2 foot long intake yields 10% boost!

A

andyinchville1

Guest
HI all,

In searching on the net I ran across a site that that had a calculator for determining intake length for "ramming" additional fuel into the engine to increase power....the principles of ramming has to do tuning the length of the intake runner to maximize the amount of fuel being "stuffed" into the engine when the intake valve or port is opened. You may want to check it out....kinda neat....according to different values I input we would need an intake runner of about 24 inches to coincide what I believe our max engine RPM should be (around 6000)....while the 6000 RPM is just my idea of max....the engine my go higher but mine at least stats feeling too vibration filled and noisy for me to feel comfortable pushing it any higher....heck with enough torque we could simply gear higher and go faster with fewer revs....of course you shouldn't go too low with the revs and risk lugging or overheating the engine.

Oh...the site to look at is...http://www.bgsoflex.com/intakeln.html

Try it you might like it....I am going to tinker today hopefully if I get off work early...I may actually go a little longer for more mid range since I really don't like to spin 6000 RPM.

Andrew
 


A

andyinchville1

Guest
OK....getting ready to head to the hydraulic shop to have some pipe bent to match my home made intake flange...only problem I see is that with the 2 feet of pipe length, the throttle cable will not be long enough probably....Any fixed anybody can think of fix for that?....Other alternative I can think of is to have a bend put in the pipe so it doubles back towards the engine then it would only extend out less than a foot. Figuring in the bend radius that brings the pipe back would cut overall length but I an worried this might impede flow....of course if one were to look at the stock intake manifold you know there
are serious problems with flow there!.....Oh well here goes!
Andrew
 
L

Large Filipino

Guest
Your essentially making the equivalent of a boost bottle. It's gonna look sick!
 
A

andyinchville1

Guest
OK guys...Got back from the hydraulic tube shop and they had a suggestion on how the pipe should be routed to keep lengths reasonable (see pics)...almost could act like a little fender if I put something in between the pipes! Neat thing is the carb ends up very close to where it started off so the throttle cable issue became a moot point. ....Total tubing length is 28" of 1/2 hydraulic pipe...(I think it is 1/2 inch) but the inside diameter was somewhat smaller than stock....I went with their smaller diameter with the theory that the smaller diameters would keep intake velocities up ....It is a long tube remember....we tried to make large gentle curves when possible for the same reason....Bottom line?....Engine idle speed went way up without doing anything to the carb....Throttle response was a little slower (because when you move the throttle remember the gases have a longer route to travel....so if you blip the throttle there is a slight lag.....But man the torque seems to have increased dramatically....maybe the ram thing is right!....BUT... OOPS another BUT while the lowest of the low end was improved the mid and upper end was severely hampered....Stock I could roll to 34.4 MPH....after the intake all she would do was 25 MPH....BUT again low end was great (puttering around with zero throttle was doable...this is with a 36 T rear sprocket and tuned pipe) ....with that I believe I will try the larger intake pipe diameter....reason being the smaller pipe was hindering top end more than I anticipated....standing with the bike motionless, clutch in, and revving it to the max you could definitely hear that the engine wouldn't pull the top end at all.....Something I could not explain tho was that there was a definite loud growl that seemed to be coming from the carb.....any ideas what this could be?....If I finish up work early tomorrow I will see about another trip to the hydraulic shop to try the bigger pipe but if not then it probably won't be until Monday or Tuesday until it gets done....Anybody have any alternate ideas on how the intake could be run? (I'll try to post more than 1 pic if I can).
Andrew
 
A

andyinchville1

Guest
Oops attachments don't work on quick replies so here it goes again....
 

Attachments

  • DSC03284.JPG
    DSC03284.JPG
    364.1 KB · Views: 665
  • DSC03285.JPG
    DSC03285.JPG
    154.9 KB · Views: 511
A

andyinchville1

Guest
Oh...I forgot to mention...I will probably try cutting the length a little on the pipe since I will try to tune for a max of 6000 RPM....I ordered a digital tach to better gauge engine speed...
Andrew
 
L

Large Filipino

Guest
You know,now that you got the carb switched around,a tunnel ram would look cool,and you would also have...ram air!
It would rool.
 
A

andyinchville1

Guest
Heh heh heh....I did think of the ram air but have to get the thing to work first! ;-O
Bigger tube diameter here I come!
Andrew
 
Top