DIY Fuel injection thread.

[Rookie]

Anyone got a rough dynamic compression ratio limit for e85?

[downtrail]

That's my zetec at 0.8lambda. But it's at 100% above about 6800 rpm. Already have high fuel pressure too.

Doesn't seem right have you logged fuel pressure at top end. Pump might not be keeping up.

[eke_zetec_RWD]

Yip, think is was 50 base pressure plus 16psi boost. Pretty sure everything is sweet. It runs genuine 044 pump

[Roman]

W

Firstly the dyno graph - green is with VVT on and red with it off:

 

 

 

Now the fuel requirements of the engine through the same rev range (obviously directly related to air flow):

And then "optimal" timing curves for the same thing:

 

 Wouldnt the VVT ON be the red line on the dyno graph? I would have expected the higher power figure to be with the cam advanced.

Either way, it's quite a drastic difference!

Regarding Aliexpress 1000cc injectors, yes I've got a set of these.

 

They're a single pintle design which generally means a narrow spray pattern.

An old crappy design hence the cheap price.

But I'm using them as seconday injectors further up the manifold. I'd be hesitant about using them as primary injectors right by the head as the spray pattern sucks for that with a single pintle. (But possibly good for what I'm doing... Maybe)

The place I got mine from flow benches them all prior to purchase to make sure they're a matched set.

As I'm guessing quality control is a bit dubious haha.

 

[downtrail]

Yip, think is was 50 base pressure plus 16psi boost. Pretty sure everything is sweet. It runs genuine 044 pump

The 044 isnt designd for e85. Id be checking for blockages filters screans in the injectors etc log your fuel pressure somethings not right you should have no problem making that power with thoose injectors.

Remember e85 will break down the varnish left from conventional gasoline in your tank and lines and will block things Up.

[Roman]

Oh stink, so you cant really switch between the two at all?

[eke_zetec_RWD]

It was a brand new setup, never seen unleaded.

I didn't realise the 044 was no good. I will check filters etc.

How do you calc your injector sizes?

[Lith]

 Wouldnt the VVT ON be the red line on the dyno graph? I would have expected the higher power figure to be with the cam advanced.

Either way, it's quite a drastic difference!

 

Ahhhh yes, I wasn't paying enough attention to what I was typing   It was a much bigger difference overall to what I was expecting, I thought there would be an overlap where it's better to be advanced or not but it ultimately made more everywhere.   I ended up setting the VVT change over to be driven by throttle position (I guess with a minimum RPM) as opposed to a window of rpm and it becomes more of a case of whether the car is in quiet cruisy economy mode or hoon mode

[Roman]

Yeah that's interesting, it's a lot different to my example where the MAF datalogs show big benefits in moving the cam around through the rev range.
(Although whether or not a dyno would reflect that...)

I'm going to start more or less from scratch again with my tune.
I'm going to manually calibrate all of my sensors, to try get all of the compensations working as accurately as possible.
As it would seem like I would tune the car on one day and it would be good, go out another day (or night) and it would be a bit off.
(in terms of WOT fuelling) It wanst awful but could probably be better and I think that comes down to accumulative inaccuracies with my sensor calibrations.

Will set the injector timing advance to match the cam advance as well, although I suspect that it wont make much difference for anything except the staged outer injectors which are small pulsewidth high CC rating.

[Lith]

Yeah that's interesting, it's a lot different to my example where the MAF datalogs show big benefits in moving the cam around through the rev range.

(Although whether or not a dyno would reflect that...)

 

Will be interesting to see how you get on with this.

 

 

 

As it would seem like I would tune the car on one day and it would be good, go out another day (or night) and it would be a bit off.

(in terms of WOT fuelling) It wanst awful but could probably be better and I think that comes down to accumulative inaccuracies with my sensor calibrations.

Will set the injector timing advance to match the cam advance as well, although I suspect that it wont make much difference for anything except the staged outer injectors which are small pulsewidth high CC rating.

 

How far off are we talking in terms of drift?  And staged outer injectors..??  What exactly is this setup, my curiosity is piqued    How are you choosing your injector timing, just purely calculated based off what you expect or with virtual dyno or lambda readings? 

 

 

[downtrail]

This one here is pretty close most of the time.

http://www.deatschwerks.com/resources/fuel-calculators/fuel-injector-calculator

Also if there are any normal efi hoses in use they are no good with ethanol either it breaks down and clogs stuff.

It was a brand new setup, never seen unleaded.

I didn't realise the 044 was no good. I will check filters etc.

How do you calc your injector sizes?

[eke_zetec_RWD]

That calc pretty much confirms it?

