injectors

[bwdogman]

I have a 2008 flhx that has 30,000 miles  which I will  have the tb off so deciced to change injectors while I have it off. I decided to to put the se 5.3 in. My question is, my current map has the constants set with 4.3 injectors so I was wondering if I can use my current map and change the injector setting to 5.3 and retune off the current map? I didn't know if the ecm would adapt to the injector change without issue. Thanks!

[Steve Cole]

Use your current calibration and change the injector size to 5.3 and tune from there.

[Ohio HD]

Use your current calibration and change the injector size to 5.3 and tune from there.

Steve, on this subject, is there potential for tuning difficulties when the increase in injector size may be marginally needed? I run out of injector in 5th gear, about 6,300. The injector usage hits over 100% and the motor cuts out. Now that being said, I can set the rev limiter to 6,000, then it won't happen. But I'm also in the 80% and higher ranges a lot too.

Just wondering if there is any negative effects to low end tuning with the 5.3 injectors.

Thanks,
Brian

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[Herko]

...injector usage hits over 100% and the motor cuts out. Now that being said, I can set the rev limiter to 6,000, then it won't happen...
The injector's behavior at saturation vs. rev limit are two different characteristics.


"Just wondering if there is any negative effects to low end tuning with the 5.3 injectors."
Depends on the injector's individualistic actions pertaining to injector offset, system pressure etc.  (How's your fuel pressure in terms of psi and flux sweep at 4500/60KPA)? But, likely, you'll be OK with a set of SE 5.3's in a healthy 107.

IMO injectors being used in builds above a stage II should be of the tested variety such as a pair from Marren et al. There's much more to an injector's personality other than stated flow rate.

[Steve Cole]

As the injector size gets larger you give up control at low engine speeds in general. I've run 6.2 g/s on a stock 103 without issue but I would not want to run them if I was going for a federal emissions test in the lab as they are on for a very short period when down at idle and that's a big emissions area for the fed's. The turn on area of an injector is not real stable and varies from injector to injector so from an emission standpoint you want to use the smallest injector possible to get the job done as it gives better control in the critical emission testing area.

I would have no issue using a 5.3 g/s injector on a stock 103 and larger build at all.

[Ohio HD]

...injector usage hits over 100% and the motor cuts out. Now that being said, I can set the rev limiter to 6,000, then it won't happen...
The injector's behavior at saturation vs. rev limit are two different characteristics.


"Just wondering if there is any negative effects to low end tuning with the 5.3 injectors."
Depends on the injector's individualistic actions pertaining to injector offset, system pressure etc.  (How's your fuel pressure in terms of psi and flux sweep at 4500/60KPA)? But, likely, you'll be OK with a set of SE 5.3's in a healthy 107.

IMO injectors being used in builds above a stage II should be of the tested variety such as a pair from Marren et al. There's much more to an injector's personality other than stated flow rate.

I do understand that there is more to utilizing the injector volume than RPM, I guess that's why it seems to do fine in the lower gears, at higher RPM's. Just when he motor is getting loaded down in the upper RPM ranges, being in a higher gear is when it happens. I lot I don't know about FI, but am learning as I go.

As far as the fuel pressure, I really don't know, or how a flux sweep algorithm even applies to that, I plead clueless.

So Marren injector tests their units for performance, flow, etc? Had I not already bought the SE's I'd call them and have them educate me in that regard. But, I don't think that my tuning capabilities will begin to tax either set of injectors for maximum performance. Currently the motor just outruns the injectors, makes more power than they can supply fuel for.

I'll give the SE's a shot when the weather breaks a little this Spring. Thanks John.

[Ohio HD]

As the injector size gets larger you give up control at low engine speeds in general. I've run 6.2 g/s on a stock 103 without issue but I would not want to run them if I was going for a federal emissions test in the lab as they are on for a very short period when down at idle and that's a big emissions area for the fed's. The turn on area of an injector is not real stable and varies from injector to injector so from an emission standpoint you want to use the smallest injector possible to get the job done as it gives better control in the critical emission testing area.

I would have no issue using a 5.3 g/s injector on a stock 103 and larger build at all.

Thanks Steve, I should be OK then, I have a medium build 107. I just wanted to see and understand if I would have any issues with the motor response or tuning in the lower RPM ranges. I'll give them a try when the weather gets warmer.

[bwdogman]

Thanks!

[Admiral Akbar]

If the motor runs fine with 4.3s and injector rate does not reach any limits, the isn't any good reason to go to larger injectors.. As Steve mentions the bigger injectors are OK except for emissions.. I'd also throw out that the lower flow injector will also help with gas mileage.. After all it's better to burn those hydrocarbons than blow em out the exhaust..

Max

[To The Max]

Max Hi, im new here so forgive any ignorance.im wondering what do you think would be max ms for injecton on my 103 at about 6400 rpm my injection timming is 380 deg. regards Max