1) Your Tuner sounds like an idiot.

2) How this is not a sticky here is beyond me, but this should be step one for ANY turbocharged system, and will easily diagnose 95% of related system issues before you even start the car for the first time. DO A BOOST LEAK TEST.

http://turboboostleaktesters.com/how...ost-leak-test/

 

Thanks Scotty, I spoke with my tuner again this evening and he said that a guy he k knows installed the same kit on a silverado and had the exact same problem. I forgot to mention all the inner cooler piping is full silicon not aluminum. so there are some pinch points and they were seeing on the dyno where the hose was collapsing due to air flow. I am in hopes this is true. i noticed two ares that were a little collapsed just from the install. I am going to get some aluminum and plum the inner cooler side and see how that goes. Would that cause boost to go from 3psi to 1 psi?

 

Scotty everything checks out. I dont have many leaks. took turbos off again and check the waste gate opening at 8psi and working and closing fine. turbos are new and spin just fine. BOV starts opening at 1BAR

 

Your BOV shouldn't start opening with boost. Vacuum opens them, boost holds them closed. You might have a junk BOV.

Also, I'm surprised nobody mentioned those worm clamps you're using on your intercooler piping. Unless those pipes have impressive beads on them, those clamps won't hold much boost before they leak or pop off.

 

Ok. So I'm getting the standard aluminum set up and gonna pipe it. The test we did on the blow off was. We put a radiator hose on the charge side. Closed it down to charge with air compressor. We put 20 psi and it would start to leak on the dump side. We did this ago with a vacuum Guage on the vacuum side and it would open I believe at 5 lbs. So not sure if that was done right but let me know. It didnt seem like much air on the charge side would open it. Considering this is my first turbo deal. I would assume you don't want much charge pressure against the trotted body flapper. During normal boost the flapper is open so pressure in pipe doesn't build up.much it rather flows.

 

I think the problem is likely the function of the waste gates, or the BOV. If the system is functioning correctly there should be enough pressure inside the silicone hose to expand it. I could see it collapsing a little on tip in, when the engine pulls vacuum, and the turbos are not yet spooled up, but my experience has been more of blowing the silicone hoses/couplers off from more boost than the clamps can hold. This is usually on complex couplers like a reducing 90, or such. That's why the best cold sides only use strait couplers,(or V bands) and make all of the bends in the metal tubing. I can't see it collapsing the silicone hose off enough that the turbos won't blow it open, especially if you are able to pull the truck into the 5000+ rpm range. Even those little tiny turbos, should be really pushing some air at that point. It should be blowing up your silicone hoses like a balloon, not collapsing them. You should actually be able to see the silicone hoses from the turbos to the intercooler swell slightly if you watch it on the dyno, as the turbos spool up. If there are any little wrinkles or indentions in the walls you should see them push out and be come hard and strait. (yes I'm talking about the cars hose here).

On the BOV, when set up correctly it works on a pressure differential between the intake manifold, and the pressure in the charge pipe. When cruising and the turbos are spooled up a little, the throttle is mostly closed, and pulling manifold vacuum the BOV will often open a little and leak, because it is being pulled open by the manifold vacuum, and being pushed by the air building up in the charge pipe and intercooler, because the throttle is closed and there isn't any other place for it to go. If you were to goose it from a cruise, as the throttle opens, manifold vacuum drops, and the air pressure drops in the charge pipe as this air transfers from the charge pipe into the intake across the throttle body. There will be no vacuum on the top of the diaphragm pulling it open, and little to no boost yet to push it open. This should slam the BOV shut tight. Upon letting out of it, closing the butterfly, the intake vacuum will spike, and the pressure in the charge pipe will spike, because of the momentum of the turbines. This high vacuum/ high pressure in the charge pipe scenario should open the BOV wide open and in rapid order, to release the air in the charge pipe. Often this can be heard with a large BOV, depending on engine and road noise at the time. If you BOV is not working in this manner then you won't make proper boost. The vacuum/boost source for the BOV, needs to be from behind the throttle body, where as the vacuum/boost source for the waste gates needs to be from before the throttle body. You may know this already, just thought I'd mention it just incase you'd not read that before.

 

Block off the blowoff valve and try again..

 

Thanks Scotty it's definetly a great bit of information. I don't know how to test the bov. The waste gates looks good. I am loosing sleep over this package. To me the chage pipes look very flimsy. So I have 3 4 feet sections of rubber pipe. 90s 45s and pinch points. I am going to put back together and see if I can watch charge pipe while revving. I'll post some pics of the charge pipe side.

 

So block off and see what happens boost wise. Will it hurt the trubos. What's the best way to Guage boost.

 

A lot of the guys here don't use a BOV with an automatic trans. They're even less necessary on turbos with antisurge compressor housings. Just remove it, block off the opening, and see if it will build boost.

 

Yet another issue that will show its face with a simple boost leak test.

 

You test the BOV YET dannyj? I've been curious about using this kit, and so far this is the most info I've been able to find on it.

 

You can ask me anything. So far i got 370rwhp but have a lot of things to fix.

 

Got a bunch of questions for you....
Was the BOV the issue? What other things do you have to fix? You mentioned that you might swap to aluminum cold side plumbing, did you do that? Are you on the factory fuel system still? What octane fuel are you running? How is the fitment compared to the pics on EBay?

 

What are you putting it on

 

I'm planning on putting it on a bone stock '04 Z71 Avalanche with 115k miles.

 

ON my 4x4 The mods i had to do were
1. take brake booster off and beat it in a little
2. 62# injectors five 0 motor sports factory but plug in
3 340lph fuel pump wal bro
4. hp tune and dyno
5. I built an after market wye pipe with no cats for better flow. That was nice
6. bend and tweak ac lines not bad.
7. custom mount inner cooler they sent. but have to do again in grill area
8. Their silicon hoses collapse when you crack it. even though people say they expand.
to much air flow causes a suction effect.

I got 370 rwhp with 6.3 lbs of boost they said the actuators are set at 8psi but got six. So I am installing a boost gauge and boost control. the suburban is better but not what they said. I am also going to turbo blankets on so I can keep the heat down. The inner cooler was not mounted on those dyno runs so i am going to mount a bigger one and up the boost it will put me in the 400rwhp. if you need anythng from me I can make and sell to you if you want. Such as the wye pipe, cold side and inner cooler and mounts when i get mine completed. I can just make another set.

 

I would look elsewhere. There are other kits around that will actually work instead of cause headaches. This kit looks very low quality and cheap construction. Do so searching around you might have to spend a little more but will be well worth it.
Check out. Vs racing, kbracing, on3, cx racing.

 

Nobody is making the twin turbo kit for Tahoe/suburbans. I have an on3 but for silverado. this was one of the only kits available. I agrees it is a cheap kit but it was my first turbo kit ever. just learning

 

I had one of these kits for eval. Just looking at it, I did not feel comfortable putting it on anything. Things like the 90% silicon tube cold side and the fact the the number 3 spark plug is COMPLETELY behind the turbo manifold and you would have to remove the whole hot side from the drivers side to even get to the spark plug was not good at all IMO.

Much much better choices for truck turbo kits out there! I've sold about a half dozen kits to guys who bought On3 kits first to "save" money and wished they hadden't wasted that money and just bought mine first.