CS Turbo Not Hitting 20 PSI Boost Target

[achulz]

I'm not sure if it's intentional, after all this is the second map revision that I have received. But in the tune it says a 20 PSI boost target, but at WOT I'm only hitting 16 at max, and tonight while drag and roll racing I only hit like 14 PSI.

I've provided a 4th gear WOT pull on this tune. If someone can tell me what's going on and if I need to check anything out in the engine bay that would be really helpful. MAF and MAP are already calibrated. I don't see it being the BPV leaking as it was holding 21 PSI no problem on my stock K04.

Mod list:

-Corksport Turbo
-Corksport Stage II SRI + TIP
-Corksport HPFP Internals
-Corksport 3-port EBCS
-Corksport 3.5 bar MAP
-3" SS Catless DP
-3" Straight Pipe

Google Docs link to WOT datalog:

https://docs.google.com/spreadsheets...it?usp=sharing

[achulz]

So I've checked the BCS lines, none of them blew off or anything. The IC piping looks good, everything is tight. So I'm not sure what's going on.

[5doorsoffury]

Talk to your tuner....

[achulz]

Originally Posted by 5doorsoffury Talk to your tuner....

I talked to him, he said according to the math at 40% WGDC it should hit 20 PSI, but he said the math doesn't always check out, each car is different.

I just gotta keep my expectation lower until the final end tune it seems. I was really expecting 20 PSI but like he said the turbo may just be lazy until you really increase the WGDC.

Much more reassuring, I thought I had a boost leak or a broken BPV or something.

[Solarsurge]

Lazy turbo? Hmm. I'm no engineer, but based on what I remember about MAF math I think your MAF g/s at 100° at sea level would be like 600 CFM. The CS Stage 2 intake is a 2.5" intake with a 2.6" MAF, which only supports like 400 CFM. Are you sure your tuner didn't pull the MAF cal for the CS Power Series 3" intake?

Edit: On a side note, you really should be running a 3" or larger intake with that turbo for exactly that reason.

[achulz]

Originally Posted by Solarsurge Lazy turbo? Hmm. I'm no engineer, but based on what I remember about MAF math I think your MAF g/s at 100° at sea level would be like 600 CFM. The CS Stage 2 intake is a 2.5" intake with a 2.6" MAF, which only supports like 400 CFM. Are you sure your tuner didn't pull the MAF cal for the CS Power Series 3" intake? Edit: On a side note, you really should be running a 3" or larger intake with that turbo for exactly that reason.

I sent him a datalog for MAF calibration, so I assume it's calibrated as he's no longer asking for it when he sends me revisions.

Could you explain to me what exactly a larger intake means? Does it prevent the MAF from being maxed out and not being able to read any higher or what?

Edit: I kind of understand. The MAF voltage represents the g/s of air, I'm already 4.7-4.8V at 300g/s, from what I've gathered the max is 5V. So my intake will only read up to 345g/s, I'm sure it will be pulling a lot more air at 25 PSI than at the 16 PSI I did the pull at.

So would a 3" intake be ideal? What's the largest I can go without having to get a smaller battery or ECU relocation?

[Solarsurge]

Originally Posted by achulz I sent him a datalog for MAF calibration, so I assume it's calibrated as he's no longer asking for it when he sends me revisions. Could you explain to me what exactly a larger intake means? Does it prevent the MAF from being maxed out and not being able to read any higher or what?

Pipes of different diameters flow differently. The MAF sensor is reading the velocity of the air (voltage), but it doesn't know the volume of that air because it doesn't know how big the pipe is. The ECU calculates air mass in grams per second based on MAF voltage, intake air temp, barometric pressure, and the MAF calibration for volume. If the tuner calibrates the MAF for a 3" MAF when there's really a 2.6" MAF, the ECU thinks there's more air mass than there actually is and things don't work properly.

