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 Post subject: Re: supercharging
PostPosted: November 6, 2017, 7:40 pm 
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throttle bracket1. i cut this out on the band saw and walked round to the belt sander to deburr it, on the way i fell over a hose, because i have a pile of junk in the shop where i am trying to finish my house and i dare not throw anything away, you all know why, i fell over it all and cut my hand, knee, wrist, hurt my back and banged my head, but whilst falling i let go of the bracket and could not find it anywhere.

bracket 2, recut the bracket and welded ribs to it but the hood wouldn't fit so i started editing it, the abridged version is a mere shadow of it's former self but seems to be strong enough for the job, have you ever tried to buy a ranger throttle cable, none of the usual suspects have a listing for it, fortunately i have the part number and it is on sale at the online dealer.

went to autozone today while on the grocery run, asking for a 840k6 belt, well every size but that one so i get a 845k6 belt and guess what its too long.

purchased some fir tree hose fittings for the idle air motor block today, at about $2.00 each so the cost went up by $12.00.

now the running total has skyrocketed to $237.00

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 Post subject: Re: supercharging
PostPosted: November 6, 2017, 9:32 pm 
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john hennessy wrote:
...the map sensor is as far as i can find out, a 1bar unit and i will be boosting to about 1.5 bar so maybe this will have to change to a 2 bar sensor...

A 1.0 bar sensor on a NA engine is normal. You said you're going to boost to 1.5 bar - is that 0.5 bar above atm prs, meaning 1.5 bar total, or 1.5 bar above atm prs?

What compression ratio is your engine?

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 Post subject: Re: supercharging
PostPosted: November 7, 2017, 12:36 pm 
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compression ratio of a duratec 2.3 is 9.7-1 and i will be adding an additional boost of 5lbs, at least that is my target.

with the size of the supercharger this may come up very quickly so i may find that i must limit the boost by having the bypass valve boost opened with a pressure switch and solenoid, if this is required, i will use the solenoid for the original tumble flaps and an adjustable hobbs switch.

the location for the MAP sensor is in the vacuum manifold prior to the supercharger so will never be subject to more than 1 atmosphere.

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 Post subject: Re: supercharging
PostPosted: November 7, 2017, 2:06 pm 
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john hennessy wrote:
... the location for the MAP sensor is in the vacuum manifold prior to the supercharger so will never be subject to more than 1 atmosphere.

No, the MAP sensor must monitor what the engine's seeing, otherwise, the engine will run so lean under boost that it'll grenade. Yes, it may cost $0.37 more - OMG - for some hose, but do not proceed with it as it is. I highly recommend reading up on forced-induction and what's involved in converting NA to FI, else all this will just result in expensive drama.

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 Post subject: Re: supercharging
PostPosted: November 8, 2017, 2:40 pm 
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i disagree completely on this and "must" does sound a bit dictatorial, we shall see what happens.

as far as grenading the engine, i remember a certain triumph bonneville drag bike that blew the cylinders right off, mind you, it was running 15 lbs of boost and 40% nitro with static compression of 8-1, we just made a "tie down" kit to hold the top of the engine to the crank cases, does wake you up with a bit of a start though when you are lying on top of it.

my MAP sensor only ever sees vacuum, if my map sensor saw boost it would be a different story and would not be able to correct the fuel for any situation above atmospheric so at least a two bar sensor would be required and the fuel map would need to be modified within the 5 volt range to deliver more fuel per volt drop up to a 5 lb boosted 2.3 engine at 6000 rpm

MAP sensors operate between 0 volts and 5 volts no matter what the range of the sensor is, a 1 bar sensor operates 0 bar = 0 volts and 1bar = 5 volts, a 2 bar sensor operates 0 bar= 0 volts and 2 bar =5 volts therefore a 2 bar sensor at 1 bar will measure 2.5 volts. ( the pcm will think there is vacuum in the manifold or you are in the upper atmosphere )

in a boosted situation, it would need to be calibrated to deliver the n/a fuel quantity at 2,5 volts for a given rpm instead of 0 volts, thus allowing an additional 2.5 volts for any pressures over atmosphere up to 5 volts allowing a boost level up to 15 psi.

ignition on, atmospheric pressure is sensed by the MAP, so 5 volts as atmosphecic pressure is 1 bar.

