I have searched through tons of threads and articles written about both and it seems to go back and forth. People say the dual springs are old tech but then I wonder why Boostin Performance uses dual springs in the Red Demon. Other shops use the beehives so I am starting to feel it is personal preference?

Anyone have any updated research comparing the two springs? What are most people running that run high boost (40+ psi) and 9k+ rpms?

I was on single SuperTech's that were rated at 76#'s seat pressure and was running 9k in 1st and 8500 in the rest of the gears. Now have Kiggly Beehives for the head. My son has dual springs on his head. His duals have 94#'s of seat pressure and I believe mine are rated at 97#'s. Just like on my SBC motors, I have to keep the valves shut at high rpm's so I look at seat pressure for my choice. I check for max lift and coil bind for my application purposes too. I currently have Kelford 272's for my cams. The higher the lift, the more pressure I want without hurting the head. Harmonics in dual springs make me a little leary at high RPM's. My 02.

from some of the stuff ive read alot of people say to go towards the beehive because of weight differences which would come into play at higher rpms. but i agree with you on the boostin part running dual springs.

Boostings running a huge F-ing cam, so the duaks duaks are possibly more suited for them, a single would also be fine for 99% of peoples agenda and goals, but alot including myself opted for a beehive because of weight, space and abit easier overall!

The V8's love the duals but they are old type engines so they favor them,

Keep it simple and work out your cams and what your rev plans are and for how long and go from there.
I went with kiggly and mines going to be revved alot for a track car but my research showed me this was fine and no question on going to duals instead of a single!

I run a smaller cam (Kelford 264) with being auto but I am going to be in the 40+psi and 9k range this coming year. I don't mind spending money where it is needed but if the Kiggly HP Beehives (97lb seat pressure) will handle without the chance of floating, I will save the money rather than buying Manley dual springs.

Josh, I was running 264 cams at that time and at 40-44lbs of boost. You will be ok. I went from Kelford 264's to 272's to stay up in the RPM's to get the HX40 working but mine was in a standard car. My DD is an auto, do your 264's have a good vacuum and work good in your auto car? I have mine "ready" to go into something (maybe the DD), but didn't know how an auto car would like them. The 264's were run with SuperTech single springs and I never had valve float, the beehives will be just fine!

The 264's work great with the auto, I am able to get up on my converter in 4-5 seconds without nitrous and they don't lose steam up top. My fear with going larger was not being able to get up on the converter without using nitrous. At idle (1k) I was seeing around -12inHg with them installed straight up, I never messed with adjusting them but would be interested to see the difference.

Using Kiggly's method of finding necessary seat pressure (1.7x your absolute manifold pressure (boost + 14.7psi), the Kiggly HP seat pressure should be good to 42 psi before it becomes a concern if you go by Kiggly's equation.

My main reason for the thread is to see what the benefit of choosing one or the other is and why some shops are choosing the "old tech" dual springs over the new and improved beehive style if the seat pressure can be obtained using the cheaper beehives. Again I don't care to spend the money but just wanted to know if I was missing something here.

im auto and got the Billet S2's not on yet currently in build of the head, these are 274 and i was told will be perfectly fine for circuit racing and extended periods of high revs, so if your running 40 psi am i assuming your going for drag racing? if so they just get the lightest spring going as the short bursts will be fine for you

Boomdeeze said:

The 264's work great with the auto, I am able to get up on my converter in 4-5 seconds without nitrous and they don't lose steam up top. My fear with going larger was not being able to get up on the converter without using nitrous. At idle (1k) I was seeing around -12inHg with them installed straight up, I never messed with adjusting them but would be interested to see the difference.

Click to expand...

ive got brian crower 272s in mine (not degreed) it takes me about 7 seconds w/o nitrous to get on the 2step (4200).

ec17pse said:

im auto and got the Billet S2's not on yet currently in build of the head, these are 274 and i was told will be perfectly fine for circuit racing and extended periods of high revs, so if your running 40 psi am i assuming your going for drag racing? if so they just get the lightest spring going as the short bursts will be fine for you

Click to expand...

Yes drag racing and I will likely go Kiggly HP's as the race only are intense.

OH91awd said:

ive got brian crower 272s in mine (not degreed) it takes me about 7 seconds w/o nitrous to get on the 2step (4200).

Click to expand...

Wonder if swapping cams would make it stall quicker?

Boomdeeze said:

Wonder if swapping cams would make it stall quicker?

Click to expand...

higher duration cams in general will slow stall is what ive read. im wondering if degreeing them will help with stall any.

