slider2828

Hence using the later gen Profec E-01 is soooo much better... can be based on RPM and speed....

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jspaeth

Haha went to U of Delaware for my BS in Chem Eng, right now doing my PhD at Princeton.

I would like to design and sell an off-the shelf (like Greddy Profec of Apexi AVC-R) boost controller that has gear-specific duty versus RPM curves.

Right now, the AVC-R says it does gear specific, but it's not really....you can just decrease the WHOLE duty in a given gear but not each RPM point.

I'd like a EBC where you can dial in duty vs. RPM for each gear separately.

This way you could have a 600 whp car RWD with perfectly good traction in 1st and 2nd gear.

I don't know why no company offers this yet, I could sure use it on my car.

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2fast4y0u

Originally Posted by jspaeth
Hmmmm well gain is a "controls" term....I remember this vaguely from my Controls class in undergrad.

Most feedback controllers are PID controllers.....Proportional (to the difference between current point and target), Integral (involving an integral over past history of this difference), and Derivative (involving instantaneous time derivatives of this difference).

Different amounts of the P,I, and D (each has their own "gain") determines the behavior.

Ideally, we want a "critically damped" boost controller.....this is the case in which the boost climbs towards the target as quickly as it possibly can, and then when it gets there, it stays there (no oscillations or overshoot).

Underdamped would cause overshoot and oscillations, overdamped would cause it not to approach as fast as it possibly could.

I like the APEX'i because it truly allows you to do this, jack up the duty in the lower RPM to help it reach full boost faster, and then tinker with the duties in the higher RPM to KEEP it there.

MBC is just crude in comparison


my head just

slider2828

Can't Motec and Autec's do this and also maybe AEM?

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jspaeth

^ Don't let the jargon intimidate you.

At the end of the day, it is a valve that lets only a certain amount of air through to the wastegate actuator (can never pull a vacuum).

Basically, when it is fully closed (100% duty) ALL of the air going to the wastegate actuator is being bled off, whereas when it is fully open (0% duty), all of the air in the vacuum line (boost source) is going through to the wastegate actuator.

So 0% duty is like running no boost control at all.


Now the EBC simply allows you tell the valve how much to open depending upon what RPM you are at.

And that is WITHOUT feedback.....literally it just opens X amount depending on the RPMS.

In feedback mode, it has a bunch of duties programmed in, right? It also is told (by you) a target boost.

Now what it does, is it uses the values you put in as guesses, and perturbs them if the target boost is not being hit exactly.....in this way, a boost controller like the AVC-R can "learn" the proper duty at each RPM.


It also has a feedback speed setting........all this does is to effect how much tolerance the computer has for not hitting target. If the feedback speed is too fast, you can get oscillating boost....if it's too slow, then it doesn't respond quickly enough, and will take TOO long to make corrections and if you are overboosted, it won't come down fast enough, and if you are under your target, it will take longer to get there.

bang

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jspaeth

Yes! Notice I said off-the-shelf......basically I meant something other than a full standalone ECU....like something that works on its own, like a Profec or AVC-R.

You shouldn't have to spend $1500++ to get this technology. The AVC-R for example already knows which gear you are in....

Adding in separate tables of duty VS RPM should be rather trivial to implement, but VERY helpful for those of us with traction issues in the lower gears

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2fast4y0u

i have a greddy profec b soec 2 and i hate it!!! looking to seel it actually.
i would love to get a avc-r but have to sell the greddy first. once i can do that, i know just who to get ahold of /\

jspaeth

The learning curve is a little steep, but I find that mine works amazing.

I get minor overboost, (of about 1 psi or so) ONLY when I am flooring it in one gear and then slam it into the next gear.

Also, I wish it had more than 8 RPM points that you could define the duty at, but, eh, that's ok

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2fast4y0u

yeah, i dont understand the whole "gain" thing. i know it was mentioned in a few posts ago.
i ran it for about 6 months and couldnt get it to work the way i thought it should. apparently i thought about it all wrong.
therefore, i think i will be better off with a avc-r.



anyone looking for a pro fec b spec 2? be looking for my FS thread coming soon thing is mint and has everything needed to install.

codyace

Wow! I really appreciate the knowledge! Being on the business side of the house, I never have learned such things. Congrats on the phD @ Princeton!

