The_Punisher454

My latest project is a blown 454 for my brother. We will be using a '730 upgraded to EBL-P4. We have 12 injector ports above the blower and they are all plumbed on the same rails (NOT a dual fuel setup).
My question is how many amps can I run on a stock '730? Also I think a stock port injected '730 only uses one driver correct? if so is it possible to bridge the second driver to be a slave of the first?
We are using Bosch design3 injectors which have around 12.2 ohms at room temp.

I dont mind soldering in some bigger drivers if that's going to be required.
Maybe I've misunderstood the injector driving scheme used, but 12 injectors should be a 50% increase in current through the driver(s)by my figuring, is that too much?


Marvin

RBob

iTrader: (1)

There is only one physical injector driver in the '7730 ECM. I'd be leery about using twelve 12 ohm injectors on it.

Should be easy to update the physical driver, it is a standard MOSFET (not logic level). A couple of bucks for an overkill one, which will also have a lower on resistance (a good thing).

RBob.

The_Punisher454

Suggestion for a good Mosfet? Do you know the specs on the factory mosfet? I'd like to make sure I order something compatible. Or perhaps I should just build an external injector driver box to be triggered by the factory driver.

RBob

iTrader: (1)

I was going to say the Fairchild RFP40N10, but they are discontinued. 40A, 100V, .04 ohms RDSon.

Looking now, the FDP3682 is a likely candidate. 32A, 100V, .032 ohms RDSon. A 32A device is as low as I would go as it is a little over double the actual current.

With twelve 12 ohm injectors in parallel that is 13.8 amps of current at 13.8 volts. With an RDSon of .032 ohms, that is 6.1 watts of dissipation.

Be sure to use both output pins on the ECM to wire the injectors (C11 & C12).

RBob.

The_Punisher454

Thanks, I think that's the way I'll go.

Marvin

Saar

I'm also looking into this now, there are a lot of options from my favored low-quantity retailer for nearly no cost.


using the Fairchild RFP40N10 as a reference, Fairchild themselves are still make something a bit better, the RFP50N06. 50 amps/.022 ohm Rds. Tayda has them listed for 56 cents a piece.


the STP65NF06 is cheaper still, 41 cents, and is rated for 60 amps and .014 ohms.


above, at 75 cents each, the STP80NF55 is up to 80 amps and down to .008 ohms.


there are a couple more above the STP80, but for how much more they're costing, at the very least their Rds and current capabilities aren't nearly as impressive.

bigal55

iTrader: (1)

Just my 2 cents, but I would be leery of the pc boards capability of carrying that much current. While you're in there, you might want to beef up those traces on the board or run a wire from the MOSFET to the female pins in the ECM connector. HTH!

The_Punisher454

Ya, that thought did occur to me. I dont think it will take much maybe a 16g-18g wire, I'm only going 50% over the original current.
And it looks like this project is getting delayed a bit anyhow. My brother dropped a valve seat in this 454 last week and tore up a piston and head. I'm now rebuilding it for him as a 496 with Brodix heads and real blower pistons, as soon as the parts start arriving next week. The EFI upgrade is now pushed back a bit (probably over this next winter). Maybe I'll get some time for bench testing.