im running 2 t3/t4 turbos on my small block dodge truck. the compressor outlet side is 2.5 inch the piping i have to run to the inter cooler and carb hat is 3 inch. im getting a whopping 1psi at 3 grand. also trying to get the motor and carb tuned. it should build boost before 3 grand shouldnt it? it hangs around 0 psi or vac longer than it should, it hovers in a state of im trying but kinda running bad. at part throttle it will come out of it and build boost. do i need to adjust the pressure regulator? it idles with 6 psi from the electric 115 gph fuel pump. could it be a simple small boost leak? did i have my bov set to low? when i close the throttle you can hear the bov work. i did adjust the bov but havent had a chance to run it again. also im running about 12 degrees advanced static timing. it did run better after i unhooked the vacuum advance from the carb. but im kinda wondering if im getting a lag from the larger pipe than the turbo charge outlet. just trying to narrow it down, while im not running the truck. theres some things im going to look at tomorrow

 

the wide band reads that im not burning lean or rich, its close to where it should be, just not perfect

 

I’d check for exhaust leaks, boost leaks, wastegate

 

Thanks wasnt sure what to check first.

 

Where is your boost gauge plumbed? You may not see boost at 3k unless you're close to wot. You're testing this while driving? Free revving will not get uou the load needed.

 

I'm driving down the road. I haven't gave it wot yet. The boost gauge is ran off the manifold.

 

Its not a transition to 3" that is causing your problems.
I assume this is a blow through?
Do you have a return style fuel system? If so what pump and what regulator?
If your regulator is not boost referenced then thats an issue. As is a vane style pump ala' holley blue.
Are these turbo's internally gated? If so did you have to reclock them?
If internally gated, disconnect the flapper from the actuator rod and see if it will close any further, if so you will need to adjust them. Its really common if you needed to reclock.
If external gate, pull both gates and make sure the fire ring is in them. There is a little round valve seat that seals the gate when its closed. If its missing, then no boost.
I'd also check TDC on the balancer just to make sure the north star hasn't moved.
As said, depending on throttle angle you may not see boost. It depends on load.
What t3-4 turbos? A pair of gt3582's or similair may show a pretty high boost threshold on a not that great small cubic inch small block. So your observations may be normal and expected depending on your parts.

 

Won't built boost until you have a load. Won't build boost if you're leaking exhaust or intake charge. Won't built boost if you aren't firing off your mixture.

 

i have been thinking about ignition. im not sure whats the best ignition to use for my setup.

 

msd 6530. My opinion.

 

No need to do that. Just get it up to speed in high gear then roll into it. It should make positive pressure pretty early on with that tiny turby. my 5.0 with twin T3 would make 10psi by about 2200rpm.

 

Toss up some pictures of your engine bay and turbo plumbing.

 

Sounds like it could be timing related to me. How much total timing? How quick is it all in? What power valve setup?

 

There's your two problems.
1. You need WOT for the turbos to make max boost
2. The pressure in the manifold is Boost minus the pressure drop through the carb. At part throttle there is a lot of pressure drop through the carb.

 

12 deg. Is this base timing with an advance curve? Or is timing locked out.
As everyone says, wot to make boost.

 

ive got it to build boost, i had 5 psi and it was building more but it seemed under powered, the wide band was reading 9, i had moved the timing to be at 0 degrees to help rule out pre detonation with the vacuum advance unhooked. when i have it hooked up it falls on its face. im going to change the distributor, i could adjust the diaphragm on the distributor. when its hooked up it goes way past the timing marks. also im going to change the carb jets. im just happy at this point im building boost even at part throttle early. thanks for the input, pretty sure im heading in the right direction.