Boost question

[RON]

Does anyone here get Max boost in 2nd? I can't. I get 4.5 lbs max...5+ in 3-5th. I have 5.5lb pulley, but Max I get is around 5.2Lbs on the VDO gauge I just installed.

[RON]

Think this may answer my question...it's about a turbo car, but I think it applies to SC cars as well? They say Turbos are "Load" dependent and SC cars are RPM dependent...but I'm pretty sure our SC is load related as well. If it was RPM, then reving the car in neutral would produce boost that's RPM dependent.... which it doesn't (very little).

http://www.mazda-speed.com/forum2/index.php?topic=18637.0;wap2

It's more about engine loading than time in gear.

Turbo's build higher boost the more loaded the engine is.

In lower gears your torque is multiplied by the transmission, so there is less load per revolution on the engine. In higher gears each engine revolution has to do more work. This causes the turbo to output more and more air while the engine is spinning more slowly, resulting in a higher boost pressure.

[1gSE]

don't quote me on this, but i remember this came up a while ago and someone said something along the lines of it gradually making more boost in later gears because of traction issues

[chaneytsai]

I think boost is liner by RPM if actuator is not connected to vacuum source. With actuator working, it opens bypass valve to release boost when not in full load. That's why you don't see any boost in P or N. Keep in mind, EBC cuts boost in first gear too.

You can try to disconnect actuator vacuum hose and see what happen. By doing this you are boost all the time so be careful for lean condition. Castro has tried this but he has URD MAP box.

Here is his post
http://www.solaraguy.com/viewtopic.php?t=45275

[RON]

I think boost is liner by RPM if actuator is not connected to vacuum source. With actuator working, it opens bypass valve to release boost when not in full load. That's why you don't see any boost in P or N. Keep in mind, EBC cuts boost in first gear too.

You can try to disconnect actuator vacuum hose and see what happen. By doing this you are boost all the time so be careful for lean condition. Castro has tried this but he has URD MAP box.

Here is his post
http://www.solaraguy.com/viewtopic.php?t=45275

Yes..that's the key. It becomes load dependent because of the BYPASS VALVE. For example, If you're COASTING down a hill with light throttle in 3rd at 4000 RPM,
there's no load and the bypass valve isn't shut...so no boost. I think in second, there just isn't enough load to fully shut the valve as it would in say 5th at 3000 RPM. I can easily get Max boost in 4th or 5th by flooring it
at 3000 RPM!

[jetbtkng]

have you bypassed the boost bottle ron, so you get instant boost, just wondering................

[RON]

have you bypassed the boost bottle ron, so you get instant boost, just wondering................

??..Not sure what you mean...the By Pass Valve? I get instant boost in all gears, it's just that I don't MAX in second (or third most of the time). I wouldn't modify the By Pass Valve, since I don't want boost in off load/low load conditions.

[RON]

Ok ....turns out I can JUUUUUST BARELY hit Max boost (5Lbs +) in second right at red line when the rev limiter kicks in. Doesn't always happen though. It's VERY easy to get Max in 4/5th and MUCH lower in the RPM range too. So, load does make a big difference.

[CASTRO]

I think boost is liner by RPM if actuator is not connected to vacuum source. With actuator working, it opens bypass valve to release boost when not in full load. That's why you don't see any boost in P or N. Keep in mind, EBC cuts boost in first gear too.

You can try to disconnect actuator vacuum hose and see what happen. By doing this you are boost all the time so be careful for lean condition. Castro has tried this but he has URD MAP box.

Here is his post
http://www.solaraguy.com/viewtopic.php?t=45275

Still running it DD with no line attached to the actuator and all is well. I think what helps is the URD box to sense boost and go into open loop faster. Def more power everwhere in the RPM range.

Somethings I've noticed:
-There is still vacuum but likes to stay close to 0 as soon as you give it a little bit of throttle.
-Drivability seems better and gas consumption hasnt really changed. At times it seems to be higher than before.