Boosted cyl. pressure?
12-12-2006, 11:13 PM
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Boosted cyl. pressure? Has anyone ever seen studies or can tell me what the cylinder pressure would be in a boosted application at as compared to N/A or nitrous app. Im looking to find out how much more strenuous it is on valvetrain parts at high boost? Especially on a cam with large overlap.
12-13-2006, 01:00 PM
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Originally Posted by mrdragster1970
There is more stress on the exhaust side, that's why we use oversized pushrods.
No idea about a formula, sorry.
No idea about a formula, sorry.
12-13-2006, 02:48 PM
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If you aint using the biggest, baddest pushrod available anyways than your missing the boat. Thats why with a properly designed valvetrain, cyl pressure is of no concern. Deflection is caused by the spring pressure more than the cyl pressure, plus the valve has help from the rocker ratio=leverage.
12-13-2006, 03:06 PM
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Originally Posted by AlkyInMyBlood
If you aint using the biggest, baddest pushrod available anyways than your missing the boat. Thats why with a properly designed valvetrain, cyl pressure is of no concern. Deflection is caused by the spring pressure more than the cyl pressure, plus the valve has help from the rocker ratio=leverage.
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12-13-2006, 03:28 PM
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Originally Posted by Nmbr1GMfan
OK, so what if you have the biggest pushrods but it breaks the exh lifter @ 20psi and only 1400hp? we need anothr 10psi to complete this project. Has anyone actually heard of someone testing the cyl. pressure?
Regardless of the actual #'s, if you know the cyl pressure is high enough to break the lifters at evo than would it possibly be beneficial (in terms of horsepower and the valvetrain longevity) to delay evo from where it's at now?
12-13-2006, 07:05 PM
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Originally Posted by AlkyInMyBlood
If you aint using the biggest, baddest pushrod available anyways than your missing the boat. Thats why with a properly designed valvetrain, cyl pressure is of no concern. Deflection is caused by the spring pressure more than the cyl pressure, plus the valve has help from the rocker ratio=leverage.
12-13-2006, 07:10 PM
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Originally Posted by Nmbr1GMfan
OK, so what if you have the biggest pushrods but it breaks the exh lifter @ 20psi and only 1400hp? we need anothr 10psi to complete this project. Has anyone actually heard of someone testing the cyl. pressure?
12-13-2006, 07:10 PM
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With today's technology and materials I thought this was an afterthought. I recently finished a 615 cid with twin 91's making around 3200hp at 9600rpm. Lifters were tool steel and pushrods were 9/16 .190 wall. This is a stupid agressive cam. 400 on the seat and over 1100 over the nose. Probably 8 runs on springs till theyre toast.
If you buy the best its not a worry.
As for delaying the EVO, that a bad way to adress that. You wanna open that sucker as soon as possible in a high hp turbo car.
If you buy the best its not a worry.
As for delaying the EVO, that a bad way to adress that. You wanna open that sucker as soon as possible in a high hp turbo car.
12-13-2006, 07:19 PM
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Originally Posted by AlkyInMyBlood
With today's technology and materials I thought this was an afterthought. I recently finished a 615 cid with twin 91's making around 3200hp at 9600rpm.
12-13-2006, 07:58 PM
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Keeping RPM down is not as eazy as you might think.
My 582" is made for 9000 RPM. Monster heads on small motors raises the RPM.
We use bigger pushrods on the exhaust even tho they are much much lighter than the int is because you have to push thru the cyl pressure. I never heard anything about the springs causing deflection. I was taught they just close the valves.
If you are that worried about being safe, get the big Jessel, I've never seen one of them break. We only use Manton pushrods.
Where are all these 3000 HP cars at. Everyone is building them, where the hell are they at. I've never seen a 3000 HP gas motor.
My 582" is made for 9000 RPM. Monster heads on small motors raises the RPM.
We use bigger pushrods on the exhaust even tho they are much much lighter than the int is because you have to push thru the cyl pressure. I never heard anything about the springs causing deflection. I was taught they just close the valves.
If you are that worried about being safe, get the big Jessel, I've never seen one of them break. We only use Manton pushrods.
Where are all these 3000 HP cars at. Everyone is building them, where the hell are they at. I've never seen a 3000 HP gas motor.
12-13-2006, 08:02 PM
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Originally Posted by mrdragster1970
Keeping RPM down is not as eazy as you might think.
