[rcoe]

So Josh peaked my interst in the smoothboost and I decided to pick one up as I really like the idea of being able to turn down the boost on the fly for street driving.

My D1sc makes about 11.5 at full throttle and on street tires that can be a little too much going through 3rd and 4th, very easy to get sideways.

For those unfamilar SB gives you a wastegate that takes the place of the BOV on the procharger intercooler. Now instead of being operated by engine vac/boost it is controlled by throttle input that can also be adjusted by a control knob. With the knob at max the wastegate operates very similar if not identical to the BOV and max boost is the same. As the control knob is dialed back, max boost is also dialed back, with it set at halfway boost is dialed back to around 2-3psi. Not as much range as I had hoped for because anything less than halfway pretty much keeps the gate wide open. But between halfway and full on I can adjust it to hit pretty much any boost level.

Now for me the best part is being able to have a scramble button that when pushed instantly closes the wastegate giving full boost. With my car I keep the knob set at 2 marks down form max which gives me about 8psi then as the rpms come past 5k mash the button and get full boost and a pretty good kick in the pants. This might be very useful at the dragstrip where with my Nitto drag radials 2nd and 3rd are very tough to keep traction in.

It will also be even more useful next year after I add more fueling and turn the boost up a little more.

Install was pretty easy, wastegate is a direct replacement for the BOV, it is a little longer and was just making contact with the inside of my bumper cover, so I trimmed just a little so it had a bit of space.






Power/ground inside and tapping into the pedal wire at pin #5. Scramble switch just grounded one side and the other to the input on the SB. Running the wires through the firewall was the hardest part. There is also another input on the SB that when triggered will cut all boost, either from a button or an external controller signaling a leanout condition. Also works with your current tune with really no changes.

Not exactly cheap but a well built and does exactly what I was looking for.

[JasonGofast]

This is awesome. I'm pretty set on getting one for a Magnuson 2650 build. I've kept the car at ~900whp because anymore seemed to be too much for the street and reliability. Now I can push for as much as I want with the idea of turning the boost down for the street and less stress on the engine.

Only issue I'd imagine is the blower will still be spinning at max speed and generating some heat.

[rcoe]

Originally Posted by JasonGofast

Only issue I'd imagine is the blower will still be spinning at max speed and generating some heat.

Yes still spinning the same just dumping all the pressure out the wastegate. Not sure if just dumping it thru the wastegate would generate less heat as it is not pushing against something but just dumping into open air.

[Gunkk]

Originally Posted by rcoe

Yes still spinning the same just dumping all the pressure out the wastegate. Not sure if just dumping it thru the wastegate would generate less heat as it is not pushing against something but just dumping into open air.

Yes.

With adiabatic compression, heat is a direct function of pressure-change. So if with the waste gate open you have less delta-P then you will have less delta-T.

[JasonGofast]

Originally Posted by Gunkk

Yes.

With adiabatic compression, heat is a direct function of pressure-change. So if with the waste gate open you have less delta-P then you will have less delta-T.

Would the same apply to a PD blower dumping the air directly into the engine through the bypass? Even if it's spinning pretty fast but generating low pressure would it be much cooler?

[Joshinator99]

Originally Posted by rcoe

So Josh peaked my interst in the smoothboost and I decided to pick one up as I really like the idea of being able to turn down the boost on the fly for street driving.

My D1sc makes about 11.5 at full throttle and on street tires that can be a little too much going through 3rd and 4th, very easy to get sideways.

Had a funny feeling guys in here were going to love the SB. Glad you got it worked out on your Procharger. The potential uses are huge between streetability, boost cut via safety activation, etc…looking forward to using it for boost-by-gear in the near future too (believe @ZL1Atlanta is already doing this).

[18.2SS.1LE]

That is a nice option to have. Can you flip it over so the actuator isn't visible behind the grille?

[rcoe]

Originally Posted by 18.2SS.1LE

That is a nice option to have. Can you flip it over so the actuator isn't visible behind the grille?

Nope would have hit the belly panel.

[cjperformance]

Does it drop boost across the whole rpm range, or only limit peak boost?

[JasonGofast]

Originally Posted by cjperformance

Does it drop boost across the whole rpm range, or only limit peak boost?

Since he says controlled by throttle input I’d imagine peak boost is limited then scaled down from there based on throttle.

[cjperformance]

I was hoping it could keep midrange boost, but limit peak.

[Joshinator99]

Originally Posted by cjperformance

Does it drop boost across the whole rpm range, or only limit peak boost?

Originally Posted by JasonGofast

Since he says controlled by throttle input I’d imagine peak boost is limited then scaled down from there based on throttle.

Originally Posted by cjperformance

I was hoping it could keep midrange boost, but limit peak.

It limits the peak boost.

[rcoe]

Originally Posted by cjperformance

I was hoping it could keep midrange boost, but limit peak.

The valve is based on throttle position alone, along with where the control knob is set.

Once you go full throttle you will get max boost for the level you have it set. With it set to max it drives almost identical to before, with it turned down still the same but you just loose boost/power. But with the centri you do not really loose any power below 3k, but where the boost would normally hit it is just scaled back according to where it is set. I found this really nice especially for 2nd and 3rd where I have had real issues with traction above 3500rpm.

The scramble button gives max available boost immediately which is fun. I have a log where I had boost turned down and mashed it around 4500 in 4th, where the boost had been on it's typical upward climb it jumped straight up on the graph. Felt like hitting the nitrous back in the day.

Nice having a quick street car with good manners and with the press of a button adding big power.

[JasonGofast]

Originally Posted by rcoe

The valve is based on throttle position alone, along with where the control knob is set.

Nice having a quick street car with good manners and with the press of a button adding big power.

It's really epic! I was considering turbos before this to have a car with good street manners, but this resolves the issue. It actually seems better than turbos because of the more instantaneous power of superchargers especially without the need of antilag or brake boosting.

Gives me hope for my car which I personally felt was too fast to be fun on the street.