EFI tuning, taking it to the next level

[MG four six eight]

It's been awhile since I have posted so I figured it was time for an update. I'm very pleased with the MS3 and Jb perf logger board!
Tuning with the EGTs has been VERY helpfull, as it allows me to see whats going on at all rpm/engine load ranges.
A couple of things I've learned about tuning with EGT's.
1) Hotter temps usualy means leaner fuel mixture or retarded ignition timing.
    Colder temps Usualy means richer fuel mixture or advanced/proper ignition timing (no detenation)
There are exceptions to the above however for example.
If the fuel mixture is to lean. A lean miss-fire can occur and actually drop the EGT reading, due to the un-burnt fuel mixture cooling down the exhaust.
If the air/fuel ratio is very rich, it can cause the EGT readings to go higher. This is because "the fire" is still burning fuel as it leaves the exhaust port.
If the EGT probes are placed to close to the exhaust port the readings with be hotter and visa-versa. The main thing is to have all of the probes equal distance from the exhaust ports.
Miss-fires can really throw off your readings much in the same way miss-fires effect oxygen sensors. Basically what a miss-fire does is make the oxygen sensor and EGT sensor read the opposite of whats really going on.
Since no two engines are going to run the same EGT temp at a given air/fuel ratio. It's very helpfull to have a good wide band O2 sensor set-up to know where your at air/fuel ratio wise.
For example, at WOT under 9 pounds of boost the EGT readings average around 1235-1250* F with an air fuel ratio of 12 to 1.
I also have seen the same 1235-1250* F readings at a lean higher rpm cruise with 14.7 to 15.7 air/fuel ratio. Same temp readings but at vastly different  air/fuel ratio mixtures/engine loads.
Attach below are some screen shots of data logs.
The first one is a link to screen shot while the car was running on MS2
http://forum.britishv8.org/file.php?6,file=6916

Above is a snap shot after  the switch to MS3 and after I did some tuning with the injector trim tables. Notice how much closer the EGT temp reading are. All 8 cylinders are there and they appear to be almost one line!

I had the ignition timing table set fairly conservative mainly because I didn't want to risk detonation. With an accelerometer (inside the JBperf module) and EGTs I decided to play around with the ignition timing some for a couple of reasons.
1) Using the accelerometer see if I could gain some more HP.
2) Using the EGTs see if the exhaust temps dropped when advancing the timing.
Below shows a snap shots during a 3000 4th gear low load lean cruise.


Notice on the bottom graph the EGT temps dropped on average about 60*F, by simply advancing the timing 2* in this area. The idea is to slowly advance the timing a little at a time until there is no change in EGT temp. The bottom squiggly line is air/fuel ratio. For this tuing method to be acturate, the air fuel ratio must be the same in all test runs. I still may do some more timing tuning in this area, just to see if I can lower the temps more.

[MG four six eight]

Now it was time to move on to some more WOT pull timing tuning. I wanted to be very carefull with this, because if there was detonation I would not be able to hear it over the blower whine!
Looking at the accelerometer data in the snap shots below, notice how the reading starts to trail off at about 4000 RPM. Most of this is because of the increased wind resistance (car is moving faster). However I had the timing pretty conservative in this area, I decided to leave the timing below 4000 RPM alone and advance it 2* at 4000 RPM with it slowly increasing by 4* at 6000 RPM.
The top graph is the before and the lower one after advancing the timing. Notice how the accelerometer reading stays higher longer. Additionally the seat of the pants acceleration felt stronger and the EGT readings dropped another 40* F as well.

[BlownMGB-V8]

Looking good Bill. I'm still dealing with fabrication issues but all of this will be relevant soon enough. What are you using for an accelerometer?

I'm getting set up to coat my headers here. Went ahead and installed egt ports in each runner but they will probably be plugged initially, I still have the dash EGT with a probe in one collector.

JB

[MG four six eight]

Jim

The accelerometer is a surface mounted unit, located in the JBperformance module. Accelerometer data can read directly from the JB board via a laptop, or through MS3 via the CAN communication line.

Bill

[MG four six eight]

I had to do some fuel supply system repairs. On our way back from Reno we stopped at a park in Northern California, and my wife commented that she smelled gas. I smelled it too and got out to check the car over, to find fuel dripping from remote fuel cell at a rapid rate! After closer inspection I could see that it was leaking from one of the welds. Fortunately a fellow MG'er had some JB weld, so I pulled the tank, gobbed a bunch of JB weld over the welded area and let it sit over-night.
Got up the next morning and it wasn't leaking! I told my wife, we better head for home ASAP since I wasn't sure how long the JB Weld would hold. It was just starting to seep again by the time we got home.
Anyway I decided to eliminate the remote fuel cell and install the fuel pump in the tank.

Donor fuel tank from out of a 98 oldsmobile. I picked this tank because of the nice flat area around the fuel pump mount. I cut out the fuel pump mount and soldered it to a stock MGB tank. Unfortunately I didn't take very many pics. It did require quite a bit of hammer/dolly work to get a nice fit on the MGB tank though. Due to the "raised areas " in the MGB tank.

A 6" hole saw was used to cut the hole in the trunk floor.

Stainless braided hoses and wiring in place. I reused my Astro van fuel pump, although I had to do quite a few modifications to it in order for it the compress short enough to fit in the MGB tank.

Then welded up this cover out of sheet metal and covered it with carpet

[MG four six eight]

Hers a pic with the carpet back in and everything all buttoned back up!


A pic of my temporary roadside repair!

I'm thinking about converting the tank into a tool box. It should make a nice heavy duty "battery box" tool storage area.

Bill