Originally Posted by mrdragster1970
Where are all these 3000 HP cars at. Everyone is building them, where the hell are they at. I've never seen a 3000 HP gas motor.
Last edited by andereck; 12-13-2006 at 08:09 PM.
12-14-2006, 07:37 AM
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I still havnt seen and EFI system that can handle the fuel demands for methanol in a 3000hp motor thats turbo'd/CentCharged. Cant do it with MFI.
Anyways, when people say that the have 3000 some horse, theyve never had it on a dyno and its a good guess. This one went on an inertia dyno.
And yes the power can be made at lower rpm, but you ever think we might WANT to make it a 9600? Figure out why and theres a prize instore. And as far as springs, if you know of a spring that agressive that has that kind of life span, please let me and every other prostock team know so we can save about 100k a year in springs.
Anyways, when people say that the have 3000 some horse, theyve never had it on a dyno and its a good guess. This one went on an inertia dyno.
And yes the power can be made at lower rpm, but you ever think we might WANT to make it a 9600? Figure out why and theres a prize instore. And as far as springs, if you know of a spring that agressive that has that kind of life span, please let me and every other prostock team know so we can save about 100k a year in springs.
12-14-2006, 08:42 AM
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I wonder if anyone is even looking at how harmonics play into the situation. If a pushrod and spring have their natural frequencies too close to each other, bad things happen when they both start to resonate at around the same rpm. From valve float, to broken parts, to an inexplicable power dip at a certain rpm. It's complicated because while you can get the natural frquency of a spring, many pushrod manufacturer's dont even know the natural frequency of the pushrods they're manufacturing. Experiments have been done by clamping a pushrod in a fixture with a transducer at the bottom and then striking the pushrod. The trace from the transducer then will give you the natural freqency. In some cases, a monster spring that barely survives isn't always the answer. If a harmonic exists, changing to a different pushrod might fix the problem and allow a milder spring.
Al
Al
12-14-2006, 11:59 AM
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I wonder if anyone is even looking at how harmonics play into the situation.
Many teams have found the pushrods to be responsible for harmonics when
tuning the valve train. Sometimes they will change the material, or even
give up a few grams of weight savings to get more power back into the system.
Even using the wrong tip profile can cause issues against the rocker arms.
Sometimes what seems to be a spring osciallating is actually stemming from
a pushrod. It's a good bit of info to retain when troubleshooting your engine.
12-14-2006, 01:38 PM
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Originally Posted by Nmbr1GMfan
OK, so what if you have the biggest pushrods but it breaks the exh lifter @ 20psi and only 1400hp? we need anothr 10psi to complete this project. Has anyone actually heard of someone testing the cyl. pressure?
This would be a good sign that your vale timming is wrong. If its breaking parts trying to open the valve you are in fact bleeding off power. Try pulling the cam back from its very early ICL to a later ICL. As for what others have posted your EVO is to early which means you have to much overlap or a poorly designed camshaft pissing away power.
12-14-2006, 01:40 PM
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Originally Posted by AlkyInMyBlood
I still havnt seen and EFI system that can handle the fuel demands for methanol in a 3000hp motor thats turbo'd/CentCharged. Cant do it with MFI.
Anyways, when people say that the have 3000 some horse, theyve never had it on a dyno and its a good guess. This one went on an inertia dyno.
And yes the power can be made at lower rpm, but you ever think we might WANT to make it a 9600? Figure out why and theres a prize instore. And as far as springs, if you know of a spring that agressive that has that kind of life span, please let me and every other prostock team know so we can save about 100k a year in springs.
Anyways, when people say that the have 3000 some horse, theyve never had it on a dyno and its a good guess. This one went on an inertia dyno.
And yes the power can be made at lower rpm, but you ever think we might WANT to make it a 9600? Figure out why and theres a prize instore. And as far as springs, if you know of a spring that agressive that has that kind of life span, please let me and every other prostock team know so we can save about 100k a year in springs.
Move your lobes around.
12-16-2006, 09:25 PM
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Originally Posted by Sean Collins
This would be a good sign that your vale timming is wrong. If its breaking parts trying to open the valve you are in fact bleeding off power. Try pulling the cam back from its very early ICL to a later ICL. As for what others have posted your EVO is to early which means you have to much overlap or a poorly designed camshaft pissing away power.