Kiggly's posting method isn't the whole story - it's simplified to give you an easy ball park. In general, on a N/A 4g even the most meager springs are good enough for most street cams - stuff around .400 lift, and a decent ramp rate - The old HKS272,280's, older BC stuff, Fp2's. The valve train is light enough/lift and ramp rate small enough that even stock spings would handle most of the og cams out there. I used to turn my car 9000 on DKS272, stock springs and lower boost. Now the newer stuff (Kelford 272's GSCs2) and bigger race grind have a steep ramp rate and need more springs. But even these don't need all that much spring in an N/A situation.

So to begin an understanding of the valve train and spring requirements and why valve float is bad we must understand that the cam is supposed to control the opening and closing. This valve is controlled by slowly setting the valve on the seat, and not letting it hammer. If the valve is allowed to hammer on the seat 2 things happen:
1. Rapid valve and seat wear
2. Extreme forces applied to the valve stem resulting in fatigue and eventual valve failure.

Next we must understand what is really happening in a valve float situation. We will start by defining a relationship between cam profile and spring force (we call it pressure but it is really force):

F = ma
This is newtons 2nd law, simply states that force (F) is equal to mass (m) times acceleration (a). So the spring force = mass of moving parts * acceleration of the parts. Now there are 3 portions of the lobe that are high acceleration, the transition to opening, the transition to closed, and the nose of the lobe. On the flanks of the lobe, the velocity is pretty constant so acceleration is low. During opening the acceleration is positive, and acts with the spring against the cam - No chance of float. Over the nose we have a chance of float, as the acceleration is negative, and against the spring - if the spring isn't strong enough the cam can out accelerate the valve, and lose contact with the cam. This is where bad things happen. If the valve catches up with the cam, it can lightly hammer the lobe, and if it never catches up, it severely hammers the seat. To summarize, in a N/A engine valve float originates from the nose of the cam - if the valve stays on the cam over the nose it won't float.

Boost adds another dynamic to the situation. The pressure differential across the valve adds/subtracts directly from the spring pressure. To ensure a further understanding we need to go in just a bit deeper.

First thing we will do is define pressure differential "dp", this is simply port pressure "pport", minus cylinder pressure "pcyl". That is:
dp = pport - pcyl.
Now because this pressure differential dp is a function of flow, it really only exists when we have a restriction to flow, it only occurs at low lift. - At high lift we assume pport = pcyl. So the risk of "boost blowing open a valve" is really only an issue if pport>pcyl, and the valve is closed or closing.

Let's take a look at what pport actually looks like. The pressure in either the intake or exhaust port is a time varying wave, the peaks can be as high as 2x the pressure measured by your map/ebp sensor. The actual peak as well as timing of the peak is highly setup dependent. So we will say:

pport = 2*pmani (intake manifold pressure, pmane for exhaust manifold)

So now lets look at when it's possible for pport>pcyl, and valve closing or closed:

1. Intake valve close, in this case essentially volumetric efficiency = pcyl/pmani. Worst case in this situation you have an engine with poor VE (70%), and a 2x peak that hits right at IVC. So say pman 45psia (30psi boost), pcyl = 31.5psia, pport = 90psia, and dp = 58.5psi, intake valve area = 1.4in^2, so 81lbs of force absolute worst case, and it's doubt full that would ever happen. I'd expect peak force of 50lbs.

3. Exhaust valve close, in this case right as the exhaust valve is closed, the worse case situation would be pcyl = pmani, and pport = 2*pmane. If we have a tight exhaust housing it's possible for pmane = 2*pmani. So starting from 30psi boost. pcyl = 45psia, pmane = 90psia, and pport = 180psi!!!! exhaust valve area = 1.0 in^2 So 180lbs!!! of force pusing the exhaust valve back open at EVC worst case. Probable case is somewhere around 90lbs.

Real life, I see signs of floating exhaust valves in my car on my HE351 setup K272, kiggly beehives, 9000RPM, 40psi boost, and 80ish EBP.

There is a whole ton of other secondary dynamics occuring that I skipped for simplicity, but these are the main factors.

Now beehives vs. duals:

Here's the deal, beehives have several things going for them, weight, internal damping. The beehives have one big negative, max spring force is limited.

A dual spring is heavier, but can have huge amounts of seat pressure and rate compared to beehives. So in a case like Boostin, the huge boost dictates huge seat pressure, and dual springs.

For us mortals with mild cams and 40ish psi, beehives are probably a better spring - be advised though it is more likelt exhaust pressure will dictate spring needs than boost or cam choice!

OH91awd said:

higher duration cams in general will slow stall is what ive read. im wondering if degreeing them will help with stall any.

Click to expand...

Degreeing them, no. tuning the cams, yes.

bastarddsm said:

Degreeing them, no. tuning the cams, yes.

Click to expand...

when you say tuning the cams you mean by adjusting the cam gears correct?

