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7.3 teardown


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On 2/11/2020 at 12:30 AM, theoldwizard said:

My "gut" still says, the reason for pushrods was to keep the block narrow enough and the "dressed" engine height low enough to fit in the E-series.

It was one of the stated objectives, a simple, compact engine that would fit where the old engines did without major changes.

 
Ford has come full circle with  pushrod engines,

pity they didn’t just keep updating the 385 Limas 

 

Edited by jpd80
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The old wizard, you are probably right but there are usually many reasons for major design decisions when related to engines and transmissions.

pushrod engines provide better low rpm torque than ohc engines. The parasitic losses are lower. If ford ever does an aluminum block version,   Cylinder deactivation is easier and cheaper to do on an ohv design.

The other thing is Long range plans always get revised. I would not be surprised if E series was all going away at one time and someone figured out that a transit cut van would not cover everything they had with E !

edselford

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On 2/13/2020 at 12:12 AM, edselford said:

The old wizard, you are probably right but there are usually many reasons for major design decisions when related to engines and transmissions.

pushrod engines provide better low rpm torque than ohc engines. The parasitic losses are lower. If ford ever does an aluminum block version,   Cylinder deactivation is easier and cheaper to do on an ohv design.

The other thing is Long range plans always get revised. I would not be surprised if E series was all going away at one time and someone figured out that a transit cut van would not cover everything they had with E !

edselford

Ford knew that the Transit on integral ladder frame could only cover so much of the E Series range

the heavier E Series versions were never going to be replaced, all they needed was upgraded

Engines, transmissions for now and ongoing improvemens to other systems.

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On 2/12/2020 at 8:12 AM, edselford said:

The old wizard, you are probably right but there are usually many reasons for major design decisions when related to engines and transmissions.

pushrod engines provide better low rpm torque than ohc engines.

First, nothing personal Edsel, I'm using your quote as an example. 

 

I see this statement frequently, and I don't understand.   Why do folks assume OHV design makes more torque than OHC (for a given displacement)?   Or are they assuming OHV implies larger displacement and OHC is smaller displacement and higher rpm?

 

OHC can be designed for as good or better breathing (torque) at any rpm range vs OHV, it's just more flexible.

 

I've purposely left out MDS and VVT, those are mostly separate issues.

Edited by GottaCleveland
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3 hours ago, GottaCleveland said:

First, nothing personal Edsel, I'm using your quote as an example. 

 

I see this statement frequently, and I don't understand.   Why do folks assume OHV design makes more torque than OHC (for a given displacement)?   Or are they assuming OHV implies larger displacement and OHC is smaller displacement and higher rpm?

 

OHC can be designed for as good or better breathing (torque) at any rpm range vs OHV, it's just more flexible.

 

I've purposely left out MDS and VVT, those are mostly separate issues.

Short answer is they don’t but I suspect the real point is that OHC is not required in a truck engine that doesn’t exceed 6,000 rpm.

 

just looking at the 6.2 Boss, it tries hard but just didn’t have enough capacity. I suspect that if Boss had been a pushrod engine, we would have seen a 5.8 and a 7.0 double act way back when, ford just couldn’t get cylinder deactivation to work reliably and that’s what killed large capacity V8 in F150

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No doubt the 7.3 makes all kind of sense as a truck engine-push rods and all.  But as for OHC, what makes the Ecoboost concept so  valid? IMO all kinds of torque at low RPM.  My SHO (3.5) could hold a higher  gear and drop down to 1200 RPM as long as you had a light foot.

 

Now my 3.0T doesn't seem to  drop as low  but it still works at lower RPMs.  To those who say Ecoboosts suck as far as fuel economy I say, it should be called.."Eco or boost".  Drive with a light foot and you get good MPG's .  Want to feel that power?  Pay the price.

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Now that the 7.3 gas is in production, why doesn’t someone ask Mr. Wolfe the reason the engine is a pushrod engine and not OHC?

