Soarer Central: SAFC II reduces boost cut? Is it true?

Soarer Central Mechanical - TT Turbo Talk SAFC II reduces boost cut? Is it true?

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Dennis Weglehner
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Friday, February 09, 2007 - 11:02 am, by: Dennis Weglehner (2jzr31)

"What happens if you hit 15psi at <3500rpm where theres little to no fuel removed? It will boost cut wont it? If you fit a FCD you wont hit boost cut, and it will lean out a few points then continue."

Just set the SAFC to "lean it out a few points" at 3500rpm instead. The lean out condition is just as bad for your engine whether it be caused by a FCD or SAFC. At least with the SAFC, if it boosts too much over the set point the cut will be there to save you. If your fuel system is up to scratch you won't need SAFC or FCD induced leanouts at all. The SAFC will raise the cut safely.

"Using an SAFC to remove Boost cut is MOre dangerous than using an FCD to clamp the voltage to remove it all together. "

Please give a scenario where this could be the case.

Daniel Clarke
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Friday, February 09, 2007 - 03:31 pm, by: Daniel Clarke (Dieseltrain)

Dennis, Im using an FCD only on my car. I have NO detonation issues, and have run the 6th fastest Stock turbo time in the club.

I have also probably run the fastest time for the least mods on a Soarer that anyone knows of.

I will stick with my FCD while all the SAFC boys and extra mods are next to me or behind me, or just in front of me. IT suits my application.

The FCD is deisgned for that. The SOLE purpose of removing Boost cut. It is gone. No more issues. The safc can ONly remove it as far as 15.8psi or so. WHAT if some of these guys pushing 17-18psi through steel wheeled turbos want to use the stock ecu? THE SAFC WONT supply enough Voltage clampage and allow enough fuel for good AFR's in the mid range to stop Boost Cut occuring whilst retaing safe mixtures

SO this guy just wasted money on THINKING the SAFC will supply him with NO boost cut at 18psi
and Safe AFR's because it JUST wont do that.

Braden was pushing 18psi through his steel wheeled turbos in his Cressida and HAD to Install an FCD because his tuner said they COULD NOT adjust the voltage enough to remove the boost cut from occuring, and also the AFR's were going way to lean to even try it any further. Not to mention he almost ran 1/2 a second faster with the SAFC turned OFF. Goes to show the FCD was doing the job perfectly on his car.

And if you are worried about not having some form of boost cut? Im using a Greddy Profec B spec 2 and it has a limiter function inside of it. I can set it to whatever boost value i want the limiter to kick in at and have it set to a Percentage of that number to reduce it by.

EG, I run 15.5psi at the track, I set my limiter to 18psi and adjust the removal percentage to 15%. If it over boosts it will automatically reduce the 18psi spikage or overboost down to 15.2 to 15.5psi. This is my new boost cut function. I can set it at 12psi if i want to.

So im not worried about removing the boost cut as i can introduce a new one with my boost controller.
Theres a couple of examples.

Anyways mate, Seems you are stuck on the whole SAFC thing. If you think they work that great and remove all Boost Cuts and Tune them perfectly, then WHy would they invent an FCD?

Not everyone ONLY wants to run 15psi. I am speaking from what guys with 1JZ's have done and tuners have done. If you think the SAFC is the bestest thing to remove boost cut , then go ahead mate. Just because it may work for you, dont mean its what others want, NOR does it mean that others could be wrong.

All scenarios could be correct, in their own practical ways. It all comes down to what a person wants with their car and what their tuner has advised them is best or what they know is best for their application.

And just so you know mate, this is a very interesting topic. Im not trying to say your wrong or im right, but we all have different views and can come to similar conclusions via different routes.

Cheers.

Cihan Aday
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Saturday, February 10, 2007 - 12:00 am, by: Cihan Aday (Cihan)

Dennis Weglehner wrote on Friday, February 09, 2007 - 11:02 am:
Just set the SAFC to "lean it out a few points" at 3500rpm instead.

