Comp 918's

[Frenchy]

Basically I was planning on using these on my motor, so I asked the parts guy at work to get me some, he's built and raced a few cars and knows his stuff and told me that they weren't gonna last very long before they started losing pressure, because of the 348# open pressure. They'd make themselves too hot and probably wouldn't last a year. So my question any of you guys having any problems running them in your DD's?

[SCIV]

I would bet that millions of these things are running around without problem. EDIT: That means the updated design.

[phantom405]

Do yourself a favor and get the PAC springs instead. I had a new revised 918 break on me after 7k miles or so. Seen lots of the new and improved comp 918s breaking and then they're customer service doesn't want to help you...

[txarkitekt]

I would bet that millions of these things are running around without problem. EDIT: That means the updated design.

+1

It also depends on the cam lobe design and how high the lift is.

[bluchevypick]

I am running a 224/238 581/592 cam on them in my motor and am constantly hard on it and also spray nitrous and haven't had a problem. I have put 18k miles on my motor so far this year with them.

[Frenchy]

Cam's .580 lift on Comp XE-R lobes, which are fairly aggressive. Not worried about them breaking, my concern is them losing there pressure. 348# of open pressure is rediculous for a hydraulic roller under .600, but then again this is my first LS.

[Madd Maxx]

Cam's .580 lift on Comp XE-R lobes, which are fairly aggressive. Not worried about them breaking, my concern is them losing there pressure. 348# of open pressure is rediculous for a hydraulic roller under .600, but then again this is my first LS.

Your frame of reference is off a little. The open spring pressure is not primarily determined by lift. It's determined by the weight of the lifter and max RPM potential of the cam being used. The higher open spring pressure is needed to control the vertical opening inertia of the heavier hydraulic roller lifter. This higher pressure is why the cams in these engines are billet, and not cast. A cast cam would flex too much at higher RPMs due to the high spring pressures and break.

The seat pressure is also higher to control the heavier lifters on the aggressive opening and closing ramps that roller cams allow.

[txarkitekt]

Devin--since you are running a street cam (even with XE-R lobes), you will be fine with the 918s. No need to worry too much about the other stuff except for making sure your springs can handle the lift of the cam.