on3 70mm turbo setup spooling strangely

[Mustang Matt]

My b-headed car is together but I'm getting strange boost behavior.

It's setup for 16 psi but it seems like it doesn't hit 16 until 6000 rpm. It's sitting around 10 psi at 5000 for comparison. It hasn't been on the dyno yet, seems like it's making good power but the spooling isn't like other on3 kits my tuner has installed.

We've tried different waste gates and boost controllers and there are no boost leaks.

Could this be caused by cam timing being off terribly?

 

[boosted2000si]

What power is the car making?

What gates have you tried? What springs? What Boost controllers? What or who is setting the controllers?

What turbo is it? How new is it? Is it making any noise? Is it free spin by hand?



Yes it could be caused by your cam timing but why would that be horribly off? The engine wouldnt run that well if it was off that bad...

 

[Modular Racing]

This soundsl like a problem in the boost controller/wastegate, to eliminate the chance of it being the controller or routing remove all lines from the wastegate and drive the car, it should make whatever pressure that the spring is rated to in the wastegate (IE 10psi spring = 10psi Boost)

Good luck, let us know how we can help!

MMR

 

[Mustang Matt]

Talked to my tuner today.

It does the exact same thing on lower boost springs.

Currently has a 38mm wastegate. Not sure on the brand. We've tried 8 and the current 16 psi springs.

Manual boost controller is currently bypassed.

It's about 2 hours from me but I'm going to try to pick it up this weekend and see if I can live with it for now or if I need to begin teardown.

It hasn't been dynoed yet but it "feels" like a 500 hp car but all the power is up top.

I'm going to do compression and leakdown as soon as I get it back.

My gut feeling is that I'm going to find the cam timing off side to side which should be revealed in a compression test.

 

[Mustang Matt]

I drove the car home today. 2 hours. No a/c and no mufflers. ugh.

It's bizare. This car wants to run. From 3k-5k boost builds and it pulls hard. 5500+ generally breaks up.

Going to do a compression and leakdown but everything is pointing to cam timing. I think it just wasn't as obvious NA. Car never felt as powerful as it should have been but I assumed it was the hci intake.

O2 reading are crazy. Tried new O2s and even swapped them and it's almost like one side runs lean and the other side runs rich.

 

[Mustang Matt]

I found the original invoice for my engine.

It never mentions installing the heads on the block or setting cam timing.

 

[adler]

Check for exhaust leaks. I have a on3 kit on my 4 valve with a Master Power 76mm, and had the same problem as you. The turbo took FOREVER to spool to 19psi and 695hp at almost 6500rpm. There are alot of people with the same kit that have had exhaust leaks at the same location on the On3 kits. Mine leaked at the drivers side exhaust manifold ball flange, and the "U" shaped pipe that wraps around the k-member. The pipes do not line up correctly, and causes the leaks. A friend and to cut and lengthen some of the piping for it to line up correctly. I also had a problem with their 2.5 inch V-band clamps leaking. I also switched V-band clamps. I had to slip a socket flange in the pipe that connects to the driver's side exhaust manifold to fix that leak.

 

[Mustang Matt]

We did modify some pipes to make it fit better and we've checked it a dozen times for exhaust leaks. I wish it was an exhaust leak at this point. We've looked for boost leaks too. My tuner made a tool to cap some of the piping with a vacuum line and a boost gauge connected and then hooked an air compressor up to it to see that it held compression. It did.

 

[CobraMac]

Man sorry to hear about the problems...it almost seems like if you had gone with another kit or even a custom build you wouldn't have these problems. To me though it sounds like a wastegate issue. Or if your BOV is no correctly tweaked it might be bleeding boost from there...had that problem with my BOV's at first

 

[Mustang Matt]

I went ahead and ordered a Tial F38 to throw on there. Mine is a tial knockoff but it's cheap enough and easy enough to swap that it's worth a try.

 

[quikcobra]

do you hear a Exhaust leak?

You can check the cam timing but its not always 100% necessary to time the cams.

 

[Mustang Matt]

We've looked everywhere for exhaust leaks and there don't seem to be any.

 

[CPRsm]

Disconnect all the lines from the waste gate. connect a vacuum source to the top of the gate. This will keep it from opening. be very careful though. If this solves your problem, boost is coming in faster, and won't stop. Don't take your eyes off the boost gauge.
What a/r ? If it's the 96, I wouldn't be surprised too much by your spool rpm

 

[red9450]

Disconnect all the lines from the waste gate. connect a vacuum source to the top of the gate. This will keep it from opening. be very careful though. If this solves your problem, boost is coming in faster, and won't stop. Don't take your eyes off the boost gauge.
What a/r ? If it's the 96, I wouldn't be surprised too much by your spool rpm

so you're saying to remove the line from the side of the wg, and plug in a vacuum in to the top of the wg?

 

[Mustang Matt]

70mm, .70ar cold/.68 hot T-4 Flanged

 

[Turbo98]

That turbo should spool pretty fast.

 

[Mustang Matt]

yah, I should make a video of it so you guys can see how slow it spools. I probably won't drive it until I put the new wastegate on.

 

[CPRsm]

so you're saying to remove the line from the side of the wg, and plug in a vacuum in to the top of the wg?

Yes. This is essentially what the boost controller does. Keeps the valve shut until it needs to bleed off boost.

Did you test the gate, make sure the diaphragm isn't leaking. There is a lot of them leaking.

 

[Tims97SVT]

Don't think cam timing is the problem. The motor would probably run rough if it was off side to side.

 

[Mustang Matt]

so you're saying to remove the line from the side of the wg, and plug in a vacuum in to the top of the wg?

What is a good source of vacuum?