You're not maxed out on your intake because your voltage isn't maxed, but you're pretty darn close and your turbo isn't even hitting boost targets. Like I said, I'm no engineer. Your tuner might have it calibrated right and my math may be totally wrong. I'm simply observing that 100° air is FAR less dense than cooler air, so 300 GRAMS (mass, not volume) per second at that temperature seems like an awful heck of a LOT for that little tube. That figure comes directly off your MAF calibration.

[Solarsurge]

See image. This is what I'm talking about. That's like 575 CFM.

[achulz]

Originally Posted by Solarsurge Pipes of different diameters flow differently. The MAF sensor is reading the velocity of the air (voltage), but it doesn't know the volume of that air because it doesn't know how big the pipe is. The ECU calculates air mass in grams per second based on MAF voltage, intake air temp, barometric pressure, and the MAF calibration for volume. If the tuner calibrates the MAF for a 3" MAF when there's really a 2.6" MAF, the ECU thinks there's more air mass than there actually is and things don't work properly. You're not maxed out on your intake because your voltage isn't maxed, but you're pretty darn close and your turbo isn't even hitting boost targets. Like I said, I'm no engineer. Your tuner might have it calibrated right and my math may be totally wrong. I'm simply observing that 100° air is FAR less dense than cooler air, so 300 GRAMS (mass, not volume) per second at that temperature seems like an awful heck of a LOT for that little tube. That figure comes directly off your MAF calibration.

I'll have to see what he thinks. I'm sure he knows what he's doing, Will has tuned a lot of Mazdaspeeds. If he tells me I'm limited by the intake, then I'll get a new intake.
It may seem like a lot simply because the turbo flows a lot better than the K04.

[Solarsurge]

Originally Posted by achulz I'll have to see what he thinks. I'm sure he knows what he's doing, Will has tuned a lot of Mazdaspeeds. If he tells me I'm limited by the intake, then I'll get a new intake. It may seem like a lot simply because the turbo flows a lot better than the K04.

Don't forget you're also putting stress on the turbo by having a small inlet pipe. Just imagine your turbo is you, and the air is a Wendy's Frosty. How would you feel if I gave you a little ass straw to suck up the frosty? Not very happy, am I right?

[achulz]

Originally Posted by Solarsurge Don't forget you're also putting stress on the turbo by having a small inlet pipe. Just imagine your turbo is you, and the air is a Wendy's Frosty. How would you feel if I gave you a little ass straw to suck up the frosty? Not very happy, am I right?

I don't think it's that drastic, the inlet pipe is still larger than the actual turbo inlet. Either way a new intake is in order.

[Fstrnyou]

Ya, you could add a 10" intake, but the turbo inlet is still tiny.

The intake you choose would depend on what your goals are. I went with a 3.5", the only downside is making it fit. The CS turbo can outflow a 3" but will NEVER outflow a 3.5", so I'll never have to buy another intake until I change turbos.

[achulz]

Originally Posted by Fstrnyou Ya, you could add a 10" intake, but the turbo inlet is still tiny. The intake you choose would depend on what your goals are. I went with a 3.5", the only downside is making it fit. The CS turbo can outflow a 3" but will NEVER outflow a 3.5", so I'll never have to buy another intake until I change turbos.

I'm not even reaching the maximum efficiency of the CS turbo at 400WHP. I think Corksport has a guy that went to 440WHP on the CS turbo, most I've seen from it.

I've been talking to a guy on FB, should be able to get CXRacing piping + TR6 + HTP 3.5" for like $450 if I play my cards right.

Side note, my tuner sent me the third map revision, it hits 18.5 PSI now so I'm for sure not leaking boost or anything. He just really cranked up the WGDC, at close to redline I'm sitting at 80% WGDC. Should be able to increase the WGDC overhead once I go FMIC since it will flow a lot better.

[Fstrnyou]

I had to pull a lot if WGDC when I switched to a better TMIC. An FMIC will have the same effect.

[sharksinspace]

Will is a great tuner. I'm sure he'd tell you to get a larger intake if you asked him. I was pulling about 4.8v with 3" intake on my CS in cool weather, so i swapped it out for a 3.5". ain't gonna outflow that with this turbo on a stock block. definitely something you should look into.