• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Cylinder Pressure Data Logging?

Dylly

Dylly

Member
Messages
183
Reaction score
3
Location
Saskatoon, Saskatchewan, Canada
Has anyone found any reasonable options for cylinder pressure data logging?

I plan on beginning a fairly radical build this summer and would like to use my current cylinder pressure as a guideline to how much boost and fuel that I can feed it after lowering compression. I’m basically trying to avoid bending connecting rods like 6.2Turbo did – Unless there are connecting rod options out there because as far as I can tell, that will be my limiting factor for this build.
 
I tried a 5000 psi gauge connected to a compression tester. The shraider valve couldn't take the heat . I'm running 30 psi boost now with 280 psi cranking pressure. This is with a GM 5 turbo. Got over 2000 miles on it so far.
 
6.2 turbo said:
I tried a 5000 psi gauge connected to a compression tester. The shraider valve couldn't take the heat . I'm running 30 psi boost now with 280 psi cranking pressure. This is with a GM 5 turbo. Got over 2000 miles on it so far.
Click to expand...

Yeah thats a big issue: heat. For me, cranking psi doesnt mean anything in the way that I want to use the data - the combustion process is a little to complicated to mathematically figure out especially when turbo back pressure, exhaust manifold design etc is playing additional roles.

I just want a pressure transducer that can handle the heat and psi - and a little logging tool to take data so I can find out what it is under wide open throttle.

Something like this would be ideal but I'm not sure if there are any compatible pressure transducers for it:

http://www.innovatemotorsports.com/products/ssi_4.php

Little side-bar but, what did you do to a GM-5 to get it to do 30 psi without being ridiculously inefficient and choke the hell out of your engine? (other than nailing it wih a pile of fuel)
 
Here's something to check out: http://www.optrand.com/fliers/PSIglow4Jan2007.pdf

I've read that GM was considering using some type of in-cylinder, real-time cyl pressure monitoring for an upcoming diesel. Don't know which one?

The concept of having the pressure sensor incorporated into the form of existing glowplugs would certainly make retrofitting this tech easier. Then gotta come up with a cost effective datalogger setup with modern, fast sampling rates. Would also be nice if the datalogger would run/work with GM's freq response signal mass air sensors so we could read actual mass air flowrates instead of guestimates of what the different turbos flow.
 
Turbine Doc said:
Possibly Omega could point you in the right direction http://www.omega.com/ they supply some of the test equipment we use in turbine testing but it isn't cheap.
Click to expand...

My professor actually recommended Omega too so, I just sent them an email - Everything that I saw wasnt cheap, thats for sure, but from what I could tell, nothing could handle the temperature that I'm going for unless combustion temperature is going to be the same as the exhaust temperature... which I find hard to believe.
 
SmithvilleD said:
Here's something to check out: http://www.optrand.com/fliers/PSIglow4Jan2007.pdf

I've read that GM was considering using some type of in-cylinder, real-time cyl pressure monitoring for an upcoming diesel. Don't know which one?

The concept of having the pressure sensor incorporated into the form of existing glowplugs would certainly make retrofitting this tech easier. Then gotta come up with a cost effective datalogger setup with modern, fast sampling rates. Would also be nice if the datalogger would run/work with GM's freq response signal mass air sensors so we could read actual mass air flowrates instead of guestimates of what the different turbos flow.
Click to expand...

This is really cool stuff. I just sent them an email too.

That 0.5-5V output makes me think that I might be able to make it work with that Innovate motorsports data collection system... Hopefully they aren't a fortune; I really dont want to resort to estimated hand calculations.
 
Am I misinterpreting the "Maximum operating temperature" because these guys also sell a glow plug transducer:

https://www.avl.com/pressure-sensors-for-combustion-analysis

And it's operating temperature is the roughly the same as the one sold by optrand (400C or 750F) but this one maxes out at ~ 3500psi.

Does anyone know how to interpret that operating temperature and whether 3500psi is reasonable/ would we fit in that range? or what might be expected?
 
There was an article on Duramax tuning, injection timing etc., in the Maxx Torque magazine (maybe just online now?) a few years back, that showed plots of cylinder pressure - vs - crank angle, that if memory serves would give some idea of cylinder pressure. And I would have guessed the data to draw the plot came from a sensor like these combo glow plug/pressure transducers?

Have also seen diesel cylinder pressure plots from Banks also so you might try searching that.

As the OEM's use this type of sensor in engine development & have wanted a sensor cheap enough & durable enough to put them on production engines as another input for engine mgmt, you'd think the tech has been in development for awhile. Now whether or not it's anywhere near affordable, or long-term tough enough to be practical yet may be another story.

Looking for sensors designed specifically for that use makes sense because it's gotta be tough enough & fast enough responding, to get useful data. Then you've got to have a datalogging system that can read & record it fast enough. Gotta be faster than a few times a second to really see how cyl pressure behaves in real-time.

As a side note - I need to inquire with Innovate to see if that logger system can incorporate the freq response curve for the now common 3.5" GM mass airflow sensors? I've got one & would like to plumb (at least temporarily) it into my air intake pre-turbo to actually measure mass airflow on our diesels. You can make logical guesses as to airflow, & it's not truly necessary for tuning,...but I'd still rather add some actual/quantitative numbers to the 6.5 knowledge base. Most other platforms where the OEM incorporated a mass airflow sensor have built significant online databases of what combinations do flow-wise.
 
