Understanding.

[JL LGT]

I plan on loading up some data logging software to my laptop (soon as my sister gives it back ) and going through some data logging how-to's from the Legacy forums to see if I can get the basics of it.

I've just ordered Corky Bell's Maximum Boost for some tootelage.

What I'm looking for is more information via internet that can help me along with learning how to read compressor maps properly along with flow charts for various engines. I'd like to ability to put the numbers together from any engine out there to build a "proper" flow chart for it and be able to match it to a compressor map of any turbo.

I've made a flow chart for the 2.5 engine, but it wasn't correct. I crossed my numbers somewhere and came up with a wierd chart.

I'd also like to learn how to read fuel maps & the basics of tuning & fuel management. Preferably for fuel injected cars (newer).

Any links, help or what not are appreciated.

Unfortunately... there are no schools that offer classes for this in my city... otherwise I'd pony up the dough for the class.

Thanx in advance!

[john]

Hope this helps at least somewhat...

Tuning isn't really the black art it's made out to be. The basics are having a target Air/Fuel (A/F) ratio, and the using the tools at hand to achieve that ratio (or ratios) throughout the RPM band.

A wideband O2 sensor is one of the tools you will need. An A/F ratio of 14.7:1 (14.7 parts air to 1 part fuel) is considered 'stoichiometric', or 'perfect'. Depending on the fuel you are using (pump gas, race gas) you can tune the car leaner, which runs hotter, and makes more power. To a point. All turbocharged motors run rich from the factory in an effort to preserve the integrity of the motor. More fuel == richer == cooler burn == less chance of burning the motor up.

Look up how closed loop vs open loop affect what the ECU is doing at various throttle position points.

Making small adjustments to your timing can have dramatic affects on the output of the motor as well. In general, more timing advance will provide more power, to a point. Finding that balance of making power and still having pre-ignition (knock) under control is where the tuners make their money. :)

Since turbochargers are heat pumps, the cooler you can keep the compressed intake charge, the more power you can make. Larger turbos are more efficient, but it takes more exhaust flow to get them spooled up. Again it's a balancing act between the size of the turbocharger and keeping the charge cooled. Intercooling, water or alcohol injection, boost pressure all affect intake temps. Spinning a smaller turbo to create 20psi vs spinning a larger turbo to make 20psi - the smaller turbo is working harder/spinning faster to create that manifold pressure, resulting in a hotter charge.

A decent writeup on how to read compressor maps can be found here (http://www.gnttype.org/techarea/turbo/turboflow.html). The Buick GN guys have always provided good data & information. Poke around that site for some basics.

Maximum boost is 'the' turbocharging book.

Which datalogger are you going to use? The reason I ask is that I'm on a mission to replace my A4 with an 05 LGT, which I believe you are driving. Are you reading www.legacygt.com?

[Conrad]

trade the lgt in and get a limited edition Spec B lgt... only 500 made and heuberger
(ms) is supposedly going to have one.

[john]

Isn't the spec b just a set of Bilstein shocks, some red leather on the interior, and 18" wheels?

[Conrad]

Isn't the spec b just a set of Bilstein shocks, some red leather on the interior, and 18" wheels?

yeah..... but its a spec B :rofl:

[rmcdaniels]

The Turbo Saturns archive has some stuff that really helped me, especially the "Deciphering Compressor Maps" articles.


http://www.turbosaturns.net/articles/articles.htm

[doctorstupid]

I already told you how to plot engine demand in July :p

OK, here's the super easy dumbed down way to make a flow chart:

calculate air flow volume for desired RPM using this formula: VAF = L/28.328 x RPM/2 x VE x PR

Now multiply that number by the pressure ratio you would like to plot.

Go into MSPaint and plot that bastard.

So, for example, a 2.5L at 2,000RPM with 80% VE will intake 70.6CFM at 1.0PR (that's 2.5/28.328 x 1000 x 0.8 x 1.0). At 3.0PR, it's 211.8CFM. So you draw a line between (71, 1.0) and (212, 3.0). Then repeat using different engine speeds and VE and you end up with straight lines that go up at an angle and do not cross over eachother, it's as easy as that
All you need is mspaint, a flow map, and a calculator.

When done right, it'll look like this:
http://mattmasonms.com/img/JBturbo.GIF

Or this:
http://mattmasonms.com/img/HolyHell.JPG

I can't wait for that second one :D

[Enthalpy]

You need to account for flow improvements as a result of the intercooler. You also need to account for pressure drop across your intake system, especially if your boost controller references manifold pressure and not turbo discharge pressure.

What you have there is an absolute minimum flowrate your system will see. To see if you are choking the turbo, you need to do the above to find the max flowrates.

Lastly, you need to correct your readings for altitude and non-standard temperatures. Use low and measure at high temp values for choke and surge, respectively.

You will find these things don't impact the total THAT much on their own, but taken together, they have a sizable impact.

[JL LGT]

Werd! Thanx for the info! (Again for you Doc!)

I wish my computer at home wasn't retarded. I can't search HAI thoroughly at work due to work site filter. I finally saw this thread again when I clicked on "new posts."

