debate: hardened pushrods, or non hardened pushrods
10-17-2006, 12:00 AM
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debate: hardened pushrods, or non hardened pushrods so i'm putting together my cam setup, its for a g5x1 cam, i'm going with a ls2 chain, ls6 pump, and 918 springs...
a friend of mine brought up a good point, if i do chromoly pushrods, and accidentally peg the rev limiter or miss a gear, it wouldnt be the pushrods that bend, it would be something much worse...
so in an event of missing a gear, would i want a bent pushrod, or something worse? i would rather have a bent pushrod, that can be replaced in an hour, and cost next to nothing.
i thought he had a very good point, which now i'm debating to use new stock pushrods, rather than hardened ones.
any advice, or info on this?
the only thing i'm worried about is if the pushrod's durability can withstand say 6500RPM with a cam and 918 springs.
a friend of mine brought up a good point, if i do chromoly pushrods, and accidentally peg the rev limiter or miss a gear, it wouldnt be the pushrods that bend, it would be something much worse...
so in an event of missing a gear, would i want a bent pushrod, or something worse? i would rather have a bent pushrod, that can be replaced in an hour, and cost next to nothing.
i thought he had a very good point, which now i'm debating to use new stock pushrods, rather than hardened ones.
any advice, or info on this?
the only thing i'm worried about is if the pushrod's durability can withstand say 6500RPM with a cam and 918 springs.
10-17-2006, 06:53 AM
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Just my opinion I would rather have my whole valvetrain be able to take the abuse(hardend pushrods and quality rocker arms and springs). I would think that maybe you would have a 50/50 chance on a bent pushrod or that bent pushrod going through the block or being thrown through the valve cover. Just my 2 cents
10-17-2006, 10:42 AM
#3
You shouldn't be bending pushrods by hitting the rev limiter anyways. About the only way you will bend **** is if you mechanically over rev the engine, like a 3-2 shift at WOT. I would run hardened pushrods just for valvetrain stability with larger cams and stronger valve springs.
10-17-2006, 11:00 AM
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Originally Posted by NicD
I would run hardened pushrods just for valvetrain stability with larger cams and stronger valve springs.
10-17-2006, 12:11 PM
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Buy them, pushrods deflect a lot at high RPM, especially a weak stocker. The base circle of the cam is most likely smaller, and you will need a slightly longer rod to keep your preload equal.
Last edited by black_z; 10-17-2006 at 07:41 PM.
10-17-2006, 12:21 PM
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Originally Posted by NicD
You shouldn't be bending pushrods by hitting the rev limiter anyways. About the only way you will bend **** is if you mechanically over rev the engine, like a 3-2 shift at WOT. I would run hardened pushrods just for valvetrain stability with larger cams and stronger valve springs.
when you say stronger valve springs, stronger than 918's?
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10-17-2006, 12:46 PM
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The thing is that your stock push rods will deflect under hard driving with the bigger cam, without overreving the engine. I'm sure that you are familar with the concept of the shortest distance between any two given points is a strait line. Therefore if your pushrod is deflecting it is bending slightly, effectively shortening its length, this means that the valve is opening less than it should and less air and fuel are entering the cylinders which is leaving power on the table. Also as Black Z pointed out you will need a slightly longer PR to accomedate for the smaller base circle of the aftermarket camshaft any way. Good luck with your build up.
AJ
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10-17-2006, 01:00 PM
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hmmm... alot of good points, and mixed opinions in here...
those of you who say i would need longer rods, you mean longer than 7.400???
arrestmered99z28- you say when its deflecting it is slowly bending, thus reducing the length of the pushrod and reducing airflow and leaving power on the table... but wouldnt you hear it ticking when it bends enough to shorten the length? if i were to run stockers, i would just wait for it to start ticking, when it gets too short and starts tapping the rocker, then replace them.
both sides have good points, keep them coming guys
those of you who say i would need longer rods, you mean longer than 7.400???
arrestmered99z28- you say when its deflecting it is slowly bending, thus reducing the length of the pushrod and reducing airflow and leaving power on the table... but wouldnt you hear it ticking when it bends enough to shorten the length? if i were to run stockers, i would just wait for it to start ticking, when it gets too short and starts tapping the rocker, then replace them.
both sides have good points, keep them coming guys
10-17-2006, 01:15 PM
#11
Stock pushrods are 7.35ish, aftermarket cams are ground on a smaller base circle, which means they need the 7.4's. I, however, ran hardened pushrods/PRC dual springs with the STOCK cam for about 10k miles. I pulled the heads to replace the lifters, and went ahead and threw in the valvesprings/pushrods while I was there.
