grinder11

iTrader: (1)

......if it fits, then bigger is better....That's what SHE said!!! Then I showed her!!!

Forcefed86

iTrader: (4)

I had to hog the push rod holes out to 1/2" for the 3/8's deal...

Che70velle

iTrader: (6)

With any performance build, the bigger diameter pushrod you can fit, the better. The reasoning behind this is pushrod flex. When…not if….when a pushrod is flexing, it’s causing two problems.
1. A flexing pushrod is a shorter pushrod. Your losing lift at the valve.
2. A flexing pushrod is causing harmonics that greatly affects spring life, as well as rocker trunnion/bushing/bearing life.
All engines fight harmonics. Harmonics are the engines enemy, fighting it against rpm potential, and overall lifespan. A larger diameter pushrod will block more harmonics because it’s flexing less than its smaller version. In pushrods, diameter trumps wall thickness for strength. Wall thickness is going to make a difference for sure, but diameter Vs. diameter, the larger diameter of the two pushrods will be stronger, irregardless of wall thickness. Always remember that the pushrod is the second spring in the valvetrain.

Forcefed86

iTrader: (4)

Right I know the reason they are used. At what point are they flexing enough to make a nats *** worth of difference VS a "real" difference is my point.

As mentioned I've leaned on the OEM stuff really hard and never seen a failure or had an issues valvetrain related. Also never saw improvements ET/Trap wise when I replaced them. What I did have was people telling me I needed larger springs and better push rods... which never helped any of my issues. Just hurt my pocket book.

What I'm wondering is if this is similar to the usual band wagon bs... like rod bolts, main studs, fancy head gaskets, head studs, forged rotating assy's etc etc...

Che70velle

iTrader: (6)

100% will make a real difference. Rather than bore you with more rambling from me, here’s a link to a real world experiment with larger diameter pushrods with real world results. Fwiw here, each build will require its own unique pushrod spec that’s determined by rpm, spring pressure, pushrod length (the longer the rod, the weaker), rocker ratio, etc. I know you already know all of this, so I’ll hush. The thread in this link is a very quick read with scientific modeling and results…enjoy.
https://www.corvetteforum.com/forums...stiffness.html

Forcefed86

iTrader: (4)

Don't get me wrong, appreciate the comments. Not trying to argue with ya. Just not sure its a warranted upgrade in some cases when you compare the failure rate and gains VS the cost. I put my 3/8 push rods in at the track and did back to back pulls. I'm not saying the valve train isn't happier... only that the previous part didn't fail and I saw no gains so to speak. Once you get into "big" aggressive ramp rates and "big" spring pressures I know the factory stuff won't be up for the job. Just wondering what that point really is.

gametech

iTrader: (1)

While I have no doubt that many experiments have shown better results with bigger/thicker/more hardened pushrods, the linked thread is nearly useless speculation. The data put into the modeling software was inaccurate, and the real world tests were done with different fuels in different conditions. Overall mass and hardness have a significant effect on the harmonics of any item, and he fudges one number while ignoring the other.

Che70velle

iTrader: (6)

Well that stinks. It’s a thread I stumbled across while looking at what the author of the thread had previously done, as his engine threads are typically informational and thorough. I honestly never bothered to check his data. I agree completely with you about the end result numbers being curious because of the fuels, but then again I never considered there being a performance inducing difference between a summer blend and a winter blend pump fuel. My main point of the link was an attempt to help Forcefed see the strength differences between the different pushrods. I suppose the bottom line here in all this pushrod talk is that, if one can’t understand the simple logic of a stronger pushrod (spring) being responsible for improved valvetrain control, and therefore improved engine performance, well…I dunno what else I can add to the discussion.

gametech

iTrader: (1)

I fully understand. It just bothers me when flawed methodology is presented to reach an otherwise accurate conclusion, because the same methodology could easily be used to support a wrong conclusion.

Che70velle

iTrader: (6)

Agree 100%.

epfatboy

iTrader: (3)

Numbers don’t lie but liars use numbers. …

that and craptastic (wonderful presentation of **** data) were my go to’s at work….

Forcefed86

iTrader: (4)

No argument its best to have a valvetrain without noodles for pushrods. But that's not the point or the question being asked. I'd love to have top of the line components everywhere! But that's not practical/economical. I was asking where the heard data and numbers are stating the RPM/spring pressure/cam rates that cause the push rods to fail or to flex enough for *measurable* power to be lost. I have no doubt I may have gained a couple HP on an engine dyno with the swap. But that translates to diddly on the race track... Because if I can run a factory push rod for free to 7500 rpm with a moderate cam and nothing lost but a couple HP... then that leaves me more money for things that are actually needed.

Also want to say I'm in no way stating the OEM pushrod is capable of the above.... But if it is.. I will save my money for other things and put push rods in the same file as rod bolts and head studs.