I've been running the infamous "918's that break" aka the pre blue stripe versions, for a bit over 35,000 miles now. They've been run with three cams:
1. Comp 221/227 .561/.569 112+4
2. Comp 238/240 .605/.609 112+2
3. Comp 228/234 .588/.598 112+4

Well, I finally snapped one on the way to work this morning. Cruising along around 40MPH, hadn't got on the car at all this morning either -- and it failed. When it failed, the car lost quite a bit of power, and started indicating VERY rich on the wideband at cruise (14.7 typical to high 11's / low 12's). Against better judgement I finished the drive to work (about 10 more miles) and parked it. A buddy ran to his house to grab a small set of sockets, and I yanked the valve cover to verify; I broke the exhaust spring on #4.

I'm lucky enough to have ZAngel and my brother Daley shuttle spare parts and tools up to me, so I can get back on the road I don't think it'd be too smart to drive another 20 miles home with a broken spring

 

It took quite a bit of miles to break and some serious lobes too. Maybe I got another 10k miles in mine.

Do you rev the **** out of your motor?

 

Sometimes, maybe Highest I regularly shifted was right around 7000 with the bigger cam. This one I shift around 6800. I've been driving it pretty nicely lately, only got in a couple of friendly street battles where I took it up over 5000. The past 6 months its been driven pretty mildly.

 

How did ya like the #2 cam on your list? I like that cam myself and will probably be runnin one of those. Hate ya broke a spring though

 

I love that cam, I'm actually going to put it back in one of these days

Now all I need is a nice set of heads to go with it..

 

Isn't that #2 cam Bigger (lift) than they recommend with 918s? I thought they were only rated to .600"

 

That sux man. Even though they broke that is not bad for pre blue stripe springs, even post blue stripe springs considering the mileage and cam lobes you were loosing. The 918s can go over .600" with no problem. Maybe not at 7000rpm but 6500 or so certainly.

 

Get with me on bein a test vehicle for my ported heads . BTW, you gotta ported TB?

 

If I remember correctly, when the 918's first came out they were rated for .625" lift. Then for some reason Comp Cams lowered the rating down to .600" lift.

 

Bah... I'm over .630" with them.

 

To hell with the duals.

 

Yep, same thing I heard. My .602 lift cam and 918's has seen 7000 rpm a number of times.

 

Comp tech still say .650

 

Maybe dual springs arent needed. You can buy 2 sets of 918's for one set of duals. Plus they are easier on the rest of the valvetrain with lighter mass.

Would 918's with a Trex cam be a bad idea?

 

The main thing to me anyway is the single spring breaking will more than likely drop a valve were the duals have some insurance on that to some degree.

 

Damn Brian....... and you didnt hurt anything?????
I ran 918s for a while... but then i switched to dual springs for the piece of mind in case the go that i didnt just destroy a piston.
Kyle

 

Bo, PM on its way

I called Comp when I put the 238/240 in the car, and they said the 918's would be just fine. With that I said "if she blows she blows!!!" and forged ahead No risk no fun, right?

Kyle - nothing hurt at all, at least that I can tell from this point. Possibly a bent valve but that can be dealt with easily enough I should have told my brother to grab a camera so you guys could see it, but here's the basic idea.. The spring is snapped at the second coil from the bottom, and basically just sat down on itself with the valve obviously hung open a touch (probably ~.250). The pistons have eyebrows (JE's, 2cc reliefs), so I don't think it got smacked by a piston -- certainly didn't "sound" like it did. I guess we'll see if the valve closes all the way or leaks when I put the new spring on it.

 

918's are way UNDERATED now as I see it, my F11 is no contest.... limiter is set at 6800. I will wait till 25K miles before swapping again, of course at my current pace if I dont do the LS7 swap after payoff (cant wait for the free up in cash),Nov 06, it will be sometime around this time 2009 hahaha.

 

Brains, about how many miles did those 918's have? I have about 15K on mine with a baby cam (sig), and wondering if I should swap them out yet.

 

My gut feeling with your cam is 10 minimum 15k max for safety reasons. In all reality probabaly longer than that.