Ford goes pushrod?

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Mark O'Neal
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Re: Ford goes pushrod?

Post by Mark O'Neal » Sat Oct 06, 2018 12:40 am

I thought I read that this is a interim motor that they'll use until they finish whatever new motor they're working on.

Or something like that.

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Re: Ford goes pushrod?

Post by barnym17 » Sat Oct 06, 2018 6:34 am

whats antiquated the dohc was invented in the very early 1900's its not exactly new.Cubic inch to cubic inch it wins much better breathing. BUT when you take it off the dyno it has to fit in the vehicle. Then engine weight must also be considered lbs do matter to both economy and performance. You must also consider ease of service during the vehicles life, manufacturing cost, longevity of the engine esp the cam drive system.
Then factor in nowadays the low cruising rpm in most vehicles due to multiple overdrives the high rpm advantage of overhead cams becomes way less of a factor.A perfect example is the newer briggs and stratton overhead valve engines on a lot of mowers true they have more power than the old flatties but they are also far more problematic due the valve train I have replaced many 18 to 20 horse overheads with 12 to 14 horse flatties when the engines blew(frequent occurance) problem solved mows just as well better fuel usage.True it doesn't cut quite as fast but gets the job done.
And that is the whole point manufacturers are trying to get the job done (enough power and economy,and reliability)at the least possible cost in terms of assembly, materials, warranty repairs after the sale.

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Re: Ford goes pushrod?

Post by Truckedup » Sat Oct 06, 2018 7:07 am

DOHC is not necessary in a working truck....Do the Ford, Toyota,and Nissan DOHC V8's give better performance or fuel mileage than the GM wedge or Dodge hemi?....
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Re: Ford goes pushrod?

Post by peejay » Sat Oct 06, 2018 7:17 am

Mark O'Neal wrote:
Sat Oct 06, 2018 12:40 am
I thought I read that this is a interim motor that they'll use until they finish whatever new motor they're working on.

Or something like that.
Given the expense of developing a new engine, it wouldn't make economic sense to make a clean-sheet "interim" engine.

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Re: Ford goes pushrod?

Post by peejay » Sat Oct 06, 2018 7:20 am

Truckedup wrote:
Sat Oct 06, 2018 7:07 am
DOHC is not necessary in a working truck....Do the Ford, Toyota,and Nissan DOHC V8's give better performance or fuel mileage than the GM wedge or Dodge hemi?....
I think that depends on your expectations.

Given the proliferation of 8-10 speed transmissions, and how many work trucks spend a lot of time at the job site idling, it makes sense in my mind to have a smaller displacement engine that uses not so much fuel while it spends 6-7 hours a day idling, and make the power needed to tow a 10,000lb trailer around with RPM.

I guess an engine that is turning 3000-4000rpm down the highway isn't "manly", but an unloaded Diesel truck with a 6 liter engine that needs 20 pounds of boost to keep up with traffic is just fine? (Put 20 pounds of boost in a 6 liter gasoline engine and watch how fast you get kicked off of the dragstrip without a rollcage!)

I remember when Ford switched out the 5.0/5.8 engines for the 4.6/5.4 Mod motors. They kept the old trucks in production up until late 1996 because some people wanted to buy up the last of the large engines because they thought the new engines were "wimpy" because they didn't cruise at 1500rpm like the old engines did. Never mind that they were a crapton smoother, cleaner, and got better fuel economy, the number on the tach made them feel emasculated.

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Re: Ford goes pushrod?

Post by midnightbluS10 » Sat Oct 06, 2018 7:31 am

It's going to replace the current 6.2L gas engine and the V10. Specifically Super Duty and medium-duty trucks.

https://www.tfltruck.com/2018/09/rumor- ... uper-duty/

Info about the 7.3L leaked quite a while ago. Maybe a year? I remember reading about it when the document from Ford was leaked showing the new engine.


This post from May quotes an article claiming it as pushrod. That's what they've been saying all along, IIRC.

http://www.svtperformance.com/threads/u ... 8.1160212/
Last edited by midnightbluS10 on Sat Oct 06, 2018 7:33 am, edited 1 time in total.
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Re: Ford goes pushrod?

