38 replies to this topic

[Scott in Bellingham]

I was talkin to a old dirt track racer the other day, says he remembers a v-8 set up so it would run like a big 4, so 2 cylinders would fire at the same time, Ive been thinkin of trying it on a EJ I got a 2.5 and a 2.2, so I have a few Qs with the stock coil pack 2 plugs fire at once? correct? also if I turned one cam 180 off to get the valves to work together what would the computer do? maybe I could ditch 2 injecter wire leads and run 2 injecters off 1 lead to get 2 to inject at the same time , lookin at the crank which would fire at the same time ?, what is the stock firing order anyway?
so you ECU experts can it be done and if so needs to be done as faf as wiring and sensors and such? if it works seems like for offroad this would give more power at low RPMs

Edited by Scott in Bellingham, 18 April 2012 - 04:35 PM.
detail

[1 Lucky Texan]

hmmm....maybe fill-in between alternate lugs behind the crank sprocket to get half the crank angle sensor pulses?????

easier if it runs 2 cycle?

I dunno - lol! proably harder to dream up ways to fool the existing ECU than to build something from scratch to run it. Easier with an older engine with a distributor and SPFI probably.

might need a heavier flywheel or a true harmonic balancer up front.....

thinking about this dained my bramage. lol!



weird

Edited by 1 Lucky Texan, 18 April 2012 - 02:50 PM.

[maozebong]

you would probably need 1 and 4 to fire simultaneously, along with 2 and 3. engine bearings are probably going to see quite a bit of additional wear.


its not unheard of, the valve timing would be the trickiest part.

firing 2 injectors simultaneously would possibly require (if the injectors are low impedance) to remove the resistors if equipped with them or, (if they are high impedance) to replace with two low impedance injectors that would add up to a similar resistance of one high impedance. otherwise your injector drivers in the ecu would burn up real quick... or just put a weber on it and simplify your fueling needs

you would also need a coil on plug or dual coil setup. 99 miata has dual coils that look like they wouldnt be too hard to wire up.


id be interested to see how this turns out...

[1 Lucky Texan]

if you stay with the Otto cycle, that thing is gonna lope like a Harley.

potato,potato,potato,potato,potato

[NorthCoast]

otherwise your injector drivers in the ecu would burn up real quick... or just put a weber on it and simplify your fueling needs

you would also need a coil on plug or dual coil setup.

What about an ECU and coil setup for aircraft? They're setup to fire simultaneously for redundancy. Something to think about.

[TheSubaruJunkie]

how about carburated??

[maozebong]

that's what i'm saying. forget worrying about fuel timing and advance until you can get ignition timing figured out. carburation works j

[1 Lucky Texan]

make a good airboat/hovercraft motor I bet - flywheel effect from the prop would be helpful.

and disty/carb equipped would be easier to set up I think.


I recall a 'nature-type' program once where the guy converted a small in-line 4 to steam. Used it to motor up/down the Amazon or Rio Negro using driftwood for fuel.

Edited by 1 Lucky Texan, 19 April 2012 - 02:29 PM.

[Crazyeights]

Probably off base, but would it help work out the valve/cam timing issues to use (2) left or right side cams instead of (1) of each?

[987687]

Since 1&2 are at tdc together, and 3&4 are at tdc together, that's how it would probably have to fire.
Which they plugs fire like that anyway with wasted spark. Then couldn't you just set the pass side cam 360° off so they were both in intake and exhaust at the same time?

I'm not sure about if you could tie the injectors together (obviously with transistors not to overload the ones in the computer, or upgrade the ones in the computer). I don't know if that would really upset the computer, or if it wouldn't care because it would be thinking the injectors were firing when it wanted. I guess you'd have to put a dummy load in the injector leads you weren't using.

EDIT: I mean 360° off, not 180 on the pass side cam.

Edited by 987687, 19 April 2012 - 04:03 PM.

[1 Lucky Texan]

nvrmd

Edited by 1 Lucky Texan, 19 April 2012 - 03:17 PM.

[Scott in Bellingham]

Since 1&2 are at tdc together, and 3&4 are at tdc together, that's how it would probably have to fire.
Which they plugs fire like that anyway with wasted spark. Then couldn't you just set the pass side cam 360° off so they were both in intake and exhaust at the same time?

I'm not sure about if you could tie the injectors together (obviously with transistors not to overload the ones in the computer, or upgrade the ones in the computer). I don't know if that would really upset the computer, or if it wouldn't care because it would be thinking the injectors were firing when it wanted. I guess you'd have to put a dummy load in the injector leads you weren't using.

EDIT: I mean 360° off, not 180 on the pass side cam.

OK thats what I thought so the stock coil system will work, now if I turn a cam 180 how will that effect the cam and crank sensor curcuit?

[987687]

OK thats what I thought so the stock coil system will work, now if I turn a cam 180 how will that effect the cam and crank sensor curcuit?

I think you'd want the cam 360 off, that way both sides would be doing the same thing.
The computer doesn't care what the pass side cam is doing, because the pickup is on the driver's side cam. So as long as the driver's side cam and crank were in the same relation, the pass cam doesn't matter. Hell, in an ea82 it'll run with the pass side timing belt off, not well.. but it'll stumble along. And the computer doesn't know why it's not running right because it has no way of monitoring that cam.


Only thing I wonder about, I read somewhere, not sure if it's true. That the opposing cylinders are slightly off, ie. they don't hit TDC at the same time. Something about balance maybe? I'm sure I read something about that at one point, but again, I have no source to back that up. Dunno if anyone else has heard that, or I read mis-information.