engine cranking, throttle closed, vacuum is sensed therefore the volts drop, fuel is added because the pcm knows the engine is going round so opens the iac

engine fires, throttle closed, vacuum increases and voltage drops even more and the pcm knows that it has reached idle rpm and adjusts the iac to suit, at this point the engine has no idea if it is supercharged or not as the by-pass valve is open and the supercharger cycles any air it sucks over that which the engine is using and the map senses engine vacuum

WOT, vacuum goes away and manifold is close to atmospheric so volts increase towards 5 volts, bypass valve closes and boost is started.

now if all i was dealing with was a 1bar MAP sensor in the pressure manifold then yes it would go lean because 5 volts would be sensed when the manifold reached atmosphere and no more enrichment could take place but i'm not.

during all this time, the MAF has been measuring the air mass being sucked in and will continue to do so as the supercharger sucks more than the engine needs enriching the fuel in line with the air demanded by the supercharger as measured by the maf.

there are two questions needed to be asked, the first is, does the MAP sensor in the vacuum manifold before the supercharger really only baseline the engine for altitude? and the second, will the MAF sensor reach 5 volts before the engine reaches 6000 rpm due to the extra air being sucked in by the supercharger? ( lbs of air per volt, 5 volts when the engine is only at ? rpm )

we are dealing with an air demand as if the engine was 50% larger given that the boost is limited to 5lbs of boost, this may be reached long before the engine reaches 6000 rpm.

prior to this point the engine has been using up air at a slower rate than the supercharger can supply causing a buildup of air in the boost manifold

this point if reached would suggest that the MAF sensor be calibrated to give less volts per pound of air passing through it and more fuel per volt was added in the PCM ( just like a 2 bar map sensor )

if this can be achieved, as long as the fuel delivered was in line with the air being sucked in by the supercharger, where this air and fuel go is of no importance as it is the correct mixture for an engine to run so if it finds it's way into the engine we can go off down the road.

i might add that throttle body size, MAF sensor size and injector size may limit performance but this is not a race car, it is a street car and the same applies to carbed engines where a small two barrel carb is factory installed and you the hot rodder swap it out for a four barrel.

look, i know that if i put a 1 bar map sensor in the pressure manifold it will go lean so i am NOT going to do that i am going to put it in the vacuum manifold where it only sees atmosphere or vacuum.

enough to say that this is not my first rodeo.

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Last edited by john hennessy on November 8, 2017, 3:35 pm, edited 1 time in total.

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 Post subject: Re: supercharging
PostPosted: November 8, 2017, 3:01 pm 
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KB58 wrote:
john hennessy wrote:
... the location for the MAP sensor is in the vacuum manifold prior to the supercharger so will never be subject to more than 1 atmosphere.

No, the MAP sensor must monitor what the engine's seeing, otherwise, the engine will run so lean under boost that it'll grenade...

john hennessy wrote:
I disagree completely on this, we shall see what happens.

Indeed we shall :lurking:
To anyone looking for advice on forced induction, this thread should serve as a cautionary tale - I'm completely serious.

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 Post subject: Re: supercharging
PostPosted: November 8, 2017, 3:59 pm 
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Depending on the ECU (my experience is with MSII) the MAP sensor is used as one of several inputs to calculate the actual air being ingested by the engine. It is also used, on startup, to determine initial ambient air pressure (altitude). A 2nd pressure sensor could be added to determine air pressure/altitude continuously. That would be plumbed to the atmosphere. The MS handles both configurations just fine.

I suspect that a MAF sensor could take the place of the MAP sensor to determine the air volume flow. Heck that is what it is designed to do. However, for a boosted conversion I doubt that the N/A MAF could be calibrated properly. One could always use the MAF from a different engine but that would require access to tuning tables within the ECU. I have no experience in that, although I can imagine it being done.

The TPS and the MAP sensor can be also used to determine instantaneous load changes that would momentarily require more fuel like an accelerator pump would do. The MS lets you even blend the two inputs under various conditions if desired, both in accelerate and decelerate condition (my physics teacher would call me on using the pseudo-word decelerate :D ). The TPS is monitored and can be used to clear a flooded engine if necessary.

The bottom line is not the actual plumbing, but what ECU is being used and what controls a person has to tune it. I am a big proponent of the MS system, but if an OEM ECU might be used, then why not try? if going that route, then whatever plumbing scheme it was designed for should be used IMO.