Such options do exist

On the affordable level:
Turbosmart Direct - EBoost 2


There are also drag race oriented options (as well as those controllable thorugh aftermarket EMS...I know AEM EMS does this as well, as it's what we used on the turbo mustang) but they can become very expensive (much like professional traction control devices...3500-4000 bucks!)

This is the best guide for the Profec 2:
How To Tune Your Greddy Profec B spec II - evolutionm.net

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2fast4y0u

i have seen that article once before, but i forgot it was out there. i think i would stil be better off with the avc-r because its my "my term"

S13 curtis

YESIR, the aem ems can control boost in each gear if you have the boost solenoid for it. Its bad ass.

My car should be ready to hit the dyno(Mustang Dyno @ Central Florida Turbo aka CFT) in mid to late january just waiting on the rest of the parts to come in, then it will be posted.

2fast4y0u

hmmm. i have an aem ems. maybe i should get her all hooked up and get that boost selinoid then.

i just want something simple...that works

S13 curtis

Yup me2 i got the boost solenoid and map sensor from jegs.

slider2828

I was thinking isn't speed and RPM dependent boost (E-01 Does this), better than gear and rpm? I was just thinking about this last night.... Gear doesn't pertain to speed all the time....

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jspaeth

Why speed?

The fact is that the torque to the wheels depends upon which gear you are in and which RPM.....

So in 3rd-5th, let's say you don't spin......so you run a duty profile that leads to boost coming on as fast as possible and hitting max boost and holding it there.

Perhaps in 1st gear tho, you spin because A) Too much torque AND B) Torque comes in too fast.

Then in that case you can run a duty profile that helps the boost to come on a little slower and perhaps doesn't reach as high of a final boost in that gear.


Not sure why speed would matter....

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slider2828

I guess torque can be linked to RPM and that is why its a better indication than speed in terms of wheel spin as speed is measured in the tranny and not in the actual movement of the car.

What I am saying is torque yes would be a good measurement, but different tires would allow different torque to be applied to before the wheel spins. But if we were to measure the actual movement of the car, would that be a better indication whether if the wheel is spinning or not?

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jspaeth

From a feedback standpoint, yes measuring speed VS engine RPM would give some indication of wheelspin, but that would be way to complex, and there is no way to measure speed really.....as you know, when you spin wheels, your speedometer goes up...

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Max_PSi

I just about done with my 2871r install. I have all the supporting mods including the PFC with the optional boost controller kit. Would this controller be simliar to the stand-alones previously mentioned?

And if so why not get this kit jspaeth instead of run the AVC-R? I think brand new they both run for about the same price. And you have the PFC right?

codyace

The only true way to measure wheelspin to the point where you can use it to control boost and power, are 3000 dollar+ units like drag race guys use (traction control) that measure driveshaft speeds.


In regard to speed vs boost vs gear.... I often wonder if the car would be 'quicker' using less boost and running a gear out, or spinning, grabbing the next gear, and using momentum to continue you on.

With that said, wouldn't you want the maximum boost per RPM at all times, and then just say XXX in first, YYY, in 2nd, and so on.?


Either way, the EboostII and Profec E-01's and AVCR's are all very neat devices. I have no complaints with my Profec B Spec I or Profec Type S (essentially a new B Spec I) though either, but boost per gear or rpm is sick.

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slider2828

You could using a bike cadence monitor. That can measure RPM or speed at the wheel. So you have the magnet at the FRONT wheel and the pick up on the arm or fender or something like that... I think that would work....

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jspaeth

I am certain you want to always put down as much torque as you can without spinning wheels...

As soon as you spin wheels, you are not really loading the turbo and spooling it.

In 1st gear (I'm sure it's the same for you).......even with a good launch, if I feather the throttle through the beginning and midrange and then floor it near the top, I can "kinda" get through first gear without the wheels spinning.

