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I Still Like Pushrods, They're Still Viable

Engine tech, for those engines, products, and technologies of yesteryear.

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frnkeore
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Re: I Still Like Pushrods, They're Still Viable

Post by frnkeore »

Sure the push rod engine, is still viable but, so is the Ford (and others) flathead engine. The push rod engine can produce more torque and HP than the FH but, the 4V will produce more than the push rod.

I suppose a point could be made in packaging a push rod, over a DOHC but, not a SOHC. If absolute weight was the main issue, I guess a push rod would have a advantage, with only one cam but, it would still have a HP/WT disadvantage.

The only reason the push rod has gotten to the high level it has today, is because NASCAR's antiquated rules. Anyone remember when NASCAR mandated that the engine you ran, had to be a regular production item, available to the general public?

Now, it's mandated that it can't be a regular production engine!!! How many think that the 5.0L Coyote wouldn't be used IF NASCAR allowed regular production engines to be used?
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Re: I Still Like Pushrods, They're Still Viable

Post by PackardV8 »

frnkeore wrote: Tue Apr 27, 2021 3:28 am I suppose a point could be made in packaging a push rod, over a DOHC but, not a SOHC.
We'll have to agree to disagree on this statement. Put a Ford Mod SOHC 4.6 (25" wide, 26" tall) beside a 5.0 pushrod (18" wide, 20" tall}. The SOHC is a huge exterior package for it's displacement and power output
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Re: I Still Like Pushrods, They're Still Viable

Post by hoffman900 »

PackardV8 wrote: Tue Apr 27, 2021 8:27 am
frnkeore wrote: Tue Apr 27, 2021 3:28 am I suppose a point could be made in packaging a push rod, over a DOHC but, not a SOHC.
We'll have to agree to disagree on this statement. Put a Ford Mod SOHC 4.6 (25" wide, 26" tall) beside a 5.0 pushrod (18" wide, 20" tall}. The SOHC is a huge exterior package for it's displacement and power output
That’s just a bad design by Ford.

Take a look at Honda’s CRF450 and KTM 450SXF engines to see how to do SOHC correctly. The Honda has a 3.78” bore and the KTM has a 3.8” bore, if you want to get a rough idea of scale.

Both are 125hp/l + on pump gas and fat powerbands.
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Re: I Still Like Pushrods, They're Still Viable

Post by MichaelThompson »

hoffman900 wrote: Tue Apr 27, 2021 8:44 am
PackardV8 wrote: Tue Apr 27, 2021 8:27 am
frnkeore wrote: Tue Apr 27, 2021 3:28 am I suppose a point could be made in packaging a push rod, over a DOHC but, not a SOHC.
We'll have to agree to disagree on this statement. Put a Ford Mod SOHC 4.6 (25" wide, 26" tall) beside a 5.0 pushrod (18" wide, 20" tall}. The SOHC is a huge exterior package for it's displacement and power output
That’s just a bad design by Ford.

Take a look at Honda’s CRF450 and KTM 450SXF engines to see how to do SOHC correctly. The Honda has a 3.78” bore and the KTM has a 3.8” bore, if you want to get a rough idea of scale.

Both are 125hp/l + on pump gas and fat powerbands.
The Ford 6.2 Raptor engine has a vastly superior valve actuation system in my opinion and it’s a lot like the bike engines you mentioned.

Ford actually went for the tallest design possible on the early Mods. For what reason I don’t know but to it’s credit the Modular Ford engine line was very durable.
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Re: I Still Like Pushrods, They're Still Viable

Post by frnkeore »

PackardV8 wrote: Tue Apr 27, 2021 8:27 am
frnkeore wrote: Tue Apr 27, 2021 3:28 am I suppose a point could be made in packaging a push rod, over a DOHC but, not a SOHC.
We'll have to agree to disagree on this statement. Put a Ford Mod SOHC 4.6 (25" wide, 26" tall) beside a 5.0 pushrod (18" wide, 20" tall}. The SOHC is a huge exterior package for it's displacement and power output
Jack, the width of the SOHC, Mod engine, doesn't come from the cam arrangement, a lot of it comes from the deck height! The Mod is about 3/4" higher but, I was not talking about existing engines, I was talking about a fresh design, in either inline 2V or rocker actuated 3V, configuration.

Imagine a 4.38 bore center x 7.5 deck height V8, 5.0L SOHC engine, then incline the valves, up to 30 degree and what would you have, as a package?
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Re: I Still Like Pushrods, They're Still Viable

Post by hoffman900 »

The way to go is with even flatter chambers than that.

Here is the new Honda CBR1000rr-r valve angle:
Image

they stood up the valves on their current F1 engine as well.
Image
Image
Image
Image
Two things, when you get around the fact you don't need pushrods passing through the head, it opens up options for port alignment. The second is when you get past a carburetor, you can do just about whatever you want with the intake port geometry... it doesn't have to pop out under a venturi like a 4bbl needs.
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Re: I Still Like Pushrods, They're Still Viable

Post by Ron E »

Packaging from my own possible projects. A 90's 300ZX TT is a narrow angle engine . Even so, its a bunch wider and is actually a small amount heavier than a LS3 which in its more simplified N/A form is good for an easy 150-200 more HP. Any comparison will be different. But, in my case there's an obvious winner.
Like almost everything else "It depends".
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Re: I Still Like Pushrods, They're Still Viable

Post by frnkeore »

Ron, this is a drawing of the Ford, Duratech 3.0, V6. It has a deck height of 8.189. I would be surprised if it was wider than a LS but, I couldn't find a measurement.