Man Kurt, I was imagining you at the potium, teaching the class. And you did a dam good job of it.
Thanks for chiming in.

bastarddsm said:

Kiggly's posting method isn't the whole story - it's simplified to give you an easy ball park. In general, on a N/A 4g even the most meager springs are good enough for most street cams - stuff around .400 lift, and a decent ramp rate - The old HKS272,280's, older BC stuff, Fp2's. The valve train is light enough/lift and ramp rate small enough that even stock spings would handle most of the og cams out there. I used to turn my car 9000 on DKS272, stock springs and lower boost. Now the newer stuff (Kelford 272's GSCs2) and bigger race grind have a steep ramp rate and need more springs. But even these don't need all that much spring in an N/A situation.

So to begin an understanding of the valve train and spring requirements and why valve float is bad we must understand that the cam is supposed to control the opening and closing. This valve is controlled by slowly setting the valve on the seat, and not letting it hammer. If the valve is allowed to hammer on the seat 2 things happen:
1. Rapid valve and seat wear
2. Extreme forces applied to the valve stem resulting in fatigue and eventual valve failure.

Next we must understand what is really happening in a valve float situation. We will start by defining a relationship between cam profile and spring force (we call it pressure but it is really force):

F = ma
This is newtons 2nd law, simply states that force (F) is equal to mass (m) times acceleration (a). So the spring force = mass of moving parts * acceleration of the parts. Now there are 3 portions of the lobe that are high acceleration, the transition to opening, the transition to closed, and the nose of the lobe. On the flanks of the lobe, the velocity is pretty constant so acceleration is low. During opening the acceleration is positive, and acts with the spring against the cam - No chance of float. Over the nose we have a chance of float, as the acceleration is negative, and against the spring - if the spring isn't strong enough the cam can out accelerate the valve, and lose contact with the cam. This is where bad things happen. If the valve catches up with the cam, it can lightly hammer the lobe, and if it never catches up, it severely hammers the seat. To summarize, in a N/A engine valve float originates from the nose of the cam - if the valve stays on the cam over the nose it won't float.

Boost adds another dynamic to the situation. The pressure differential across the valve adds/subtracts directly from the spring pressure. To ensure a further understanding we need to go in just a bit deeper.

First thing we will do is define pressure differential "dp", this is simply port pressure "pport", minus cylinder pressure "pcyl". That is:
dp = pport - pcyl.
Now because this pressure differential dp is a function of flow, it really only exists when we have a restriction to flow, it only occurs at low lift. - At high lift we assume pport = pcyl. So the risk of "boost blowing open a valve" is really only an issue if pport>pcyl, and the valve is closed or closing.

Let's take a look at what pport actually looks like. The pressure in either the intake or exhaust port is a time varying wave, the peaks can be as high as 2x the pressure measured by your map/ebp sensor. The actual peak as well as timing of the peak is highly setup dependent. So we will say:

pport = 2*pmani (intake manifold pressure, pmane for exhaust manifold)

So now lets look at when it's possible for pport>pcyl, and valve closing or closed:

1. Intake valve close, in this case essentially volumetric efficiency = pcyl/pmani. Worst case in this situation you have an engine with poor VE (70%), and a 2x peak that hits right at IVC. So say pman 45psia (30psi boost), pcyl = 31.5psia, pport = 90psia, and dp = 58.5psi, intake valve area = 1.4in^2, so 81lbs of force absolute worst case, and it's doubt full that would ever happen. I'd expect peak force of 50lbs.

3. Exhaust valve close, in this case right as the exhaust valve is closed, the worse case situation would be pcyl = pmani, and pport = 2*pmane. If we have a tight exhaust housing it's possible for pmane = 2*pmani. So starting from 30psi boost. pcyl = 45psia, pmane = 90psia, and pport = 180psi!!!! exhaust valve area = 1.0 in^2 So 180lbs!!! of force pusing the exhaust valve back open at EVC worst case. Probable case is somewhere around 90lbs.

Real life, I see signs of floating exhaust valves in my car on my HE351 setup K272, kiggly beehives, 9000RPM, 40psi boost, and 80ish EBP.

There is a whole ton of other secondary dynamics occuring that I skipped for simplicity, but these are the main factors.

Now beehives vs. duals:

Here's the deal, beehives have several things going for them, weight, internal damping. The beehives have one big negative, max spring force is limited.

A dual spring is heavier, but can have huge amounts of seat pressure and rate compared to beehives. So in a case like Boostin, the huge boost dictates huge seat pressure, and dual springs.

For us mortals with mild cams and 40ish psi, beehives are probably a better spring - be advised though it is more likelt exhaust pressure will dictate spring needs than boost or cam choice!

Click to expand...

I always knew I liked you! Great explanation, looks like I will stick with the original plan and get the Kiggly HPs.