On a 240, the gearing is such that an upshift from 8K in 1st gear to 2nd gear puts you somewhere around 4200 RPM (if I remember correctly).

SO any significant breaking of traction, and you are not moving at the MAXIMUM speed at redline in 1st........when you downshift, you end up in 2nd gear in like the 3-4K RPM range, and it will take some time to respool the turbo.

My opinion is that you need wheelspin off the line, obviously, but you really want it gone by the end of 1st gear.....

......however, maybe things are different for those of you who flat-foot shift, but I am not in a position where blowing out my transmission, axles, or rear end is desirable/convenient to fix, so I don't do that.

Cody, when I break traction and hit the rev limiter in 1st gear, I only build like 10-11 psi boost, versus like 18-20 psi target.




Someone above mentioned the PowerFC boost control kit..

Generally, the solenoid for this is the same solenoid that comes with the AVC-R....however, there is a general consensus that the AVC-R is far more effect and has more features than the "built-in" boost control in the PFC, which people usually disenable

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mattsil80wis

I know in Cody's car and my own (same build but in a s13) that our cars go to 20psi even when there is no traction in 1st than you hit 2nd and the car keeps spinning at 20psi until you hit 3rd....even if you go WOT in 2nd at like 3k once the turbo hits 20psi it breaks the tires loose and you start spinning again

jspaeth

Interesting....all I know is that when I floor it from a dig (lets say) in 1st gear, the tires break loose in the mid range, where the boost would normally build, and the turbo never builds more than 10-12 psi.

This is actually consistent with what I've seen in other places.....under no (or significantly reduced) load, the turbo will not spool all the way....I don't understand how you are building full boost in 1st gear anyway, even with spinning wheels.

I have read in other places as well where people don't hit full boost in 1st gear bc the revs go up from 4K--->redline before the turbo can even reach full boost.

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KoukiMonsta

i am with you entirely on this one. i can never make more than 10-12 pounds in 1st. and thats with or without traction. typically once i hit ~4k it just straight "jumps" to redline. no traction at all ftw...

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codyace

Well, we don't hit 20 psi, but both cars make above 14 psi. I've made it a point to watch this.

BUt yes, 2nd gear is a real nitemare sometimes depending upon where you go WOT...i know if I roll into it it will sometimes be nice and stick...but there are also times where I stab it at 4 or 5 ki and it'l bust them all loose.



BUt back to the issue of traction, would feathering the car in first, be faster than lugging a bit in 2nd and using the mechanical advantage to keep going. I know if I hit 2nd gear hard after spinning first off, 2nd gear will keep the tires right on spinning...can get hairy!

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jspaeth

Honestly, I feel like any answer I give may just be bullshit, bc I am not an expert enough driver to be able to get amazing launches.

On stock SR swap, I cut a 1.9 60' on street tires and ran 13.5 @ 100 mph.

With GT2871R (no headwork tho), I could only manage 13.3, but @110 mph because of a TERRIBLE 2.4 60'......I just could NOT control the wheelspin.

My feel is that controlling the wheelspin through 1st gear is even MORE important on our turbo cars than a V8, because if you spin too much, then you shift into 2nd and come in at an RPM below the point at which the turbo is fully spooled.....I would guess that this could potentially even cost you like 0.5 sec on a 1/4 mile run.

In a V8, who cares if you shift into 2nd and go all the way down to 3000 RPM.....many of them make full tq at that point, if not earlier!

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2fast4y0u

im gonna jump in here with out reading completely everything you 3 guys are saying.
i can not build full boost in first. maybe 10 if im lucky
i ran mid to high 13 in the 1/4 at 100ish mph. i have never had a good 60 foot, dont know why.
havent had a chance to run it with the turbo upgrade(2871rs) yet, but i can assure you next season i will be spending lots of time at the track.

i dont even build 12psi in second gear!

jspaeth

1st gear is understandable, but you should be able to hit full boost in 2nd.....are you using the stock actuator?

Any boost controller?

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2fast4y0u

stock acuator
no boost controller...cant figure out the pro fec yet