I was talking to my friend today about my build up, and I mentioned that I was going to use a Apexi VAFC II to tune my H22. He tells me that I need to use a fuel pressure regulator with the VAFC if I want to be able to adjust the Air/Fuel ratio. Is this true? Can someone shed some light on this? Thanks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dand39 &raquo;</TD></TR><TR><TD CLASS="quote">He tells me that I need to use a fuel pressure regulator with the VAFC if I want to be able to adjust the Air/Fuel ratio.</TD></TR></TABLE>

The VAFC 2 itself has an ability to adjust the AFR, that is why you get it right? I guess you are talking about adjustible FPR, you don't need one. When you dyno tune your VAFC 2, they will tune your AFR by adjusting your VAFC. Adjustible FPR is useless if your set up is for NA, even I heard people run turbo with stock FPR. I 'm having AEM FPR with VAFC 2, AEM FPR does nothing. VAFC will do all the work.

 

imagine a V-AFC had one setting for all rpms and all cam profiles. so +5% is +5% everywhere in the map...

that's a fpr.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xbn83 &raquo;</TD></TR><TR><TD CLASS="quote">

The VAFC 2 itself has an ability to adjust the AFR, that is why you get it right? I guess you are talking about adjustible FPR, you don't need one. When you dyno tune your VAFC 2, they will tune your AFR by adjusting your VAFC.</TD></TR></TABLE>

it would still benifet him to have a FPR. the VAFC isnt adjusting the PRESSURE that the fuel is sent at, only the ammount of fuel. a combination of both a regulator and the VAFC would be benificial.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xbn83 &raquo;</TD></TR><TR><TD CLASS="quote">Adjustible FPR is useless if your set up is for NA, even I heard people run turbo with stock FPR. I 'm having AEM FPR with VAFC 2, AEM FPR does nothing. VAFC will do all the work.</TD></TR></TABLE>


you sir are an idiot. a FPR is never useless when talking about tuning. saying the AEM FPR does nothing is wrong. mine works great. please stop talking.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Shakes &raquo;</TD></TR><TR><TD CLASS="quote">you sir are an idiot. a FPR is never useless when talking about tuning. saying the AEM FPR does nothing is wrong. mine works great. please stop talking.
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You 're an idiot. Read it carefully fool!!! Like satan_srv said, fpr raises or lowers the whole fuel curve only, not at individual rpm. If you have VAFC already, you don't need adjustible FPR, VAFC will fine tune the fuel curve.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xbn83 &raquo;</TD></TR><TR><TD CLASS="quote">

You 're an idiot. Read it carefully fool!!! Like satan_srv said, fpr raises or lowers the whole fuel curve only, not at individual rpm. If you have VAFC already, you don't need adjustible FPR, VAFC will fine tune the fuel curve.

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go tune a car and then tell me that. yes it does adjust the entire curve that you are correct about. but having both is quite benificial. there is only so much that you can or would want to do electronically.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Shakes &raquo;</TD></TR><TR><TD CLASS="quote">

go tune a car and then tell me that. yes it does adjust the entire curve that you are correct about. but having both is quite benificial. there is only so much that you can or would want to do electronically.</TD></TR></TABLE>

Let say at 36 psi, need to make +15 at 5000 rpm to richen the fuel. If the fuel pressure is increased to 40 psi, the adjustment will be smaller, +8 with same result. The adj FPR will help only if the adjustments you make are out of range (use the highest or lowest settings on Vafc and still don't have correct tuning). My Vafc 2 was dyno-tuned with stock FPR fine. Like I said, adj FPR helps only if you can't make large adjustments (exceed highest and lowest points on VAFC) with stock FPR. Otherwise you benefit nothing.

 

Does anyone know what the FPR should be set at? I know stock is around 40-47 psi but I have an I/H/E and test pipe.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xbn83 &raquo;</TD></TR><TR><TD CLASS="quote">

Let say at 36 psi, need to make +15 at 5000 rpm to richen the fuel. If the fuel pressure is increased to 40 psi, the adjustment will be smaller, +8 with same result. The adj FPR will help only if the adjustments you make are out of range (use the highest or lowest settings on Vafc and still don't have correct tuning). My Vafc 2 was dyno-tuned with stock FPR fine. Like I said, adj FPR helps only if you can't make large adjustments (exceed highest and lowest points on VAFC) with stock FPR. Otherwise you benefit nothing.</TD></TR></TABLE>

go to a dyno and see how much fuel you can actually add with an afc alone. you will then realize it doesn't help you add much fuel at all. and then you will realize why you need an fpr along with an afc for better tuning. and then you will realize why your an idiot.

oh yeah, i'd like to see someone try and adjust +50% or -50% on an afc, hahah, can you say fucked up timing?

 

If you need 50% fuel adjustment you probably shouldn't be using a V-AFC anyway. You need a engine management system.