It is ok to disagree with me on low end torque but for a given piece price level on the engine components, it going to be very difficult to get an OHC engine to the same low rpm torque levels when compared to a pushrod, two valve per cylinder design!

Also does any one remember the experimental 777 engine in Hot Rod magazine?  I think the bore was 4.22” . I would like to know if this engine was an OHC or a pushrod?

Thanks

edselford

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1 hour ago, Bob Rosadini said:

No doubt the 7.3 makes all kind of sense as a truck engine-push rods and all.  But as for OHC, what makes the Ecoboost concept so  valid? IMO all kinds of torque at low RPM.  My SHO (3.5) could hold a higher  gear and drop down to 1200 RPM as long as you had a light foot.

 

Now my 3.0T doesn't seem to  drop as low  but it still works at lower RPMs.  To those who say Ecoboosts suck as far as fuel economy I say, it should be called.."Eco or boost".  Drive with a light foot and you get good MPG's .  Want to feel that power?  Pay the price.


Thats what I love about my F150 3.5Leb.  It just loafs along at 1200 rpm in 10th gear even going uphill and I can easily get 24-28 mpg depending on speed.  They also made a lot of improvements with the 2nd gen ecoboosts that fixed early problems.

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Mr. Wolfe was very clear in the 7.3L teardown videos that the reason the 7.3L is pushfor is for packaging (smaller exterior size) and because an OHC design does not offer any meaningful advantage at the r.p.m. range the 7.3L works at.  I suspect Ford also sees a cost advantage with OHV as well.

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2 hours ago, edselford said:

. . . . 

Also does any one remember the experimental 777 engine in Hot Rod magazine?  I think the bore was 4.22” . I would like to know if this engine was an OHC or a pushrod?

Thanks

edselford

OHC.  It was based on the 6.2L V8 in the F Series.

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Bob

I think the final drive axle ratio on the Explorer is around 3.67, probably to improve acceleration on the 3.0 ecoboost. On an f150, I suspect the final drive is more like 3.31. So assuming that the tire rolling radius is not too different between the two, the f150 would be at a lower rpm than the Explorer at the same road speed.

With the great torque from the 3.5 ecoboost, at road load, the 3.5 ecoboost throttle opening is probably opened more then the 3.0.

Greater throttle opening.  At 1200rpm this would significantly reduce engine pumping losses, helping get 23 to 28 mpg on a pickup truck!

edselford

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8 hours ago, 7Mary3 said:

Mr. Wolfe was very clear in the 7.3L teardown videos that the reason the 7.3L is pushfor is for packaging (smaller exterior size) and because an OHC design does not offer any meaningful advantage at the r.p.m. range the 7.3L works at

That's also what the chief engineer said at the unveiling of the engine.

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5 hours ago, edselford said:

Bob

I think the final drive axle ratio on the Explorer is around 3.67, probably to improve acceleration on the 3.0 ecoboost. On an f150, I suspect the final drive is more like 3.31. So assuming that the tire rolling radius is not too different between the two, the f150 would be at a lower rpm than the Explorer at the same road speed.

With the great torque from the 3.5 ecoboost, at road load, the 3.5 ecoboost throttle opening is probably opened more then the 3.0.

Greater throttle opening.  At 1200rpm this would significantly reduce engine pumping losses, helping get 23 to 28 mpg on a pickup truck!

edselford

EF-I'm comparing 3.5 in my Taurus SHO vs MKZ with 3.0T.  Not sure what axle ratios are in each but the 3.5 really had low  end grunt.  Even using the paddle  shifters in the MKZ  try to grab a higher gear,  Flashing light and it holds the lower gear until RPMs are up.  P255/45 -19 on SHO and 245/40-19 on MKZ

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Uncle Tony's Garage gave his opinion on this engine and I agree with him that if Ford were smart they would be cranking them out as fast as they can, crating up the ones they don't put in Super Duty, and selling them for engine swaps.  Id love to put one of these in my International truck project but I have a feeling they are going to be a pain to find.   Does anybody know if Ford has any intentions for a crate engine version of this?

