maf placement on sr20det

[sileghtychad]

hey everybody, im a lil confused about a to4e turbo and kit i recently purchased, the maf on my sr20 with my gt28 is placed on the intake side, but this new kit wants me to place the maf on the cold pipe??? whats the benefit of that?

[Lev_96_240sx]

The person tuning your car for the new turbo and boost level so you don't blow up your car will be able to answer that for you. If you're thinking about doing it with a AFR controller and a boost controller you're doing it wrong. Talk to Jim Wolfe or a reputable tuning shop. upgrading the turbo isn't as simple as just slapping it on there.

[sileghtychad]

Agreed! but right now im running 10psi with an hks actuator, and i plan to keep it at 10psi with the to4e untill i get a tune, but should i keep the maf on the intake side or should i put it on the cold pipe?

[Lev_96_240sx]

you will eventually need to move the maf, but if you move it now you will mess with the current tune of the car. if it's set to run at 10psi the entire engine performance is based on how much air the maf registers, if you move the maf to cold side you are getting the compressed air passing through it which will screw with every setting and your car will probably not run. 10psi from a t28 is NOT the same as 10psi from a t04, that's only a measure of pressure, a t04 will actually put out a larger volume of air at 10psi than a t28.

[sileghtychad]

i figured the same thing, the maf meters cfm and not psi, but i you could clarify something that ive never understood, ive always thaught that 10psi is simply 10psi, if a small turbo is putting out 10psi and abigger turbo is set at 10psi, whats the diff? i know that there is a difference but why?

[Lev_96_240sx]

Imagine the inner tube from a road bike tire and the inner tube from a semi truck. Let's say we want to inflate each one to 10psi. Which one do you think will take more air to reach that pressure? The semi of course. It's the same concept for turbos. The exhaust side on different turbos varies greatly, that's where you get the size differences and higher capacities. A large turbo has a large exhaust chamber. The wastegate controls when the turbo allows exhaust gases to escape, that is at what pressure. for that chamber to get up to 10psi takes longer on a larger turbo then on a smaller one. Put simply, the wastegate measures the pressure in the exhaust housing of the turbo, not the compressor side.

[sileghtychad]

I UNDERSTAND WHAT YOU SAYING, YOUR PRETTY MUCH EXPLAINING THE LAG DUE TO A LARGER TURBO. BUT WHAT IM REALLY CONFUSED ABOUT IS THIS: IF THE PBR (POINT OF BOOST REFERENCE) FOR THE BOOST gauge IS IN THE INTAKE MANIFOLD AND ITS READING 10PSI WITH MY GT28 AND ITS ALSO READING 10PSI WITH THE T04 WHY WOULD THE TO4 PRODUCE MORE POWER, SO FROM MY UNDERSTANDING, AND IM PROBLY WRONG, BUT IM THINKING THAT AT 10PSI WITH BOTH TURBOS THE ENGINE IS GETTING THE SAME AMOUNT OF AIR WITH BOTH TURBOS, SO WHY DOES THE TO4 PRODUCE MORE POWER?

[Justin35ll]

HE JUST GAVE YOU A PERFECT EXAMPLE. READ IT AGAIN WOW

the bigger turbo is pushing much more cfm then the smaller one even at the same psi

[DuckyD]

Agreed with Justin and Lex.

As far as blow-through MAF, I would talk to your tuner and see what they suggest. I am under the impression that blow-throughs are hit or miss whether they meter air correctly (with problems cause by turbulance).

[Lev_96_240sx]

Look I don't know what else you want me to tell you. You have a larger turbo with a larger outlet, larger hot pipe, etc, this all leads to a higher volume of air being required to bring the pressure up to 10psi. If you try to run the t28 piping on a t04 you are choking the turbo and getting no benefit from it.

What does this all mean? Well you have increased the volume of the air chamber in between the turbo outlet and the throttle body, meaning that it now takes more air to get up to pressure, just like the semi vs road bike inner tube example. So while your boost gauge won't show a difference and the waste gate is set to 10psi, you are getting more cfm or air moving through the system.

Hope that clears it up.