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DIY Fuel injection thread.


yoeddynz

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If the air goes straight through the engine due to valve overlap it doesn't help produce any power whatsoever.

  

Just now, Yowzer said:

Your airflow puts a cap on how much power you can make. No point tuning for maximum power before you have the maximum available air entering the cylinder.

 

What you're suggesting is pretty much equivalent to saying is the amount of poop a cow makes puts a limit on how much milk it can produce and therefore you should make cows shit as much as possible - whacking them with a stick is ideal for milk production!

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Yep you'll see that on the wideband, I'm actually hoping to see some evidence of this happening once I've got exhaust side VVTI.
But I think there's just not enough overlap with only one cam moving and stink arse factory cam profiles.
But I might need bigger cams. Or you just might not actually see this at all.
Your MAF readings, then how much fuel you're putting in to suit, wont end up reaching your target AFR. It'll show leaner than it should.
If there was evidence of this happening currently I'd expect it to curve my fuel table a bit. 

But this is the most accurate fuel table I've ever had, and it's nearly a straight line all the way across. Especially at high load.

MAF.PNG.9ef8245428832472184432fd9b18d609.PNG


Where as when I tuned same motor with MAP sensor, because the relationship between MAP and actual oxygenated fresh air airflow is convoluted, it looks like a complete mess because of harmonics and shit like that. As well as needing to compensate for internal EGR making the lower parts look weird too. 
There are heaps of variables which mess with the pressure>mass equation.

MAP.PNG.97bd746d864000daa274846895e0844a.PNG

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Just now, ajg193 said:

What you're suggesting is pretty much equivalent to saying is the amount of poop a cow makes puts a limit on how much milk it can produce and therefore you should make cows shit as much as possible - whacking them with a stick is ideal for milk production!

That's a terrible analogy, perhaps closer would be to say that a cow cant produce more milk than the amount of water it drinks.

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Just now, Yowzer said:

The amount of air you'd lose to scavenging would be pretty fuck all, wouldn't it? If anything it's beneficial as it's clearing all the exhaust out before it fills again? Pretty sure that's how it works

 

Thats more what I'm thinking, that a more likely scenario is that you're actually only ever clearing the old gas out of the cylinder with a certain efficiency. 

But with some much bigger cams its probably more of a thing.

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Just now, Yowzer said:

Best get those cams then. I wanna see more graphs!

And then you can play with getting an NA engine over 100% VE

Yeah the problem has been that there arent any aftermarket cams which could fit the single VVTI engine. 
They only fit the manual dual VVTI motor (which is now in the hole! hooray)

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Just now, ajg193 said:

Yeah I realized it's a stupid analogy straight after posting. 

 

It's actually a pretty reliable metric though, like ECUs which have a torque request strategy use a calculated grams/sec of airflow as their torque estimate (Motec M1 etc)

I guess an easy way to visualize it, is why does shutting the throttle make your car make less power... less air flow. increasing airflow is just like making your throttle go 110% open haha.

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Just now, Yowzer said:

OK I'm gonna go build a loom to connect my MS2 to a 5MGE now

Shit have you seen the MS2PNP stuff? The whole pre-built ECU's are pretty expensive but they did a run of all sorts of common nippo-denso ECU connectors which you put on a extension board and can plug and play your factory loom. Lots of the ones we would want are discontinued but I would hunt one down if I had a 80's Toyota EFI project because the normal MS connector is gay.

https://www.diyautotune.com/support/tech/hardware/diypnp/available-models/

I would have bought a few of the 4age ones just because if had know about them when they were available. A couple have come up on facebook MS groups.

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