Batch injection with siamese ports, injector timing

Converting To Delco ECU From Carby Or Other Injection Systems
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Re: Batch injection with siamese ports, injector timing

Postby Charlescrown » Fri Jul 06, 2018 3:47 pm

I would still consider 3 injectors and place them as far away from the ports as possible to get better fuel mixing. I am using 12P on a TBI with 2 injectors and it works a treat.

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Re: Batch injection with siamese ports, injector timing

Postby Jayme » Fri Jul 06, 2018 3:55 pm

Holden202T wrote:the problem with the grey motor though is the head only has 3 small holes for the inlets, so they might not even work like this unless the injector is almost in the head itself!

2yxnc51.jpg


plenty of room there to drill the injector into the head :P as long as you dont hit a water jacket :P

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Re: Batch injection with siamese ports, injector timing

Postby FBUTE » Fri Jul 06, 2018 7:58 pm

I had originally tried to get 2 injectors on each inlet runner but they simply arn't wide enough so went with 1 per inlet .My thinking at the time was that as all the injectors squirted together(hope i have this correct)then it may still work.Also have made a straight fuel rail for simplicity so mounting 3 in a line was easier .I was aware there would still be a question of getting enough fuel out of the three injectors only and pulse width etc.Im not sure if its relevant but this setup uses 3 Toyota 4AGE 20 valve throttle bodies.Yes the idea of putting the injectors in the head had gone thru my mind ,something for another engine maybe.Really appreciate everyones input on this,thanks.

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Re: Batch injection with siamese ports, injector timing

Postby VL400 » Sun Jul 08, 2018 2:10 pm

Another issue with siamese ports is AE, rather than fuel sitting waiting for the valve to open on each cylinder the first to open gets most or all of it (and pulls more of the condensed fuel from the intake), then when the shared cylinders intake valve opens there is bugger all left sitting waiting.

There are two modes of AE in operation all the time, one that extends the regular pulsewidth (the manfuel items in 11/12P) and another that adds fuel between normal openings (called async and is dTPS AE ie in carb tuning the throttle pump) which is the one that can cause issues with lean cylinders on throttle changes.

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Re: Batch injection with siamese ports, injector timing

Postby v6bucket » Mon Jul 09, 2018 8:02 am

VL400 wrote:Another issue with siamese ports is AE, rather than fuel sitting waiting for the valve to open on each cylinder the first to open gets most or all of it (and pulls more of the condensed fuel from the intake), then when the shared cylinders intake valve opens there is bugger all left sitting waiting.

There are two modes of AE in operation all the time, one that extends the regular pulsewidth (the manfuel items in 11/12P) and another that adds fuel between normal openings (called async and is dTPS AE ie in carb tuning the throttle pump) which is the one that can cause issues with lean cylinders on throttle changes.

Would this still be an issue if the injectors were moved further away from the port(similar to a carby), or would it introduce other problems?
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Re: Batch injection with siamese ports, injector timing

Postby FBUTE » Sat Dec 01, 2018 12:22 pm

Am i correct in thinking the fan should run with the ALDL plug ''paperclipped'' between the black and white wires.This is not happening.The check engine light flashes to indicate 12(which i assume means everything ok).I had been told this puts ECU into Diagnostic mode and the fan should go. I think I need to get these basic functions sorted before trying to run engine.Has no engine driven fan.Next will be to tackle the TBI thing.

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Re: Batch injection with siamese ports, injector timing

Postby Holden202T » Thu Dec 13, 2018 10:50 am

yep thats correct.

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Re: Batch injection with siamese ports, injector timing

Postby FBUTE » Thu Dec 13, 2018 6:37 pm

Just an update .It turns out my Fan Relay was incorrectly wired so was never going to go. Many thanks to VK3800 for the diagnosis and the instructions to wire correctly. Cheers

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Re: Batch injection with siamese ports, injector timing

Postby Ken » Fri Dec 14, 2018 9:02 pm

antus wrote:Ken, im not sure what your talking about. In MPI all injectors fire at the same time,

Missed your reply, just re-read this thread now..
Not sure why, though for some reason I had it in my head the older systems were banked (2x3), not batched (all 6)injection.

Edit:nevermind, dumb a** here took little notice of the title. :roll:

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Re: Batch injection with siamese ports, injector timing

Postby FBUTE » Tue Feb 12, 2019 6:06 pm

Just an update on this project.We now have a LC2 Wideband fitted and the NVram set to Type J and 6 cyl. Engine was very hard to start,took 1/3 throttle
to start and ran rather rough i thought.Is everyone still of the opinion that that TBI is the way to go? I have just read back through the original assembly instructions that came with the NVRam to startback at the start as i seem to remember the engine did originally start and idle.Having been on this for a couple of years now im losing track .Any suggestions out there? The Strombergs on the shelf are looking mighty tempting.

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