fabrication question

General engine tech -- Drag Racing to Circle Track

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mk e
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Re: fabrication question

Post by mk e » Fri Mar 23, 2018 2:01 pm

Here's the rest of the info from Jared who draw it up. As far as I know only the the 12 cyl version was ever actually built but the board was design do it could simply be cut to length and I did test a sawed down version iirc.
The files are posted here. 

https://github.com/jharvey/MultiMAP


I see I created gerber files in folders like as noted here for the 6cyl. You should be able to find what ever number of cyls you are dealing with and get the MFG files from that folder. 

https://github.com/jharvey/MultiMAP/blo ... p_6cyl.zip


Most fab houses can accept the zip file. For example you should be able to upload that zip file to OSHPark, and then you should be able to order it. As well I see the BOM in that folder should provide you with the components which are needed for making the board. 


If something goes wrong and different files needed by the PCB MFG, the source KICAD files can be found at the below link. With the source file(s) pretty much any MFG can be supported. 

https://github.com/jharvey/MultiMAP/tre ... _map_kicad
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Re: fabrication question

Post by Belgian1979 » Fri Mar 23, 2018 3:01 pm

Thanks Mark. Seems like I have something to chew on the next couple of days :)

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Re: fabrication question

Post by mk e » Fri Mar 23, 2018 5:04 pm

Yeh, have a look, its pretty straight forward. Its an open design which generally means anyone can build it but no one actually does...which is why I've lost my love of open stuff generally.

This was drawn up and prototyped...6 years ago? I'm pretty sure the sensors specified are the obsolete 105kPa version so if nothign else you'll need to find the part number for the 115kPa replacements, not sure what else might need to be updated. If you want one though I'm sure we can get you threw building one.

If there is any other interest we could probably put some kits together or maybe assemble a few?

Having done a couple ITB setups in the past without this little gem and now seeing what I get for a MAP signal with it, I probably wouldn't do an ITB setup any other way.....but other options work too so preference maybe.
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Re: fabrication question

Post by Belgian1979 » Sun Mar 25, 2018 4:51 am

This is what I came up with :

connection of the lines to the runner with screw to pinch the rubber line and adjust airflow
Image

Vacuum reservoir made out of a Moroso oil catch can. Stubs for the rubber lines are on the opposite side of the IAC/PCV/Brake entrance and around the perimeter so they all have equal access to the IAC air supply.

Image
Image

Now I need to drill the holes for the 8 map sensors.

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Re: fabrication question

Post by mk e » Sun Mar 25, 2018 8:16 am

Each line going to the vacuum can needs a check valve....a simple inline will do. I'm not sure you need to connect to more than 1 cyl...the Weber carbed Ferraris with power brakes just connect to 1 cylinder and seem to work fine.
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Re: fabrication question

Post by ptuomov » Sun Mar 25, 2018 8:34 am

mk e wrote:
Sun Mar 25, 2018 8:16 am
Each line going to the vacuum can needs a check valve....a simple inline will do. I'm not sure you need to connect to more than 1 cyl...the Weber carbed Ferraris with power brakes just connect to 1 cylinder and seem to work fine.
Is this for power vacuum of signal vacuum?

For power vacuum, yes, I think check valves make sense.

But why would one want check valves for signal vacuum? I don’t think any of the factory map systems have check valves on signal vacuum lines. Logically, I also don’t understand how that’s going to improve the signal consistency. Perhaps this wasn’t the intention anyway.
[b]Paradigms often shift without the clutch[/b] -- [url]https://www.youtube.com/watch?v=cxn-LxwsrnU[/url]

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Re: fabrication question

Post by ptuomov » Sun Mar 25, 2018 8:42 am

It’s my understanding that connecting all eight intake ports to a small volume vacuum log with small diameter flexible hoses will give a good signal. Combining that vacuum signal with the throttle position signal would be the way I’d go in a normally aspirated ITB engine. I think that’s the standard arrangement in four cylinder motorcycle engines.

I think that the power vacuum should be completely separate from the signal vacuum. To generate the power vacuum, one needs check valves, Venturi jet pumps, and reservoirs.

Curious whether others agree with my opinion.
[b]Paradigms often shift without the clutch[/b] -- [url]https://www.youtube.com/watch?v=cxn-LxwsrnU[/url]

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Re: fabrication question

Post by mk e » Sun Mar 25, 2018 8:44 am

Right, no check valves for anything but brakes.

My thought was, and I was just going back to clarify, use the canister as is for iac, but add a separate line to 1 or mabe 2 cylinders for brakes....i think someone else already suggested it.
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Re: fabrication question

Post by mk e » Sun Mar 25, 2018 9:24 am

ptuomov wrote:
Sun Mar 25, 2018 8:42 am
It’s my understanding that connecting all eight intake ports to a small volume vacuum log with small diameter flexible hoses will give a good signal. Combining that vacuum signal with the throttle position signal would be the way I’d go in a normally aspirated ITB engine. I think that’s the standard arrangement in four cylinder motorcycle engines.

I think that the power vacuum should be completely separate from the signal vacuum. To generate the power vacuum, one needs check valves, Venturi jet pumps, and reservoirs.

Curious whether others agree with my opinion.
That is a very common path and usually works ok.

Ganging the MAPs drops the signal to about 1/3 to 1/2 of what you get with individual MAP sensors so npt a great stategy on a setup that has a poor vacuum signal.

