C918 Test Pressures 4800miles TR224
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C918 Test Pressures 4800miles TR224
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.
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.
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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.
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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?
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Originally Posted by Ryan02SS
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?
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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.
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.
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Originally Posted by Ryan02SS
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.
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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
Chris
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Originally Posted by PREDATOR-Z
Chris, are those standard on Patriots or an option? Ferrea's SCCS right?
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Originally Posted by gomer
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.
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Originally Posted by Carvinta
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.
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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)
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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.
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Originally Posted by gomer
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.
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Originally Posted by Carvinta
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.
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Originally Posted by 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.
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.