VAFC Hack Completed!

[thermal]

Wow!!! What a big difference! Awesome response on throttle. It took me about 3 hours trying to make the DSM 450cc's fit. It actually slides in perfect. Just gotta make sure that a replacement O-ring or gasket is available. I had to modify the stock gasket to make it fit. My setup is:
-1-4K= -40%
-4-55K= -37%
-55-8K= -35%
Smooth transition without hesitation. I'll be installing my 255LPH intank pump and B&M next weekend. Any questions, forward it to me. It was simplier than I thought.......

[MrCLoWnY]

Thermal, What exactly is a VAFC HACK??? Im confused..

[thermal]

Okay. I'm gonna make it as simple as possible.

On Honda cars, ECU can not read boost or it will give a MAP CEL. Well, we all know that. What the S/VAFC does is modify that signal and still let the tuner map the fuel setting. The pressure signal on the MAP sensor is interpreted by voltage reading. The voltage measurement is what's being modified.

The fuel setting is mapped per changes on the RPM through various Wide and Narrow throttle position in relation to boost. But to configure that setting safely, Wide and Narrow throttle is set at least -35% for the boost not to register. I set mine a little leaner starting at -40%. As the RPM increases in demand, the tuner have already altered the throttle per RPM setting to allow fuel enrichment. Since, most common hondas use 240cc injectors, this is where the DSM 450cc helps. Under a negative (-) throttle setting, fuel will be lean. But the DSM 450cc's compensates for that after a tiny wiring modification.

The difference is freaking amazing! It is priceless! It almost feels like a different car. I hope that helps. I will have a write up done with pictures once I get more time..... Peace!

[Sivik]

sounds great... how much does a set of the DSM injectors run? is it only compatible with the DSM ones? looking forward to the writeup. putting my turbo on this weekend. any advice?

[pdiggitydogg]

Im lost...Im obviously not "in the know":paranoid:

[thermal]

how much does a set of the DSM injectors run?
I went to the junkyard and pulled it off a turboed Plymouth Laser. It cost me $23.75 for the set and got it reconditioned for $25:yes:
is it only compatible with the DSM ones?
I do not quite understand this question. I have a 99civicEX. I converted the DSM 450cc using a resistor box from an older honda.
putting my turbo on this weekend. any advice?
Too late to respond to this. I just saw your post. GREAT JOB!


Im lost...Im obviously not "in the know"
pdiggitydogg, it's really easy man. What happens is, since the AFC altered the voltage signal of the MAP sensor, the honda ECU still compensates and does it's own calculation of fuel like there is no boost present. The AFC hides the boost reading from the Honda ECU and at the same assisting the ECU to add more fuel per RPM. Having the DSM 450cc injectors allows more fuel in the cyclinders due to its rating size. It assists the "actual" flow of fuel via the signal from the ECU that is hacked by the AFC. Peace:yes:

[Sivik]

is only compatible with the DSM ones?

sorry, what I mean is that can I use other brands of 450cc injectors (such as RC), or does the AFC hack work only with the DSM injectors?

[thermal]

Originally posted by Sivik
is only compatible with the DSM ones?

sorry, what I mean is that can I use other brands of 450cc injectors (such as RC), or does the AFC hack work only with the DSM injectors?
Definitely! You can use an RC 440cc as well. The only reason why I have the DSM 450 cc is because of budget. The "hack" has nothing to do with the DSM 450 cc at all. The point was, to ensure a bigger injector size is in placed.... doesnt have to be a DSM 450cc.;)

[da_konig]

Hey thermal, Im doing a custome setup for my 95 h22 powered accord. I have a FMU similar to the Vortec fmu but I also have a V-afc. My ? is can I use the FMU and still fine adjust my fuel curve with my V-afc. Im also doing a missing link check valve.

[thermal]

Hey thermal, Im doing a custome setup for my 95 h22 powered accord. I have a FMU similar to the Vortec fmu but I also have a V-afc. My ? is can I use the FMU and still fine adjust my fuel curve with my V-afc. Im also doing a missing link check valve.
First off, nice car man! Do you know the rating of your FMU? How much boost are you pushing? Yes you can still fine tune your set-up with the VAFC even with the missing link. BUT, it will be limited since there is no input from MAP. You can use the function of RPM versus fuel points. The best way to figure out if it is doing anything is to take it to the dyno. I've read an article that gave an H22 prelude extra 20 lb/ft torque and 36 horsepower by just tuning that VAFC. Goodluck to you man.......

[da_konig]

Not sure what the fmu is rate dat most likely a 10:1. I plan on runing 5-6psi daily and 9-10psi (100+ octane) at the track. Im also using the MSD boost retard. Im using a T-25 turbo, how much hp do you think it will add along with a NX N-tercooler.

[thermal]

Do u have a high volume fuel pump and an adjustable FPR? You may be able to get an extra 20-25 HP if you have a decent fuel components upgrade. Be carefel tho, at 10 psi, your T25 will be pushing it close to the limit. You will gain a lot of low end power.

[Sivik]

sorry for the dumb question, but whats does 10:1 or 12:1 mean for a FMU? I have the blue box, so whats that at?

Thanks!

[thermal]

No problem Sivik. A boost dependent FMU raises fuel pressure on demand during boost conditions. All it does is restrict the flow of fuel going back to the fuel tank. This action keeps the fuel rail flooded with fuel so the injectors are continiously providing ample fuel to the cylinders. 10:1 means that a 10 psi rise of fuel pressure is gained at 1 psi boost. A 12:1 FMU is 12 psi rise at 1 psi boost and so on and so forth..... see the pattern?

I have a diagram on the way to better understand this whole FMU stuff. Some people are confused the difference between an FMU and an adjustable FPR.......

The blue box is a totally different story. What it does is hide the MAP reading to avoid CEL. It enriches fuel management by changing the pulses on the injectors. It plays around with the injectors duty cycle. If you look at it, that is why the wires are tapped into each injectors. The pulses, which are small voltage signal, makes the injectors open up to supply more fuel...... peace!

[pdiggitydogg]

^Oh now I get it all :yes::D (really)

[thermal]

Okay, i finished the S/VAFC "hack" procedure on my website. Here's the link:
www.geocities.com/thermalfid16/VAFChack1.html

While at it, please leave me a note in my guestbook...peace!