I have done the 3-2 shift from 6800 (after the cam went in) in my car with PRC duals and hardened p-rods with no problems. The back tires will actually slide and you'll push the clutch back in faster than you think possible when it happens lol.
I would go hardened, with a huge cam and stout springs (even the 918's), you could bend, or even break, a stock pushrod.
As far as deflection is concerned. They are going to deflect at higher RPMs, then return to straight. If one bends to the point where it's still bent after the revs come down, you'll definatly know it. Bending/ticking at high RPM's will be drowned out by the exhaust sound.
I have done the 3-2 shift from 6800 (after the cam went in) in my car with PRC duals and hardened p-rods with no problems. The back tires will actually slide and you'll push the clutch back in faster than you think possible when it happens lol.
I would go hardened, with a huge cam and stout springs (even the 918's), you could bend, or even break, a stock pushrod.
As far as deflection is concerned. They are going to deflect at higher RPMs, then return to straight. If one bends to the point where it's still bent after the revs come down, you'll definatly know it. Bending/ticking at high RPM's will be drowned out by the exhaust sound.
10-17-2006, 01:16 PM
#12
hmm i understand whats being said about deflecting, but i cant say that i have noticed any power loss (i know it would be there from day one) on the dyno my car makes power all the way to red line and makes good power for a smaller (compared to alot of cams) cam 230 227 .591 571 112
oh and NBMgreg after 2 years and 25k miles all of my pushrods are perfectly striaght.
oh and NBMgreg after 2 years and 25k miles all of my pushrods are perfectly striaght.
10-17-2006, 01:22 PM
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Originally Posted by TheBlurLS1
Stock pushrods are 7.35ish, aftermarket cams are ground on a smaller base circle, which means they need the 7.4's. I, however, ran hardened pushrods/PRC dual springs with the STOCK cam for about 10k miles. I pulled the heads to replace the lifters, and went ahead and threw in the valvesprings/pushrods while I was there.
I have done the 3-2 shift from 6800 (after the cam went in) in my car with PRC duals and hardened p-rods with no problems. The back tires will actually slide and you'll push the clutch back in faster than you think possible when it happens lol.
I would go hardened, with a huge cam and stout springs (even the 918's), you could bend, or even break, a stock pushrod.
As far as deflection is concerned. They are going to deflect at higher RPMs, then return to straight. If one bends to the point where it's still bent after the revs come down, you'll definatly know it. Bending/ticking at high RPM's will be drowned out by the exhaust sound.
I have done the 3-2 shift from 6800 (after the cam went in) in my car with PRC duals and hardened p-rods with no problems. The back tires will actually slide and you'll push the clutch back in faster than you think possible when it happens lol.
I would go hardened, with a huge cam and stout springs (even the 918's), you could bend, or even break, a stock pushrod.
As far as deflection is concerned. They are going to deflect at higher RPMs, then return to straight. If one bends to the point where it's still bent after the revs come down, you'll definatly know it. Bending/ticking at high RPM's will be drowned out by the exhaust sound.
10-17-2006, 01:27 PM
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This is what happened to my buddy's stock pushrods when the motor was mechanically over-revved. Just invest in some good springs and you won't have to worry too much about bending pushrods. Besides, I've banged the limiter a bunch of times with my F13 and nothing was hurt except my pride.
10-17-2006, 01:33 PM
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so what are you suggesting...
you say good springs, you mean 918's? and are you suggesting to run stock, or hardened pushrods?
i have seen the same thing you pictured, snapped pushrod, and the pushrod hole in the cylinder is now eccentric
you say good springs, you mean 918's? and are you suggesting to run stock, or hardened pushrods?
i have seen the same thing you pictured, snapped pushrod, and the pushrod hole in the cylinder is now eccentric
10-17-2006, 01:36 PM
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I really doubt anything would have happened if they were hardened. He replaced them with hardened ones but I don't think he's over-revved the motor since then. There's a reason that hardened pushrods are sold as a part of most cam kits and aren't an option.