Post by peejay » Sat Oct 06, 2018 7:32 am

Ken_Parkman wrote:
Fri Oct 05, 2018 2:21 pm
Often though the 4 cyl was not a very bright engine. The problem with a V8 is it makes too much power with todays technology for the average driver. So scale a V8 down to say 3 liters instead of a 2 litre 4 cyl.

Better weight, packaging, cg, aerodynamics, slightly worse parts count, better balance and shaking forces, run it as a 1 1/2 litre 4 with cylinder deactivation for low cruise pumping losses and better running pressure ratio for better sfc. You would think the inherently small chamber would help compression and emissions?

What's not to like?

But it's not DOHC 4 valve, must be obsolete.
It turns out that, when you take into account combustion chamber size/shape and thermal efficiency into account, the "best" displacement for a gasoline engine is a slightly oversquare 500cc/cylinder. More than that and you lose a good combustion chamber for a good burn, less than that and you lose thermal efficiency.

Notice that Ford has replaced its 1.0l 3-cylinder for a 1.5l. And pretty much everyone in the world is standardizing on 2 liter 4-cylinders and 3-liter V6s, give or take a few cc.


The main issue with pushrod engines, in 2018, is that it is difficult to control intake and exhaust valve timing separately. Not impossible, it HAS been done, but it is difficult. With DOHC, it is a piece of cake. Without fine cam timing control, you lose control over cylinder pressure and you have to resort to crude methodolody like controlling torque with the throttle plate and controlling cylinder temperatures with EGR valves.

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Re: Ford goes pushrod?

Post by midnightbluS10 » Sat Oct 06, 2018 7:39 am

Why would there be a need for Egr valves? If GM can take them off of a gen 1/2 sbc-style V6 in 2002 with no ill effects, why would someone else need them 16 years later? Or am I missing something in your post?
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Re: Ford goes pushrod?

Post by peejay » Sat Oct 06, 2018 7:41 am

grandsport51 wrote:
Fri Oct 05, 2018 5:23 pm
427 3-valve Calliope This engine was intended to run at LeMans, but rule changes outlawed it before it was ever fired. Displacing 427 cubic inches, it was out of place in a class limited to 183 CID. Two engines were produced. One even made it into a test car.
Even though mainly of aluminum construction, this monster weighed 577 lbs.

But it was no boat anchor. The Calliope produced 630 (supposedly reliable) horsepower at 6400 RPM.

While displacing 427 cubic inches, the Calliope was no FE family engine. It used an aluminum block engine with cast iron cylinder liners. Bore was 4.34", stroke was 3.60". The unique feature of this engine are its twin camshafts, one for the intake valves and one for the exhaust. Both are in the block in an over-under arrangement. The intake camshaft lies 6" above the crankshaft centerline. Pushrods from the intake cam run parallel to the cylinder bores. The exhaust camshaft is found 4.5" above the intake cam. Its pushrods lie in a horizontal plane. The camshafts are driven by chains as are the pressure and scavenge pumps for the dry-sump oiling system.
427 Calliope cylinder head, top view 427 Calliope cylinder head, bottom view
The aluminum cylinder heads feature 3 valves per cylinder, two intakes and a single exhaust, in a pent-roof combustion chamber. The heads are sealed with copper O-rings. No intake manifold is used. Hilborn style injection stacks are cast integrally with the cylinder head. No coolant passes between the block and heads. External water lines are used instead. To shorten the engine to assist in fitting it to the racecar chassis, the standard front mounted water pump is replaced by two pumps on the cylinder banks, similar to the scheme used on the Flathead V-8.
427 Calliope timing chains 427 Calliope piston

Man, what could have been!!!

Seems like a modernized (for the 1960s) version of the GAA tank engine that Ford built. Pushrods for smaller package with the 90 degree bank angle, only one exhaust valve...

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Re: Ford goes pushrod?

Post by peejay » Sat Oct 06, 2018 7:50 am

midnightbluS10 wrote:
Sat Oct 06, 2018 7:39 am
Why would there be a need for Egr valves? If GM can take them off of a gen 1/2 sbc-style V6 in 2002 with no ill effects, why would someone else need them 16 years later? Or am I missing something in your post?
2002 is sixteen years ago already! That is the difference between when catalysts were mandatory in the US, and the 1950s. Time marches on!

Variable cam timing is used to control cylinder pressures on the intake side, and the amount of exhaust gas residuals on the exhaust side. 20 years ago manufacturers decided that it was cheaper to have varlable exhaust cam timing than to plumb an EGR valve, so this is absolutely nothing new.

