Ryan02SS

iTrader: (3)

Had the day off today and decided to pull the valve covers and tinker around. I pulled off my YT's are checked them out and reinstalled them just for the heck of it. While I had them off I decided to test one of my Comp Blue Stripe 918s just to see how they were doing after about 4800 miles. My car is not driven hard but I don't drive Ms. Daisy either. WOT shifts for max power are made at 6500rpms.

Cam: TR 224/224 .561/.561 112LSA

Valvetrain consists of
Yella Terra 1.7 Rockers
Comp 918's
Comp Titanium Retainers
TR 7.4" Hardended Pushrods

Comp states that open pressure is 130lbs at 1.800" Installed Height
When new my springs measured exactly 129-130lbs at 1.8"

I only tested one spring, should have done a few more but ran out of time.
The one C918 I tested came in at 112-114lbs at 1.800" after only 4800 miles! I would not have thought that it would lose 16lbs of pressure after only 4800 miles. Could some of you guys with more experience with spring pressures after use chime in here with your thoughts? Is this the normal loss of spring pressure with an aggressive cam like the TR224? At what point should the springs be replaced 105lbs etc? TIA

I am also considering swapping these for a good dual spring, Crane's or Patriots haven't really decided yet as I can't afford to drop a valve and destroy a piston.

gomer

iTrader: (13)

Hmm.. I ran a set of 918's for 4,000 miles on a TSP 231/237 .598/.595 and then checked them. They were all in the mid 120's. From what I understand, after a valvespring is ran for the first heat cycle or two, they loose some seat pressure. Maybe you should have checked more than one.

Ryan02SS

iTrader: (3)

Update.... Just got back from lunch and called and talked to Paul at TR. He said to check them at 1.780" instead of 1.800" for a better reading. After doing this the first one tested came up to 118lbs. I also pulled another spring off and tested it and it came to 119lbs so I don't think it's the case of just a single spring losing pressure. I also tested them at 1.200" closed pressure and they both came to 287-288lbs. Comp states new 918's should have 318lbs pressure. Right now I am deciding between keeping the current springs for awhile longer and testing them again in a few thousand miles or buying a new set of duals. What do you guys think?

gomer

iTrader: (13)

If it were me, I'd pull them and buy one of the Patriot "GOLD" dual spring kits. Spring seats, valve seals, Ti retainers, and Springs for less than $300. That's what I ended up doing. I was loosing too much sleep at night thinking about that big cam and my 918's.

Scalpel

iTrader: (4)

What are you using to measure the pressures with? Is the tool calibrated? What you should do is find a new 918 and measure it at the same installed height and see what you're tool reads. That'll give you a better idea.

Ryan02SS

iTrader: (3)

Cannibal...I'm using a Tavia Valve Spring Pressure Gauge that is made for testing the pressure's of valvesprings along with a set of RCBS Dial Calipers to measure the height. When my 918s were new they specd out at 129lbs at 1.8" height with the same Tavia gauge so I would think it's pretty accurate.

Gomer.. On the TSP 231 on 918s I would be losing sleep also as that's alot of lift for a spring rated at .600 max. I'm still debating on what I'm gonna do as of now.

Scalpel

iTrader: (4)

Good deal, just making sure there was consistency used with this measurement. I.E. the same tool was used to measure the same springs before and after at the same installed height. Therefore, you have lost quite a bit of pressure :O

PREDATOR-Z

Time for some 921's

Cstraub

iTrader: (1)

It is common for a Chrome Slicon spring to drop 10% at initial set. I posted a few weeks ago a thread about springs pros and cons. The Super Clean Chrome Silicon like Terry uses with the Patriot springs is the best material. Seat pressure loss during initial set is minimum to non-existant.

Chris

PREDATOR-Z

Chris, are those standard on Patriots or an option? Ferrea's SCCS right?

gomer

iTrader: (13)

All stage II and above Patriot heads come standard with the GOLD duals.

verbs

I'm also willing to bet that the YT rockers are fatiguing the springs a bit with the extra weight on the tips.

lsx24

iTrader: (45)

Not to go off on too much of a tangent, but wouldn't duals (not any one in particular...) negate some of the benefits of single behive springs going with that heavier setup? I mean, I'll probably go dual when I built it for peace of mind, but for a performance application, do you think the weight of duals would cost some hp up top? Regardless that is a fantastic deal and includes everything you need. I'm probably just referring to a strip only application where long life really doesn't matter and radical cams are all too common.

gomer

iTrader: (13)

I went off on that tangent a while back when I was trying for every last HP on the dyno. I had my heads done with a set of 918's and Ti retainers. After I switched over to the duals.. I dyno'd again and didn't loose anything. I read about how the beehive springs had better harmonics, weight, and several other benefits.. but I never was able to prove thru my testing that any of them helped me. Now I just run the duals with super 7 locks and don't loose sleep over my valvetrain

LeadSled1

I wouldn't think the weight of the spring would have anything to do with HP loss as the weight is supported by the seat and not the moving valve train. (in the minimal weight difference we are talking about with the springs)

Cstraub

iTrader: (1)

Spring mass can affect HP.

Chris

LeadSled1

How would it? If it takes 300lbs of pressure to close a spring that weighs 100 grams and 300lbs of pressure to close a spring that weighs 200 grams and 300lbs to close they both take the same amount of pressure to close (generated by the HP of the engine thus the same amount of HP loss). You could get into the arguement of inertia and getting the weight moving but the difference would be very minor with the low weight. (in normal operating ranges) We are talking about a noticeable HP loss which you would not get, it would probably be less than 1%. (You could get that much of a variable in running a motor twice on a dyno with no changes) The extra weight of the spring is supported by the spring itself and incorported into its pressure rating. Now we are talking the same 300lbs at peak lift springs and 125lbs at install height. If the springs are of different ratings or extreme weight differences..... that is different.

lsx24

iTrader: (45)

That's an interesting back to back measurment, actual hp difference was unmentionable during that operating test. I don't mean to be a pessimist, but would upgrading the springs offset weight savings from putting on titanium retainers? I read that somewhere also about the weight savings of tit vs steel, and the gram % difference was small but noticeable there; much closer than the difference of dual vs single I would guess during movement. When accelerating mass of any sort the operating range is crutial to look for matched parts, so I suppose it would be cool if you ran a set of matched dual springs and titanium retainers as long as they were meant to stay as a set.

gomer

iTrader: (13)

The duals I replaced the 918's with had Ti retainers also. The dual I used to replace my 918's were the Patriot stock diameter GOLD duals. They are lighter in weight than the 977/978 type of dual spring. One of those large diamer dual springs with a steel retainer would be VERY heavy.

LS1derfull

Spring mass affects valve control, especially past peak power rpm. This valve control affects hp and more importantly engine accelleration. The 918 style springs do control harmonics better than traditional dual spring setups, because of their stack up design at hi lifts. This is a fact, there are many good tests and articles done on barrel wound, beehive design springs.