Cam duration starting point on intake.

cummin get it

cummin get it

coal train
Joined
Sep 13, 2009
Messages
1,267
Curious as to what degree people are starting there intake valve descent and how long of a duration you are running also at what degree are your exhaust valves are closing. Also at what rpm is the engine smoothening out at. Could be a good thread!
 
90% of people on here dont know so My guess is this thread will not blow up any time soon. Sorry
 
Ill start, here's my current LSM cam. Interested to here what some of you guys think of it.

2012-07-01_13-58-31_608.jpg


https://www.youtube.com/watch?v=iA-EB_dtcMo&feature=youtube_gdata_player

Video of my last hook with said cam.


Sent from my Motorola Electrify using Tapatalk 2
 
Well... not really sure how it spools I've drove it on the street once this year. lol right now its holding 1600-1680 all the way down the track with water to air, but I can change the egt quite a bit w fuel. Likes to run around 44-4500 down the track and pulls down to 4200 at the big end on a tight track.

Sent from my Motorola Electrify using Tapatalk 2
 
Its my custom exhaust that gives it the sound :rolleyes:

Sent from my Motorola Electrify using Tapatalk 2
 
Can't believe no one else will chime in!

Sent from my Motorola Electrify using Tapatalk 2
 
I wish more people talked more about cams, then they would see why some are better than others. You hit the nail on the head in terms of importance. I hear people ignorantly talk about different LSA's saying that wider lsa's are better for higher rpm and narrow LSA's are better for Lower rpm. That is not accurate at all. What they should be discussing is valve events. Where do they open and close and where do the .050" happen as well as what is the ratio of open time to .250". That will shed light on the velocity of the ramp.

Another thing to help your discussion is that most engines take up lash and start to crack the valve at about .006" cam lift for the intake and .012-.014" on the exhaust. I use those numbers for "opening" and "closing". If you were to put a dial indicator on the valve, this is the cam lift that you would see the valve move off of "0". I don't want to muck up the thread other than that and I do not want to give up all my secrets.
 
Last edited:
You fine zach I don't mind informative post at all and I thought I was on to something. It will take me years of playing with multiple cams to figure out which one is for me. I am a machinist and have worked in factory's running many different pieces of CNC and manual machines. I like how you are informative and chime in and during the off season this year plan to talk to you about ordering a couple cams and do some testing with just changing cams and see what performance changes I see on the dyno. I think cams and piston bowls are one of the biggest keys to hp. I will be sharing all info with compd as well. I started this thread so I could try to find a starting point. Hope it picks up.
 
Last edited:
You must log in or register to reply here.
Top