nasty ss

iTrader: (1)

I personally run that cam and have run both springs(on different setups). I currently run the 921's. I would never even consider running a 918 on the g5x4. Maybe it can handle the lift for a while, but if that spring breaks game over. Get the 921's and worry about the other parts that you will be breaking with the extra power!
-matt

turborail

iTrader: (11)

I just read an article on valve springs in the latest Popular Hot Rodding ( I think that was it-September) It has an article about a 1000+ turbo LS1. Thats why I bought it but there was an article on the 918 style springs against double springs. I don't know they may have been 918's. All I can say is read the article!! It will make you think. I read it at work and came home and bought a set of 918's after work.

masterdill

iTrader: (2)

Am I the only person who realizes that 918's DO NOT create enough spring pressure to deal with such a large cam? Maybe LG can comment on this? Letting people think you can run 918's with a large duration ~.600 cam is insane.

turborail

iTrader: (11)

I seriously wonder if the 918s are the best thing you could run on a hydraulic roller. You really should check out the article on the behive springs in the Magazine. You may change your mind.

PREDATOR-Z

It is not insane, as Patrick mentionned "shimming" for more seat pressure.

For a street setup, I would run duals as stated, for a race setup I would run 918's.

You can find quite a few of my posts trying to dismiss this 918 "phobia".
The failures that happened in the past are in majority with "Green stiped 918", they have since been revised to "Blue stripe 918", and failures are far and few between.

Poeple protect themselves with duals and big cams but still run stock lifters. that is protecting your left flank while exposing your right.

dug

iTrader: (10)

I got 30k miles out of mine without any problems. The rev limiter is stock (6200rpms) might have helped.

I love the 918's but was always paranoid. Sometimes a plug wire would come loose and I would think a spring broke. I never had any peace of mind because I cant afford to lose an engine.

PREDATOR-Z

But you were still running stock lifters right?

dug

iTrader: (10)

Yes, stock lifters.

Brian, you are missing the point. A while back your company, Comp Cams, let a lot of people down with a bad batch of 918's. Thats why there are skeptics.

You guys should do some real world testing of the 918's with popular cams to get a better idea what they are capable of. Like a mule thats a hard driven daily driver with all the bolt ons with stock heads. And test cams like a 224 .581 112, Trex cam, LG Cam, and maybe a TSP MS3 cam. See what kind of life the springs have with different lifts and duration.

PREDATOR-Z

So Dug, you made the right choice. Big duals with higher seat pressures put more stress on lifters and even timing chain.
Trick is one should upgrade "ALL" the valvetrain not just only springs. We don't usually want to yank the heads for upgraded lifters, but with big duals, that is necessary IMO.
and as Brian says, this "protection factor" is pure phobia, big cam = high rpm = 0 protection upon failure no matter what spring you run.
Read around, most of the poeple praising duals for saving their motor were not a 6K+ when they failed.
Also you'll find that there is quite a few more failures with duals instead of "Blue" 918's.

dug

iTrader: (10)

I agree the 918's are great springs and that duals put too much stress on the rest of the valvetrain. If 918's can handle bigger cams like the Trex or LG cams how long would they last in a daily driver thats driven hard? 10k, 20k miles?

1fastWS6

iTrader: (3)

Brian,
Regarding checking springs, can you pull and check 2-3 springs and if those are OK assume the rest are also fine? Or is it really necessary to pull all of them and have them all checked? Mainly asking as it relates to a race motor with springs in the 250# seat / 800# open pressure range.

dug

iTrader: (10)

Just out of curiosity, what was the cause of the earlier failures? Improper heat treatment, wrong material, something else?

ArticLS1z

i ran 918's blue stripes on my 232/238 59x/59x lift cam for 15 k no probs spinning to 7100rpm.. only spring id ever use....

JRracing

iTrader: (35)

I have a set of used TEA 5.3's with 918's and a g5x2 speced cam. I don't know how many miles are on it. But I think they are 2 years old or so. should I change the springs on it. I pmed brent at TEA and he recomended yes!
I have a set of crane duals on my stock heads with about 7K miles on them. Should I put those on???
I also have stock rockers and TR hardened stock length rods. I plan on buying the 850-16 lifters. Is this setup very safe to run upto 7K.
I race it about 6 times a year. And weekend worrier!!!

