TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

Has any one tried the Optimum EFI® – TBI Throttle Body Injection

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Old Jan 2, 2019 | 10:36 PM
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Has any one tried the Optimum EFI® – TBI Throttle Body Injection


I found this on Ebay and was wondering if anyone has any info on this

Last edited by Marks90rsz28; Jan 2, 2019 at 10:42 PM.
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Old Jan 3, 2019 | 08:08 AM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

Looks like a modified GM TBI setup, it's only a 2 barrel, why would you want to use that?
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Old Jan 3, 2019 | 12:01 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

I don’t think a tbi injector driver would even handle the two high resistance injectors.
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Old Jan 3, 2019 | 10:52 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

That's what I was wondering. I like the idea of using modern injectors but wasn't sure if the computer could handle them. I'm thinking of switching to the dynamic efi computer and that's why I was looking at this to see if they were compatible
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Old Jan 3, 2019 | 10:57 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

And I'm fine using the 2 bbl for now because I currently have a 305 in as 90 rs and I'm trying to get 300hp out of it. And for the record the only reason I'm staying with the 305 is I love telling people I beat them with that boat anchor. I'm also gathering part for my future gen 4 iron block 6.0 ls build for the car
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Old Jan 4, 2019 | 10:55 AM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

A TBI ECM injector driver can easily drive a high impedance injector (12 ohm+). Figure that instead of a 4A drive current, it is about 1A of current.

If the injectors happen to be low impedance port injectors (2.2 - 2.4 ohms). Will need to wire the two of them in parallel on one driver.

RBob.
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Old Jan 4, 2019 | 08:47 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

Originally Posted by RBob
If the injectors happen to be low impedance port injectors (2.2 - 2.4 ohms). Will need to wire the two of them in parallel on one driver.

RBob.
That would make the resistance even lower, wouldn't you mean wire them in series?
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Old Jan 4, 2019 | 09:22 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

I mean, these would offer a wider range of injector choices, I guess.

But if are upgrading a TBI engine, you'll have to have a better fuel pump. With an adjustable regulator, you'll be able to get all the flow you'll need from 5.7L injectors, and tweak it as needed with the turn of a ****. So I'm not really seeing an advantage.

They don't appear to my very amateur eye to offer a lot more air flow potential (slimmer profile).
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Old Jan 4, 2019 | 09:42 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

I'm currently running a tpi fuel pump so I have enough pressure for my nitrous system so I'm not to worried about fuel pressure.
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Old Jan 5, 2019 | 01:26 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

Originally Posted by scooter
That would make the resistance even lower, wouldn't you mean wire them in series?
Wired in parallel. A TBI injector is 1.2 ohms.

Wiring injectors in series is bad form. It halves the voltage to each of the two injectors.

RBob.
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Old Jan 5, 2019 | 05:27 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

Thanks for the information
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Old Jan 7, 2019 | 11:51 AM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

Originally Posted by RBob
Wiring injectors in series is bad form. It halves the voltage to each of the two injectors.

RBob.
Oh yeah, ok, I wasn't thinking about that but why would you want to lower the resistance to the driver? I thought that was a bad thing on the factory ecm?
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Old Jan 7, 2019 | 04:57 PM
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Re: Has any one tried the Optimum EFI® – TBI Throttle Body Injection

The TBI ECM injector drivers are a peak-and-hold (PnH) type. Once the injector current hits 4 amps the driver folds back to a 1 amp holding current.

So going to 2.2 - 2.4 ohm injectors is no big deal. The stock TBI injectors are lower at 1.2 ohms.

RBob.
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