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Discussion Starter #1
For the guys who have more fuel or the same amount of fuel what horsepower are you typically maxing 750cc injectors at? 43psi fuel pressure walbro 255lph pump. Mine are at 85% duty cycle in 2nd and top of 3rd. Afrs are 11.8 under full boost.
 

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I tried replying to this thread a couple times, the keyboard on my kitchen computer has a power button just above the backspace button (since been removed).

This isn't an instant answer question.
Lets start at the beginning:
1CC = 1Milli liter
Injectors are rated by flow at 100% duty cycle over 1 minute.

How injectors are fired makes a huge difference in fuel delivery.

Lets look at my 1988 626GT, it runs a walbro 255 pump and adjustable rising rate (1:1) FPR, Neither of these items increase fuel delivery from the injectors but simply make sure to supply enough fuel to the rails.
The car runs a chipped factory ECU and factory injectors, they are rated from 323cc to 347cc (from my research), lets use 325cc for this thread. So the factory fuel system runs 4 X 325cc injectors. I have a very heavy foot but I can't think of a single scenario where the injectors would be at 100% duty cycle for 1 full minute without shifting or redlining 5th gear...
If I could manage to hold 100% duty cycle for 1 minute than the 4 factory injectors would deliver a total of 650cc's of fuel per minute. Why, because the factory injectors are batch fired 2 X 2 (1+3 and 2+4 I believe) therefore with 100% duty demand each injector fires 50% of the time or 30 seconds.
The SDS Extra Injector Controller runs 2X 650CC injectors, it runs off a map sensor and RPM pulse and batch fires the injectors full time so at 100% duty cycle for 1 minute the EIC will deliver the actual injectors rating of fuel 1300cc's.

The total injector rating on the 626GT is 2600cc's and at 100% duty cycle for 1 minute the injectors would deliver 1950cc's of fuel.

You are running 4X 750cc injectors, total injector rating 3000cc's of fuel per minute.
Are you batch firing them 2 X 2 = 1500cc's fuel at 100% duty cycle per minute.
Are the injectors firing indevidually 1, 3, 4, 2 = 750cc's at 100% duty cycle per minute.
 

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Discussion Starter #3
I used to run full sequential fuel injection then an injector driver failed on the ms3x expansion board. Since then I switched back to batch fire on the main ms3 board.
 

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What was the duty cycle in 4th and 5th maintaining the same boost before the clutch started slipping?

Is boost constant in every gear from spool to redline? it should be with that external wastegate, if not then are you connecting to both ports and using the right kind of boost controller? You want one that bleeds of boost pressure without a ball and spring, the controller should be inline before the wastegate actuator connection. the boost bled off by the controller should go to the other port on the tial or tial knock off wastegate with a T bleeding to atmosphere just before the wastegate, this helps stabilize the air bladder in the waste gate and keeps it from spiking or dropping boost at different rpm's in different gears.

So your question is how much power can you generate in 3rd gear with a 1.194 gear ratio, 1275cc's of fuel delivery at wot and an air fuel ratio of 11.8. sounds like you have all the info to use online calculators and get estimates.

Their is a limit to how much fuel can be batch fired (2X2) before fuel begins to puddle, but each car is diferent and for the f2t I don't know what that is, all my eic controllers deliver fuel before the throttle body allowing it to atomize and mix evenly with the air flow. Puddling can result in predetonation under compression or non ignition of the liquid fuel causing that cylinder to burn lean...

To deliver the same amount of fuel sequentially firing the injectors at 85% duty cycle you would need 4 x 1500cc injectors. This thread has made me think of my plans for the 1989mx6 gt running a split second eng. eic controller and 4 injectors, i will have to check the settings in the fuel map and see if I can run them 2x2 or all four injectors fire at once, I want to mount 4X 450cc on the intake manifold before the factory injectors but if they all fire at once than they have to stay on the charge pipe before the TB.

What A/R is your turbine housing? you aren't running a huge turbo, a .48a/r housing will spool at or bellow 3000rpm and hold boost to 6250-6500 rpm, Turbine housing A/R decides the rpm at which the turbo operates (starts and stops breathing), the F2T isn't a high rpm engine even with tuning, cam and standalone mods, turbo A/R is like tire wall size, it applies to the actual size of the turbo and not to it's designation. So like a 205/50series r16 tire will have a side wall of 102.5mm from rim to tread a 325/50series r16 tire will have 162.5mm side wall but doth tires should have identical sidewall deflection resistance. A .48a/r turbine housing on a stage 1 T3 turbine housing and a .48a/r stage 3 T3 turbine housing will move both turbos power band lower in the rpm range, the stage 3 will take longer to spool of the same engine as the stage 1 so turbo seizing is as important as housing A/R ratio's.
 

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Discussion Starter #5
It makes 8psi then the spring opens and it maintains boost the rest of tbe way up the revs. Currently my boost controller is shut off and its just using a boost refrenfe signal off the throttle body on the wastegate actuator. Its a controlled leak style and its worked in the past just cant hold the power currently so its turned down. The turbo has a .63 ar turbine 53mm t3 with a .60 ar 57mm t4 compressor. I havent thought of using both ports on the wastegate it def sounds like it will come in handy when I open the boost controller back up. Thanks for the info! I will look online for hp calculations. Based on the logs I've taken this set up makes boost round 3500 and holds it the rest of the way. When i had the 14psi set up it would load up at the same rpm. Thanks for the input btw!
 
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