure, lengthen to lower it.
 
I have been running the he at around 20 lbs. and it just didn't feel right. I tightened the spring up to 28 to 30 lbs. and it made it alot more responsive. I'm thinking about bumping the he up to around 35 just to see what it does. I tow alot with this truck and looking for the best response with a trailer. I'm thinking a 20 it just wasn't building enough volume to light the 3b but I'm not sure.
 
gwhammy said:
I have been running the he at around 20 lbs. and it just didn't feel right. I tightened the spring up to 28 to 30 lbs. and it made it alot more responsive. I'm thinking about bumping the he up to around 35 just to see what it does. I tow alot with this truck and looking for the best response with a trailer. I'm thinking a 20 it just wasn't building enough volume to light the 3b but I'm not sure.
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I have my top charger set to get loose at 34psi. I'm running a 64/71/16ss and it seems to like it at 34. My 62/14 liked being set a bit lower. The 28-30 suggestion should run well enough to take it out of the "things that might be causing a problem" catagory. If it is still a dog, it's probably a boost leak.
Don't forget that when you set it this way it will actually open earlier when running due to drive pressure pushing up on the pucks.
 
Well i tried setting the gate around 25 to start and that did help, The truck doestn feel quite like a dog anymore the power is very smooth and doesnt just hit like before the twins but the highest boost i have seen so far is about 30-35 with about 15-20 on the big turbo. Do you think the wastegate still needs to be tighter? Also i have an adjustable boost elbow should i try tightening it a bit?
 
If tightening it up helped, tighten it up some more. 15-20 off the primary at 30-35 overall is good. Sounds like you probably have a leaker.
 
Hows your egts and smoke out the pipe? Maybe if there low it could be that you need more fuel!!!!!
 
Well i set the wastegate on the 62 to start to open around 35 psi (i just used some air and pressured up the wastegate to set it at 25) But i cant seem to even make 35 psi of total boost it seems that the total boost will be at about 15-20 psi when i can notice by the boost gauge in the cold pipe that the s475 is just starting to light. And it will hit maybe 10-15, with overall at about 30-35 psi. by this time i have blacked out the entire street and my egts are way up there.. Soemthing isnt quite right. Any help would be awsome.
 
I used a pvc end cap with a schrader valve in it and put it in the intercooler pipe that connects to the intake horn
 
This is why I went with an external wastegate. I disabled the wastegate on the top turbo and control everything with one dial. When I first installed mine the boost gauge was hitting like 70 or 80 psi but like yours it didn't run well. I added a backpressure gauge and one between the turbos and found out that the wastegate wasn't opening soon enough and the top turbo was doing almost all the work with over 100psi of backpressure. I set the gate to open earlier to allow the s400 to do more work and it was night and day difference. Backpressure is equal to boost until 70psi (after that it's higher). If boost is around 60 the bottom turbo is doing around 25 psi, before the change it would barely do 10 with the top charger screaming. Check for leaks between the turbos first.
 
Well i found a few boost leaks and the truck runs so much better now... It was leaking at the intake manifold, and at one of the boots. I think i still need to tune the wastegate a little bit more though. How much boost are you guys running total that have similar set ups? also does any one have an in cab video of twins with similar setup just so i can compare.. Thanks for all The help guys!!!
 
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