Thats the thing. Again you're thinking linear.
Doing so via the SAFC will remove the fuel as long as your foot is to the floor. That means from a MAP sensor input of 1.0v to a MAP sensor input of 4+ volts it will lean out X % of fuel.
When you remove any fuel between 0 and 6psi, you're lifting the air fuel ratios above stoich, past 14.7:1.. At the same time, the ECU is thinking "oh great, less boost, less fuel to inject, MORE timing!" and it advances ignition a few degrees extra. Running a lean'er mixture, under boost with an extra 2-5degrees timing is not safe - period. The engine will also make less power, have higher peak cylinder pressures and generally tend to cause other problems (failed coilpacks, burnt plugs you name it.)

Its been trialed and tested, a good tuner will know that toyota runs stoich before 5-6psi and heavy advance for light load fuel economy/response/emissions. Toyota also figured out ("shock horror") that above this range, stoich with heavy advance spells trouble and has tuned higher boost regions accordingly. This has left us with the following two problems;
1. < 6psi = 14.7:1 @ 20-28degrees advance, 38degrees max advance during deceleration.
2. > 6psi = ~12-10.5:1 @ 12-18degrees advance.

Its very lean, then VERY rich. Pulling fuel before its necessary slows you down. The FCD pulls fuel when its necessary, using a piggyback as a FCD doesnt. It slows you down and creates problems.
I am sure you will realise this as you push it a little harder, running the emanage as a FCD Maurice pulled 215rwkw; with boost cut enabled and retuned properly with 2psi extra boost he made over 250rwkw using the same turbos. Timing is the most important aspect of tuning a turbo car, too heavy advance and power DROPs like you would not believe. Turbo response goes downhill and engines have very short lives.

Dennis Weglehner
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Saturday, February 10, 2007 - 01:00 am, by: Dennis Weglehner (2jzr31)

Great info there guys. The thing I am trying to say is that IF you have enough fuelling, the SAFC will need to be trimmed down to subtract voltage and a SIDE EFFECT of tuning for POWER (not tuning to remove the fuel cut) will be that the boost limiter is raised. So if it has been tuned for power, there obviously cant be a power loss! If tuning for power leaves you with a low boost cut get more fuel into it so it.

The SAFC can subtract up to 50% (I think) of the value so it can get rid of the cut for sure. 15.8psi? only if lean outs are happening at that point. In which case the safest option would be to do something about your fuelling.

Cihan I see your point about the SAFC not being able to raise the cut too much more without acting like a FCD with the stock map sensor since its out of resolution. (does this happen at 15.8 psi that Dan speaks of) If you set it to subtract whatever percentage is needed to go from max resolution to 4.3V it will act like a FCD anyhow (but it will still subtract fuel before that point). With the stoich mixture, are you sure its mapped in there or does it run closed loop up until 6psi? If its closed loop it shouldn't worry it.

Dan I can see your point about leaning out at the boost transition point. There are ways around this. Check it out.

http://www.2gnt.com/www/corbin/foolafc.html

It totality removes the prob you are describing. This will make it boost related and not throttle position related. Don't want any signal modification at 6 psi? Fine you can do it like this. This is what I will be doing.

BTW I built my own voltage clamping FCD and have used them on a few cars including my own so I know exactly what they do and how they work. I think they are great. But I just reckon that if you have already have an SAFC some extra fuelling and a decent tune will make the FCD redundant. The FCD's only cost like $5 to make anyhow.

Cihan Aday
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Saturday, February 10, 2007 - 01:01 pm, by: Cihan Aday (Cihan)

Dennis Weglehner wrote on Saturday, February 10, 2007 - 01:00 am:
Cihan I see your point about the SAFC not being able to raise the cut too much more without acting like a FCD with the stock map sensor since its out of resolution. (does this happen at 15.8 psi that Dan speaks of) If you set it to subtract whatever percentage is needed to go from max resolution to 4.3V it will act like a FCD anyhow (but it will still subtract fuel before that point). With the stoich mixture, are you sure its mapped in there or does it run closed loop up until 6psi? If its closed loop it shouldn't worry it.

