fsp31

Thinking out loud here (yeah i know it's dangerous and my head hurts already)...

There are a lot of mixed reports from afc "hack" setups. For some, power is off, idle is terrible, or the rings last a matter of months, etc. Meanwhile, others (my daily driver included) have been happily "hacked" for nearly 2 years now. I'm wondering why there is so much disparity. That's what this topic is about.

Since the typical "hack" involves a certain sized injector (dsm 450's), and a certain setting on the AFC (~ -40%), is it possible that a compressor map with particular traits would also be desirable?

The fact that the hack can (and will) interfere with ignition timing has been well documented by Mr. Davis (thanks!). Recently I read the thread where he explained that running boost levels approaching the "limit" of the hack (10 - 12 psi) could very well be safer than running boost in the 5 - 7 psi range due to ignition timing advance.

Since there is a tendancy to run "big" turbos at 6 psi around here, people with this type of setup don't really have the option of boosting 10 - 12 psi unless they have a built motor. However, that's not the case with a smaller T3 or a T25. Since the "hack" has a lot of appeal for people doing junkyard setups (assuming they already have a vafc), they are also likely to be utilizing smaller turbos since that's what is available in most junkyards. For myself, I'm not interested in more than about 230 whp (autox car), and I don't care about power on the interstate below 4000 rpm's, so a T25 is adequate. At about 12 psi, it will be close to the limit of it's efficiency, and hopefully the motor will be in the 220 whp range. This is also close to the limit of the standard hack, so ignition timing should be close to correct without too much manual intervention (moving the dizzy).

Joseph Davis

Turbo size doesn't matter quite so much, although a larger compressor flows air at a lower temp which does help avoid detonation. As far as level of boost and the AFC hack, yes they are inextricably intertwined with how they affect quality of tune and engine life.

Read my writeup here: https://honda-tech.com/zerothread?id=841443

USDM 4G VTEC

on the hack people usually just run the VAFC and thats it

on a setup in wich theVAFC is used in conjunction with a MSD BTM, the timing will be retarted no matter what the ecu does since is overides it into the engine

if u have a BTM, the ignition cna be mantained where u want it and avoid detonation. u are just limited to the amount of boost (11-12psi max)

uberdata, hondata or turbo edit are the better options,

BUT on a HACk, the hack works

G"UNIT

i want hondata.. i hate the hax..

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by USDM 4G VTEC &raquo;</TD></TR><TR><TD CLASS="quote">on a setup in wich theVAFC is used in conjunction with a MSD BTM, the timing will be retarted no matter what the ecu does since is overides it into the engine

if u have a BTM, the ignition cna be mantained where u want it and avoid detonation</TD></TR></TABLE>

Wrong. BTMs do nothing to address AFC hack ignition. Read my writeup I linked to above.

fsp31

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">Turbo size doesn't matter quite so much, although a larger compressor flows air at a lower temp which does help avoid detonation. </TD></TR></TABLE>

I don't think I did myself any favors by referring to turbo size specifically. I guess a better way to put it would be to refer to a given power level at a given boost level. A smaller turbo is more likely to make "acceptable" power levels @ 12 psi on a stock Honda motor than a typical t3/4 hybrid. So, given the shortcomings of the hack, I'm thinking it would be better to run a smaller turbo if hack users are "bound" to the 10-12 psi range. That's my theory anyway... Please feel free to kick holes in it. That's why I posted it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by USDM 4G VTEC &raquo;</TD></TR><TR><TD CLASS="quote">uberdata, hondata or turbo edit are the better options,

BUT on a HACk, the hack works</TD></TR></TABLE>

This is NOT meant to be a "hack is good/bad" or "hack vs. the world" type of thread. There are *much* better and even cheaper solutions now. But for a variety of reasons, the hack is what some of us are living with. For me and others though, "it ain't broke" so why fix it? Part of the goal of this thread is to figure out why some some "ain't broke".

Joseph Davis

Alright, I see where you are coming from. Your powerband is a little different - more midrange torque and top end torque - due to the hack. You fall on the efficiency island of all the compressors used based on your engine's flow, not with how the AFC hack ignition curve affects your powerband. Suit the turbo tothe engine, THEN worry about the engine management.

I can understand the if it ain't broke mentality - just read through my thread for a few tips on living with the AFC hack. There are lots of successful AFC hackers out there, and you can keep yourself as one of them. I just point out the quirks in the system so you can go out and play the game well informed and THAT will have a bigger effect on your engine longevity than any other single factor - engine management, boost level, or turbo selection.

