EMANAGE: Top feed vs Side feed injectors

[bruinbear714]

As we all know, the Emanage can correct for injector sizes up to +150%. I interpret this as a 50% increase over stock injector size. For the KA engine, that means we are guaranteed that injectors up to 400cc will work without problems.

There are people that run 550cc's without any problems, but I am unsure of whether they are top feed or side feed injectors. The circuit that drives the two types of injectors are different - one is a saturated type (high impedance) and the other a peak and hold (low impedance), with the latter being more costly and difficult to implement.

To use top feed injectors with a side-feed system, you need some resistors to bump up the resistance so the total resistance is the same as the side feed injectors. This works... but I am weary of the fact that the driver was designed for saturated injectors, thus the top-feed injectors may behave a little different. Also, the response time of a top-feed injector is slightly quicker than a side-feed by about 0.5ms.

So the million dollar question is: Given the same size injectors, additional resistance for top feed, and everything else remaining the same, would a top-feed injector squirt out the same amount of fuel as a side-feed injector?

[andrave]

people are using e manage (on other cars, for other engines) with injectors well over 550...in combination with a larger mafs I am hoping to support 850's.I have seen them support in excess of 660's on eclipses, larger on supras...(and thats with six of em).

[Jonny 290]

e-manage can only do maps +/- 50 percent or something like that

it will allow however for HUGE injectors via the injector correction feature.

If you're ok with 1200rpm idle, it'd run 1000cc injectors.

[C-Kwik]

The injector correction figure is limited to the same restrictions as the airflow adjustment map since they use the same method to fool the ECU. The injector correction feature is just automatic where the airflow adjustment map is not.

The +/- 50% is rather arbitrary according to many in the E-Manage community. There are probably ECU's that can not handle more than this much change. It may put the ECU out of it's range. Apparently, Nissan ECU' do not seem to have much problem running some insanely large injectors using the E-Manage. I think someone is running 720cc injectors using an E-Manage. I can't remember if this was on a KA or SR, but either way, it's more than 50% increase and much closer to 100%.

[bruinbear714]

The injector correction figure is limited to the same restrictions as the airflow adjustment map since they use the same method to fool the ECU. The injector correction feature is just automatic where the airflow adjustment map is not.

The +/- 50% is rather arbitrary according to many in the E-Manage community. There are probably ECU's that can not handle more than this much change. It may put the ECU out of it's range. Apparently, Nissan ECU' do not seem to have much problem running some insanely large injectors using the E-Manage. I think someone is running 720cc injectors using an E-Manage. I can't remember if this was on a KA or SR, but either way, it's more than 50% increase and much closer to 100%.

There's a BIG difference on how Greddy words the injector increases. 150% OF stock injectors would be only 405cc while 150% OVER stock injector size would be 675cc.... I don't think they meant 675cc because the stock Nissan ECU can only shorten the pulse width so much...

Anyhow, my question doesn't deal with that... I want to know given the same conditions, injector size, etc etc... would a 550cc top feed injector squirt out the same amount of fuel as a 550cc SIDE feed injector? I believe the step response of the two types of injectors are different, hence one is called PEAK AND HOLD and the other SATURATED. One has a faster response time than the other, etc etc. The circuit that drives the two types of injectors are DIFFERENT, but people just add resistors to present a larger resistance to the drivers so it doesn't burn out.

[TrunkMonkey]

Anyhow, my question doesn't deal with that... I want to know given the same conditions, injector size, etc etc... would a 550cc top feed injector squirt out the same amount of fuel as a 550cc SIDE feed injector? I believe the step response of the two types of injectors are different, hence one is called PEAK AND HOLD and the other SATURATED. One has a faster response time than the other, etc etc. The circuit that drives the two types of injectors are DIFFERENT, but people just add resistors to present a larger resistance to the drivers so it doesn't burn out.

low impedance = peak and holdhigh impedance = saturated

wether an injector is top feed or side feed does not determine an injectors impedance.

prime example: the ka24e uses top feed injectors while the ka24de uses side feed injectors...BOTH are high impedance (saturated).

the ecu determines how much fuel is delivered (how long the injector is open). so regardless of the impedance, you will get the same amount of fuel.

-demetrius

[C-Kwik]

There's a BIG difference on how Greddy words the injector increases. 150% OF stock injectors would be only 405cc while 150% OVER stock injector size would be 675cc.... I don't think they meant 675cc because the stock Nissan ECU can only shorten the pulse width so much...

I wasn't talking about the semantics of what Greddy says. I was actually posting in response to Jonny's post in saying the injector correction feature and the airflow adjustment feature are essentially the same thing. One is automatic, the other is manual. They both work by altering the MAF signal. So the limitations, if any, are the same. And at the same time I was correcting the comment about the +/-50% that he posted. While it is what Greddy says, just that many have already surpassed that limit without any probnlems. Which is not in any disagreement to anything you have said so far.

As far as the side-feed, top-feed debate, I don't have an answer, but, I have heard sidefeeds respond quicker since they run cooler(cooled by the gasoline). But I can't confirm if this is a fact or not.

[IvoryJ30t]

oh, and just to clear it up, in the manual greddy says 150% increase, so its 150% OVER, not OF. they also say that the limitation is an issue with factory ECU's, not the emanage unit itself. it comes down to the ecu.

as far as the side feed/top feed goes, its might be more of an injector specific issue, and not side/top feed in general.

the rating is just peak flow, but the map characteristics may vary between the two if they are not of the same manufacturer.

[bruinbear714]

I wasn't talking about the semantics of what Greddy says. I was actually posting in response to Jonny's post in saying the injector correction feature and the airflow adjustment feature are essentially the same thing. One is automatic, the other is manual. They both work by altering the MAF signal. So the limitations, if any, are the same. And at the same time I was correcting the comment about the +/-50% that he posted. While it is what Greddy says, just that many have already surpassed that limit without any probnlems. Which is not in any disagreement to anything you have said so far.

As far as the side-feed, top-feed debate, I don't have an answer, but, I have heard sidefeeds respond quicker since they run cooler(cooled by the gasoline). But I can't confirm if this is a fact or not.

That's the just the sort of information I wanted to hear. If it does respond quicker, then given the same pulse width, the side feed would in theory let out a little more fuel than a top feed injector, no? The reason I'm interested in this information is because I might used an emanage map tuned for 550cc top feed injectors in a system with 550cc side feed injectors.

[MikeMurphy]

I suspect they would be extremely close anyways, so as you goto dyno the setup maybe grab yourself a wideband o2 sensor and fine tune it. The 550cc map would be a starting point that you could alter ever so slightly, if at all.

Sorry I dont have the exactly info you want, but its just an idea I hope you can benifit from.

[C-Kwik]

It certainly can make a difference. However small. But JWT requires that you send one injector to them for testing if you are having them tune for an injector they have not tuned for before. They confirm the actual flow rate and response times and such. So it can make a difference. But it shouldn't be much.

As far as the limitations of the E-Manage, a similar discussion is going on in the E-manage Yahoogroups. While the ECU can be a limiting factor, it is doubtful this is the case with Nissans. But too large an injector results in too long a minimum duration at idle. So in this case, it would seem to me that a car that usues smaller injectors can handle a larger increase than a car that starts with larger injectors. In fact I'd suspect all Nissan ECU's are limited to the same size injectors for a given motor.