Author Topic: 8 injectors on a 4 cylinder  (Read 19993 times)

Offline se7ensport

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8 injectors on a 4 cylinder
« on: April 17, 2007, 09:55:36 pm »
Evening

I'm currently making up the loom and unsure what to do regarding the injectors, which will be run sequentially. I've got 2 options:

1. wire two per cylinder in parallel

or

2. wire all 8 independently



Suggestions gladly received.


Alex



Offline Agriv8

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Re: 8 injectors on a 4 cylinder
« Reply #1 on: April 17, 2007, 10:24:01 pm »
Personally I would wire seperatly as I you can run 8 injectors so I would suspect that you will be able to stage them. ( might be wrong but Vems seems to be able to do everything else  ;D ;D )

Worst case senario and it cant you could always pair them up just before they go into the econoseal/vems.

Presently running this on the V8 ( running batch fire - left bank and right bank fired together) so 2 of the injection drivers  running the v8 but my loom allows these to be split into the individual 8 ( sequential )  when time allows

hope that makes sense.

regards

agriv8
'The older I get the faster I was'

Offline dnb

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Re: 8 injectors on a 4 cylinder
« Reply #2 on: April 17, 2007, 10:29:47 pm »
Yes, you can stage the injectors :)

Offline se7ensport

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Re: 8 injectors on a 4 cylinder
« Reply #3 on: April 17, 2007, 10:40:25 pm »
I'm a little way off at the moment but does the benefits of staged injection outway the extra setup time (or is it straight forward), I'm not sure where to start with it, a nudge in the right direction would be appreciated.

Offline rob@vems.co.uk

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Re: 8 injectors on a 4 cylinder
« Reply #4 on: April 17, 2007, 11:26:42 pm »
The best nudge I'd give is towards getting it running on four first.
Injector staging will follow on once you've got that nailed.

Rob

Offline cliffb75

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Re: 8 injectors on a 4 cylinder
« Reply #5 on: April 18, 2007, 06:53:01 pm »
Can I ask why you want to run staged injectors? Is it because you're using funny fuel in the secondary injectors?

The main reason why staged injectors became popular was because older injectors did not have the dynamic range to cover everything from idle to full load cleanly. More modern designs and better injector driver stages generally get around this problem - see SM's 1000cc injectors on his car for example.

So unless you are running parallel fuel systems, or you are really running absolutely MASSSIVE bhp/litre figures, I would expect you could use a set of four correctly sized injectors without problems.

As Rob says, its not really much more effort to add extra injectors later than now, but why put the work in if it isn't needed?

Offline se7ensport

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Re: 8 injectors on a 4 cylinder
« Reply #6 on: April 19, 2007, 08:23:50 pm »
It's not a desire to use staged injectors, I'm using GSXR 1000 TB's off of a 2006 bike, they come with 8 injectors as standard.

I'm going to need to use both injectors per cylinder to cover the fuel requirments (bike is circa 180bhp, my engine should be close to 190).

funny fuel would be cool, but way beyond the scope for this project, I'm after the maximum power I can get while keeping a degree of drivability.

I figured staged would allow smoother progression at the bottom of the rev range (I could be completly wrong), is it best to have both banks to fire at the same time while running sequential or as an example 1 bank up to 2000revs then the second bank kicks in (still running sequentially).

I'm going to go with Robs suggestion to get it running, but long term I'm curious as to what I should go for.



Alex

Offline cliffb75

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Re: 8 injectors on a 4 cylinder
« Reply #7 on: April 19, 2007, 10:17:04 pm »
Hmm, interesting. Didn't realise anyone was still using multiple injectors as standard. Haven't kept up with the bike scene for several years now....

But, if they are there already, then fair enough its easier to keep them then try to blank them off.


I figured staged would allow smoother progression at the bottom of the rev range (I could be completly wrong)

No, you are completely correct  :), and this will be the way they're controlled by the standard ECU. As I recall most of the early fuel injected bikes got slated for the tip in response being nasty (tip in shunt), which was most likely caused by the injectors having to go from overrun fuel cut and come back in. Injectors have a minimum pulsewidth at which they reliably deliver fuel, which means when you switch them on you get a small 'kick' or shunt as the bike goes from negative to positive torque. In the OEM car world we get around it by retarding the spark at the point the injectors cut in to smooth the torque transition. I guess Suzuki have got round it by running staged injection so that the minimum pulsewidth cn be reducd, helping to reduce that step in torque.

As for staging them, rather than by speed you should ideally control by required flow, i.e. use the primary injectors up to a certain flow requirement, which could be high speed low load, or could be high load low speed, and then start running the secondaries after that. Not sure if thats possible with VEMS or not? (One for Rob I think  ;)) Primary injectors shoud ideally be fully sequential, but secondaries would normally be less important, as they would be installed much further up the inlet giving plenty of mixiing and vapourisaion time. However, if they are in basically the same loaction as the primaries on your TB;s. then it would be good to keep them sequential too, or at least semi sequential.

Got any pics of the TB's? I'd be interested to see them :)


Offline se7ensport

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Re: 8 injectors on a 4 cylinder
« Reply #8 on: April 19, 2007, 11:58:23 pm »
pics

Offline se7ensport

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Re: 8 injectors on a 4 cylinder
« Reply #9 on: April 19, 2007, 11:59:07 pm »
pics

Offline se7ensport

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Re: 8 injectors on a 4 cylinder
« Reply #10 on: April 20, 2007, 12:01:04 am »
more pics

Offline cliffb75

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Re: 8 injectors on a 4 cylinder
« Reply #11 on: April 20, 2007, 06:37:25 pm »
Cool. A very neatly packaged little lot.

Is that a fuel pressure sensor in the middle of the rail?


Offline rob@vems.co.uk

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Re: 8 injectors on a 4 cylinder
« Reply #12 on: April 20, 2007, 07:20:56 pm »
I am still trying to find out how the staged injectors are phased in, the settings are that the secondary are a % of the primary pulse.
The phasing occurs based on TPS % and|or MAP pressure.

Like much of this stuff you can bet that theres a debate over the multiple methods of phasing, and that if you give enough feedback via Datalogs and experimentation that the various methods will be implemented until the right one is found.

Rob

Offline se7ensport

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Re: 8 injectors on a 4 cylinder
« Reply #13 on: April 20, 2007, 11:29:25 pm »

Is that a fuel pressure sensor in the middle of the rail?



Nope, it just joins the two fuel rails together. The fuel regulator on a GSXR is within the pump unit that sits in the tank, however, I'm planning on useing a blackbird pump as due to the shape of the pump housing it has a built in swirl pot, I know they both run at 45psi, but the blackbird pump looks as though it has a return line... I need to find more info  ;)

Rob, cheers for any info you can find  ;D

Offline miniminor63

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Re: 8 injectors on a 4 cylinder
« Reply #14 on: July 29, 2010, 03:18:42 am »
sorry for dragging up this old topic, but my question is related.

take a look at this.

I am running the same engine basically. And I am intrigued by these claims:

"The obvious changes on this engine over its "sister" engine is the addition of the 4 extra external injectors. We did this as an option to help with the NOS control, in reality the engine loved using these injectors in N/A (no NOS) from as little as 3000rpm - high load, all the way through to the top end of the rev range. So much so it picked up 6% torque over the "sister" engine all the way through the range. The trick thing with the 8 injectors is that they are not switched, they are phased in and out depending on load/speed - so there are no transient "lumps" in the response of the engine and neither set of injectors handles the fuelling 100% - the other 4 always provide a percentage.

Are we able to sort this with VEMS?