USDM 4G VTEC

when the MAP readings goes up and the engne revs go up of course the ignition goes up

if u have a BTM, wich of course u know how works and its setup, even at 0psi its advanced, once boost comes into play, it will start retarding the ignition.
it overides whatever its supposed to be and retards it directly proportional to boost... if a ignition fully advances around (lets say) 39 deg....@ 1psi, u go down to 38
@ 3 psi, u already down to 36, once u full boost, (10psi example) u are on 29 degrees... wich IS NOT fully advance

the VAFC overides the signal from MAP to ECU
the BTM overides the signal between ECU and Ignition

if u say that the BTM doesnt retard timing and doesnt overide the timing, i will like u to write that to MSD, prove them wrong and see them admit it doesnt do what is supposed to


i am not saying the hack is the best thing, but i am saying that the hack with BTM works to a certain extent

fsp31

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">You fall on the efficiency island of all the compressors used based on your engine's flow, not with how the AFC hack ignition curve affects your powerband. </TD></TR></TABLE>

Aha!! Ok, that definitely makes sense. Thanks for the clarification. I was thinking of turbo size/capability as a possible explanation for the more successful hacked setups out there. Of course, I am "nice" to my car most of the time...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">I can understand the if it ain't broke mentality - just read through my thread for a few tips on living with the AFC hack.</TD></TR></TABLE>

Absolutely. I've got it bookmarked. Saying the hack isn't "broken" in my case certainly doesn't mean there is not room for improvement. I think I am in the same boat as a lot of "wannabe" tuners these days. I'm on a tight budget, and I'm not too sharp with electronics. I'm working to better understand Uberdata, but it's still a bit "scary" to me. You guys have gone to great lengths to bring ECU programming to the masses, but you can only "dumb down" the explanation so much. Then it's up to the rest of us to catch up. I'm pedalling as fast as I can...

fsp31

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by USDM 4G VTEC &raquo;</TD></TR><TR><TD CLASS="quote">if u have a BTM, wich of course u know how works and its setup, even at 0psi its advanced, once boost comes into play, it will start retarding the ignition.</TD></TR></TABLE>

I believe that even the "0 psi" scenerio is potentially dangerous with the hack, and this is before the BTM has any boost to "work" with.

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by USDM 4G VTEC &raquo;</TD></TR><TR><TD CLASS="quote">the VAFC overides the signal from MAP to ECU
the BTM overides the signal between ECU and Ignition

if u say that the BTM doesnt retard timing and doesnt overide the timing, i will like u to write that to MSD, prove them wrong and see them admit it doesnt do what is supposed to</TD></TR></TABLE>

It doesn't override the ~15 degrees advance at 0 psi, and it can't begin to address the ~7-8 degrees advance (from where 0 psi timing should be in the stock Honda maps) founf at 5 psi.

Read my write up already. I demonstrate how fuel maps are more or less linear, as is the AFC's manipulation. I also say

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">- Ignition maps aren't like fuel maps, bitches.</TD></TR></TABLE>

Your ignition is recurve via AFC hack is NOT LINEAR. How does a BTM which retards ignition timing in a linear manner deal with this? Quite simply - it doesn't.

TurboBumblBee

sorry kinda OT but i have a little question bout the hack..

ive been running the hack on my new motor since it was built motor consists of

b18c block aebs sleeved to 2.0
9:1 cp pistions
rc 440cc
stock head
turbonetics .48a/r 60 trim
tial wastegate, boosting approx 8psi

i have been driving the car at approx -28% it runs really rich and friends driving behind me say it stinks.. would i be safe to do down further to - 30-35 without a problem? im just scared of messing something by detination and not have having any guages hooked up to look how the motor is doing..

thanks everyone! as im a noobie when it comes to boost and dont want to buy a new motor!

boostincoupe

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fsp31 &raquo;</TD></TR><TR><TD CLASS="quote">
Absolutely. I've got it bookmarked. Saying the hack isn't "broken" in my case certainly doesn't mean there is not room for improvement. I think I am in the same boat as a lot of "wannabe" tuners these days. I'm on a tight budget, and I'm not too sharp with electronics. I'm working to better understand Uberdata, but it's still a bit "scary" to me. You guys have gone to great lengths to bring ECU programming to the masses, but you can only "dumb down" the explanation so much. Then it's up to the rest of us to catch up. I'm pedalling as fast as I can...</TD></TR></TABLE>

Man oh man, I couldn't have said it better myself. THAT is one of the reasons I'm sticking with the hack - that and the fact that my buddy's giving me his VAFC for 100 bucks.

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by USDM 4G VTEC &raquo;</TD></TR><TR><TD CLASS="quote">when the MAP readings goes up and the engne revs go up of course the ignition goes up</TD></TR></TABLE>

WTF?

Higher MAP readings are caused by higher manifold pressure, which all else being equal causes the timing advance to go DOWN.

Think about how the BTM works, and how the hack works. When you run the hack, you get extra timing advance EVERYWHERE. EVERYWHERE!! The BTM only will retard timing while in boost, which does absolutely nothing to counter the extra advance everywhere else.

Not to mention the point that J. Davis brought up about the curves of the two not matching each other...