I think all of the differences in this discussion are due to different perspectives and personal experiences. What's the worse thing that can happen here? The engine doesn't start and the system needs to be rethought/replumbed or maybe it even blows up. The best thing is that it works just as John expects it to. Let's grab a :lurking: and see what happens.

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 Post subject: Re: supercharging
PostPosted: November 8, 2017, 4:20 pm 
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 Post subject: Re: supercharging
PostPosted: November 8, 2017, 6:01 pm 
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KB85, perhaps you could elaborate, i am willing to learn.

why is this so critical to have the map sensor in the pressure manifold?

if the pcm knows the rpm of the engine all it has to do is supply fuel and air to sustain that rpm, if it is supplied with more air and fuel at the correct ratio it will accelerate until the amount of air the throttle plate will pass is reached or the physical ability to rev higher is the limited by the volume of the engine

the air and fuel that the engine demands is of no importance if you supercharge it, as long as you have a means to measure the mass of the air going in to the supercharger you can add the right amount of fuel to suit and a maf does exactly that.

if you by some misfortune, have unmetered air going in or escaping like a split hose or defective pcv valve it is sensative enough to affect the tune because the maf is now telling lies and a map won't change that or compensate for it.

lets be a bit more basic here, if you change some components like a header, then the ability to move air into the engine will increase due to the scavenging effect of the exhaust increasing the pull on the incoming air charge far above the piston moving down the bore, the effect is an increase in the size of the charge in the cylinder. ( supercharging the cylinder )

how does a carb know how much fuel to add to the incoming air to keep the mixture correct, it has a venturi, a section if the intake where the air pressure drops causing a suction on the fuel which is at atmospheric pressure in the float bowl, drawing fuel out of the jet at the correct amount, this differential is what gives the correct 14-1 ratio based on jet size and the mass of air passing through the venturi.

therefore if we measure the mass of air going into the engine electronically we can then add fuel to that specific amount of air by increasing or decreasing the injector pulse width thus maintaining the 14-1 ratio, simple isn't it.

of course a carb is already at atmosphere on top of the fuel in the float bowl so it knows what the particular pressure is on a particular day at a given altitude, with fuel injection there is a degree of separation between the atmosphere and the fuel delivery system so we have to tell the engine management system what the true pressure is, a map sensor does this by shifting the whole fuel map sideways if you will dependant upon the pressure it sees when the key is turned on.

over and above this, it keeps track of the pressure or lack of it in the inlet manifold where the engine displaces air at a given level for its capacity and rpm and the throttle plate strangles that displacement dependant upon it's angle thus causing a partial vacuum or not if the throttle plate is open sufficiently to pass more air than the engine can consume at a given rpm, the engine will increase in rpm until that point of equilibrium is met where the engine consumption of air is equal to the throttle opening.

in real terms it does not equal but maintains a vacuum as it wants to accelerate and always suck in air even if it is not available, the map sensor has a handle on this vacuum and trims the fuel pulse width until the vacuum deminishes at which time it increases the pulse width and the engine accelerates or the vacuum increases and it trims the fuel causing the engine to slow down.

in a n/a engine the map only has to measure pressures at atmosphere or below in a vacuum, in a s/c engine where positive pressure may exist and it is located in the section of the manifold where that pressure does exist it is required to measure the pressure over that which would normally exist if it were not s/c. now it needs to be capable of reading from X Hg to what ever boost lbs are intended so that the fuel quantity will be corrected by the pcm for the amount of air entering the engine, increasing or decreasing the pulse width to suit.

this returns us to the above requirement for the map of reading the actual atmospheric pressure before the engine cranks as it is required to make very very small adjustments constantly, some are less than the normal changes in atmospheric pressure due to altitude or climate conditions. ( poor little sensor, all that responsability, you'd think they would give it a little help, especially if you were racing up Pikes Peak where the base line atmospheric pressure is nothing like that at the top.)

enter the maf sensor which instead of measuring pressure or lack of it, it measures the mass, that reads weight, of the air being ingested by the engine and as the fuel pressure is a known quantity therefore it's mass, it will and does calculate in live data the fuel ratio many times a second, if that's the air going in right now, this is the amount of fuel the pcm must add right now.

so which would you choose map sensor or a maf sensor, i've got both.

