safcII help

[GnArKiLl]

need some help tuning my safcII...the set up is.. pte 50 trim, 650's, 2g maf, fmic, rewired walbro 255, AFPR.. now i have not realy messed with an safc befor and i have done some searching on tuners but still could use some help..thanx

[niterydr]

1g or 2g vehicle? What year ecu?

[dedlewamp]

650's are a little large to be running a S-AFC with. Are you just using a stock ECU or are you chipped?

[GnArKiLl]

stock eprom.. and i know you cant realy do anything over 650's on the safc

[iceminion]

Alex over at modern had 1000cc's on his 1G DSM with an safc. He was using E85, but still, 650cc's should be cake for the safc.

my brother runs 550's on a stock 1g ECU with a 2g mas, no adjustments necessary.

[scheides]

Just remember, like mentioned above, the 2G mas will add another offset to your overall formula. 650's are 44% bigger than stock, so you should shoot for about -44% (take out 44% to get back to zero.

The 2G mas scaling is 20% higher than stock, so you need to add 20% more fuel to make up for it.

This brings you back to your initial target of about -24% on the AFC. Now, in practice, because injectors are injectors, you want to keep your idle rpm-area values close or possibly even above zero. Then, swoop down to about -18 as you get to 3000rpms, and then find a happy place (you have a logger, right? ) that is *around* -20 to -24 through the rest of the rev range.

High throttle you will be at roughly -10 to -15 at 2500rpms, gradually going down to -25 at 4000, and then keep a semi-steady value up to redline.

I've had 2G mas (or 2G maf-t) and 650's both my DSM's, and even tunining hughes' laZer w/ 550's we got *vaguely* similar numbers.

The real answer though is: get a logger, or go get a tune from shane

[xveganxcowboyx]

No concern about timing?

[niterydr]

Originally Posted by niterydr

1g or 2g vehicle? What year ecu?

These simple questions are very relevant before anyone should be answering any factors on the tune.

What fuel pressure?

[Shane@DBPerformance]

The bigger the injectors the more likely you are going to have knock/detonation problems at medium airflow because of too much timing from going negative on the SAFC or by putting on a 2G MAS. At high airflow(race gas boost levels) you are less effected by being very negative in the SAFC, because of how far off the top of the timing map you are, and race gas also tolerates a lot more timing. Putting a 2G MAS on a 1G tricks the ECU in exactly the same way going say -18% on the SAFC does. The 2G MAS just reports less Hz to the ECU than the 1G MAS does at the same airflow. Some people are fine with 650-680cc on pump gas with an SAFC, some have knock problems and some don't give a crap or log their timing/knock and run it until it blows up or the compresson is down to nothing.

[GnArKiLl]

i dont have a logger... and i have an adjustable fpr so i can set it to any psi i want... right now the car is just wating for the turbo to get here so im just trying to figure this out

[GnArKiLl]

Originally Posted by niterydr

1g or 2g vehicle? What year ecu?

1g, 93, 93 auto

[xveganxcowboyx]

Awesome, even more correction.

[GnArKiLl]

i am also thinking about going with a 3g maf since i have one sitting here

[asshanson]

Originally Posted by scheides

Just remember, like mentioned above, the 2G mas will add another offset to your overall formula. 650's are 44% bigger than stock, so you should shoot for about -44% (take out 44% to get back to zero.

I believe this is incorrect? While it's true you have to add 44% to get to 650, you don't take out 44% from 650s to get back to 450s. You take out 31%

650 * .69 = 448.5

On my 660s I think I had -32% correction for the low throttle settings.

[GnArKiLl]

ok so just so i can get the car moving again can i just set all the settings to 0 and run my 450's

[Shane@DBPerformance]

1g Automatic ECU runs 390cc injs.

[GnArKiLl]

yes but i am using 450's