PDA

View Full Version : how to tune (dial in) a gn


figga8n
09-16-2005, 12:49 AM
ok im new to this gn ttype stuff. can these cars be dialed in like a old school muscle car. what i mean is how do you adjust timing or air fuel mixture. how do you get these cars to run there best

kenmosher
09-16-2005, 09:36 AM
Timing is function of the chip, so a chip change (usually from a street to a race chip) does a lot of the adjustments.

There are also chips with adjustable timing (see the Extender/Translator at Full Throttle Speed and the TurboTweak at Turbotweak.com).

A/F is basically balancing your manual boost adjustments (controlling the air) and the fuel pressure.

With a scan tool, you look for the most boost you can run while maintaining 0-1 degree of timing retard and a good A/F ratio.

PaCemkr86
09-16-2005, 02:30 PM
If you dont have a scan tool get one. Its a must for these cars.
I highly recomend it.

kenmosher
09-16-2005, 05:22 PM
If you dont have a scan tool get one. Its a must for these cars.
I highly recomend it.


:yesnod:

Another valuable tool is a wide band O2 kit and install it post turbo (in the downpipe) ... something like the Innovate or the PLX units. Pretty trick!

Keller
09-16-2005, 07:24 PM
Something tells me the WB O2 is a little much for a beginner. I haven't used one (let alone touched one), and I'm OK (so far). I think its far from a 'starting out' tool...

kenmosher
09-16-2005, 08:26 PM
I think I'd disagree ... although I've done fine without one for many years, it's amazing how much it makes the tuning process easier.

It's kind of like the "AHA"! moment when you start using a scan tool ... just that much easier to see what's going on.

Now that I've used a couple different ones (FJO, Innovate, PLX) on tuning various motors on the dyno (including my own), I highly recommend it!

PaCemkr86
09-17-2005, 02:08 PM
http://www.fullthrottlespeed.com/itemdesc~ic~3273765~eq~~Tp~.htm
Ken im thinking about gettin one of these, have you used one yet?
give me your thoughts and input on it. thanks

kenmosher
09-17-2005, 02:25 PM
Hmmm ... the link tells me that my shopping cart expired.

Is that the Innovate that you were pointing to?

PaCemkr86
09-17-2005, 02:35 PM
http://www.fullthrottlespeed.com/mmFTSS/Images/3273765.jpg oops , lol yeah , the inovative wide band kit

Keller
09-17-2005, 02:55 PM
Do the WB O2's get knocked out as fast by leaded fuel? I've never seen a mention of that.

PaCemkr86
09-17-2005, 02:59 PM
the one we use on our dynojet does.
But im gonna be using alky, and it comes with a plug so i dont have to use the o2 all the time.

kenmosher
09-17-2005, 03:27 PM
The NTK sensor (about $125 ea) seems to be a little less tolerant of lead than the Bosch LSU4.2 sensor (about $50).

They are both pretty tolerant due to the heater elements in them preheating the sensor.

I've got one LSU4.2 (using a PLX device) on a dyno cell in Oshkosh that's been running both leaded and unleaded fuel with a ZZ4 mule engine for about a year and still seems to be going strong.

As far as the standalone unit shown in the picture, I haven't used it, but it sure looks like a slick deal!

I've been using the PLX M300 and it looks to have the option of using a guage with it as well as the digital display box. The big thing was we use the 0-5v output off the box to feed into our ECUs and dataloggers as a double check against our software.

One of the guys in Oshkosh has the R500 and says it's pretty neat, but kind of hard to use.

The Innovate is a nice unit too, and I liked using it, but just from where we had to mount it in the dyno cell (didn't have enough lead to string it into the control room), it was hard to read strapped to the front of the engine stand. The LCD is probably fine in a real car though, since it is a couple feet away instead of 10 feet away (and looking thru reinforced glass on top of it all).

Both nicely executed and were within 0.1 A/F of the expensive gas analyzer in the cell. The FJO was also a nice box, but no display.

In short, I don't think you can go wrong ... these things have come a LONG way and are really pretty slick!

kenmosher
09-17-2005, 03:31 PM
Do the WB O2's get knocked out as fast by leaded fuel? I've never seen a mention of that.

One important thing is to mount the O2 bung so the sensor is pointed slightly downward. These things really don't like being shocked with cold water ... kills them almost instantly.

As long as we let them heat up before starting the motor (about 15-20 seconds from a dead cold start), they seem to last pretty well. We also mounted them towards the tops of the header collectors pointing downwards to keep the moisture "shock" to a minimum.

PaCemkr86
09-17-2005, 05:07 PM
nice info Ken... I didnt know that.. thanks !

Keller
09-17-2005, 07:08 PM
I guess the question is where in the downpipe to weld the bung. As these become more common, the bungs may become a standard option. However, not yet. Somewhere up top near the turbine, I suppose?

kenmosher
09-17-2005, 08:33 PM
Actually, you want to be a little ways away from the turbine, since excessive heat can kill these things too.

On mine, we welded the bung down in the final bend of the downpipe, just in front of the test pipe (ummm... cat, yeah ... catalytic converter I meant! :music: )

Seems to be pretty accurate and lets the heater control the element temp instead of the EGT.