I gather, based on an thread convo and excel spreadsheet comparing JDM 1JZ and JDM 2JZ map sensors, 1bar is 4.82v. I have had the factory map read higher tha 4.90v, but not always. Kinda depends how hard the boost comes on. If it can output 5v, that would be about 15.8psi. In practicality it maxes out at about 15.3-15.5psi. I suppose this is where he got the figures from.

Mate timing is based on MAP input whether you're in closed loop or not, otherwise you wouldn't have to worry as you suggested.

Regarding fuelling under closed loop its all based on oxygen sensor input as you suggested unless its in limp home mode. I think there is a seperate low end map for fuelling.. Probably the startup enrichment and idle area share the same map then get corrected by the MAP, intake and water temp sensors. You need MAP input at idle because of the idle speed controller valve. Looking at the wideband, i can make adjustments to idle AFR's for a short while at idle until it corrects itself. Upto 0psi its harder to make adjustments as the ECU compensates easily and quickly, upto 6 or so psi its easier then after that its switches to all map sensor. Im guessing there is a base map, then boost enrichment based on the map sensor. If you look at toyota tech sheets, boost enrichment is in blocks in a table VS rpm. For example; at 2500rpm and map input of 2.55v, a value of 1.1 would mean, we need 1.1 x (the fuel required to run stoich at this boost level at this RPM). And another example; at 4500rpm and 4.2v map input, we need 1.6 x (the fuel required to run stoich at this boost and this RPM).

That essentially means you can take the MAP input voltage, subtract 10% and watch your AFR jump from 10:1 to 11:1. I've done it many times and its nearly linear. Boost fuelling correction is relative to stoich. Makes it easier to tune a piggyback when you know how the factory ecu works!

As a side conversation, i think (not more than 50% sure) that in closed loop, the injectors are not driven via the primary driver circuit unless its running in the coldstart/idle map. I say this because i cant make adjustments to midrange closed loop maps via injectors drivers, this could be a safety thing for the emange because the resolution isn't fine enough for tuning in that region, or it could be that there is another piece of circuitry that piggybacks the original injector signal input under closed loop operation and resends the factory corrected base signal.

Sorry if im being confusing.

Cheers

Dennis Weglehner
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Monday, February 12, 2007 - 10:45 pm, by: Dennis Weglehner (2jzr31)

Some interesting info there

"Mate timing is based on MAP input whether you're in closed loop or not, otherwise you wouldn't have to worry as you suggested."

A few more degrees won't hurt it at low boost. If you are worried about high cylinder pressures you better wind the boost pressure back down to stock. Plus there are knock sensors to save it from detonation. So you could almost say the ignition system is closed loop in some conditions. Some cars will even modify the ignition map based on knock readings.

WAAAYYY to many people are proving that in real life its fine SAFCs won't hurt your car coming onto boost.

There is no way that it will lead to bad performance unless its tuned wrong.

A mates 2JZGTE supra was running 15's at the drags because of a dud fuel pump. It had been cained in this state of tune for ages until the pump was replaced. There was no damage to the engine despite major lean outs under much higher boost than 6 psi! Thanks Mr knock sensor

In any case most people with an SAFC are not running a stock fuel system and the cars normally run horribly rich coming onto boost. The main reason they get the SAFC is to compliment the fuel system mods.

We just tuned my brothers soarer with twin VF10 Subaru turbos (similar to a WRX turbo). The only fuel system mods are a malpassi reg and a FCD I made.

It is super rich coming onto boost and was super rich at below 1 bar. We kept raising the boost up to 1.3 bar for an AFR of high 11's low 12's. The FCD works quite well in this application but an SAFC set to minus 13% would achieve the same thing as the FCD but trim some of the richness out as the boost comes on.

My brother is getting my 440s when I get my 550s. I think we will find that the FCDs will become redundant as the SAFCs will remove the fuel cut by virtue of tuning for good AFRs.

SAFCs and FCDs are both great and can be used for excellent results depending on the mods the other car has. With the map sensor mod the SAFC would be even better with regards to tuning accuracy and your fears of dangerous low boost operation will be gone.

