Please login or register.

Login with username, password and session length
Advanced search  

Author Topic: 110 head flow numbers 325 intake 250 exhaust how much better is possible?  (Read 710 times)

0 Members and 1 Guest are viewing this topic.

Mountainman streetbob

  • Just Ride, Daily if possible, Just Ride!!!!!!!
  • Full CVO Member
  • ***
  • Offline Offline
  • Posts: 149
  • 2012 SE7 CVO Electra Glide Ultra
    • GA


I am back looking at 110 flow numbers again getting ready to improve the new scooter.

I am looking at worked over heads flowing 325 intake and 250 exhaust at .650 lift...

Less than $750 including shipping EVERYTHING included...

#1 these are GOOD numbers right?
#2 what is possible?

BTW these heads are outflowing the factory 110 head at only .420 lift...

Would love to hear opinions!
Logged
2012 CVO SE7 ElectraGlideUltra Cams??? PowerCommanderV Crocodile Seats, rhinehardts,xm, Ipod, Nav-Zumo...
Windscreen, driver backrest handlebars, fulsac COMING SOON

HD Street Performance

  • Vendor
  • 2.5K CVO Member
  • *
  • Offline Offline
  • Posts: 3118

Oh boy the big question, LOL

The numbers do not guarantee anything.
First there is the issue of accuracy of the bench, calibration.
The fixtures used to test with, bore size, pipe extension, manifold? All variables
So this speaks to comparing one guys numbers to another.
I calibrate my bench, a Saenz 600, every 2 months with precise calibration plates.

Next will the higher numbers get you performance you can feel and use. Answer: not always
Will the heads shape and dimensions affect ride-ability and how easily they tune, absolutely

The larger the head orifice gets when shaped right the higher the numbers get.
Works on both sides. Problem is as the size gets larger the air speed gets slower. There is an ideal air speed range and motor demand comes into play. These motors are for the most part done at 6200 with a 3/8 stroke, lower with a 5/8 stroke. Limit is piston mean speed.  So how much air do you need when you will be riding from 1800 to 3200 99+% of the time? And how much is too much? How big do we make the heads cross sectional area? I can get you very big numbers!

From enginebuildermag
Simple airflow capacity should never be the first consideration in evaluating cylinder heads. Characteristics that are far more important include air speed, port cross-section, port volume and shape, and the relationship between the size of the throat and the valve seat.

Gregg Dahl GMS engines
Most of us being engine guys knows that an open barn door will move tremendous amounts of atmosphere but will not make horsepower. The same goes for drawing air through heads. The head must be correctly sized for the job with the straightest possible path to the back of the valve from the beginning of the intake tract.  I feel that providing approximate power figures and rpm range is a good indicator of potential.

In summary those big numbers can kill torque. Again experience will get you the right quantities, sizing, air speed, and last but not least and seldom mentioned cylinder heads that will at least last as long as the rest of the motor package and do so not allowing oil to enter combustion from the head (valves).
« Last Edit: October 05, 2019, 06:14:52 PM by HD Street Performance »
Logged
 

Page created in 0.125 seconds with 25 queries.