Maxing out injectors

[twenty5psi]

I'm currently running 660's at 95 % duty and I have a SBR g50 running at 23 psi..I had a question..Would running 850's cause my timing to go all out of wack?..I'm tuning with a maft and a safc..I also have a aeromotive afpr that I did not hook up yet and i have a 255hp..I just don't want to buy 750's and then need to sell them if I go bigger down the road again..Thanks for the help in advance..
chris

 

[twenty5psi]

20k plus members and no one can help me out?..

 

[anconover]

850's will be a total whore to tune with just a maft/s-afc, basically next to not possible. Turn up your base fuel pressure, and lean out the s-afc a little to try and bring the IDC down.

 

[steve]

Correcting in the ECU would work better than using the MAFT. The 850's are too large for just SAFC to correct. That way your timing won't be all messed up.

Steve

 

[Boiler2]

850's will be a total whore to tune with just a maft/s-afc, basically next to not possible. Turn up your base fuel pressure, and lean out the s-afc a little to try and bring the IDC down.

This is exactly what I have done for 1.5 years now (on 550's though). As long as your fuel system and fuel pump can handle the added pressure, you are good.

 

[twenty5psi]

Thanks guy's..I think I'll just buy 750's and if I ever max those (prob not anytime soon) I'll just upgrade..

 

[anconover]

750's are going to be pushing it as well honestly. But itll be 'do-able'.

 

[awd4g63]

www.dsmchips.com

I'd get a chip and set your AFC and MAFT at their zero settings. Then just fine tune with the AFC.

Matt (dsmtrance) has 1000cc injectors with his PTE 60-1/MAFT/AFC combo and his car runs phenomenal with them. No idle problems, no bogging, nothing that would suggest injectors that large. Even with the 272's he has, the car still holds great idle at 850 rpms.

I would definitely call them up and invest in a chip. Best 115 bucks you can spend

 

[anconover]

Best 115$ if you already have an e-prom ECU remember.

 

[NOSLO2PT0]

I'm currently running 660's at 95 % duty and I have a SBR g50 running at 23 psi..I had a question..Would running 850's cause my timing to go all out of wack?..I'm tuning with a maft and a safc..I also have a aeromotive afpr that I did not hook up yet and i have a 255hp..I just don't want to buy 750's and then need to sell them if I go bigger down the road again..Thanks for the help in advance..
chris

Hook up the AFPR, and turn your base fuel pressure up a tad. I was running 45psi base pressure, with a Supra pump on my 660's. I was at 25psi on pump gas on my 50 trim, while seeing a max of 94% IDC. I was using the exact same devices you are, MAFT and AFC. MAFT was set for a base of 600cc injectors, and AFC was around -5%.

A keydiver would help you out regardless, even if you kept the 660's. Those injectors are enough to get you into the lo lo 11's, high 10's.

 

[twenty5psi]

I think I'll hook up my afpr and play with the fuel pressure and settings to see what I can do..Thanks again for the help

 

[twenty5psi]

I had another question for someone who can help me out..I just took out my avcr which let me see my IDC and I don't think I can view it from the pocketlogger (i looked) and I can't find it on the safc to view either..I bumped up my fuel pressure to 43 psi and I'm currently running 25-26 psi on pump gas with 1-2 counts of knock in 3rd and my timing is good around 20-21* advanced..Is there a way to still read IDC or convert it from pulse width to read by any chance?..

 

[Quasimondo]

IDC = (rpm*ipw)/1200

Injector duty cycle calculator