Basic SAFC on KADET question, stock injectors?

[Fred Allen Burge]

Unbelievably basic question about the SAFC, embarassed that I don't already know this honestly but anyway.

With stock injectors how much boost can you run generally on the KA with the SAFC II? I never see anyone use stock injectors but instead most always upgrade to larger injectors then cut them back a certain amount w/ the SAFC. Wondering if you can keep the stockers open longer then how much boost can I safely run?

thanks,
Fred

[yoni_nismo]

check out ka-t.org they have alot of info about ka turbo setups

[BoostedCoupe]

5psi would be the max on 270cc injectors(ka Injectors). I would just get some 370cc(sr injectors). that away you could run 7pounds easily. and not have to worry about stressing the ka injectors.

[97KATURBOSILVIA]

When they are talking about using larger injectors they are only pulling fuel at low rpms to recreate stock settings since at low rpms you have no boost. DO NOT RUN A KA-T ON STOCK INJECTORS you can really only run like 4-5lbs of boost and even then your lean and that really doesnt make any power at that level. Sr injectors are your next step at a minimum

[Fred Allen Burge]

Ok thanks for the head up guys.

My buddy was saying it can go +/-50% meaning that it can make your stock injectors stay open 50% longer or 50% shorter and should then be able to do around 10psi. I didn't believe him so that's why I asked here.

Can anybody lay down the law here and give me the math behind why he is wrong about the SAFC so I can fully shut him down tomorrow at the office?

[97KATURBOSILVIA]

YOU CAN GO +/- 50% with in the range of the maf. but when the maf is maxed out and its pushing the ka injectors at there duty cycle they are still only 270cc. The only way you can stretch this is by upping duty cycle from factory setting, and for that matter just buy bigger injectors for the sake of doing it right.

[UNISA JECS]

Originally Posted by Fred Allen Burge

Ok thanks for the head up guys.

My buddy was saying it can go +/-50% meaning that it can make your stock injectors stay open 50% longer or 50% shorter and should then be able to do around 10psi. I didn't believe him so that's why I asked here.

Can anybody lay down the law here and give me the math behind why he is wrong about the SAFC so I can fully shut him down tomorrow at the office?

You will never make any injector flow more than what its rated with a SAFC alone period.

[Fred Allen Burge]

Originally Posted by UNISA JECS

You will never make any injector flow more than what its rated with a SAFC alone period.

All right guys, thanks for your patience w/ me on this one (I'll be using larger injectors w/my setup BTW, I'm just trying to better understand how the AFC works).

I understand that the stock injectors will only flow a certain amount when fully open (270cc).

So your saying basically that by the time I'm at 4-5 psi on the stock injectors they ARE fully open and can do no more, right?

And how on the SAFC do you know when you've reached this point, is it by MAF voltage or do I need a wideband to read the AF directly to be sure?

thanks again,
Fred

[UNISA JECS]

For all intended purposes you should only use the SAFC for idling purpuses and leave everything else alone (at ZERO) becasue when you mess with %ages on the SAFC you indirectly mess with timing in a bad way, and if you running a stock ECU back of the base timing about 6-7 degrees if you want your KA24DE(T) to last and or just use minus .875 timing retard per psi boost.

.875 x 7psi = 6.1* retard
20*base - 6* = 14* new base for 7psi