SmithvilleD said:
Looking for sensors designed specifically for that use makes sense because it's gotta be tough enough & fast enough responding, to get useful data. Then you've got to have a datalogging system that can read & record it fast enough. Gotta be faster than a few times a second to really see how cyl pressure behaves in real-time.
Click to expand...

That sensor has a natural frequency of 130 kHz which would easily be able to output enough data since 3600 rpm is 60hz so it should be able to 2000+ data points per revolution; so that's covered. But it doesnt state what it's output is so IF that glow plug is a 0-5V output AND that innovate performance SSI-4 is compatible; it is capable of doing 15kHz which is still 250 data points per revolution which is fine.

I dont remember the range on that MAF sensor but there are often tables for the voltage outputs and the Innovate Performance SSI-4 does have an RPM input (frequency) so I can't see why you wouldn't be able to use it as a frequency response system for tuning ... as long as that MAF is a 0-5V output.
 
That oughta be plenty fast/high enough resolution to see a reasonably smooth curve. And then for your application, can you use either the rpm freq input, or use inj pump optical sensor freq input (or crank angle sensor) so you can index the pressure readings correctly to crank angle.

Believe the LS engine GM mass airflow sensors output a frequency signal proportional (although not that linear) to mass airflow. Unfortunately these airflow sensors aren't as simple to setup for other uses as the common 0-5V signal hotwire MAS like were used on the mass airflow managed Ford engines. Those were easy to adapt to other aftermarket ECM's. I've seen an aftermarket freq converter box to allow using the modern 3.5" GM MAS (with plenty of of flow headroom) on the turbo Mitsu engines (that originally used a freq output MAS that didn't have enough headroom to accurately meter 2-3x stock airflow levels those engines move when getting 450 hp plus out of 120 cubic inches.

I do like the idea of a couple of us 6.5'rs working with that Innovative logger. Tuning these things & turbo comparisons could be brought into the new millenium with some modern datalogging capability. The GMTDScan tech is a very useful tool, but no logging & crude in comparison to more modern tuning tools.

I built a wideband O2 sensor from a kit utilizing one of the first OEM broadly used sensors Honda put out; did this back in the late 90's. Now you can buy a notably more durable, ready-made & relatively cheap setup. Be interesting to see if these combo glowplug/pressure sensors develop into mainstream, cost-effective OEM use. Expecting them to be $ now.
 
SmithvilleD said:
Believe the LS engine GM mass airflow sensors output a frequency signal proportional (although not that linear) to mass airflow.
Click to expand...

To bad you didnt have an OBD II truck and could just log data with HP tuners.

My plan is to go with the mechanical injection system so tuning is out of the question for me BUT for you, there are plenty of small chips that can be wired up to convert the frequency into a voltage; I just dont know what you would need specifically but I found this today:

http://www.globalspec.com/learnmore...converters/frequencytovoltage_converter_chips

Under related products, you should be able to find what you need... I think.

Also, still no word back from either of those glow plug pressure transducer companies and Omega claims they have nothing for me which I find hard to believe but from the quickness and tone of the email that I recieved, that girl hates her job there/ probably didnt even look, so I guess I'll search elsewhere.
 
Have you tried Racepak ? They do alot of data logging for drag racing . They might have something or know how to do what you want to do .
 
EWC said:
Have you tried Racepak ? They do alot of data logging for drag racing . They might have something or know how to do what you want to do .
Click to expand...

I have not; although I did just check their website and they dont have anything listed that would be applicable as a cylinder pressure transducer; 1500 psi isnt enough.

BUT I did get a reply from Optrand and they do build those glowplugs for $1045 each (owch). I'm getting more info as to whether it would be compatible with that innovate performance SSI-4 data collection system and what that operation temperature of (-40 to 350C) actually means... IE) 1100 F = ~600C.
 
Ok, so the operating temperature is a sustained temperature so, since the combustion process occurs quickly, the temperature that the transducer will be at is roughly the temperature of the cylinder head, or in some rare cases it might get to 200 C; So still easily within the range of the transducer.

They also think that the SSI-4 from Innovate Motorsports should work; I'm going to contact Innovate Motorsports to confirm though.
 
Well good news on the data logging - The SSI-4 WILL log any 0-5V analog signal so the pressure transducer from Optrand will work BUT according to the guys at TFX engine, they think that the SSI-4 will only be good for logging peak pressure (which I'm fine with). TFX offers a sick system that converts the analog signal to digital and takes WAY more data points and as a result can create a much more accurate diesel cycle plot which would likely show the two bumps caused by peak pressure and initial combustion pressure - fortunately this would only come in handy for timing the pump(s) which I think I'll stick with trial and error considering that TFX system is $4000+.

The only problem that I have run into is that the SSI-4 needs a 12+V DC square wave for the tach input and they assume that we do not have that since it comes off the alternator... Is this true?
 
VW uses a combination glowplug/pressure transducer in their latest TDI's. Mass produced, I bet they're a far sight cheaper than that grand a pop one-offs you quoted above. If not a direct screw in for the glowplugs on the 6.5, I bet a little ingenuity could make them fit/adapt mechanically.
 
Husker6.5 said:
VW uses a combination glowplug/pressure transducer in their latest TDI's. Mass produced, I bet they're a far sight cheaper than that grand a pop one-offs you quoted above. If not a direct screw in for the glowplugs on the 6.5, I bet a little ingenuity could make them fit/adapt mechanically.
Click to expand...

Thanks man. I'll have to take a look at what they output for a voltage because a little adapter would be a joke to track down.
 
You must log in or register to reply here.
Back
Top