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Tbi injector size 13b sp

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Old 07-30-17, 01:52 PM
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Tbi injector size 13b sp

I trying to find out what size injectors I need for my efi hardware ida style throttle body. The engine is a 13b streetport 4port. Fi swap fb project. I don't see much activity in this N/A forum. Has everyone gone turbo or something. ?
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Old 07-31-17, 09:46 AM
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Most activity on the forum is in the turbo sections, yes. N/A people generally know what they want and build the car/engine once and don't have a whole lot of things to post afterwards lol.

The easiest setup currently for n/a that should provide plenty of fuel for up to 300 HP is running 2x ID1000 injectors in the primary position only and not running any secondary injectors. This simplifies your throttle body setup so you only need to run a throttle cable to the TBs and you also don't have to muck around with injector transitions. What engine management are you planning to use?
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Old 08-11-17, 04:34 PM
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Efi hardware

I thought you wanted to run four injectors. Primary and secondary. I just got a EFI Hardware ida style throttle body. I put four turbo 2 injectors 500cc each. With a adaptronic universal 440d ems. Aem smart coils. I picked adaptronic because I thought it was the easiest to tune. I have no prior experience with aftermarket fuel injection. Especially tuning on a laptop. I always had carbs on my rx7's. Any advice would be appreciated on installation in a first gen. Got pretty much all my parts now. Going to install soon.
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Old 08-12-17, 08:12 AM
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You don't need four injectors. Modern injectors and computer hardware are precise enough that you can get away with a pair of 800-1200cc injectors and be done with it.

I went for years with a pair of 680cc injectors and fairly low-end injection that could only control pulsewidths down to the tenth of a millisecond. This led to high granularity when idle/low load pulsewidths were in the 1.6-1.7ms range. Given that large ported engine tend to be less efficient at low load, and we're not shooting for the kind of precision needed to make a catalyst happy, this was more than sufficient.

A word of caution to future readers. GSL-SE ran on 2.5 bar base fuel pressure, NOT 3 bar like practically everything else. 680cc is the flow rating at 2.5 bar. When you buy a pair of RC1000 injectors to replace those and give yourself more headroom, and use them at 2.5 bar, you only get about 900cc/min. No wonder my duty cycles didn't change all that much 900cc/min was still sufficient fuel for my bridge port to give me a safe fuel-dump at the top end to slow the engine down so I wouldn't overrev.
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Old 08-14-17, 02:43 PM
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Yeah, I agree with most stuff said above. 500cc turbo injectors will probably work, but on a budget I think I would try 4 yellow RX-8 injectors, and with a more spacious budget I would go with a single ID1000 injector per rotor, which is what I run on my semi PP 2-rotor.
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Old 08-14-17, 04:33 PM
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Injector technology has come a long way since the mid 80's. Previously they ran 4 injectors because large volume (1000cc/min plus) injectors flow did not scale linearly with duty cycle so they would have very poor idle quality at those low flow duty cycle levels. So you would use a smaller injector and then at some determined RPM and load when the primary injectors start to get close to max flow/duty cycle you would turn on some secondary injectors to supplement how much fuel you needed for the high end.

However, the injectors being made today do not have these same limitations so you can just get 1 for each rotor that can meet your top end fuel flow needs but they still perform very well down at really small duty cycles which completely erases the need for secondary injectors. This does not necessarily apply to turbo applications because often they need considerably more fuel flow (over 2000cc/min per rotor!!!) than a naturally aspirated application. Hopefully that kind of helps clarify and give background to the advice we have given above.

As far as tuning and using the Adaptronic, can't really help you there. I'm just about to install a megasquirt ms3-pro evo into my '86 GXL. However, go hang out in the Adaptronic section of the engine management forum. I'm sure there are some good base maps to help get you up and running so you can actually start tuning. Let us know how it goes!

Last edited by Lavitzlegend; 08-14-17 at 04:37 PM. Reason: adding last paragraph
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Old 08-15-17, 06:52 PM
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Well I already got 4 550cc turbo 2 injectors for $50 tested and cleaned . So I'll see how that works out. . Making the harness now using nylon rope as a template cut to the length I need (+3inch).
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Old 08-16-17, 09:42 AM
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That should provide plenty of fuel to meet your needs. Let us know how it goes and post some pics!
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Old 08-18-17, 11:59 PM
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Originally Posted by Holdfast View Post
Well I already got 4 550cc turbo 2 injectors for $50 tested and cleaned . So I'll see how that works out. . Making the harness now using nylon rope as a template cut to the length I need (+3inch).
that is plenty of injector. its just that 2 is simpler. you can run staging with 4 injectors, and that will get around the 'not linear at low duty cycle' thing. 2x550 will idle around 2.2-2.5ms, so you're good there.

i'd try staging with load/throttle position, but you may have to play with that

Last edited by j9fd3s; 08-19-17 at 12:02 AM.
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