Upgrade from 255 Walboro to bigger?

Calibrations for S-Manager - Use all calibrations at your own risk (dyno tuning recommended)
Post Reply
G. Wiffington
Posts: 67
Joined: Tue Nov 21, 2017 12:24 pm

Upgrade from 255 Walboro to bigger?

Post by G. Wiffington »

Hey do you guys think I should upgrade from a 255 Walboro to a bigger pump to lower duty cycle? I have attached two datalogs.

I have the old fat body style RC 750cc's & the fuel pump is not relayed by the pump, so I am just using the stock wiring as of now. Would a relay setup at the pump help give more pressure?

I also have a JDM stock fuel rail so I used a longer, skinnier -4AN hose for the rail to stock fuel filter line. I was wondering if that is way too restrictive causing the duty to be higher.

I do have a stock fuel regulator & no fuel pressure sensor. I guess I should Install those? (fuel pressure gauge & adjustable regulator)

Setup is F22B non vtec stock head & bottom end, 98 EK hatch chassis.

Finally spun third pretty good on street tires Hankooks (9psi, 82% duty 13 degrees timing).
Attachments
10lbs 4.2.22.s3d
(28.6 KiB) Downloaded 80 times
finally spinning 3rd lol 4.10.22.s3d
82 percent duty cycle
(42.92 KiB) Downloaded 77 times
User avatar
Spunkster
Site Admin
Posts: 22737
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: Upgrade from 255 Walboro to bigger?

Post by Spunkster »

You need to see what the pressure is doing. You may need larger injectors. This is something you may want to discuss with your tuner.
G. Wiffington
Posts: 67
Joined: Tue Nov 21, 2017 12:24 pm

Re: Upgrade from 255 Walboro to bigger?

Post by G. Wiffington »

I am my tuner in this case lol. Still learning for sure

Okay I will see what the fuel pressure is doing.

Thank you!
G. Wiffington
Posts: 67
Joined: Tue Nov 21, 2017 12:24 pm

Re: Upgrade from 255 Walboro to bigger?

Post by G. Wiffington »

Okay update:

I have an adjustable fpr now installed & it is set at base 43psi. The duty cycle is a little lower about 82% for the same pull as I uploaded before.

Would 50psi base pressure on RC750's too high?
User avatar
Spunkster
Site Admin
Posts: 22737
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: Upgrade from 255 Walboro to bigger?

Post by Spunkster »

It is probably ok.
G. Wiffington
Posts: 67
Joined: Tue Nov 21, 2017 12:24 pm

Re: Upgrade from 255 Walboro to bigger?

Post by G. Wiffington »

Thank you.

Raised the pressure a little more & looks like I definitely lower the duty cycle.

Here is another pull finally hitting 11lbs.

New wastegate with 7-8lbs spring, the old one had a rip in the diaphragm & the spring was only about 4lbs.
Attachments
11.6 78 perct 52 fuel press.s3d
(30.12 KiB) Downloaded 64 times
Post Reply