Going to Megasquirt, More questions Options

[bbrock]

Im just going to leave this here to give you more to consider about your injector selection. (IMG:style_emoticons/default/poke.gif)

This is the datasheet I got with those A280H injectors

The 26lb rating was at 3bar pressure however they provide the flow specs and voltage corrections for running them all the way up to 7 bar!!!

I would imagine the 36lb sets come with similar abilities.

Have read that higher pressures improve atomization, and if you wanted to look at shortening your injector pulse even further, its something to consider.

I was actually wondering about that. What's a safe pressure a Bosch 69133 could run? Need to find specs.

[KELTY360]

Obviously, while the snow is on the ground you need to build a dyno in your garage.

You'll never be able to test your results til you do and you'll never be satisfied til you can test the results of all variables. (IMG:style_emoticons/default/poke.gif)

[Superhawk996]

Here's the view from my window today so I'm already done driving until the middle of June '22.

(IMG:style_emoticons/default/chair.gif) Don't be such a cynic. With all the climate change it'll be 60F by late next week and then you'll be back to mud season!

[bbrock]

Obviously, while the snow is on the ground you need to build a dyno in your garage.

You'll never be able to test your results til you do and you'll never be satisfied til you can test the results of all variables. (IMG:style_emoticons/default/poke.gif)

Ha! You talk like you have met me... oh wait... you HAVE (IMG:style_emoticons/default/biggrin.gif)

The testing will be a bit of a bummer. If I was a good person, I'd tune this thing with wasted spark and batch injection, drive it long enough to collect some data, and THEN switch to sequential. That seems too much like work though.

BTW, I assume MS can calculate and log fuel consumption as mpg - correct?

[KELTY360]

Obviously, while the snow is on the ground you need to build a dyno in your garage.

You'll never be able to test your results til you do and you'll never be satisfied til you can test the results of all variables. (IMG:style_emoticons/default/poke.gif)

Ha! You talk like you have met me... oh wait... you HAVE (IMG:style_emoticons/default/biggrin.gif)

The testing will be a bit of a bummer. If I was a good person, I'd tune this thing with wasted spark and batch injection, drive it long enough to collect some data, and THEN switch to sequential. That seems too much like work though.

BTW, I assume MS can calculate and log fuel consumption as mpg - correct?

You're asking me? (IMG:style_emoticons/default/confused24.gif) I still think a log is something you burn in the fireplace.

[bbrock]

(IMG:style_emoticons/default/chair.gif) Don't be such a cynic. With all the climate change it'll be 60F by late next week and then you'll be back to mud season!

It's actually supposed to be 60 this weekend. Whose the cynic now? (IMG:style_emoticons/default/confused24.gif)

You're asking me? (IMG:style_emoticons/default/confused24.gif) I still think a log is something you burn in the fireplace.

That question was for the collective. I expected nothing more from you (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/poke.gif)

BTW... (IMG:style_emoticons/default/idea.gif)


https://www.youtube.com/watch?v=XUX_YWsECWs

[Superhawk996]

BTW... (IMG:style_emoticons/default/idea.gif)

see PM

[ClayPerrine]

If you want distributorless ignition, there is an easier way.

GM built DIS (waste spark) ignition systems on a LOT of their cars in the 80s/90s. Some of the 4 cylinder models used an external sender for the trigger. Years ago, I fitted waste spark to the Type -IV engine in my 914 using the GM system. I took the flywheel off the motor, and machined in the correct grooves to trigger the sender, and mounted the sender in the hole in the back of the case used for flex plate bolts in VWs. I made the mount eccentric so I could fine tune the timing.

This has to be machined into the engine side of the flywheel, properly indexed to the hole.



The ignition module has a base timing curve that it will follow if there is no ECU input. The curve is really close to the stock 914 advance curve. I had carbs on the engine at the time, and it ran way better with the distributorless ignition than it did with the stock distributor.

There is lots of documentation out there for connecting megasquirt to GM waste spark ignition.

The only reason I pulled it off the car was that I had a starter eat the ring gear on the flywheel. I was in a hurry, and had to get the car running to get to work. So I put the stock distributor back in. I still have all the parts in my attic.

[jd74914]

That question was for the collective. I expected nothing more from you (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/poke.gif)

BTW... (IMG:style_emoticons/default/idea.gif)

Well...since you asked...

You can get a wireless strain gauge amplifier; strain gauge up your axles, and have live torque measurement...all of the time!

http://www.izzeracing.com/ewExternalFiles/...2_Datasheet.pdf

Same thing could be done with homemade hardware or from other vendors...

[Frank S]

Had a chance to check some of my data.
With the 21lb/hr injectors I run with 5ms PW at idle and down to 2.5ms in some areas in overrun, which is the smalest PW I have.
Linear range of my injectors ends at 1.5ms and if you add deadtime this is getting close to the none linear region.
This is meassured data, not calculated...

[Frank S]

And here how it looks like if you integrate the MS3 into the D-Jet housing:



Just the Injector driver board for Full Sequential is not in jet...

[bbrock]

And here how it looks like if you integrate the MS3 into the D-Jet housing:

Just the Injector driver board for Full Sequential is not in jet...

I like it! Is that a bluetooth module at the bottom? And are you running inputs/outputs to the original ECU harness header?

Thanks for posting those pulse widths. That is VERY helpful.

[bbrock]

Had a chance to check some of my data.
With the 21lb/hr injectors I run with 5ms PW at idle and down to 2.5ms in some areas in overrun, which is the smalest PW I have.
Linear range of my injectors ends at 1.5ms and if you add deadtime this is getting close to the none linear region.
This is meassured data, not calculated...

