If I have a set boost pressure let's say 13psi, by getting a 13psi spring for an external Wategate (tial) would it be better running a vac line straight to the wastegate other than trying to play around with a boost controller? I have a blitz type S digital boost controller and I hate all the complexity.

 

That depends on the setup. But if the gate is sufficient enough and over boost is kept to a minimum, then I'd go with just running one source line from the compressor housing to the lower/side port one the gate.

-J

 

controlling boost with only a wastegate spring will hurt spool (in comparison to using a boost controller) because the valve will open earlier than it needs to.

 

yes but at that low boost. a controller isnt going to make a huge difference anyway

 

In my opinion it will. when I was a kid I turbocharged my moms 1 lt Seat. it was making 45ps and using a T25 I got 136ps

Before using a boost control I got 0.5 bar and 0.75 in 1st and 2nd gear. All the spool up felt very lazy

then I got one of the older Greedy units and I could see 1.3- 1.5 bar in all gears

After a while I used the same Greedy on my first proper car , I mitsubishi GTO 3.0lt V6 twin Turbo . with only an Exhaust , filter and boost Control I saw 376ps. The car was originaly doing 0.7bar. The coost was set at a mild 0.8 but because it spooled up so quickly it felt like I had an extra 50ps.

Finally on my RX7 with the new profec B spec 2 if you get it set right it make a huge difference

What I mean with my experience over the years is that with boost controls is that you might get it right at first or strugle a bit but if you get it right IT DOES MAKE MASSIVE DIFFERENCE

 

Mazda first introduced electronic boost control on series 5 FC engines. They did back-to-back testing to show the improvement in spool and torque:





the arrow points to the hashed line. it shows the inflection point in the boost curve when no EBC is used. At this point the wastegate valve cracks open and boost increases at a slower rate. In contrast a boost controller can keep the valve closed longer.