JRracing

iTrader: (35)

Do you think they offer better performance because they are single springs and weigh less? I could see the reasoning in that. Thanks for your opinions!!

Derek98z

iTrader: (55)

I've ran numerous sets of 918's on smaller cams. But now with a larger cam, I went duals and comp lifters.
Question is this: why is the 918 only marketed at a max lift of .600 if it can handle more? Is it to avoid the average builder the need to shim?

Derek98z

iTrader: (55)

makes sense. I assume then the only person running a 918 with a higher lift cam is either very knowledgable about what they are doing including shimming, or doing it by mistake and having problems.

turborail

iTrader: (11)

I have been doing some research and I have come to the conclusion that the 918 is better than any dual spring on cams at .600 lift. maybe even lift up to .625(that may be pushing it). Ok before you get on the defensive here is why. A dual spring with a large retainer has a lot of mass and weight. If you took a 918 and a dual spring with the exact pressure open and closed then the 918 would turn about 1000 rpm more before the valve becomes unstable. In order to get the dual spring to turn the same rpm you would have to increase the pressure to such a high amount that you would probably collapse the hydraulic lifter with to much pressure. No matter what you want to run titanium retainers. Running behive springs saves as much weight in motion as swapping from stainless to titanium valves. If the 918 will not work for you and you want to run a bigger cam then they can handle then I think it is time to switch to a solid lifter. Any dual spring will just take to much pressure before it ever catches up with the 918 and believe it or not all the extra pressure is needed to support the movement of the extra weight of the top one third of the spring and the much larger retainer. There is a limit to how much pressure you can run with the hydraulic but a solid you can use as much pressure as your valvetrain parts will open. Look at the new LS7 chevy is building for the c6 z06. It has .591 lift and a 7000 rpm redline and will be expected to be reliable for a long long time. Guess what it has behive springs. The 918's are new school and I hate to say it but the dual springs are old school. If you really want to rev put some huge duals and a solid roller in it. I am running 918's and to possibly get it to rev even higher the only way I can see is to use a rev kit. That way you will have extra spring pressure to control the lifters but there still will not be excess pressure to collapse the lifter. I think it would be impossible to make a hydraulic cam rev higher than with a pair of 918's and a rev kit.

turborail

iTrader: (11)

I forgot one thing. The reason 918's are only rated to .600 lift is because of coil bind. For the most longevity out of a spring you would idealy like to keep it around .100 from coil bind. I would never shim it past .05 from coil bind and I think .05 is pushing it also. As long as the .050 is controlling the valve better than if it is at .100 then it may actually last longer. If you push a spring past its limit as far as contolling the valve then it will waste it quickly no matter how close you are to coil bind. I don't even know where a 918 coil binds but I would guess it must be around 1.2 if they rate it for .600 lift. Being a single spring the wire diameter needs to be a little bigger than a dual but I think the spring wire on the 918 is ovate which is more of an oval shape which helps retain thickness for spring pressure but gives some extra room before coil bind. There is a lot of technology in these new style springs!!! I know what I am going to use but I guess the broken spring stories have spooked me a little. Would a broken 918 actually let the valve fall into the hole much more than a broken dual spring?

turborail

iTrader: (11)

Woops,
I totally screwed up when I said they probably coil bind around 1.2 Basically I took the 1.800 which is installed height and subtracted .600 for the lift and came up with the 1.2. I totally forgot to ad the .100 (safety margin distance from coil bind. What I meant to say was they probably coil bind around 1.1. 1.8(installed height)-.600(lift)-.100(extra space in spring before coil bind)=1.1
That was my guess for coil bind. I actually went and looked and they have coil bind listed as 1.085 so in all reality you could have a .615 lift cam and still have the .100 margin from coil bind. You would have the option to shim the spring anywhere from .100-.050 from coil bind. .100=longevity, .050=higher rev range but less longevity but remember any time it is revved so high that the valve bounces and starts to crash then the spring will not live long at all!!