Difference between JR VPAC vs VAFC

[kobe 8]

Is there any difference between the two, besides Vtec control. Which one would you choose for a JRSC GSR. Thanks...

[keebler65]

lol 11 views and no replies? [img]confused.gif[/img]

the VPAC only allows you to move the vtec engagement point. a VAFC allows you do to that and also tune how much fuel is delivered at different rpm points, whether you're in vtec or not.

[JRCivic]

The only thing these two devices have in common is that both have the letters V, A, and C in their respective names !!!

The JR VPAC is designed to "augment" the supercharger system by allowing you to change the VTEC crossover point from that which is fixed at a specified rpm in the ECU to one that is both rpm adjustable AND boost/TPS dependent. It does not change any deficiencies in air/fuel throughout the powerband nor does it ultimately increase peak HP.

The Apex-i VAFC is both an adjustable VTEC controller (however, it is still a static rpm setting and is NOT boost or TPS controlled as well) and a simple fuel controller. Basically, it has limited ability to increase or decrease fuel delivery to suppliment the stock ECU programming to help smooth the peaks and valleys of the A/F curve during wide-open-throttle operation.

All of the above information means that you cannot choose between the two... they do TWO DIFFERENT THINGS. The advantages of the JR VPAC would be the ability to make greater low and midrange power by switching to the high-lift camshafts sooner WITHOUT the burdon of having to be driving around in VTEC at highway speeds. (This means that all '99-00 Si drivers could actually cruise at 90 mph on the interstate without engageing VTEC... and get improved fuel economy). The VAFC cannot change the VTEC point automatically. I suppose one could get handy at operating the unit and adjust the VTEC crossover point CONSTANTLY... switching from a lower rpm to a very high one when you are cruising on the Interstate, and back down when a possible "street fight" looms in the near future. The VAFC's adjustable fuel settings will allow some some correction to the A/F during WOT operation... and this is not possible with the VPAC.

So, ultimately... you need BOTH devices to solve problems AND improve driveability and performance... which brings up another option: Since the cost of a JR VPAC and an Apex-i VAFC is nearly $600.00, why not buy a Hondata system and have FULL control of both fuel delivery and VTEC engagement... along with maximum rev-limit control, A/C cutout, sensor bypass options and more ??? The cost would be similiar... maybe even LESS in some cases.

[kobe 8]

22 views, one reply, thanks mang...

[kobe 8]

Hmmmm, very interesting. I will definately consider Hondata then. How much you think the total will be (hondata + tuning).

[JRCivic]

If you factor in a set of new RC 440 injectors... you would be looking at around $1150-1300 including dyno time. You could save some $$$ by finding a used set of RC injectors... and save even more by buying a set of DSM 450's (although I am not recommending the latter choice). Let me know if I can help you further.

Jim