I tried finding it a couple days ago.... but that damn work site filter keeps blocking me! Now I've got it book marked.

John: I am driving an LGT right now. Or will be once it's back from the shop.

I'm shooting for edimecation here cause I've already ordered the 18G for my car and the FMIC will come soon enough. I want to understand what I'm doing since this isn't just another bolt on like things were with my Honda! The down pipe I bolted up has a bung right on top for ease of installing a wide band, once I've found a friggin gauge pod. I want to be able to monitor A/F, boost & temp. Unfortunately.... I'm having no luck locating a gauge pod.

Conrad: I like my LGT better than the Spec B's (fake anyway) that were released. I plan on finding a source the the JDM 2.0GT Spec B front bumper to finish the aesthetic touches! View it HERE! (http://www.subaru.co.jp/legacy/b4/exterior/04/w.html)

[Conrad]

i dont know if I like that bumper better or not...

[doctorstupid]

You need to account for flow improvements as a result of the intercooler. You also need to account for pressure drop across your intake system, especially if your boost controller references manifold pressure and not turbo discharge pressure.

What you have there is an absolute minimum flowrate your system will see. To see if you are choking the turbo, you need to do the above to find the max flowrates.

Lastly, you need to correct your readings for altitude and non-standard temperatures. Use low and measure at high temp values for choke and surge, respectively.

You will find these things don't impact the total THAT much on their own, but taken together, they have a sizable impact.
Oh I know, just too much work to ballpark it; it's just simplified engine demand. I don't need to see my compressors' resolution to a minute reolution of 1 rpm and 0.01psi :p

[Enthalpy]

I don't need to see my compressors' resolution to a minute reolution of 1 rpm and 0.01psi
I'm not actually sure what you are saying here, but the effects I laid out add up to be far from minute.

Your ballpark is a good way to get close, though.

[doctorstupid]

I'm not actually sure what you are saying here, but the effects I laid out add up to be far from minute.

Your ballpark is a good way to get close, though.
I'm just saying that close enough is damn close enough. No need to nitpick the bejesus out of engine demand, especially considering that the compressor's flow DOES extend beyond its printed lines; and where your engine demand lays relative to compressor effeciency really isn't that big of a deal (think back to my excessivle long post on compressor vs. ic effeciency).

In my opinion it's not worth the added work of calculating that crap when a very simplified engine demand plot will size up a compressor very quickly and easily :)

[Enthalpy]

Compressor flow might lay beyond the lines, but it's a horrible idea to operate there. You either over rev the turbo, choke it or surge it.

I didn't see your compressor efficiency vs. intercooler effectiveness thread. I don't see why you would use the word, "versus."

I guess it's all about the amount of work one wants to put in. It's the whole 80% designed versus 20% designed idea. Use the quick way to narrow the field of choices, then look at exact operating points using the thorough way.

We are probably violently agreeing.

[doctorstupid]

Compressor flow might lay beyond the lines, but it's a horrible idea to operate there. You either over rev the turbo, choke it or surge it.

I didn't see your compressor efficiency vs. intercooler effectiveness thread. I don't see why you would use the word, "versus."

I guess it's all about the amount of work one wants to put in. It's the whole 80% designed versus 20% designed idea. Use the quick way to narrow the field of choices, then look at exact operating points using the thorough way.

We are probably violently agreeing.
I NEVER said to operate a turbo outside those lines, I'm saying that even the flow map itself is approximate at best, and for the sake of sizing up a compressor, you don't need much beyond the air flow capabilities of your engine, any more is just a waste of time, and nets you minute resolution on your engine demand for no real reason. It's not 80 vs. 20%, please :rolleyes:

This is the thread in regard to comp vs. IC effeciency and which one is more important (by a huge margin) : http://www.highaltitudeimports.com/showpost.php?p=436176&postcount=23

[Enthalpy]

I think we are going to have to agree to disagree, chalking it up to semantics. Include in the calcs what the intercooler nets you and do a difference betweeen the two. I consider that a difference that justifies the extra work. Others might not.

Potato, potatoe.

[nxbrennan]

How do you find the VE of the engine?

[doctorstupid]

How do you find the VE of the engine?
Educated guess work, mostly.

One decent method is take your stock torque curve, and follow that, assume peak torque is somewhere in the low 90%.

[Enthalpy]

If you have an EMS, you can calculate the VE curve from the output of the logs with AFR included. You know the injector base flow from pressure-corrected advertised flow. You have AFR, which is in terms of mass of air/mass of fuel. You know the mass of fuel from the log's injector pulsewidth. From there, you can calculate your VE because your engine's airflow in mass is P/T * RPM/2 * VE * displacement, where P and T are measured in the manifold.

I do this on every engine whose EMS I tune to get a feel for what engine does what. Stock turbo cars have peak VEs in the high 80s. The best turbocharged VE I have ever seen is 99%. Supercharged engines with long duration cams can exceed 100%, maybe even get to 110%. Long-cam NA engines can get as high as 125%, but that's F1 territory.

Most 4-valve engines have VEs in the high 80, perhaps low 90s on a VTEC Honda. 2-valve engines almost never hit 80%.