is the ARC 2 made by GOD?
11-26-2001, 05:16 PM
#1
Nordschleife Master
Thread Starter
is the ARC 2 made by GOD?
I will be picking up a MAF upgrade by a company called Modernperformance very soon.
this sensor has fuel adj. for WOT and idle.......(same as lindsey's)
i am now being told that this is dangerous because there will be horrible flat rich/lean spots along the fuel curve.
can anybody expand or share expiriences?
Could this be a dangerous move.?
this sensor has fuel adj. for WOT and idle.......(same as lindsey's)
i am now being told that this is dangerous because there will be horrible flat rich/lean spots along the fuel curve.
can anybody expand or share expiriences?
Could this be a dangerous move.?
11-27-2001, 05:41 AM
#2
Race Director
Yes, you will have problems because the computer is still mapped for the stock flow. The adjustments on the MAF just fools the computer into thinking air-flow conditions are other than what they really are for certain RPMs. At a minimum, I would get a set of AutoThority Stg2 chips.
Last June, I installed the Huntley Stg2 ball-bearing turbo and MAF Stg4 kit (ARC2, FPR, ARM1). Got everything bolted and tuned by Huntley's instructions. Ok great, car felt like it had 100 extra horses! But I noticed that the ARM1 air:fuel display wasn't always ideal and scheduled a dyno-tuning session.
Initial run shows 220rhp (20% better than stock) at a way-too-rich 10:1 mid-range mixture (common problem with AutoThority Stg2 chips). By turning down the fuel-pressure and adjusting the ARC2, we got it to a more acceptable 12:1 air:fuel ratio and I picked up 70hp to 290rwhp!!!
BUT (here's the catch), my APE Stg2 chips were programmed for the STOCK turbo and STOCK air-flow meter (see dyno charts posted on the 944 Turbo Upgrades thread). The higher-flow of the MAF kit and flat boost curve of the Stg2 turbo meant that while mid-range flow can be similar to stock, high-end flow is well above what the stock turbo can deliver. However, the APE Stg2 chips was still thinking that I had a stock turbo and was metering fuel for a dropping boost curve. So the result was that I was running way lean (14:1) in the upper RPMs and blew a headgasket (OUCH). It didn't help that the "tuner" calling the shots on the "tuning session" couldn't tell the difference between CV-joints clicking and engine KNOCKING like mad.
So my suggestion would be to do some mild dyno runs after you get that MAF kit installed. Have fuel-pressure adjusted too high to be safe and see if you can get a flat 10:1 fuel-curve across the board. If not, fiddle with the available adjustments. Then when you can get a flat 10:1 fuel-curve, start turning down the fuel-pressure until you get a optimum power-producing 12:1 air:fuel ratio.
If you can't get a flat fuel-curve no matter what you do, then set the adjustments to ZERO and get a dyno-plot with air:fuel readout and then it's time for some custom chips.
That's why if I had it to do all over again, I would've skipped the MAF upgrade and gone straight to MAP speed-density sensing and an aftermarket engine-management system from SDS. Would've been cheaper than MAF + headgasket job and I would have 400rwhp instead of 300.
Last June, I installed the Huntley Stg2 ball-bearing turbo and MAF Stg4 kit (ARC2, FPR, ARM1). Got everything bolted and tuned by Huntley's instructions. Ok great, car felt like it had 100 extra horses! But I noticed that the ARM1 air:fuel display wasn't always ideal and scheduled a dyno-tuning session.
Initial run shows 220rhp (20% better than stock) at a way-too-rich 10:1 mid-range mixture (common problem with AutoThority Stg2 chips). By turning down the fuel-pressure and adjusting the ARC2, we got it to a more acceptable 12:1 air:fuel ratio and I picked up 70hp to 290rwhp!!!
BUT (here's the catch), my APE Stg2 chips were programmed for the STOCK turbo and STOCK air-flow meter (see dyno charts posted on the 944 Turbo Upgrades thread). The higher-flow of the MAF kit and flat boost curve of the Stg2 turbo meant that while mid-range flow can be similar to stock, high-end flow is well above what the stock turbo can deliver. However, the APE Stg2 chips was still thinking that I had a stock turbo and was metering fuel for a dropping boost curve. So the result was that I was running way lean (14:1) in the upper RPMs and blew a headgasket (OUCH). It didn't help that the "tuner" calling the shots on the "tuning session" couldn't tell the difference between CV-joints clicking and engine KNOCKING like mad.
So my suggestion would be to do some mild dyno runs after you get that MAF kit installed. Have fuel-pressure adjusted too high to be safe and see if you can get a flat 10:1 fuel-curve across the board. If not, fiddle with the available adjustments. Then when you can get a flat 10:1 fuel-curve, start turning down the fuel-pressure until you get a optimum power-producing 12:1 air:fuel ratio.
If you can't get a flat fuel-curve no matter what you do, then set the adjustments to ZERO and get a dyno-plot with air:fuel readout and then it's time for some custom chips.
That's why if I had it to do all over again, I would've skipped the MAF upgrade and gone straight to MAP speed-density sensing and an aftermarket engine-management system from SDS. Would've been cheaper than MAF + headgasket job and I would have 400rwhp instead of 300.
