School me on wastegates!

Starting to sound like a boost leak. You got a stock intercooler?
 
roachie said:
If you close off the boost elbow and tighten the rod you will then have drive pressue opening the gate. Is the S400 gated?
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the s400 is not gated. just the 62/14.

can you explain in detail what you mean by your first sentance? closing the boost elbow nets from 60 to 65psi. how does changing the rod length effect any of this?

thank you!


i don't know how it could be "overfueled"... i should have enough air and mods to support it. there is a real clear idea in my head that after the amount of smoke WOT that there needs more air... the back that i can make no more than 60psi boost on WOT regardless of boost elbow open or close says i got an air issue. i hear of people with the same turbos making well over 80psi.
 
if you close the elbow of the boost pressure is no longer effecting the wastegate. The gate now has a sping holding it shut. Tightening the rod would increase tension on the spring and its ability to stay shut.

Now the only thing that will open the gate is drive pressure. Unless its to tight then it wont open at all. So the boost will increase.

I think you need a bigger primary. Or an external gate.

No intercooler leak then, how about the plastic cold pipe from the intercooler?
 
I would check for leaks on both sides, charge and exh. No leaks I would start thinking about ext wg or larger exh housing on the 62. The s400 flows alot of air but the exhaust has to get to it before it will spin up good.
 
i'm going to try to adjust the wastegate rod and see if that does anything. wastegate is opening about 32-35psi right now. i would like to see that about 20psi. maybe the bigger charger making more air will help the overall boost.... no?
 
Crank the waste gate tighter you do not want the waste gate to open at 20 psi. I have mine open up at around 40 psi. If the spring is weak in the WG then the drive pressure will force the gate open and lower your over all boost. I would fab up a set up to pressurize the intake system from a air comperssor. Use a air regualtor and you can increase pressure to find leaks and adjust WG. Make sure you do this with the Water meth system (if you have it) diabled other wise you might pump the enigine full of water.


Malcolm
 
Scott, you should have plenty enough air to make more than 700 hp. Somebody correct me if im wrong but I believe Lenny maid somewhere around 950 hp with his CR on fuel only. He was running a 62 over an s480.
 
Knowing the boost in the cold pipe and drive pressure will help determine what is going on. The boost elbow will only do so much. Drive pressure will open the spring without air if it is high enough. I would bet you need to go with a 80mm wheel in the S400 to see much of a gain. 693hp on Lenny's dyno with 40" tires is pretty go for a S400 because with smaller tires you'd be over 700hp easily. You have to remember that the motor might still be making the power even though you are losing it through the drivetrain due to rotating weight. A standard S400 is done at or below 750hp uncorrected on a CR truck.
 
4.8's though????

3.3's do 760 plus with 37's!!!!!!!!

Nathan's right...primary must be too small and the wastegate is wacko.
 
Idaho CTD said:
Knowing the boost in the cold pipe and drive pressure will help determine what is going on. The boost elbow will only do so much. Drive pressure will open the spring without air if it is high enough. I would bet you need to go with a 80mm wheel in the S400 to see much of a gain. 693hp on Lenny's dyno with 40" tires is pretty go for a S400 because with smaller tires you'd be over 700hp easily. You have to remember that the motor might still be making the power even though you are losing it through the drivetrain due to rotating weight. A standard S400 is done at or below 750hp uncorrected on a CR truck.
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agreed you have alot of rolling weight there....
 
thank you nathan et all!

i'm going to play with the waste rod and see if that helps at all. i didn't realize that the wastegate could open without air.

sounds like my first step after getting the boost gauge hooked up is to tighten the rod a bit (put more tension on the wastegate from opening) and getting the wastegate to open about 40psi or alittle more.
 
if i can't get this to work... probably going to have to upgrade the bottom turbo. we'll see what everything looks like after getting boost / dp readings.
 
some of you guys were onto something with the input. i think we got more tuning to do but i want to know your guys recommendations.

malcom and cliff seem to be very inline with what needs to take place and our findings today. what say you guys? and thank you!!!!

i don't disagree with you and thanks for the thoughts on the matter. i think we got some progress today. byron and i tightened the wastegate rod 8 rotations. it did turn out the drivepressure was opening the wastegate whenever it wanted to. it had little tension on the wastegate rod. we also got the bottom turbo gauge on.

with the boost bolt wide open and loose wastegate:
i was seeing 59 psi overall.


with the boost bolt still open and the wastegate rod tightened:
WOT - 67psi overall and bottom turbo 30psi

30psi overall and bottom turbo is 10
20psi overall and bottom turbo is 5



curious to hear everyones thoughts and what they think i can run my plane jane s400 at. i can play with the boost bolt now if recommended.

many of you are on the right path and thank you for the info trying to help!
 
That's pretty good! I am still trying to tune my twins. I am getting about 55 to 60 total and only 20 lbs max out of my primary. I was told to set my waist gate lower on the secondary to drive the primary harder. Any thoughts? This is a 62/71/.8 over an S480.
 
I have question. Did you buy the kit or was the top turbo bought and then the kit. I believe they use diff. WG for the twins setups. I know HTT wanted me to send them the top turbo to replace the WG. Just a thought.
 
I found my truck dyno'd better with the top gate opening at 20 and wide open 35 to the bottom turbo, peak boost on # 2 only 58 psi. If I closed the top gate I see 74 psi but less power due to restricting of the exaust flow. The idea is flow as much air as possible, get the top gate open and work the bottom turbo harder. Just my $0.02.
 
cbtoyz said:
That's pretty good! I am still trying to tune my twins. I am getting about 55 to 60 total and only 20 lbs max out of my primary. I was told to set my waist gate lower on the secondary to drive the primary harder. Any thoughts? This is a 62/71/.8 over an S480.
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You should see alot more boost out of that big girl... I seel 30 + out of mine... You should have a 2 to 1 ratio at higher boost numbers... for the most part when i hit 60+ psi on the top turbo the bottom one is right at 30+ psi... this is at higher peaking boost numbers driving around town the numbers aren't quite the 2 to 1 ratio. but they're close:rockwoot:

tuning twins can be frustrating as hell... I have blown three intercooler boots smashed the chit out of air filter to the point it looks like waffle!!:bang:hehe:
 
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