So I put together a b20vtec and put a turbonetics turbo, 38mm tial wastegate ect.. Went to get it tuned last weekend and on the dyno the wastegate has a 14psi spring, and it opens at 14psi, but as soon as it opens the boost drops to 9psi and stays at 9 the whole time the wastegate is open, shouldn't it regulate the boost to stay at 14psi even with it open? We put a boost controller on to see if that would help at all, set the boost to 17psi, when we hit 17psi the wastegate opens as it should be then the boost drops back off to 9-10 psi as wastegate is open. I don't think this is normal, the tuner thinks its a bad manifold design but I believe it to be the wastegate having issues?

 

It holds at the target pressure..once it goes below 14psi the spring is supposed to close the valve in the Watergate. I would lean more toards wastegate/spring or even boost leaks then the manifold itself


where is your boost reference?

also what manifold? Which turbo? What motor?

the more information you give us the better we can help

 

manifold i bought used, unknown brand, turbo is a Turbonetics 57 trim, 63ar, motor is a b20b with a b16 head. Boost reference is straight from the turbo. Could the greddy type rs bov be causing issues as well? It was set to a soft setting, i was wondering if when wastegate was opening at 14psi if the pressure differential was causing the bov to open some?

 

What is the manifold design?

boost reference should be at the intake manifold not the turbo, there can be pressure losses along the intercooler and piping so it may read higher at the turbo compared to what is actually happening at the intake manifold.


a quick search found that bov could be to soft and cause this issue aswell

 

Ok thanks for the help, should i just plug the nipple at the turbo then and run the wastegate reference from the intake manifold?

 

Yes.

Also take an air compressor and boost your wastegate to verify it opens and shuts at the proper times

while your at it use it to boost leak test to see if anything is leaking at 14 psi

 

Here is a picture of the manifold

 

Does it gradually fall as rpm raises or sudden drop of boost ?

 

drops pretty fast to 9 psi, its alamaost like thebwastegate is opening all the way up and no closing fast enough to sustain 14psi.

 

Those manifolds are notorious for having problems controlling boost. Look where the wastegate placement is, the exhaust has to make a 120 degree turn to exit out of the wastegate. My advice would be to get a new manifold with a better wastegate placement, plus those manifolds are also know for cracking unless it has been braced. I would get a ramhorn manifold or a cast iron manifold with the wastegate placement in the middle part of the manifold. Don't get a mini ram manifold, you will have oil return issues since the turbo sits so low.

 

Typically those manifolds boost creep rather then lose boost. As far as cracking really depends on who made the manifold if its an ebay version then yes they crack mini rams made with good materials not so much.
Is that Genuine Tial or knockoff? If its a knockoff I would not trust it at all, if its genuine I almost wouldnt even bother testing it as it looks new. From your description about "not closing fast enough" sounds like a knockoff, a genuine Tial would never do this...but you need to test its operation at this point

double check your vband connection is tight looks to be on the looser side in this pic The dumptube portion looks extremely loose...which wouldnt cause this issue but would still be an exaust leak, just dont over tighten, Also looks like you are using Intake manifold studs on the exhaust side Make sure everything is tight, Personally I use OEM studs and OEM exaust nuts. Make sure those are nice and snug aswell
I also recommend getting a 4 port Boost controller to utilize the top port
But again I stand by my previous post about testing operation of wastegate, and boost leak test. Plenty of information on youtube about how to do this all you need is an air compressor. If you need further assistance I will be happy to help

Below is a picture of how tight my Tial vband clamp is, for reference only do not overtighten

 

I think you have a massive exhaust leak pre-turbo. Cracked/broke manifold, loosened turbo to manifold bolts etc...

 

Thanks guys its going to warm up a little this weekend and I will double check everything.

 

Are you sure youre not using a 9lbs spring that spikes to 14 ?

 

That would totally explain it wouldnt it. I bet your right.

 

the wastegate supposedly has a 14psi spring, im going to hook a regulator up this weekend and test and see where its actually opening. What doesnt make since though is even with a boost controller, it would open later but still drop to 9-10 psi. guess we will know more this weekend. I did however check all the manifold bolts and was able to tighten everyone of them. I appreciate all the help from you guys and I will keep pecking away at it. I will keep everyone posted.

 

Did you see any carbon buildup blowout

 

You sure it still has the fire ring? Pretty common for people to forget about it

 

ok guys put together a regulator ,wastegate has a 14psi spring, so along with finding bov set very loose, exhaust manifold bolts not very tight, i found the the plugs on the wastegate was leaking some as well. I sealed them up and ill test again shortly.