groove66

can you guys do a boost leak check. Maybe leaking from the intake manifold seam where it was taken apart. just a thought

Bramage

I just did a bunch of goolging, and the most common reason for a break up is a boost leak. The advice: Pressure check the entire system including Air to Air inter-cooler. Some of the other forums I read said it is very, very common to find leaks you knew you didn't have.. until you found them. Good luck!! I still have HIGH HOPES!

RAWE55

Craig, you said you made a pull on 12lb springs a couple pages ago with no issues brotha. Id start by looking into the reasons why the 17lb springs are causing heartache. If the springs are opening the actuator early you will lose boost down the wastegate. Are the turbos running internal or external waste gate diaphragms? Internal wastegates will overpower the actuator springs and the power curve will look like yours at high rpm. Especially with cars clocking 500+hp.. A good quality bigger external waste gate will help control boost levels and level out the power curve, it will also ensure you don't overload the actuator springs. the boost controller works in as much the same way by controlling the amount of vaccum the wastegate sees. But I suspect hardware failure with the 17lb springs. The way it's climbing you should be seeing 650+ whp at 6500rpm. What does the exhaust manifolds look like on each side? There may also be turbulence at high rpm? I got my fingers crossed brother. Your almost there, hang in!

Sir-Boost-a-Lot

iTrader: (1)

Swap the heads for a pair with some nice port and polish work done. You'll pick up power everywhere while dropping backpressure simultaneously. That's a band-aid way to get some more power out of a MAP sensor with a fixed range, but it's a win/win band-aid (except for the $$)

Good luck with the breaking up at RPM issue though.. I know that's frustrating.
It's just a car though, keep at it and don't let it beat you dude.

StarvingArtist

We're all pullin for ya!

chawkins2001

This is the latest findings, damaging news to say the least.

The problem now is the 38mm waste gates are too small because it is causing high egts, building up immense cylinder pressure and spark blow out at higher than 11lbs. Anything over 11lbs and it rears its head.

We are talking to IPS today to send these back and get bigger units. We have not asked them for anything, so I feel they need to step up and provide us with 44mm or 46mm waste gates.

That means the car has to come off the dyno, pull the turbos off, pull the down pipes off and remove the puny 38mm critters. New down pipes have to be made by BIP to fit the bigger waste gates.

I sure hope IPS steps up and provides these things.

99lightning

man turbos are killer but wish you would slapped that weistec on and gave it hell.

chawkins2001

You hit the nail on the head bro, see my post above

rockthemullet

I've held a single 38mm to 600whp... If anything the lower the boost, the more control those gates have to do because you're flowing more air through the turbo and less air through the gates at higher pressures. The general rule is small gates for high boost control, big gates for low boost control. Are the two banks operating independently of one another? As in, one exhaust manifold to one gate to one turbo. If so, one bank could be malfunctioning and it would erratic pressures.

Nevertheless, this is a MAP car. Even boost leaks or reversion through one of the turbos would not cause a breakup because the sensor is reading the actual air within the manifold/intake ports.

blackbenzz

Truth

chawkins2001

Yes sir, one exhaust manifold to one gate to one turbo.

Joncl

Sucks that you are going through this bro. Get a whipple, make crazy power and call it a day

rockthemullet

Do you guys have a thermal gauge at the shop? If so, check the temps on each exhaust manifold during a pull and see if they vary. Also check temps on the wastegate discharge tubes both at the 12psi, consistent level and the 17psi, erratic level.

Also, if available weld a bung on each and set up a pressure gauge to read the actual backpressure. If the pressure gauge is not heat rated, run the line through a bin of water to try and cool the air before it hits the gauge. Your readings won't be true, but they will be comparable from one side to the other

whipplem104

Someone correct me if I am wrong but my understanding is if you are getting to high of exhaust back pressure at higher boost levels the exhaust side of the turbo is too small. The waste gates should be closed more at higher boost and less flow through them and more through the turbo. If you were getting boost creep that you could not clamp down on with the waste gates by opening them more then the waste gate would be to small.
You should put some ports in to check exhaust back pressure regardless.
Are you gapping the plugs?

chawkins2001

We are getting boost creep brotha, we really noticed it yesterday when we turned up the wick.

typhoon43

Wastegate placement can affect boost creep a ton as well.
Just spitballing here man. I've been in your shoes. I ran a 76mm wheel in my truck and a 44mm wastegate worked like a champ. Stepped up to an 80mm wheel and it crept like a b*tch. I had my gate welded up in a decent configuration though, so I knew I had just maxed the gate. Stepped up to a 52mm and life was good up to 25 pounds (of course, then the motor went lol!). Where are yours on this chart?

chawkins2001

here you go brotha:

typhoon43

Need to see how angles are INTO the wastegate off the headers to be honest. Again, it may be nothing, but I'm just trying to look for what I can.

Worth the wait

I feel ya bro...been there done that.
What a freakin nightmare. Doubt IPS will step up, but you never know.
GL!

chawkins2001

can you tell from this pic:

whipplem104

Are you running through stock manifolds?

chawkins2001

yes sir.

whipplem104

I would start there. I think you are hitting the choke on the stock exhaust manifolds. Look up restrictors and air going supersonic. The problem is that once you reach the flow limitations of the cfm no more air can go through. You will end up with very high back pressure in the exhaust. Most likely you would see a 10-15 psi increase almost instantly. Right after the choke you will see a pressure drop. I think you said you were able to run through at 11 psi. Try 12 psi and then 13 psi, etc. What you should see is that at some point you hit the choke at a higher rpm. Then when you increase boost and therefore flow you will hit the choke at an earlier rpm. So according to your dyno you are hitting at 4500 rpm at 17lbs. At 15lbs or 14 lbs you would hit a little higher in the rpm range. At 13 even higher. If it does not change at all then it is a different problem but I am betting it will.

Need4Speed

that's a beast I just fell upon this thread.

chawkins2001

that does make sense brotha, the only thing I am scratching my head about on your post is that the TT CLS in Jersey also ran the stock manifolds. He was also running 44mm waste gates.

tomorrow we are putting a bung in the exhaust and measuring back pressure. We are also stepping the spring down to a 8lber, and going to increase boost with the controller.

44mm waste gates are on there way. I don't know how much difference going from a 13lb spring to a 8lb spring will make and manipulating boost via the controller.