Maybe when I do the timing belt on my legacy I'll put one side 360 off and see what happens... It's non-interference, what bad could happen.....

Edited by 987687, 19 April 2012 - 04:53 PM.

[Markus56]

The ecu reads the cam and crank sensors for spark timing. because only the driver side cam has a sensor, it might work due to the waste spark system. i need to think about it for a while though. you are hurting my brain!

edit: if you turned one crank 180 degrees it probably would not run due to compression problems. what you should start working on is how to make adjustable cam gears so that we can retard or advance cams without having to get delta cams.

Edited by Markus56, 19 April 2012 - 04:54 PM.

[987687]

So I'm thinking of how I could design an repeater circuit so it wouldn't fry my computer running two injectors at once. I think I might give this a try when I do my timing belt, because, why not! Heh. I'm not going to hurt anything.

You can make offset keys if you want to change cam timing.

[1 Lucky Texan]

ran across references to 'big-bang' engines and then saw this wiki article about several weird firing sequences tried in motorcycles;

http://en.wikipedia....der#4-stroke_V4

[Scott in Bellingham]

so keep the crank and drivers side cam in stock position, turn the passenger side cam sprocket 180 and maybe shuffle the spark plug wires around and run a carb or get 2 squirters to work at once , sounds quite simple and doable, so with the stock firing order 1-3-2-4, what 2 would fire together with the cam turned 180 ?

http://www.google.co...A5rDi9quiQ5AN2A

[1 Lucky Texan]

you have to shift the plug wires to fire the cylinders that just finished their compression stroke so, the ones at TDC immediately after close of intake valves.

and because it's a boxer - it must be the cylinder on the other side.

So, either 1 & 2 will fire, followed immediately by 3&4 - followed by a long pause, then repeat

OR

1&2 will fire, followed by a long pause, then 3&4 will fire, repeat.

Edited by 1 Lucky Texan, 20 April 2012 - 11:44 AM.

[987687]

It would fire 1&2 - 3&4. The coilpack is wasted spark, so that actually works out for this quite nicely. Each bank would fire every other rotation, which means you'd get a power pulse every turn of the crankshaft.

[1 Lucky Texan]

Each bank would fire every other rotation, which means you'd get a power pulse every turn of the crankshaft.

Pretty sure that can only happen if you find a way to run 2 cycle.

[987687]

Pretty sure that can only happen if you find a way to run 2 cycle.

no. 1&2 would fire. The next rotation they would exhaust, the next rotation they would fire. That's how a 4-stroke works.

So while 1&2 were exhausting, 3&4 would be firing, and vica-versa. So every rotation of the crank, every 360°, you have a fire stroke.

It's correct that each bank only fires every 720°, but both banks are a phase off, or however you want to look at it. So every 360 it fires.

[1 Lucky Texan]

no. 1&2 would fire. The next rotation they would exhaust, the next rotation they would fire. That's how a 4-stroke works.

So while 1&2 were exhausting, 3&4 would be firing, and vica-versa. So every rotation of the crank, every 360°, you have a fire stroke.

It's correct that each bank only fires every 720°, but both banks are a phase off, or however you want to look at it. So every 360 it fires.

front fire and then back fire , not each bank.



12 fire, begin power stroke down ----- 34 begin compression

34 fire, begin power stroke down ----- 12 begin exhaust

12 begin intake ----- 34 begin exhaust

34 begin intake ----- 12 begin compression
repeat


the last two actions occur with just the force of inertia from the flywheel. Unlike normal when each compression stroke is powered by one other cylinder's power stroke, that only happens with the second firing pair in this 'big bang' scheme. that is, one pair's compression stroke relies on inertia alone. That's why I suggested you may need more flywheel mass/effect. There's gonna be some increased torsional forces on the crank and flywheel parts too.




it's gonna sound like a harley

Edited by 1 Lucky Texan, 20 April 2012 - 10:35 PM.

[obk25xt]

Good read! Someone make it work already, then take some video or rather audio, and post it up! I wanna hear it........

[Gloyale]

Maybe when I do the timing belt on my legacy I'll put one side 360 off and see what happens... It's non-interference, what bad could happen.....

It might work if it was either 90 or 270 off. But I actually don't think so...try to follow my thinking (not sure of anything)

You gotta think about it, the lobes of the cams are timed 90 (crank) degrees apart relative to the next firing cylinder.

to actually make the valve timing of 2 pairs happen at once you'd have to make that 90 degree shift somewhere.

going 90 forward with the pass side cam would put the #3 valves in time with #2 valves.....which wouldn't work out for compression with the piston arrangement. But #1 would be 180 from #4

going 270 forward (or 90 back) with the pass cam would put the #1 in time with #4. But #3 would be 180 from #2

The best either combo could yeild is to fire 2 cylinder toghether, and the other 2 seperate....like some freaky 3 cylinder???


So....you see, the problem is that the lobes on each cam would actually need to be 90 degrees further off on each cam (#1/#3 and #2/4) Custom cams needed.

I think......

[987687]

Hmm, I hadn't thought of it that way. The way I was thinking of it was like this.
When 1 is at TDC compression, 2 is at TDC exhaust.
At the same time, 3 is at BDC intake. and 4 is at BDC after firing.

Turning the pass cam 180 would cause it to run as the 2 cyl. But, now you have me doubting that. I can't visualize the camshaft lobes in my head very well. Next time I'm in the garage I have an engine with the timing covers off that needs a rebuild or something. Still has compression on all cyls though, so maybe I'll mess around with that and see if it's even possible to get the compression at the same time on opposing cylinders.