Milwaukee Midget

[jdincau]

Take a look at this and see if there is an answer

[Milwaukee Midget]

Chris, I don't mean to beat a dead horse on the A/F thing but how far is 8" form the end of the tail pipe from the head pipes collector? My experience has been to have the sensor with in 12" of the collector to keepthe sensor heat up.

Worry not about extinct equine flailing. 

My question regarding the placement of the O2 sensor to the guy I got ahold of was regarding the heat issue.  My exhaust is wrapped in order to keep heat out of the passenger compartment.  This also keeps the exhaust hotter longer while in the pipe.  His suggestion for placement was based on the heat, the pipe diameter and the engine speed I intended to run.

I guess the end result is - something's not working.

I'll figure it out. 

[Peter Jack]

Take a look at this and see if there is an answer

There's a lot of good information in that PDF. 

Pete

[jdincau]

And if I remember correctly AEM told me to put the sensor at least 18 inches from the end of the pipe

[jdincau]

How much does it bounce? Sitting at the start line mine varies from 9.56 to 14.51. Pulling down the course the trace can go from 13.00 to 12.69 in a half of a second. The trace is not a line on the graph but a fuzzy band about .3 wide.

[Milwaukee Midget]

How much does it bounce? Sitting at the start line mine varies from 9.56 to 14.51. Pulling down the course the trace can go from 13.00 to 12.69 in a half of a second. The trace is not a line on the graph but a fuzzy band about .3 wide.

It'll go from 9 to 17 to 14 to 12 to 19, all within a couple of seconds, constantly jumping regardless of load or throttle position.

Ground is solid, BUT, it is grounded to the same ground bolt as the coil - albeit on the other side of the firewall.  It is shielded, but yes, proximity can have a huge effect on inexpensive electronic devices.

As to data logging, I'm using the XDI 2 ignition, which can record sessions if the computer is hooked up, but I haven't been able to get it to save.  I can observe knock and if I wire the A/F sensor to it, I'd be able to observe that as well in real time, but the record function has been problematic since the second chassis dyno session last September.

Many of these issues have been overlooked because the engine spends more time on the engine dolly than it does between the fenderwells.  The last year was spent developing the engine as a subsystem, rather than the car as a unit, so the chassis related engine issues, such as the A/F gauge and the logging issue have gone unresolved.

[hotrod]

If you suspect noise on the ground side aside from the obvious of moving the ground point, or giving it a direct ground path to the battery, you can also try putting a ferrite choke filter on the ground line. You can get them from radio shack as clamp on devices. The strongly inhibit AC signals on a DC wire.

Similar to:
http://www.radioshack.com/product/index.jsp?productId=2103222

[Milwaukee Midget]

If you suspect noise on the ground side aside from the obvious of moving the ground point, or giving it a direct ground path to the battery, you can also try putting a ferrite choke filter on the ground line. You can get them from radio shack as clamp on devices. The strongly inhibit AC signals on a DC wire.

Similar to:
http://www.radioshack.com/product/index.jsp?productId=2103222

Or I can just grab one from work - I manage an AV department. 

One of the things I plan to do is to pull the entire dash and set up all of the electricals in a more logical configuration.  I've attempted to use the switch placements and gauge cut-outs in the stock dash, but a clean sheet of paper will make troubleshooting a lot easier.

[lsrjunkie]

MM, I talked at length, with Buddy aka 38flattie about voltage supply to the car while running. One thing that he does is run two separate batteries. One for starting, gauges,etc. and another dedicated unit for the ignition system. Granted, you don't have a forced induction engine, but this may help any voltage problems in the system. I plan on incorporating the same system in my car.

As far as O2 sensors go, and I may have missed it earlier in the post, but what type of sensor are you using? A heated sensor is much more accurate than one that relies on the exhaust temp to keep it warm. New stuff uses a heated sensor to get the system into closed loop faster for emissions, and keeping the catalytic converter hot, but a heated sensor could give you the info you need almost immediately. As for using an O2 to gauge A/F ratio... I believe there are better ways to do that. IMHO exhaust gas temp is a very good indicator of A/F mix.

Just a country boy from western Colorado's opinion.

[Milwaukee Midget]

Just a country boy from western Colorado's opinion.

Well Boy, Howdy - we can talk threshing machines Holsteins another day - BUT -

It's a Bosch piece - it has a heating element - I think it's probably GM spec, but it came with the gauge.

I have a pair of EGT bungs welded to the headers.  I'm beginning to think I need to uncork those.

