Ok according to desk top dyno on my current combo if all i was to do is swao from my 274 XE flat tappet cam to a Etreme Hyd Roller 282 i would see a 20 hp jump at 4000 rpm and a 47 hp jump by 5500rpm torque would also be up with 49 more ft/lbs at 6000 rpm. Now im a little scepticle. can these really be right? the roller cam actually lifts the intake valve less then the flat tappet cam. i know there is more duration but nearly 50 hp from a cam swap? is this possible?
Roller vs Flat tappet.
- Thread starter 86bluecobra
- Start date
I am no cam expert, but I know that the design of the roller and flat cams are totally different. Just get a roller and a flat cam and look at the differences. The ramp rates are usually much steeper on the rollers while the flat it's more gradual and comes to a point, while with the roller it's more rounded. So although the flat cam may have more peak lift, the roller actually holds the valve open more at a greater rate for a longer period of time, even if they close at the same time.
Did you compare hydrolic vs. hydrolic???
Did you compare hydrolic vs. hydrolic???
bluevenom867
I will have images of molesting stuffed animals in
86bluecobra said:
Ohh,I got this one cam article saved.Maybe Ill try and post pics or send it to you.
But basicly,if its a fairly mild cam,the flat will beat the roller.
bluevenom867 said:
I never got to read that article (you sent it to me a few months ago). When I printed it out it was not legible. Can you point us to the mag you found it in? I still really want to read this.
I would think that a well designed roller cam could beat the crap out of a well designed flat cam. Just look at the size of the lobes. Area under the curve if you will. More mass to the lobe means more air can flow with less restriction.
It will depend on the cam though. I am sure that if you look hard enough on the dyno software, you can find a flat cam that will out perform the roller.
jason
bluevenom867
I will have images of molesting stuffed animals in
vristang said:
Its the article "THE TRUTH ABOUT STREET CAMS" by David Vizard pages 72-85 of PHR.
If you look closely, you can see it says September 2005 Popular Hot Rodding.
bluevenom867
I will have images of molesting stuffed animals in
ok so i looked up the info on my heads and it turns out i could run up to .600 lift. on a flat tappet cam running near that lift i lose a bunch of bottom end torque with my curret combo. if i put a higher lift HR cam it seems that according to desk top dyno I retain the lower end torque gain more through tthe mid range and also see big gains in the peak HP numbers.
bluevenom867
I will have images of molesting stuffed animals in
86bluecobra said:
Dont worry to much about the lift,more the duration @ .050 and .200,also how agressive the ramp rates are.The LSA will also have an effect on streetablity,and in your case I would say something around a 108,you want some more overlap to help scavenge with your exhaust.
edit: can you adjust parameters in that program?Try narrowing the LSA and adding some duration and lift to your cam.Also,a note on that article I told you about,it show some serious increases using the new "bee hive" springs by comp cams.Only thing is,I would be worried if one of them things fail,as there no secandary spring to hold the vavle up if it broke.
Similar threads
