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My life, My coding

Started by Rx7man, May 27, 2015, 09:09:36 AM

Rx7man

In case you're wondering, I'm still here.. I check in often, but while I'm waiting to get my Robotshop stuff from my buddy so I can start experimenting with the stepper motor, I've gotten a little sidetracked...

I found another forum with about 3 members and a total of 10 posts between them all.. It's more coding and fabrication... I don't know if I mentioned I build and modify chainsaws (yes, more power out of them too!), and 2 stroke engines are very dependent on their exhaust systems to make power.

Since they have no valves and a lot of processes happen at the same time, they have expansion chambers in the exhaust system.. so as the piston opens the exhaust port, there's a sudden strong pulse sent down the header, as the diameter suddenly increases in the expansion chamber, a negative pressure wave is reflected back to the piston.. this helps suck the last bit of exhaust out, and helps it draw fuel in... As the original high pressure wave continues, it meets the decreasing size of the end expansion chamber, this time the wave reflected is positive pressure, and it travels back to the piston as well,.. IF it's timed just right, it'll get there just as the piston closes the exhaust port, and will effectively ram extra air back into the cylinder....
So there's LOTS of math, a fellow made a very good effort with a spreadsheet, and I'm trying to take it one step further and put it into a VB program that will give a neater user interface and be a lot more powerful too.

If anyone feels like snooping and learning
How an expansion chamber works
Free forum : Expansion Chamber Design Forum

'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

Now we should get into the, can you turbo a 2 stroke
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

I want a he351VGT on my chainsaw!

a tuned pipe is essentially a turbo as far as a 2 stroke goes.. it helps draw fresh fuel in, and increases cylinder pressure
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

without valves how do you pressurize the cylinder
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

I'm not quite sure how it works in turbo applications...

but the tuned pipe pressurizes the cylinder using sound waves just before the piston closes the port
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

Ya that was always a topic of debate.

I would imagine a super charger would be the best application, then you could actually have a tuned pipe setup for it, otherwise I imagine you're just tossing out the intake charge once rpm climbs.

The 2 stroke detroit diesels had no intake valves but had exhaust valves, which made sense. Used a roots blower for exhaust scavenging since no intake valves.. but exhaust it needed something to drive the charge in.

Now if someone could design a boosted system that as rpm rose, boost lowered, you could have an almost static output off idle power response.. but obviously a topic for later discussions :D
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

some detroit diesels were v16's with twin superchargers and quad turbos.. I saw one on a genset.. probably 1000-2000 hp.. I guess since the turbo probably has about a 1.2:1 drive pressure ratio, the extra exhaust pressure itself keep it from blowing all the fresh charge out the exhaust?
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

The 6v71 / 8v71 / 10v71 etc series of detroits had exhaust valves just no intake
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

I think all the detroits had exhaust valves and ported intakes..
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

Rx7man

Here's a screenshot of the program I'm working on for the expansion chamber... I've gotten the worst of it done, I still have some math problems to work out with the temperature drop as the gas expands... I'll see what I can do to figure it out
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

Rx7man

OK, I decided I needed to get *something* done I can talk about here...

So I have a sparkfun arduino breadboard, and since the smartlynx motor controller uses a totally incompatible cable, I broke the cable out on the breadboard.. the pins I know (MOSI, MISO, Clock, 5V and Ground) I wired directly to the right pins, and those that may change I put a male header on so I can jumper them to whatever I choose.. I'll also need to put a 12V supply on it, and then do the code behind it, but I should have this thing up and running this weekend at least.. I'm not going to put it in the truck right away, but at least I can start fiddling... Still haven't put my Mouser order in, since it's free shipping over $200 and I have $600 worth of stuff, I might be a pain in their butt and split it into a couple orders so I can add/remove stuff later and still get it shipped free.

I really need to get a better soldering iron, this industrial sized thing isn't meant for  .100" spacing and tiny wires...

Oh, and just a tip to all of you, don't use gray jumper wire on a spool... you don't know how many times I picked up that spool instead of the solder!
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

Rx7man

OK, except for a lack of torque at higher speeds (I'll be contacting STmicro about this), I have the stepper working decently, and by some sort of funky luck, using 1/32 steps, I have 64000 steps between full travel stops, which is a very nice number for binary math :)

Some of my machining wasn't quite on center so it wobbles a little, but it'll do for a test run methinks... I guess I should order the Mouser stuff now so I can install it with some pressure sensors. 
One more thing I need to do on the hardware side of it is to make some internal electrical switches that ground at a certain point so that I can zero it without stalling it for 2-3 seconds... I also am getting some copper clad board from mouser and will be making an internal switch that the rack 'feeler' touches and grounds out on a digital pullup input, so I can know when it's on an AFC limit or governor limit.... just some nice things to be able to know... Heck I might even be able to make it so that it doesn't rely on the pressure sensors at all, it just move forward at a given rate as soon as the governor arm touches it and tells it that it's limiting fuel... so you can adjust the forward rate to give the turbo time to spool, and to heck with the pressure.... it would be a poor man's way of doing it

'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

STmicro took a week to even acknowledge the receipt of my email.. maybe next week?  damned slow if you ask me
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

Rx7man

Wel...

ST micro is STILL apparently working on it.. SLOWEST TECH SUPPORT EVER!!!

I was gone last weekend to a friends party, had a good time, got 500 miles on a tank and I was driving pretty hard.. works out to a little over 18 mpg, which is decent in my books with 4.10 gears... Injector pump seems to have smartened up and isn't hunting for idle anymore.. .hopefully when the weather cools off is stays smart.

It's currently raining on my hay :'(.. oh well, the cows will eat it anyhow
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles