Boostaholic

iTrader: (4)

I have not been posting for a while and now I am considering finishing what I started.


I have a 408 twin turbo setup that has two problems, here is the important information about this setup.
408 iron block
twin mp t70s on forward facing headers
downpipes dumping out the front side of the car drivers side
tial vband wastegates
tial vband 50mm bov
griffin intercooler
BigStuff3
twin A1000 fuel pumps
Aeromotive pressure reference regulator, Aeromotive rails
60psi base fuel pressure
unknown custom ported heads, adjustable roller rockers
approx scr 8:1
electric water pump, only belt accessory is the alternator


Problem 1
I can't seem to get it to go past 9psi of boost.

We have checked the following
Cold side piping can be pressurized to 40psi with a air compressor and old pressure, we did find a small leak in a weld with this method but corrected it.

Hot side piping has a perfect seal with the heads and turbos

Wastegates are staying closed, we have created blockoff plates that we can vband where the gates go to make sure they are not opening.

Problem 2
It seems like the timing is getting off under high rpm load and eventually causing the car to shut down mid pass, we thought this to be the pickup wheel vibrating or some such thing.



If anyone has recommendations about this I am open to suggestions on how to trouble shoot them, these problems have plagued me to the point where I would probably sell the car for my 7k payoff and walk away but right now I happen to have enough cash to do anything I need to fix it, so if there is a problem that I can fix or things I can try now is the last chance for this car and me.


The only thought that I have left is the heads jacked up or the lifters are not working right and I'm getting floating valves where I get no compression under high rpm load and no boost is being built

Silver_TransAm

iTrader: (2)

What a/r are the turbos .96?
What valve springs?

4SFEDZ

iTrader: (6)

so you tested the cold side, but what about the intake? if you had a bad intake leak that would cause it not to build much boost. look for a vacuum leak!

Boostaholic

iTrader: (4)

Yes .96 and I believe they were comp 921 -- they came with a TREX package and I put a toned down cam in there with much less lift.

Boostaholic

iTrader: (4)

We have all ports in the intake accounted for and it is making a good seal.

Just FYI the car jumps up to 7psi really fast and as the RPM increases it creeps up to 8 or 9 but it won't go past. So making a little boost happens really fast.

Silver_TransAm

iTrader: (2)

.96 seems a little big to me. Especially if you block the wastegates and that still all it made. I would think .68 would be better, but I'm no expert.

Boostaholic

iTrader: (4)

no there is something wrong with it, this used to work a long time ago when I first started the project it would pop open the gates on 9psi of boost right away