Using TPS as the main load sense also works but down near idle, were street cars spend about 99% of there time, just a couples % change can mean double of triple the air flow when large itbs are used with no vacuum cams...so again not ideal.

Usually you can switch between the 2 signals to get something the works well...crossover points are always a challenge but can be managed. Sometimes the signal qualities are just not very useable.

I think focusing up front on getting the best quality signals you can get is the right place to start. Individual MAPs gets you the best possible signal short of going to fancy transducers. Making sure the there is no air flowing in through anything but the TB does the best you can do to get the TBs open and avoid the massively nonlinear portion of the flow curve near TB close. Then you work with it....
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Re: fabrication question

Post by Belgian1979 » Sun Mar 25, 2018 10:00 am

In my understanding neither brakes, iac or pcv would have a problem with an inline check valve as the air should only flow in one direction. So yes this is on the list.

I have seperate take off for vacuum signal for the map and fpr. I just made up a piece of fuel rail with holes drilled to accept a fitting for the rubber hose and only a 1.5 mm hole connecting it to the log itself. That way cross talk between cylinders should be limited via the map hoses.
Afterwards I might take out the maps altogether and deal with it via electronics.

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Re: fabrication question

Post by mk e » Sun Mar 25, 2018 5:37 pm

Progress.

I remember reading somewhere MS lets you sample MAP based on crank angle...can you do that?

If so you could just connect the MAP to a single cylinder and set the angle for the strongest signal at or near idle. That is basically how I pull the individual cylinder data from the output on my multMAP, I read in 30 degree windows. You'd only be getting a signal from 1 cylinder but pulling it when the crank is around 90 degrees down intake should double or triple the vacuum reading you see. Maybe worth a quick try when you get it back together, if it doesn't improve things you can always go with your improved plenum.

There is some downside to only reading 1 cylinder....you add a bit more lag to the signal and it may not be representative if the TBs are way out of sync., but if it helps you can switch to a multiMAP type setup to solve all that if its a problem.
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Re: fabrication question

Post by ptuomov » Mon Mar 26, 2018 9:41 am

On the idle air controller: That needs to bypass the throttle plate. I don't see how the idle air controller can be productively hooked up into this power vacuum canister. Maybe I've misunderstood the intent.
[b]Paradigms often shift without the clutch[/b] -- [url]https://www.youtube.com/watch?v=cxn-LxwsrnU[/url]

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Re: fabrication question

Post by mk e » Mon Mar 26, 2018 10:04 am

ptuomov wrote:
Mon Mar 26, 2018 9:41 am
On the idle air controller: That needs to bypass the throttle plate. I don't see how the idle air controller can be productively hooked up into this power vacuum canister. Maybe I've misunderstood the intent.
The hoses connect on the engine side of the TB and the check valve allow follow toward to engine so in theory it can work.

In practice allowing the pcv and iac flow into the chamber will drop the vacuum available to the brakes, but I guess he's already got an electric vacuum pump so that will still work...but separating the systems might eliminate the need for the vacuum pump.
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Re: fabrication question

Post by ptuomov » Mon Mar 26, 2018 10:49 am

mk e wrote:
Mon Mar 26, 2018 10:04 am
ptuomov wrote:
Mon Mar 26, 2018 9:41 am
On the idle air controller: That needs to bypass the throttle plate. I don't see how the idle air controller can be productively hooked up into this power vacuum canister. Maybe I've misunderstood the intent.
The hoses connect on the engine side of the TB and the check valve allow follow toward to engine so in theory it can work.

In practice allowing the pcv and iac flow into the chamber will drop the vacuum available to the brakes, but I guess he's already got an electric vacuum pump so that will still work...but separating the systems might eliminate the need for the vacuum pump.
I don't think it's a good control system to feed the idle air from the vacuum canister to the intake port with a control valve in the middle. In fact, that's a terrible control system once you consider the operating modes. How's the control system suppose to predict the drop of the pressure insde the vacuum canister and stabilize idle? I wouldn't do that.

As an atlernative arrangement, allowing the IAC to bleed air into the vacuum canister defeats the whole point of having a vacuum canister. To first order, the IAC is going to attempt to regulate the vacuum canister pressure to some level that runs the idle well, which is likely not the level of vacuum that one wants to power vacuum operated devices. That's in my opinion another ill advised control system.

Instead, I'd just have a single hose inlet from the air box (post filter) to a IAC and then a manifold to distribute the idle air to inlets between each throttle blade and intake valve. I assume each throttle body has some idle adjustability one way or another, and the pressure measurement from the vacuum signal ports can be used to equalize the air flow to each of the cylinders.

Each throttle body is going to need three ports between the throttle blade and intake valve. First, the signal vacuum. Second, the power vacuum. Third, idle controller bleed. Need is a strong word, of course. I don't think one "needs" a controlled idle, one could just tune the idle with the screws like in the old times. One could also just use a pump for power vacuum. But I'm sure you're getting my point.
[b]Paradigms often shift without the clutch[/b] -- [url]https://www.youtube.com/watch?v=cxn-LxwsrnU[/url]

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Re: fabrication question

Post by mk e » Mon Mar 26, 2018 11:12 am

I would separate the brakes and iac too, but he's been running a very similar setup with the MAP in the same chamber and it's been working so while not ideal it has proven functional. I think this is certainly better than what he had if not yet everything that could be done.
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