New pump and larger injectors; runs like crap

[NY_GN]

Put in DW400 and 80# injectors and it's running like smacked A$$. I can get to 15# of boost, but there is also some lag or drop out that wasn't there before, after 15# I get knock. I added fuel at WOT and same result.

Previously had a DW340 and 60# injectors and I could get to 25# boost no problems and it ran great.

Did I miss something or do I need to start adjusting FP as well?

 

[Chuck Leeper]

Stock lines? If so, your knok may be rich. A 400LPH pump can overrun that little return line.
A test: try turning the fp down, and see if it will go at least 5psi below the desired setting.
What do the plugs look like?
How about data logging it?
Post the SM numbers.

 

[PSID6]

Did you change your chip for 80’s?

 

[NY_GN]

Stock lines? If so, your knok may be rich. A 400LPH pump can overrun that little return line.
A test: try turning the fp down, and see if it will go at least 5psi below the desired setting.
What do the plugs look like?
How about data logging it?
Post the SM numbers.

got -8 An return and feed lines. I was gonna put some new plugs in and regap them.
I'll try lowering the FP after a few runs and I'll post the SM numbers.

 

[NY_GN]

Did you change your chip for 80’s?

Yep, chip and injectors are matched.

 

[PSID6]

Maybe put the 60’s and matching chip back in to eliminate one of the two things you changed and she how she runs.

 

[NY_GN]

Maybe put the 60’s and matching chip back in to eliminate one of the two things you changed and she how she runs.

I was waiting to do that, but I might go ahead and knock it out after I mess with the FP and make a few runs.

 

[earlbrown]

If your return line is too small, backing off on the FPR isn't going to change a thing.

 

[Mr.Spool]

Put in DW400 and 80# injectors and it's running like smacked A$$. I can get to 15# of boost, but there is also some lag or drop out that wasn't there before, after 15# I get knock. I added fuel at WOT and same result.

Previously had a DW340 and 60# injectors and I could get to 25# boost no problems and it ran great.

Did I miss something or do I need to start adjusting FP as well?

thats alot of pump and it wants to dump alot of fuel and 15psi cant eat it up.my thought would be to use a controller to curve the fuel into the motor,when i looked into a fuel pump years ago that the buggatti used it needed a controller to drop voltage.i ended up using a smaller one and it needed a bigger return line regardless.

 

[Mr.Spool]

widwband will be your best friend in this case as a plug read will only be at wot and if its too rich it will foul out the plugs on a con stant basis and feel like a slug hesitate to start as well