hybridpatient95

can someone please tell me the best setting there able to find for their turbo setup on the vafc. cuz right now im running a p28 chipped to run rich ,vafc and a fmu. is this to much gas? should i be fine if i tune my vafc to the right specs?? thanks guys!!!

Mag00n

Basic vafc settings are

-36 High cam for all rpms
-35 low cam for all rpms

98%lo 99%hi

Sensor 6in 6out

4cylinder

hybridpatient95

thanks man!!

Mag00n

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kinkbmx159 &raquo;</TD></TR><TR><TD CLASS="quote">thanks man!!
</TD></TR></TABLE>

NP just remember the closer you get to 0 the richer you will run, while cloer to -50 is leaning it out. Also the closer you get to 0 the less boost your map will be able to read before throwing a code. I also think the FMU is over kill and I dont like prefabbed chips because every car is different. If I were you I'd ditch the fmu and the vafc and get uber.

V-SPEC 1

sorry for off topic, but Does uber be able to tune automatic cars? i have a friend that owns a 98 prelude and it's an automatic and he want's to get some kind of fuel management system like uber. thanks.

AzntaggeR

uberdata can't tune on obd2 like your friends 98 prelude.

hybridpatient95

1994 Del Sol VTEC
B16A3 Turbo-T3 60/63@10psi how is the turbo b16 going ?? what is your engine manegment or fuel manegment???

MooreBoost

Don't boost for long periods.

4_door_teg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kinkbmx159 &raquo;</TD></TR><TR><TD CLASS="quote">can someone please tell me the best setting there able to find for their turbo setup on the vafc. cuz right now im running a p28 chipped to run rich ,vafc and a fmu. is this to much gas? should i be fine if i tune my vafc to the right specs?? thanks guys!!! </TD></TR></TABLE>

use the vafc or the fmu, not both. If you're using the vafc, I hope you have 450's before you go put -36 in there lol. Most people start with -40 and work from there...

sneezyh22a4

why can't he use both?
i would like to know.to me if he use a 12:1 fmu and run 390cc injectors that should be fine on the rich side.because the fmu increase
the fuel pressure 12 psi for every 1psi of boost right?now with the vafc you could use it to pull fuel up to 50% someone correct me if am wrong and give some info on this setup as to it's upside and downside

Chrome Pipes

You can use 440's and an FMU, I've been doing it for like two years now with no problems.

Here's an old post of the setup I'm talking about:
https://honda-tech.com/zerothread?id=101392

Once you figure out what works for you, get that thing to a dyno asap! Good Luck!

hOndafienD 04

what size are stock b16 injectors? cuz thats what this thing is running on.....i think we gonna need bigger injectors...would 345cc be enough?

Chrome Pipes

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hOndafienD 04 &raquo;</TD></TR><TR><TD CLASS="quote">what size are stock b16 injectors?</TD></TR></TABLE>

240cc

hOndafienD 04

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

240cc </TD></TR></TABLE>

holy sh*t thats small....theres no way we can run 10psi with these

Chrome Pipes

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hOndafienD 04 &raquo;</TD></TR><TR><TD CLASS="quote">what size are stock b16 injectors? cuz thats what this thing is running on.....i think we gonna need bigger injectors...would 245cc be enough?</TD></TR></TABLE>

Sorry, didn't see the second part of your question. It really depends on how much boost you plan on running. For up to 8 psi, you could run a 12:1 FMU and stock 240cc injectors with a V-AFC - but that's it. I wouldn't run more than that on stock injectors. When I had my B16, I was running 10 psi with RC 310's, a 10:1 FMU disk and a V-AFC and had plenty of fuel.

The setup I'm running on my LS/VTEC is modeled after InlinePro's setup with RC 440's, V-AFC and a 12:1 FMU. It seems *** backwards because with bigger injectors you should be using a smaller ratio in the FMU, but it works fine.

hOndafienD 04

ok...because at 6 psi the car hauls ***....as soon as we turn up the boost to8-9 the car starts cutting off and it feels like its lacking fuel...

Chrome Pipes

Do you have an intank pump? Im not a fan of the inline pump that comes with the DRAG kit. I used the Holly 255 lph intank replacement pump and it worked great. Just make sure it is the high pressure version for "forced induction". We had a similiar problem until we switch to the high pressure pump.

hOndafienD 04

nope....we have the stock pump......i think that its prob one of our biggest issues right now.

Just Checking In

Hello,

I wrote this to someone on this forum a while ago who was asking a few questions slightly different then your's but similar enough. Magoon's suggested percentage cuts can work too, it all depends on your specific setup.

Here was what I wrote to the person:

With the vafc hack, maximum amount of boost before 11 psi when the map sensor errors, is dictated by the injector size you choose to run. 450 cc injectors are popular with the vafc hack because they will allow you to scale the map sensor voltage nearest 3.09 volts with room to increase the amount of fuel needed above the percent differance between the injectors. This lets you clear the greatest timing advance section of the ignition table and lets you create a close 14:1 air/fuel ratio per psi of boost.

Mathematically heres an example.

Say you want to run 10 pounds of boost and you bought the correct 450cc injectors for this.
The differance of flow is 46% because (240/450)-1= .46
Then because larger injectors have to be compensated for latency we subtract about 5% for 450cc's leaving us with a 41% fuel difference
This means at -41% setting in your VAFC your 450's are giving you the same fuel your 240's were.
Now the map sensor goes into limp mode at 3.1 volts so you need to stay below that, and 10 psi is about 4.7 volts.......... so 4.7-(4.7x.41)=2.77
This shows us that 450's give us enough room to reduce the map signal below 3.1 volts with enough differance in volts between 2.77 and 3.1 to increase the fuel %cuts to accomodate for boost.