420hp crank (350 hp plus guess )

E85

Supercharger

=83lb injectors @90% duty cycle

[Roman]

How far off are we talking in terms of drift?  And staged outer injectors..??  What exactly is this setup, my curiosity is piqued    How are you choosing your injector timing, just purely calculated based off what you expect or with virtual dyno or lambda readings?

Cant remember exactly about drift, but the thing is that the calibration for some of my sensors was a bit of a bodge because I just wanted to get the car going.

I just guessed that my car would idle at about 40kpa, and that was my map sensor calibration haha! So this time I want to do it properly. (First time with an aftermarket ECU)

 

Okay soooo regarding staged injectors. The idea is that for an NA motor you have a set of injectors higher up the intake runners, that come on at high rpm. Gives more time to mix air/fuel at high RPM and so a little more power for 'free'. (yet to be confirmed...)

When you're using small CC injectors close to the head, at max load they're spraying most of the time anyway so injection timing isnt particularly important.

But to avoid reversion spitting fuel out the top of the runners, when using injectors higher up, You need to have a short injection period. So higher CC rating to keep them working at say 20% duty.

As luck would have it the cheapest type of big CC injector is an old single pintle design which as a general rule have a very narrow spray pattern. (which is what makes them awful for most applications) But this is what I'm after as I dont want it fanning out onto the runner walls.

This means the injection timing becomes more important though. Currently it's set to end injection 400 degres BTDC static across the rev range. which has worked "fine" with the standard injectors by the head.

I can set an injection timing map seperately for the inner or outer injectors. So at the very least I would imagine that I will need to make the outer injection timing move advance with the cam.

I figure that I can 'blindly' check for reversion (I cant take my plenum off to eyeball it!) by adjusting the timing across the board and seeing if it gets leaner or richer at various rpm points.

I would imagine that the lowest amount of fuel required to reach the AFR I want will mean the least amount of reversion going on. (guessing)

I had this all setup and spent a very small amount of time tuning it, and it "seemed to" go a bit quicker, but I ran into what ended up being a coincidental ignition problem so chickened out.

I was only a few days ahead of a few big events that I needed a reliable car for, so I went back to a standard manifold... Then blew the clutch up so car's back in bits and so redoing a few things.

I wasnt expecting any difference but it actually sounded pretty cool having the big injectors clacking away, they make a racket! You can hear when they start coming on.

Ideally I want an RPM vs Load map by which I can specify inner/outer injection ratio. As you end up wanting to transfer across to mostly outer injectors at high rpm full load. But lower rpm / low load using only inner injectors. I've Asked Link about this and they said they'll be putting it in the next major firmware update, woohoo. As currently you can only specify an injection ratio based on TPS or MAP reading. More designed for turbo applications currently.

Glenn AKA Celica RA45 mentioned that when using staged injection on his beams motor (admittedly one that's a lot further from standard) it gave a notable midrange onwards power increase.

So I thought I'd have a play with the idea too, but so far it's been largely inconclusive due to lack of testing.

[downtrail]

That calc pretty much confirms it?

420hp crank (350 hp plus guess )

E85

Supercharger

=83lb injectors @90% duty cycle

Ahh super charger. Sorry assumed turbo charged.

[eke_zetec_RWD]

Ahh super charger. Sorry assumed turbo charged.

Ohh yea and now I think about it eaton charts says a m90 will use about 60hp to run it at 16psi and 14000 rpm so if I make 350hp at wheels add to that drivetrain losses and supercharger driving losses it might be up to 450hp worth or fuel?

[Rookie]

Roman, the reason you make more power is because of the fuel cooling the intake charge, not because of has more time to mix. When I read about that it was a bit of a eureka moment.

[peteretep]

So I should get some copper and run the fuel line in front of my ontake runners?

[Rookie]

That won't have much of an effect seeings as it is evaporative cooling.

[downtrail]

Yeah could be havnt worked with superchargers much that website calculation will add a rough loss for driving a supercharger but obviously cant cover all setups.

Your on the right track tho. I just assumed turbo thats why i was like wtf thoose injectors should be ok for what your doing.

Ohh yea and now I think about it eaton charts says a m90 will use about 60hp to run it at 16psi and 14000 rpm so if I make 350hp at wheels add to that drivetrain losses and supercharger driving losses it might be up to 450hp worth or fuel?

[Spencer]

yip rookie is on to it with the evaporative cooling of the fuel in the intake. One other thing I have read in racecar engineering is that race teams run their outboard injectors at insane pressures (most classes have fuel pressure rules now) for pretty decent power gains. You should run those injectors at 15 bar fuel pressure roman.