Detroit Injector Opinion

[Liquid Asset]

Since we are in the stage of tear down on our engines to rebuild, I have been looking at rebuild kits. But while I was doing that, I asked the parts counter to look up what was the origional injectors in our boat. When I replaced an injector that was bad previously, I found that it was not the origional number. Detroit says that the 9a31 injectors we have are 130mm nozzle and the origional 9215 injectors were 110mm nozzle.

The prevous owner did this, and I do not know if we should leave it that way, or go back to the smaller injectors. Am I actually getting more HP because of the extra fuel, or is it just a waste of fuel being dumped into the cylinders and causing shorter engine life? If I am actually benefiting from this in a HP incrrease, I may leave well enough alone, but I want some opinions from the guru's.

[captddis]

Stick with the 9A31. Or You will probably notice a power loss. There is a good chance that Covington modified the engines. The ser# won't show changes to the engine after it left the factory. The 9A31 is for the 650 HP engines. The 9215 is for 585 HP.

[Liquid Asset]

That is what the Detroit Parts guy was thinking, but he shows my engines in his computer as in a Hatteras. Just was not sure.

[Capten]

Our 1983 8V92s also use the 9A31 and are Covington conversions rated at 650HP.

[Liquid Asset]

What supprises me about it, is that detroit shows our engines, and that they are in a Hatteras, but does not show the correct parts for the engine.

My next question is where do you find the correct information so that parts are correct? Is it neccisary to contact covington to get the correct parts? I sure would hate to purchase and incorrect part.

Also, When convington does a conversion, what do they change? Internals? Externals, or just injectors?

[captddis]

Good luck trying to get any info from Covington. Everything was on paper only and most of it left with the old guard. Covington said my 650s were factory, but using the ser# gives the wrong injectors, wrong turbos , wrong blower drive gear,even the wrong trans gear reduction. I have maintained the boat since new, Covington did update the engines in 1984. They removed the 140 injectors and the rackstops[which limited the 140s to 130]. They also added the modulators.
I have a set of Covington specs and tune up information. FWIW the 130 [ # 5226390] injectors have been discontinued and the 9A31 is the replacement.
Dave

[Genesis]

Yeah, Covington conversions can be a ROYAL pain in the tush.

I went through some major crap trying to get the proper data from them myself......

[Liquid Asset]

Well, Somehow the FDDA parts guy got all of the correct information for my engines. So I am just waiting on the parts quote now. I am afraid.

[dailo]

Hi, I know this is an old thread, but was wondering if anyone knew what turbos matched to the 9A31 injectors?

I have 8V92TI's rated at 550SHP with 9215 injectors and THO8A Turbos.

The DD dealer here recommended me swapping out to 9A31s to get a little more power, as we are only reaching 2230RPM on both sides.

Thanks!

[kelpy]

Which injectors and turbos are called out on the engine tags? Those are what you want to run. Gaining 30-50 HP a side and sooted up turbos and transom isn't worth the $$ expenditure.

2230 RPM is pretty close to optimum with tuned up engines, clean bottom and half load.