I'm going to try and hook my map sensor up to the TPS input on my SAFC and see how it goes. Manifold pressure as a load reference is so much better than throttle position.

Cihan Aday
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Tuesday, February 13, 2007 - 09:45 am, by: Cihan Aday (Cihan)

Dennis, im trying to convey that the car can run a lot faster tuned properly - Stick in an emanage ultimate, an AEM wideband setup and start to tune ignition and injector duty cycle separate. You'll be amazed at the difference it can make when the knock sensors don't intervene, the ignition is spot on and the fuelling is just right no matter where your foot is.

You don't know if its leading to bad performance until you take the car to a circuit and race it. I'd confidently run a car i tuned with an emanage around phillip island until it runs out of fuel without worrying, could you do the same with oversized injectors, a FCD and an SAFC? Thats crunch time, when workshops take a customers hard earned hundreds you expect longevity, they can't leave things to chance.

I know for certain my cars factory knock sensors dont work. Factory sensors dont work below 1800rpm or above 5600rpm due to harmonic interference and they have a limited correction range. Thank the fact that 2JZ pistons are as strong as they are, not the engines two knock sensors.

With 550cc injectors, getting a sound tune without running 300rwkw is not going to happen with an SAFC. For one you'll be overfuelling in closed loop and coldstart fouling plugs more often. And you wont be able to remove enough fuel to get a decent tune without having it ping its tits off.

But if you think you can do it, kudos my friend.

Dean Carsen
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Tuesday, February 13, 2007 - 09:49 am, by: Dean Carsen (Deano)

So Cihan, if its runnig Stoic/14.7 up until 6psi is it still in closed loop up until then ? Or when does it change over.

Cihan Aday
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Tuesday, February 13, 2007 - 10:12 am, by: Cihan Aday (Cihan)

Dean its about 5-6psi then it changes over, before then its in closed loop running stoich unless its in enrichment. When it changes over it it gradually gets richer then dives to the 10's as peak torque arrives and peak power passes.

Dean Carsen
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Tuesday, February 13, 2007 - 10:19 am, by: Dean Carsen (Deano)

OK , when you say enrichment you mean the extra fuel kicked in for acceleration , yes?
just an aside,how does fuel work in closed loop, are there base maps for the O2 sensor to trim or visa vresa?

Todd Williams
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Tuesday, February 13, 2007 - 03:30 pm, by: Todd Williams (Jza70_r)

Can someone please summarise this topic in factual point form please?... there is way too much debating on the 2 pages to make anything of this thread in regards to an actual answer...

Cihan Aday
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Tuesday, February 13, 2007 - 04:00 pm, by: Cihan Aday (Cihan)

1. Getting rid of boost cut with an S-AFC alone is dodgy when running above 14psi of boost.
2. Refer to 1.

I don't care what dudes in the U.S. have done with their Supra's, MAP sensor trickery can only take you so far whilst retaining longevity.

Dennis Weglehner
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Tuesday, February 13, 2007 - 08:41 pm, by: Dennis Weglehner (2jzr31)

I hope you are wrong about blowing my engine.

No one is arguing that a SAFC is going to be as good a decent ECU.

Cihan Aday
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Tuesday, February 13, 2007 - 10:49 pm, by: Cihan Aday (Cihan)

Nah Dennis seems like you know what you're doing.
Looked into an ultimate or the like? You'll love tuning it!

Check this out;

A prelim tune for Ben Vandie, he has 650's and it takes 3 seconds to make it idle like it did from the factory under all conditions. No overfuelling during coldstarts or in closed loop.
Ben will notice i've enabled all of the menu options; showcasing what the unit offers

Dennis Weglehner
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Tuesday, February 13, 2007 - 11:02 pm, by: Dennis Weglehner (2jzr31)

Yeah I know Vandie from the Supra forum. I showed him how to make his FCD

That ECU looks like the goods. How much does it cost all up? Trust me I would MUCH rather something like that than a SAFC. Can you get them secondhand easily?

