Selin Dual Intake and Dual POP History

A little history first……
Way back in the day JWT was the only one making larger turbo bolt on solutions for the Z.
The Single factory MAF has a zero to five volt scale and JWT found that the single MAF voltage happened to correspond to about the same HP. So the 5 volt signal was good for about 500 HP.
The JWT solution was to remove the stock intake TEE and used a single MAF on one side and a dummy MAF on the other side…….this measured half the air going into the engine and by splitting the injector size in half in the chip, the ECU could measure 1000HP.
Because the Z32 has a idle air control system that pulls all the air at idle from the left side of the engine where the MAF was placed, It measured all the air at idle causing a rich condition at idle and low speed.
The JWT fix for this was adding, what they called the low speed drive-ability kit.
What this did was cut the idle air hose with a TEE and run the same size hose to the other side, Because the hose was longer going to the other side this was not perfect and JWT added a small restrictor to the driver side to try and provide a better balance.
Well that all worked, but was not perfect and just bolting them on did not always offer a great idle.
What is interesting and why I bring this up, is because the reason JWT developed the dual pop was because of the electronic limit of the MAF.
The limit was 5 volts and this was about 500 HP.
Because of this electronic limit of the meter being 500HP, that got miss-interpreted and people started saying you do not need a dual pop until over 500HP…….
Well, electronically that was true, but power wise it makes a difference completely stock. We found in testing over 11 years ago that getting rid of the stock TEE and completely separating the two sides of the air intake system made great gains…….The only thing we did not know was if some of the gains were in the tuning of the chip that was required to go to dual pop at that time.
Jim Selin came along and decided to create a better solution…….
The Selin translator does not require a low speed hose and it also does not require a chip change to split the ECU value if your under 500HP. The reason it does not need these extra items is because it still measures all the air, Jim’s translator simply takes any air coming into the engine from either side and adds it together and sends it back to the ECU as one signal just like 1 meter does stock.
The reason dual pops work is that stock, the 2 sides are fighting for air in the tee, both sides are pulling from the same center section causing the turbos to work much harder to suck air.
By completely separating the two sides it makes it much easy for air to get into the turbo and the results speak for themselves.
When going over 500HP the Selin translator can be switched to average and this still measures all the air, but adds both sides and sends exactly half of the total it measures back to the ECU. This setting requires a chip change to cut the injector size in half to allow measuring higher HP up to 1000hp.
Jim came to us with a few customers watching to have us help him perform a test before and after going not from stock, but from a single pop to Jim’s dual pop set up.
This was done while strapped to the dyno and no other changes were made except installing the Selin complete dual intake set up.
The car had 2.5″ exhaust and a JWT pop and JWT chip.
We made sure the car was stable before starting the tests.
We then made 3 pulls to make sure the reading was consistent…..We then added the Selin Elbows, a second MAF with second pop, and the Selin translator…..
We then made 3 more pulls.
I believe Jim only posted one before and one after of the dyno work.
I think showing all of them helps people to see that it was not some trick or strange anomaly.
I will show separate Horsepower charts from the torque charts make it easy to read and include Air fuel ratio and Boost readings.
Again, this was all the same chip and only adding the second pop.



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Comments (3)

  1. What an awesome way to explain this-now I know evenythirg!

  2. Jacob Griffin

    I have been doing research and cant seem to find my answer, if I install the selin dual translator and later decide to upgrade instead of having the injector value cut in half in the ecu(already jwt from previous owner) can I simply double the injector size to 740cc and not adjust ecu? Thanks

  3. You could but its not recommended to do it this way. It may end up a little too lean.

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