280Z28

iTrader: (1)

** NOTE: The example I use here is extreme. I'm using it to clearly demonstrate the concept of my question, not asking whether the specific numbers listed are good ideas. **

Say someone was running a built 408 with an S88 turbo in front of it pushing 20+psi. For normal driving however, they want to be able to turn the boost down to 5psi. The wastegate on the car is fine for the 20+ psi adjustment, but even held all the way open the motor is producing 10psi.

Now say this driver had perfect vision and perfect coordination and was able to back off the throttle quickly and accurately to hold the MAP readings at 5psi (at his "adjusted" WOT).

Would he be causing some sort of damage by doing that? I mean, clearly he's not putting out as much power as he could be. Clearly the turbo's doing some good since he's seeing 5psi. What kind of reliability problems might he be looking at by doing that?

PS: Assume the motor can take 20psi, so don't say the problem would be "he might mess up and spike boost" because the spike wouldn't be damaging.

WIPLSH

There shouldn't be anyproblems at all. I did something like this in my GSX, i would keep the boost low <5 psi going around town, or id try my best. My High boost was 18.5 psi.

im assuming the car is proprly tuned
Also a larger wastegate could be used to lower the boost, if its making 10psi and the WG is wideopen. Larger wastegate and a boost controler that has 2 different boost settings.

280Z28

iTrader: (1)

Larger WG is the obvious real solution, I'm just curious about this from a theoretical standpoint.

Stupid Boost

iTrader: (1)

Go with an S88 and a 50mm powergate from Turbosmart. Then you can run low or high boost without any concerns of spiking.

280Z28

iTrader: (1)

This car and motor doesn't exist, it's purely a theoretical question.

chuntington101

so why not fit say a 5psi spring in a bigger gate?? could you then run 20psi still with a boost controler????

thanks Chris

Stupid Boost

iTrader: (1)

You would need CO2 to blow the gate shut at those pressures. Typically you can double the spring pressure with a boost controller.

bboyferal

iTrader: (9)

Well... Do it anyway!

WIPLSH

lol

then no it won't hurt anything to do what you speak of in this theoretical vehicle

coop5885

iTrader: (2)

the only problem i could see is if you wernt running a speed density tune. it would have your MAF maxed out and then i would imagine would lean out since its not seeing as much of a load as it would WOT. Thats just a guess tho

Smearin

You dont run a MAF with speed density

280Z28

iTrader: (1)

I think you misread him.

Man the BOV would be SCREAMING if you tried this :haha:

coop5885

iTrader: (2)

that raises the question of would the BOV be open, because it needs to see vaccum to open, so if it was in boost then the WG would be the only thing open

280Z28

iTrader: (1)

:hmm: :dunno:

They will also open under [lots of] pressure, but now that I think about it I don't think you'd have that much build up.

WIPLSH

The bov shouldn't open till it sees vacume (negative pressure)in the system.
The WG should stay shut till boost builds (reaches preset level)then open and maintain a constant boost level

280Z28

iTrader: (1)

Well I got my throttle body working with a program I wrote. I plan to use this concept for gear and rpm-based boost control (among other things). The wastegate is a Progate so it's big enough to adjust where I need it as well.