Paul Brockbank
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Wednesday, February 14, 2007 - 12:13 am, by: Paul Brockbank (Brockas)

Cihan Aday wrote on Tuesday, February 13, 2007 - 09:45 am:
You run out of fuel with standard injectors when your S-AFC screen looks like this; 0,0,0,0,0,0,0,0
That is essentially the factory tune which runs the injectors into the high 90's injectors duty cycle. Too many people upgrade to 440cc injectors without needing them.

THANK GOD!!!!!!!!!!!!!!!!!!

I'm glad someone else is saying the same thing. I remember starting a thread about this months ago yet still saw people with exhaust + boost upgrading injectors cause "my mates said it's safer"....

Cihan Aday
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Wednesday, February 14, 2007 - 11:00 am, by: Cihan Aday (Cihan)

Paul that only applies if you're under boost cut. If you're pulling 5% fuel and you go over boost cut 5% your eating into any reserves and quickly on the way to being out of fuel even though the SAFC says -5.

The only reason you're able to make 260rwkw is because the gt35 is a large turbo for a mild 1JZ. Peak efficiency doesn't arrive until higher pressure ratios meaning the turbo is taking it easy at current power levels. You'll see fuel requirements VS boost go up more and more non-linearly as you lift the boost. At 22psi it will push a disproportionately denser charge than at 18psi.

Your tuner wont push this setup any further because coming onto heavy boost it will run lean and he needs to leave a gap for boost cut. This is because the base efficiency range of the 1JZ is highest at peak torque ~4000-5000rpm depending on your setup. This is where it drinks a disproportionate amount of fuel and air mix, hence why the SAFC numbers would be closest to ZERO in the lower regions (i'd imagine) of the 8 cells. The factory setup is aimed at providing absolute midrange, even the exhaust port design and the flow/efficiency characteristics of the ct12a are engineered towards midrange thrust rather than all out power.

--
Off topic a little, i'd keep your car and install a set of 650's and an emanage ultimate. Get some USDM spec cams and exhaust camgear, a gizzmo EBC, 040 and a HKS ignition amp then run 22-24psi pushing over 300rwkw. If you haven't already done so, you'll need a rebuilt box

Yummy

Cihan Aday
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Wednesday, February 14, 2007 - 11:18 am, by: Cihan Aday (Cihan)

Dennis Weglehner wrote on Tuesday, February 13, 2007 - 11:02 pm:
That ECU looks like the goods. How much does it cost all up? Trust me I would MUCH rather something like that than a SAFC. Can you get them secondhand easily?

Not many second hand mate. I don't know of any.
Complete setup is about a grand installed and setup.
Unit alone is about 800 with all harnesses (off memory!).

They havent been popular in the U.S. they've had trouble getting them running.
I took on my first EMU installation dreading the outcome, but everything went smooth. Since then i've been recommending them.

Combined with a wideband setup, they have an auto tune facility that keeps a region at a target AFR regardless of the ambient, humidity or atmospheric pressure.

Grant Rowan
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Wednesday, February 14, 2007 - 01:22 pm, by: Grant Rowan (Booster13psi)

Is their any problems running a SAFC and a FCD?

Paul Brockbank
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Wednesday, February 14, 2007 - 03:37 pm, by: Paul Brockbank (Brockas)

Cihan Aday wrote on Wednesday, February 14, 2007 - 11:00 am:
Paul that only applies if you're under boost cut. If you're pulling 5% fuel and you go over boost cut 5% your eating into any reserves and quickly on the way to being out of fuel even though the SAFC says -5.

The only reason you're able to make 260rwkw is because the gt35 is a large turbo for a mild 1JZ. Peak efficiency doesn't arrive until higher pressure ratios meaning the turbo is taking it easy at current power levels. You'll see fuel requirements VS boost go up more and more non-linearly as you lift the boost. At 22psi it will push a disproportionately denser charge than at 18psi.

Agreed Cihan, I'm talking more about the number of people who have 440's and no aftermarket management because they believe it's "safe".

And no chance I'll be keeping the Soarer, I'd have to throw at least 4-5k at it to make over 500rwhp, which the 33 GT-R I've just bought has anyways... Time to start saving for a rebuild.