DaveX

I don't think there is any difference in the horsepower. But I also don't think dual springs are any safer if one does happen to break because the one remaining spring is not going to be strong enough to keep the vavle away from the piston. The only advantage I see to the duals is the individual springs don't have to work as hard as the one single spring. But with either, breakage will most likely lead to a piston smaking a valve.

Tony Mamo @ AFR

iTrader: (13)

Dave...

When a single spring design fails, the valve drops into the chamber resulting in an array of carnage not limited to and including a destroyed piston(s), bent rod, crankshaft damage, typically un-repairable cylinder head damage, possible cracked cylinder sleeve/blocks (or pieces missing) etc. etc. And if you drop a valve at high WOT and high RPM I give you a guarantee in writing you might be able to salvage the intake manifold after you thoroughly clean all the blown up parts out of it that got barfed up in the fractions of a second the engine grenaded itself into alot of smaller pieces.

When one of the springs in a dual design fails, while you certainly may tag the valve and possibly bend it, that pales in comparison to the carnage discussed above.

The dual design is a much better insurance policy than a single in a performance racing engine...

A lightweight small diameter dual with a titanium retainer can offer you the benefits of a single spring in terms of valve control and alot more peace of mind. The key is the right spring and the right spring package. Some duals are better than others at controlling valve float...

Tony

DaveX

I agree with your theory. But I have seen several cases on here where a single spring broke (918's in particular) and the valve did not fall into the cylinder because the spring broke at the top, leaving most of it intact. But with either style it can be disasterous to the bottom end when one breaks. Anytime the piston and valve comes in contact the result can be damage to the head, piston, and cylinder wall. This can and does happen with both duals and singles. In theory the duals are safer, but the reality is when one lets go at high rpm it's likely to be disasterous with either style. I think it's just less likely to happen with duals.

edcmat-l1

iTrader: (10)

The point is, with duals, you have a better that 80-90% chance to save your motor from catastrophic damage. With beehives, you have a 95% chance of destroying every damn thing, except maybe the intake.
Fact is, most people that break a dual spring only find out its broke when they go looking for why their car is running funky. The same cannot be said by those that break a single spring.

DaveX

Actually the same thing can be said for singles.

https://ls1tech.com/forums/showthrea...ght=broken+918

Look at page 3, there is a guy that never knew he had a broken one until he had his motor rebuilt/stroked and the builder informed him of the find. And several others reporting breakages without catastrophic engine failure. But there is a nasty one on page 6. So yes it can happen but the results aren't usualy much different than what would happen with a broken double at low rpm and if either breaks at high rpm it's most likely terminal for the motor. This is the only point I'm trying to make.

I'm not just defending singles because I'm running them or to be different. But it's my opinion based on what I see on the net. If the singles hadn't come on my heads I would have went with duals. If it were a race only motor I would most likely run duals. But single springs are fine on a street car with occasional strip use as long as you use springs that can handle your setup and you don't use 918's.

wrd1972

iTrader: (12)

I had three busted Comp (bad batch) beehives on the top coil just prior to rebuild, thank god none of them dropped a valve. Now running PAC beehives.

eallanboggs

iTrader: (1)

I too had a single 918 break(several years ago) and didn't know it until I pulled the heads apart to ship the to Richard at WCCH to be CNCed. I wouldn't have believed it if I hadn't seen it for myself. The spring broke, but the broken coils did not sepatate from each other so the spring was still functional although broken. I know that sounds hard to believe, but it happened.

mvvette97

iTrader: (18)

yep the 8 I had break done the exact same thing as yours did so I believe it..

vettenuts

iTrader: (4)

I really like the idea behind the beehive design and currently have PSI 1511's on my car. My new setup will be running the AFR 8019's though.

cals400ex

iTrader: (27)

not that this should be the only factor but with my goal being a fast streetable setup, i like quiet valvetrain. the duals can be louder at times. so, i prefer a single spring within limits of course.

mvvette97

iTrader: (18)

I have heard that but in my case when I switched to the patriot duals my valve train didn't get any louder

Travis99LS1

iTrader: (2)

I had a stock spring that was broken when i did my cam swap, the bottom coil was broken off..there's no telling how long i drove around like that for ..i was pretty surprised when i found it..