PSI vs BHP and what waste gate spring.

[jaffaz32]

I'm just wondering what color waste gate i will need to install.

I have an TIAL wastegate.

The engine will be a 3.4 stroker, apparently these make more power with less boost but wouldn't know yet.

What sort of psi would i be running for different bhp levels?

Is there a chart or anyone know in 50hp increments from say 450hp vs the psi?

Also, lets say we put in a spring to allow for more psi how would this affect me when on the lowest boost setting? can i go lower than the waste gate spring? i'm guessing not. As mentioned in my other post i will have 12 boost settings. would be nice if they were spread across from 400 - 600 rather than all within a 500-600 range.

I would love to drive around on 400 for reliability and having more than enough for fun but then when i'm feeling naughty or sitting next to something where i need more power turn it up. I don't tend on going all out all of the time. Can only afford to do this build once haha.

 

[foundry3]

What sort of psi would i be running for different bhp levels?
Is there a chart or anyone know in 50hp increments from say 450hp vs the psi?

Take a look at your turbo's compressor map, that will tell you how many lbs/min the turbo flows at various pressures. A rounded calc of lbs/min flow to hp is a power of 10, although this isn't completely accurate, it is ball park close. For example, in the middle of your compressor map you see 58 lb/min, follow that to the corresponding axis on the chart and you will see the pressure needed for that flow, in this case for the sake of explanation lets say it is 2 bars (~29 psi) of boost pressure, then you can estimate that at 29psi you will be in the 580 whp range. There are many many other variables to get the actual final number, but for spit balling and needs estimation the above process will work.


Also, lets say we put in a spring to allow for more psi how would this affect me when on the lowest boost setting? can i go lower than the waste gate spring? i'm guessing not. As mentioned in my other post i will have 12 boost settings. would be nice if they were spread across from 400 - 600 rather than all within a 500-600 range.

Assuming you are setup to use a boost control solenoid. You cant ever go lower than the spring pressure resistance. It is common knowledge that you can double and sometimes close to triple the rated boost pressure when using a boost control solenoid. There should be more than enough window with a smaller spring to span a few hundred horsepower.

I would love to drive around on 400 for reliability and having more than enough for fun but then when i'm feeling naughty or sitting next to something where i need more power turn it up. I don't tend on going all out all of the time. Can only afford to do this build once haha.

Most aftermarket ECU's allow for the setting of various target boost levels, via an external switch so this should certainly be achievable by any reputable tuner.

Hopefully the above remarks are helpful. Feel free to PM for further assistance.

 

[jaffaz32]

What sort of psi would i be running for different bhp levels?
Is there a chart or anyone know in 50hp increments from say 450hp vs the psi?

Take a look at your turbo's compressor map, that will tell you how many lbs/min the turbo flows at various pressures. A rounded calc of lbs/min flow to hp is a power of 10, although this isn't completely accurate, it is ball park close. For example, in the middle of your compressor map you see 58 lb/min, follow that to the corresponding axis on the chart and you will see the pressure needed for that flow, in this case for the sake of explanation lets say it is 2 bars (~29 psi) of boost pressure, then you can estimate that at 29psi you will be in the 580 whp range. There are many many other variables to get the actual final number, but for spit balling and needs estimation the above process will work.


Also, lets say we put in a spring to allow for more psi how would this affect me when on the lowest boost setting? can i go lower than the waste gate spring? i'm guessing not. As mentioned in my other post i will have 12 boost settings. would be nice if they were spread across from 400 - 600 rather than all within a 500-600 range.

Assuming you are setup to use a boost control solenoid. You cant ever go lower than the spring pressure resistance. It is common knowledge that you can double and sometimes close to triple the rated boost pressure when using a boost control solenoid. There should be more than enough window with a smaller spring to span a few hundred horsepower.

I would love to drive around on 400 for reliability and having more than enough for fun but then when i'm feeling naughty or sitting next to something where i need more power turn it up. I don't tend on going all out all of the time. Can only afford to do this build once haha.

Most aftermarket ECU's allow for the setting of various target boost levels, via an external switch so this should certainly be achievable by any reputable tuner.

Hopefully the above remarks are helpful. Feel free to PM for further assistance.

Awesome thank you.

So i can possibly leave the spring in there i have currently got installed and see if it will allow me to run enough boost for the desired bhp.

Thanks.