I plugged 21 lbs/hr into my spreadsheet and played with the VE at idle until I got glose to 5ms PW. It hit at about 29%. I used 25% as a lower VE for a margin of safety and recalculated the VE curve. With that adjustment, calculated PW for 36 lb injectors at 850 rpm is 2.5ms (3.5ms for 26 lb.).

[Frank S]

And here how it looks like if you integrate the MS3 into the D-Jet housing:

Just the Injector driver board for Full Sequential is not in jet...

I like it! Is that a bluetooth module at the bottom? And are you running inputs/outputs to the original ECU harness header?

Thanks for posting those pulse widths. That is VERY helpful.

Yes, this is a bluetooth module at the bottom and the real time clock module at the right and yes I'm running inputs and outputs through the original ECU harness header but for the actual install I had to feed also some extra cables as I have added a second EGO sensor and an external knock module.

[JamesM]

Had a chance to check some of my data.
With the 21lb/hr injectors I run with 5ms PW at idle and down to 2.5ms in some areas in overrun, which is the smalest PW I have.
Linear range of my injectors ends at 1.5ms and if you add deadtime this is getting close to the none linear region.
This is meassured data, not calculated...

I plugged 21 lbs/hr into my spreadsheet and played with the VE at idle until I got glose to 5ms PW. It hit at about 29%. I used 25% as a lower VE for a margin of safety and recalculated the VE curve. With that adjustment, calculated PW for 36 lb injectors at 850 rpm is 2.5ms (3.5ms for 26 lb.).

Well your math is good as that is roughly what i was seeing when running the stock 36lb injectors.

Now stop playing with spreadsheets and build the damn thing (IMG:style_emoticons/default/poke.gif)

[bbrock]

Had a chance to check some of my data.
With the 21lb/hr injectors I run with 5ms PW at idle and down to 2.5ms in some areas in overrun, which is the smalest PW I have.
Linear range of my injectors ends at 1.5ms and if you add deadtime this is getting close to the none linear region.
This is meassured data, not calculated...

I plugged 21 lbs/hr into my spreadsheet and played with the VE at idle until I got glose to 5ms PW. It hit at about 29%. I used 25% as a lower VE for a margin of safety and recalculated the VE curve. With that adjustment, calculated PW for 36 lb injectors at 850 rpm is 2.5ms (3.5ms for 26 lb.).

Well your math is good as that is roughly what i was seeing when running the stock 36lb injectors.

Oh wow! There are several school teachers who would likely keel over in shock to here that if they are still alive.

It's a great relief to have real measurements that agree with my chicken scratch! Thank you.

Now stop playing with spreadsheets and build the damn thing (IMG:style_emoticons/default/poke.gif)

Shit. I thought this was just a mental exercise. You mean I actually have to build this? (IMG:style_emoticons/default/biggrin.gif)

Got a few smaller projects I need to finish before I can dedicate serious time, but I'm ready to pull the trigger on ordering the MS3 kit. Think I finally figured out how the daughter boards figure in. If I've got it right, the v3 board is just a base "non denominational" board and the daughter board determines which version of MS. That was a little muddy until I looked at the assembly instructions. Think I'm going to go with MS3Extra as it will be easier for only about an extra $50 overall.

I sent Mario an email to get an idea of when his goodies will be available for purchase again, and also when the v2 of his CAM SYNC might be ready. That would also greatly simplify things. He has this note on the description: "It will incorporate a small trigger wheel in stead of the flying magnet. For basic applications this can be used without a crank trigger. In performance applications both are still recommended."

Still not sure how much precision is being sacrificed using a gear driven distributor to send tach signal vs. a crank sensor.

[Frank S]

Still not sure how much precision is being sacrificed using a gear driven distributor to send tach signal vs. a crank sensor.

In theorie you will sacrifice some precision, in paractice I don't experience a difference.

[bbrock]

I've been wondering if there is an advantage in adding a CHT ring sensor on #3 spark plug to the system beyond just generally being able to track head temps. Since we have to run these engines a bit rich to keep the head temps down, it seems like the most efficiency at cruising could be had with a feedback loop between AFR and CHT so the mixture could go as close to stoich as possible while maintaining safe head temps. The TunerStudio manual talks about CLT to monitor coolant temp for warm up (I'll be mounting mine in the stock CHT location), but I'm not seeing anything about integrating CHT with the AFR targets or VE table. Would this be a bad idea?

[JamesM]

Still not sure how much precision is being sacrificed using a gear driven distributor to send tach signal vs. a crank sensor.

This is entirely observational but "some"

I went from picking up my tach signal from a pertronix on a locked dizzy to Marios 36 tooth crank wheel and the difference under a timing light was visibly noticeable. couldn't tell you in a number what the difference was and im sure its very minor, like less than 1 deg, but with the dizzy trigger there was a bit of jitter under the timing light, the timing mark had a slight haze to it. After moving to the 36 tooth crank wheel the mark under a timing light was rock solid, like i was looking at a laser pointer.

[JamesM]

I've been wondering if there is an advantage in adding a CHT ring sensor on #3 spark plug to the system beyond just generally being able to track head temps. Since we have to run these engines a bit rich to keep the head temps down, it seems like the most efficiency at cruising could be had with a feedback loop between AFR and CHT so the mixture could go as close to stoich as possible while maintaining safe head temps. The TunerStudio manual talks about CLT to monitor coolant temp for warm up (I'll be mounting mine in the stock CHT location), but I'm not seeing anything about integrating CHT with the AFR targets or VE table. Would this be a bad idea?

I mean it would be cool if you could figure out a way to do it, but AFAIK its not an existing feature.

The other issue you need to look at is the spark plug ring sensors are are thermocouples where as Megasquirt uses thermistors for temp sensors.