I've inscribed the 2 red lines, point out what it might look like if it was a SOHC engine. Based on the bore and stroke, the DH could be reduced to 8.0, making it even narrower, in both SOHC & DOHC.

Although SOHC won't produce the HP of DOHC, SOHC, in a race engine, will produce more HP than a push rod engine, if only because of the higher rpm potential.
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Re: I Still Like Pushrods, They're Still Viable

Post by hoffman900 »

frnkeore wrote: Wed Apr 28, 2021 1:56 am Ron, this is a drawing of the Ford, Duratech 3.0, V6. It has a deck height of 8.189. I would be surprised if it was wider than a LS but, I couldn't find a measurement.

I've inscribed the 2 red lines, point out what it might look like if it was a SOHC engine. Based on the bore and stroke, the DH could be reduced to 8.0, making it even narrower, in both SOHC & DOHC.

Although SOHC won't produce the HP of DOHC, SOHC, in a race engine, will produce more HP than a push rod engine, if only because of the higher rpm potential.
It’ll produce the same as a DOHC if it’s a 4 valve like the MX engines I shared!
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Re: I Still Like Pushrods, They're Still Viable

Post by David Redszus »

The ability of an engine to produce specific power is primarily a function of combustion chamber design.

The most potent designs in order are:
four valve pent roof,
two valve hemi,
two valve wedge,
two valve bathtub,
two valve flat head.

The valve train mechanics will allow higher engine rpm without valve float problems,
in order are:
OHC gear drive
OHC belt drive
CIB push rod.
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Re: I Still Like Pushrods, They're Still Viable

Post by frnkeore »

David Redszus wrote: Wed Apr 28, 2021 5:25 pm
The valve train mechanics will allow higher engine rpm without valve float problems,
in order are:
OHC gear drive
OHC belt drive
CIB push rod.
Doesn't the gear drive create harmonics and friction, that the belt drive would mitigate, at least to the limitation that valve springs have?
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Re: I Still Like Pushrods, They're Still Viable

Post by nicholastanguma »

David Redszus wrote: Wed Apr 28, 2021 5:25 pm The ability of an engine to produce specific power is primarily a function of combustion chamber design.

The most potent designs in order are:
four valve pent roof,
two valve hemi,
two valve wedge,
two valve bathtub,
two valve flat head.

The valve train mechanics will allow higher engine rpm without valve float problems,
in order are:
OHC gear drive
OHC belt drive
CIB push rod.

Then, theoretically, a pushrod architecture that uses a four valve pent roof head would still be making a broader torque band and higher wheel hp than the same pushrod architecture with a two valve hemi head, despite the fact a pushrod mill doesn't rev as high as an ohc mill?

Or does the fact the pushrod mill can't rev as high mean the two vale hemi head is the better practical , real world, non-race head to use?
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Re: I Still Like Pushrods, They're Still Viable

Post by nicholastanguma »

David Redszus wrote: Wed Apr 28, 2021 5:25 pm The ability of an engine to produce specific power is primarily a function of combustion chamber design.

The most potent designs in order are:
four valve pent roof,
two valve hemi,
two valve wedge,
two valve bathtub,
two valve flat head.

The valve train mechanics will allow higher engine rpm without valve float problems,
in order are:
OHC gear drive
OHC belt drive
CIB push rod.

Then, theoretically, a pushrod architecture that uses a four valve pent roof head would still be making a broader torque band and higher wheel hp than the same pushrod architecture with a two valve hemi head, despite the fact a pushrod mill doesn't rev as high as an ohc mill?

Or does the fact the pushrod mill can't rev as high mean the two vale hemi head is the better practical , real world, non-race head to use? I ask because, as someone else pointed out earlier, the new Harley-Davidson Milwaukee Eight v-twin uses four valve heads but is still pushrodded, and it makes more torque sooner in the revs than the two valve Twin Cam v-twin it's replacing. And it makes more top end hp as well.
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Re: I Still Like Pushrods, They're Still Viable

Post by David Redszus »

frnkeore wrote: Thu Apr 29, 2021 1:57 am
David Redszus wrote: Wed Apr 28, 2021 5:25 pm
The valve train mechanics will allow higher engine rpm without valve float problems,
in order are:
OHC gear drive
OHC belt drive
CIB push rod.
Doesn't the gear drive create harmonics and friction, that the belt drive would mitigate, at least to the limitation that valve springs have?
Everything that moves creates harmonics. Monitoring hydraulic belt tensioning pressures clearly indicate the
instability of belt (or chain) drives.

Gear driven systems are more stable but much more expensive to make and maintain.
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Re: I Still Like Pushrods, They're Still Viable

Post by David Redszus »

nicholastanguma wrote: Thu Apr 29, 2021 5:44 am
David Redszus wrote: Wed Apr 28, 2021 5:25 pm The ability of an engine to produce specific power is primarily a function of combustion chamber design.

The most potent designs in order are:
four valve pent roof,
two valve hemi,
two valve wedge,
two valve bathtub,
two valve flat head.

The valve train mechanics will allow higher engine rpm without valve float problems,
in order are:
OHC gear drive
OHC belt drive
CIB push rod.

Then, theoretically, a pushrod architecture that uses a four valve pent roof head would still be making a broader torque band and higher wheel hp than the same pushrod architecture with a two valve hemi head, despite the fact a pushrod mill doesn't rev as high as an ohc mill?

Or does the fact the pushrod mill can't rev as high mean the two vale hemi head is the better practical , real world, non-race head to use?
Your points are valid and are considerations the engine designer must face, in addition to cost, packaging,
and other design constrictions.

Didn't Penske, Chevy, Ilmor once build an Indy race engine using pushrods? Sort of? Kinda.
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