Upgrade Injectors Install. S1 and S4 or S2 and S3?
 

Hi,

I'm trying to figure out the best place to install the two higher flow injectors that I have, so I can have proper fuel support for boost.

I was told that the secondary injector ports is the best place for adding 2 higher flow injectors, but there is a difference between the 1&4 and 2&3 secondary ports.

The 2&3 (Middle) secondary ports only allow fuel once a secondary port or valve opens. And the 1&4 secondary ports allow fuel to flow to the rotors directly, without the need for a secondary valve to open.

Can someone clarify this for me please.. I heard that some tuners prefer installing them in the middle (2&3), but some prefer the 1&4 locations because there's less chance for failure, due to not relying on another part to function properly, such as a secondary valve that needs to open before it allows fuel from the 3&4 injectors..

Thanks,
Mark

This is correct.

https://www.rx8club.com/showpost.php...0&postcount=16

So why do people put their larger injectors on the inside, if the inside 2 injectors only open intermittently during operation. Thanks,
Mark

You've got to move away from calling the injectors inside or outside its confusing
https://www.rx8club.com/series-i-tech-garage-22/fuel-injector-info-150432/

I'm not sure I understand what you are asking:

4 Port model:
There are only 4 injectors, The P1's and Secondaries.
The secondary fuel injectors can be blocked by the Secondary Shutter Valve if it gets stuck closed. Thus causing a lean condition.

In the 4 port model the only reasons why I think people would put their larger injectors in the Secondary position is because they don't know any better.
Larger injectors can also make finer adjust tougher to do ... aka getting a good idle might be harder with larger injectors in the P1 position.

6 port model
Most people upgrade all the injectors. However the largest injectors are typically in the P2 position (not available on the 4 port model).
The P2 position is not blocked by a valve and will deliver fuel hi load and WOT situations.

FWIW I'm running yellow/yellow/uncapped yellow

That is expressed by most people in the following format P1's/Secondary/P2's

If you read that link I posted it will give you the CC value.

Now there is a tonne of controversy about uncapped Yellow injectors.
But most people will agree they flow somewhere between 550cc and 800cc