Watch a modern car running with a scantool hooked up watching the cam timing and throttle opening PIDs. It's mind-blowing.

Chevy was probably able to eliminate the EGR by a combination of better combustion chamber shapes, and reduced performance thanks to the GM-typical response of saying screw it, if people want more power then they can buy a V8. Ford offers multiple high end V6s in their pickups, Chevy consders the V6 to be the bottom-rung truck that you only sell because it allows you to charge more for the V8 options.

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Re: Ford goes pushrod?

Post by Truckedup » Sat Oct 06, 2018 8:17 am

peejay wrote:
Sat Oct 06, 2018 7:20 am
Truckedup wrote:
Sat Oct 06, 2018 7:07 am
DOHC is not necessary in a working truck....Do the Ford, Toyota,and Nissan DOHC V8's give better performance or fuel mileage than the GM wedge or Dodge hemi?....
I think that depends on your expectations.

Given the proliferation of 8-10 speed transmissions, and how many work trucks spend a lot of time at the job site idling, it makes sense in my mind to have a smaller displacement engine that uses not so much fuel while it spends 6-7 hours a day idling, and make the power needed to tow a 10,000lb trailer around with RPM.

I guess an engine that is turning 3000-4000rpm down the highway isn't "manly", but an unloaded Diesel truck with a 6 liter engine that needs 20 pounds of boost to keep up with traffic is just fine? (Put 20 pounds of boost in a 6 liter gasoline engine and watch how fast you get kicked off of the dragstrip without a rollcage!)

I remember when Ford switched out the 5.0/5.8 engines for the 4.6/5.4 Mod motors. They kept the old trucks in production up until late 1996 because some people wanted to buy up the last of the large engines because they thought the new engines were "wimpy" because they didn't cruise at 1500rpm like the old engines did. Never mind that they were a crapton smoother, cleaner, and got better fuel economy, the number on the tach made them feel emasculated.
Work trucks idling 6-7 hours a day? That would be an oddball situation compared to my life long experience in construction both large and small. A diesel PU will cruise at 70 mph with no boost if it were designed as a non boosted engine like the gutless GM 6.2's or the earlier Fords with the IHC Diesel....
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Re: Ford goes pushrod?

Post by hoffman900 » Sat Oct 06, 2018 8:44 am

hoffman900 wrote:
Fri Oct 05, 2018 10:24 pm
The valves don’t care how they are actuated.

OHC engines are absolutely necessary as rpm’s rise. Horsepower is simply work done over time = more rpms. They are much stiffer valvetrains.

From an absolute performance point of view, they are superior. You’ll never see pushrods in Formula One or a Moto GP bike. COG, packaging, and light weight are critical there too.

For a mass produced, low rpm, truck engine? Absolutely...

Ford going back to push rod for a truck engine doesn’t validate some of your love affair for antiquated engines. :)

Had an incomplete thought - pushrods can make sense in a mass produced, low rpm, engine.

Also, great points about variable cam timing and throttles. Drive by wire is very interesting, even from a performance aspect.
-Bob

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Re: Ford goes pushrod?

Post by emsvitil » Sat Oct 06, 2018 9:08 am

It should displace 7.54 liters for 460cuin

:mrgreen:
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Re: Ford goes pushrod?

Post by Lem Evans » Sat Oct 06, 2018 9:44 am

Four bolt caps plus cross bolts...it's a nice deal.
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Re: Ford goes pushrod?

Post by Ken_Parkman » Sat Oct 06, 2018 9:54 am

An argument could be made the 4 valve advantage is in rpm range as opposed to common misconception you need it for high rpm. In any kind of a usable street application there is no problem at high rpm with a 2 valve. But where the 4 valve really shines is low rpm, cause the cam timing for the power is so much less due to the little valves and their effective curtain area. Why the Ford OHC killed in the EMC, which is all about power range. The pushrod stuff did not have a chance.

And when there is a rules limitation on displacement there is simply no debate.

But in the real world if you don't have that limit it's not necessarily the same story. GM dumped the Northstar and the Lotus DOHC, Chrysler dumped the 4.7 OHC, and Ford is now going back to pushrods. Their design trade offs came to the same conclusion. And while obviously cost is a big player in those trade offs, the engine still has to get the job done in a competitive world.

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