So what we do in terms of setting the vafc is this. We know the differance in flow between 450's and 240's is -41% and at idle air/fuel ration does not change with the turbo. So at idle, if you run 450's you will set your VAFC to -41%. As your rpms increase you want to add fuel to compensate for boost you could be making at those rpms. So on average, people add 1% per 1,000rpm's above 3,000rpm where boost begins to build with average sized compressor housings and wheels. You don't really want to go past a 5-6% overall increase though because you will be increasing your flow differential at the same time the ecu is increasing pulse duration. This can make for a really rich combustion.

Here is a good example of settings for a b16 running 450's and VTEC set at 4,500 rpm:
Same settings for wide and narrow with hi and lo
1000 -41%
1500 -41%
2000 -41%
2500 -41%
3000 -40%
3500 -39%
4000 -39%
4500 -38%
5000 -37%
5500 -36%
6000 -36%
7000 -35%
8300 -35%

Do you see how you want to transition into the air fuel ratio gradually? If you just set it at -35% across the board you are running entirely too rich at idle and anything below 4k roughly. Different setups will build boost at different rpms so this is just an example of something average.

Once you grasp the concept you'll notice some issues. You will see why the VAFC is a piece of **** for spirited city driving. It works for cruising below 3,500rpm or full throttle runs and thats about it. Otherwise all your settings that you input so that you have a correct a/f mixture when flooring it......creates entirely too rich a/f's when you're just trying to cruise around and you just happen to go past 3,500rpm with anything less then half throttle on the average sized compressor housing, on a small displacement motor. You will also see why to run safe with the vafc you should run 10 psi, so that your fuel correction values aren't putting you dead center of the highest ignition advance on the table. You also should slightly compensate your idle and low end power by retarding your base TDC timing down to about 12 degrees instead of stock 16-18.

:

If you look at a spark bin on ghettodyne or zdyne or whatever you choose, you will understand why your timing is advanced for boost. Because at 5 psi for instance, a -38% cut in fuel will move you into the advanced middle area timing section of the stock table. This is why people suggest running 10psi, because a -38% cut of 10 is a higher number.....thus not moving you so far back into the advanced area in the middle columns. When looking at those value bins you can regard the vacuum/boost column headings as being linear and directly related to your map sensor voltage....which is the only thing the VAFC is altering.




Modified by Just Checking In at 3:56 PM 11/28/2004

hybridpatient95

thanks alot man!!! were gonna try this tomorrow

hybridpatient95

are these specs the same for all motor or totally different?? cuz were talking off the boost and going all motor again. cuz the turbo lacked top end power cuz its a t3 and its going back in my other friends car..

Weston

Throttle points should be more like 20% and 50%... anyone who sets it to 76/77 or 98/99 for this setup clearly doesn't understand how they work. You want to use it to give you a nice smooth transition from the narrow throttle map to the wide throttle map as you start to hit boost. The wide throttle map is what you'll need to tune with a wideband on a dyno (you need the load on the engine); the narrow throttle map should reflect the wide map, but use a little less fuel (since this is the map that will be used when you're not on it much).

Don't waste your time or money on the FMU crap... all you need is 450cc injectors (with resistor box, if applicable), a high flow fuel pump, and a VAFC. Retarding the distributor 2-3 degrees will compensate for the dynamic ignition advance caused by this setup (it's not really 7-8 degrees like some BS'ers like to claim). It wouldn't be a bad idea to run spark plugs that are a degree or two cooler than stock. Initial settings for the VAFC should be about -38% at idle to -35% at redline, but you really need to get it properly tuned as soon as possible, as every setup is different. Aim for a 12.5:1 AFR when tuning.

Just Checking In

Thank you for your post Weston. When I wrote that response above I was unaware that the Vafc can take the differance in value between say 20% and 50% like you wrote, and increase to the wot value over the 30% differance. I was under the impression the narrow and wot points were only able to be used together as distinct crossovers...at which point differing values between the two would make for horrible drivability with the forced induction method.
Using throttle settings with distance from eachother does help to be able to use two seperate fuel correction sets without <U>as much</U> issues in drivability. Never the less, it doesn't solve everything. Take for instance closed loop where the o2 sensor is being utilized to modify the fuel value used. As your narrow throttle setting richens the mixture up at higher rpms as set, your o2 is telling the ecu it is too rich, and is trying to slightly counter act it. Another problem is immediate depressing off the throttle...

Scenario: B16 with t3 .60/.48 and 450's

Say your cruising down the highway at 15% throttle, with a small ratio y1 tranny at a common 4,000 rpm. You are creating little to no boost, and you have your vafc narrow set to say -39%.....to be slightly over stock 240cc flow. You instantly hammer it....at this instant fuel pulse in milliseconds changes to your wot setting, which you had to calculate to be at full boost with this turbo at 4500 starting from a stop. You are at -36% for about a full second and a half before full boost. So for 112 revolutions of your motor you are running entirely too rich...thats a lot. Granted its better then running too rich all the way to full boost, but its still pretty bad.

About your timing advance, I don't see how you see it that way. When building boost with certain fuel correction values necessary to create a good 12:1 with your set up, you will pass through that advanced area of the table when one should be preferably all the way to the right. Add to the fact these values should be reducing about 1 degree per psi and 2-3 degrees of base timing retard is not enough even enough to cover just the differance in spark on the stock table at points. Let me know how you see it.

Edited: To remove what I thought was unimportant ideas to the topic at hand.


Modified by Just Checking In at 11:21 PM 11/28/2004