[Sumner]

EGT's are important and we run one on each bank and they can tell you about air/fuel but a quality air/fuel sensor/gauge like the innovate ones that can compensate for altitude and such will tell you what your air/fuel is to the tenth.  They use a heated wide band O2 and they control that wide band.  It is the controller that is the important part of getting a good air/fuel reading.

If you don't have EGT's on every cylinder do you know if it is the one that will run the leanest?  What reading is acceptable for your engine?  How far should it be from the head?  What reading is comparable to what air/fuel ratio.  I find air/fuel to give us lots better data to tune with as we can see what it is under any condition at any time of the run.  Data logging isn't cheap but it is way cheaper than replacing a blown motor.  Most modern tuners that now have good air/fuel reading capabilities use that more than the EGT readings which is pretty much all they had to use before reliable/accurate wide band O2 reading was possible.

Not to say you still can't blow one up but taking a cautions approach (very rich) approach with air/fuel and looking at the data kept our old motor alive for a lot of runs/years and it set 2 records.  Without data logging I'll bet we would of blown it up at least once.

Now for some sobering data and you can check me on it here....

http://www.mountaincanyonflying.com/DA%20Workbook.pdf

If you arrive on the salt at about 4500 feet with a 120 HP motor and it is 'standard temperature', 43 F or 6 C your motor is going to make 104 HP  .

Now the temp is a more realistic SpeedWeek temp in the morning of 75 F and the density altitude has gone up and your 120 HP motor is going to make 97.2 HP.

Later in the afternoon with a 95 F temp and an even higher DA of over 7000 feet it is only going to make 93.4 HP.

If you are running faster in the hot air then something else is going on and I don't think it is aero,

Sum

[Milwaukee Midget]

If you don't have EGT's on every cylinder do you know if it is the one that will run the leanest?  What reading is acceptable for your engine? 

Well, there's the rub.

I'm running a Weber DCOE.

The engine has 2 intake ports.

It has 3 exhaust ports.

Typically on SCCA and vintage race cars, they take the temp on the outside 2 pipes and pray there isn't an issue on the 2 and 3 cylinders.  An EGT on the center pipe would be hard to judge, because you wouldn't necessarily know which, if either cylinder was running hot or cold, and it wouldn't necessarily mirror the outside pipes.

That's why I went with the O2 sensor and jetted conservatively on the rich side to start.  The plugs looked good, and no autopsy needed to be performed.

Let's face it - this BMC lump has more in common with a GMC 6 or a Buick Straight 8 than any modern engine.

The block has been tapped for a knock sensor, which feeds info to the ignition.

I don't doubt your numbers, Sum.  We pulled 95.1 on the dyno, and probably left 10 in Milwaukee going to Utah.  That it went as fast as it did is still one of the most pleasant surprises I've ever had.

[Sumner]

............... We pulled 95.1 on the dyno, and probably left 10 in Milwaukee going to Utah. ....

The facts of life for everyone that doesn't have a blower of some kind 

........
  That it went as fast as it did is still one of the most pleasant surprises I've ever had.....

The rewards of doing a good job  ,

Sum

[Andy Cooke]

I favor a second small 12V battery as well.  I am devoted to the KISS principle . . . . . .     besides, it's an LSR car, not the Space Shuttle.    I think the suggestion to add a 2V
battery in series to the existing system, is to keep B+ voltage for the ignition from falling below 12.0 volts.     Some electronic ignitions don't work reliably below 12.0 volts, as I am sure you are aware.
[/quote/]

I originally added the 2V to make an early AFR sensor work, there weren't enough volts without an alternator for the heater to work correctly.  However, the electrical power jump from 11.5V to 13.5V is massive (power = V^2/R) so the extra volts give me the power that I need for my fuel pump, and the faster injector switching times that my engine needs (I'm turbo and injection).  I'm also devoted to KISS, and won't have anything on my race car that doesn't have to be there

Andy

[Crackerman]

is there anything prohibiting you from running another head? something crossflow and japanese or korean from one of their small .8-1.3L engines? sohc or dohc? or are you limited by class rules on using the BMC piece?
blocking all passages via heagasket and cooling the block and head seperately would be doable if the bore spacing and head bolt pattern were somewhat similar... and i imagine 15-30hp would be feasible and easier to track what is happening in every cylinder.

this is not an easy solution, merely me putting bad thoughts out there for others to pick up.
(swapping a dodge neon 2.0dohc head onto the lowly mopar 2.2, or 2.5 turbo engines is worth around 75 hp without much other work, based on sheer flow alone)