Ormand
09-26-2005, 08:47 AM
An O2 sensor, wide band or otherwise, is going to tell you what, exactly? Will it tell you if the engine is knocking? Or if the change you just made increased power or decreased power? The idea of using an A/F ratio to tune is kind of backwards, since different engines will have different requirements. Tune to max performance, with min knock, then see what the A/F ratio turned out to be. Nice to use, so you can get back to that optimum point easily, but not much good for actually FINDING the optimum, IMO.
You need a scan tool, but mostly, you need to know when/if you have knock, and how much.

kenmosher
09-26-2005, 09:50 AM
With the stock ECU, you can quickly establish boundaries and ranges with a Wideband without getting to the edge and actually causing knock (rich or lean).

Take your first guess at a safe tune, make a run with your scan tool and wideband and see where you are at ... hopefully well to the rich side of the A/F. With the wideband you can get a sense of HOW rich you are and how close to the edge you are. From there you can make as fine or coarse of an adjustment to get closer to the target. Once you are getting in the "zone", then you start making finer and finer adjustments to zero in on best power/safe.

Even though every motor/combo will be a bit different in BSFC and A/F "happy spots", you know that in general a Buick turbo V6 is usually making best power safely at around 11.5:1 - 11.75:1. So the wideband helps you narrow in on that A/F to fine tune for best power without knock.

With the aftermarket ECUs (and the dyno cells we work with), it's a different story. You actually have a target A/F function in the ECU that uses the wideband as the feedback part of the fueling strategy. Ours uses the MAF and speed/density calculation models to predict the airflow and the fueling (and the Tau/X strategy for maintaining fuel puddle around the intake valve) and the applies correction to the strategy via the observed A/F from the wideband. It then does adaption to the VE map to adjust.

In practice, it takes a half hour or so of various load pulls on the engine dyno and the engine is pretty much mapped in via this method. Pretty neat! :tup:

Ormand
09-26-2005, 10:53 AM
I hear you, Ken. But on one of the other boards, I've seen A/F ratios for "peak" performance vary over a wider range than what you mention. Bruce P has provided info on how to set up/use a broadband, starting out on the DIYFI site, and various folks have come up with anything from 10.5:1 to 12:1, and that's a pretty wide "target". If you had an engine with the right combo of compression, quench space, head cooling, mixture distribution, etc, then you might get away with 12:1, but until you see just a tiny bit of knock, you won't know that. (I think you can run a little leaner with a Power Plate, for example) Also, the A/F ratio you read is the "composite", for all six cylinders, and you might have one or two running much richer, and one or two running much leaner, such that the number doesn't really mean much. I do agree that some time on a dyno will get you in the right part of the ball park much quicker than trying to tune on the street or on the track though- but that's another controversial claim on "the other board".

kenmosher
09-26-2005, 11:02 AM
I hear ya ...

I think some of the "edge cases" have more going on than meets the eye. The basic build up (I'm talking 300-600 HP Buick) is going to want between 11 and 11.75 for best power. From what I've seen (admitted only from a few similar Buick combos), the aluminum headed combos can run a tad leaner, but need more actual fuel volume, leading me to believe the BSFC isn't quite as good with aluminum (probably the heat conduction factor?)

Also, I wonder about some of the accuracy of some of the DIY WB kits ... I'd bet that Bruce's is pretty darn close in calibration, but the heater circuit is the key to making readings that are accurate, and I wonder about home assembly of some of this stuff in other's hands? I've been a bit spoiled I think with fully instrumented dyno cells (EGTs per hole, data acquisition of flow rates for air, fuel, WB on each bank, etc) ... BTW, it's pretty cool that the WB is fast enough that you can actually see each cylinder fire in the data stream.

Anyway, as you pointed out ... anything can happen in the field. I'd say in the majority of the cases, a WB (commercial) and a scan tool are a great combination for accurate tuning. I know I find it pretty valuable on boosted stuff (maybe not as critical on N/A motors we've tuned).

Ormand
09-26-2005, 12:23 PM
In a "perfect world", I would tune on the dyno, with a WBO2 for each cylinder, and one of those knock sensors that tells you which cylinder is knocking. Then, I would find the "limit" for each cylinder, and adjust the fueling so there was a little margin for each one. But that kind of tuning is only possible/practical if you have LOTS of money, and/or if you are setting up to build a bunch of near identical vehicles, like Saleen, or Lingenfelter. The rest of us will just get by with "imperfect" tuning! And for those of us tuning our daily drivers, with many miles, the margin better be pretty well on the safe side...

kenmosher
09-26-2005, 12:43 PM
Yep, absolutely!

It's amazing how the stock ECM does what it does ... and like you say, you have to tune to be safe for the worst case/hole (or risk damage). Even so, we get amazing performance and driveability with pretty much a "big hammer" type of approach!

The new stuff has per cylinder spark and fuel (and knock in some cases), so you can compensate for manifold/head compromises (usually for packaging or cost). However, it usually comes down to best emissions and not necessarily best power, because you know there's going to be some sort of condition out there in the field that will cause you to go over the edge if you aren't consdervate. And despite all that technology and wizbang stuff, it isn't like you get a huge percentage increase in power (unless you are compensating for something really bad, like one really poorly flowing cylinder).

figga8n
10-11-2005, 12:41 AM
thanks everbody for all of your resplies!!!