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 Post subject: Re: supercharging
PostPosted: November 8, 2017, 6:14 pm 
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well we progressed with the idle air motor housing, just a block with the idle air motor on one side and two 1/2" hose stubs on the other and complimenting hose stubs, one on the inlet manifold and one in the intake runner from the maf sensor.

no additional parts purchased.

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 Post subject: Re: supercharging
PostPosted: November 9, 2017, 1:59 am 
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john hennessy wrote:
i disagree completely on this and "must" does sound a bit dictatorial, we shall see what happens.


Kurt's point is that if you're using a MAP-based algorithm like Speed Density, your MAP sensor needs to be able to see boost.

From the rest of your post, it seems like you plan to keep MAF but somehow hack it so that it gives you enough fuel?

Quote:
look, i know that if i put a 1 bar map sensor in the pressure manifold it will go lean so i am NOT going to do that i am going to put it in the vacuum manifold where it only sees atmosphere or vacuum.


No one is telling you to feed bad information to your stock ECU.

Quote:
enough to say that this is not my first rodeo.


Really? It certainly doesn't sound like you've done anything with forced induction or engine management before.

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 Post subject: Re: supercharging
PostPosted: November 9, 2017, 3:41 am 
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not speed density, if you had chosen to read my post you would know that but i guess you didn't read anything so until you do read the post stop commenting.

and just a point about comments, if you think you know more, please say what you know so we can all know what you know or just don't comment put your money where your mouth is, don't just say that i'm doing it all wrong, i have asked for you to explain why i should do it differently but no answers were forthcoming.

this is directed at Kurt and Laminar, do either of you know anything about Ford EEC-V engine management?
if you do tell me.

you have no idea what i have or haven't done, know or don't know, just like i have no idea what you know because you won't say

i will find out if it works when it's done, i don't like to post things like the above but really?

in fact i don't think i'll post about this any more as it's clearly over your heads!

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 Post subject: Re: supercharging
PostPosted: November 9, 2017, 2:25 pm 
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What year PCM are you using?

If it's a four-wire TMAP, it's used as part of the differential equation to measure EGR flow, and BARO on startup.

My guess is the boost will upset the OBDII monitors to the point you will have a check engine light. You may run out of injector, too. If you try to run a bigger injector, that will *really* screw up the tuning. That is the main reason I ran M/S on my SVO clone (well, that and the fact I was running 63pph injectors, no vane airflow meter and E85).

I suggest investing in a cheap wideband to see where the A/F ratio ends up at WOT.

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 Post subject: Re: supercharging
PostPosted: November 9, 2017, 3:56 pm 
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With the MAP sensor at the proposed location, assuming a new inverted MAP calibration, and using a pressure-relief valve to limit boost, the MAP sensor can't differentiate where the air's going, only what the pressure is. An example:

1. At partial throttle, just below the relief valve's opening point, let's imagine that the ECU is injecting the right amount of fuel to give the proper air/fuel ratio per what the MAP sensor reads.

2. At any point above that, the ECU continues injecting whatever the MAP sensor tells it to, only now the pressure relief valve has opened and some portion of that total never makes it into the engine. The higher the boost, the worse the error, and if you're lucky the engine will keep running; if not, it'll flood or possibly even hydrolock.

The above is true whether a MAP or MAF sensor is being used since both aren't measuring what's flowing into the cylinders. All this is a non-issue when the MAP sensor is in the downstream location.

The above assumes the vented air is released to atmosphere. If instead, it's recirculated, it very quickly heats up the air charge and will threaten preignition. The IAT "should" be directly on the intake manifold to measure the air entering the cylinders. If it's instead located upstream of the supercharger, it's another disaster in the offing.

There are other issues as well, attempting to scale down true MAP yet expect accurate readings with a 1 Bar sensor. Then there's the noted issue with injector sizes, where the stock parts will probably lean out. Another issue is where the fuel pressure sensor reference line is going. If that's not run to the proper location, the engine will run dangerously lean. As suggested, an AFR gauge isn't a mere suggestion, it's a requirement.

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Last edited by KB58 on November 9, 2017, 4:16 pm, edited 1 time in total.

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 Post subject: Re: supercharging
PostPosted: November 9, 2017, 4:13 pm 
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I'm honestly leaning towards carb(s) on the inlet to the SC being the right idea here. :ack:

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