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11 hours ago, packardbob said:

Uncle Tony's Garage gave his opinion on this engine and I agree with him that if Ford were smart they would be cranking them out as fast as they can, crating up the ones they don't put in Super Duty, and selling them for engine swaps.  Id love to put one of these in my International truck project but I have a feeling they are going to be a pain to find.   Does anybody know if Ford has any intentions for a crate engine version of this?

P-Bob- What model IH?

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1 hour ago, packardbob said:

1952 L-160. I would feel bad about removing the stock SD-240 engine but it was replaced in the late 1960's by a BD-264.  I think the 7.3 would be an excellent engine choice to swap.

Well it would  be a hotrod  for sure.  Now if you wanted to keep it "pure" an International V-345 would  be a good choice.  Must be a ton of them in the junk  yards.

Drove the attached B-180 while I was working my way through college in 60's. V-345, 5 and 2 and juice brakes! Truck was registered for  24,000 but I would often CARRY close to 12 ton of asphalt!  Drove it and always split it when  it had that kind of weight.  Motor was a bear!

fullsizeoutput_7b6.jpeg

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21 hours ago, packardbob said:

Does anybody know if Ford has any intentions for a crate engine version of this?

With all the "this mill was built around the duty cycle of mediums," I would've thought no, but with it going into hot rods before it even made it into a production Super Duty, I'm thinking the chances are better than average.

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1 hour ago, 30 OTT 6 said:

I'd like to read an explanation on how a pushrod makes more low end torque. I need a good laugh.

 

This is the closest thing to a literate explanation I can find. It's not the method of how the valves are moved, it's the placement of the valves themselves.  There must not be an example available of the exact same valve size & placement with both methods of movement.  HRG

 

https://axleaddict.com/auto-repair/Overhead-Valve-OHV-vs-Overhead-Cam-OHC-Which-Engine-Design-is-Better

 

Another feature of the OHC design is that the overhead placement of the cams allows for more valves per cylinder. The pushrods and rockers get in the way and make placing more than 2 valves an engineering challenge. With only 2 valves, the valve diameter is limited on how large the cylinder is. Being able to reduce the size of the valves and have more of them actually increases the effective area covered by the valves and this translates to more airflow, which is why OHC engines tend to produce more high-end torque and horsepower. However, it's not a clear win since the extra flow offered by multiple valves comes at the expense of more laminar flow. What I mean by this is, the smaller valves require less severe changes in flow direction around the valve so the air is less turbulent. In an OHV engine, the air has to flow around a very wide diameter valve and recirculate on the other side, making it turbulent. Turbulence encourages air and fuel to mix more completely prior to combustion so the OHV design offers gains in low-end torque naturally while it suffers at the top end, where absolute flow is more important than mixing efficiency.

Edited by HotRunrGuy
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3 hours ago, 30 OTT 6 said:

I'd like to read an explanation on how a pushrod makes more low end torque. I need a good laugh.

 

Yeah, me too!  What I think they are getting at is that a wedge combustion chamber with moderately sized in-line valves works very well at lower r.p.m.'s (port velocity for one) for torque.  And, with that design there is no reason for an overhead cam.  So, it isn't that an OHV design has an advantage over an OHC design for low r.p.m. torque, it's just that there is no disadvantage to an OHV in that application.  In addition the OHV design has other advantages over OHC such as cost and external size.

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On 3/24/2020 at 7:24 PM, SoonerLS said:

With all the "this mill was built around the duty cycle of mediums," I would've thought no, but with it going into hot rods before it even made it into a production Super Duty, I'm thinking the chances are better than average.

 

I am not so optimistic. Ford does not understand (or has no interest in) 'crate engines'.  Half the time you can't even buy new replacement production engines after the model year is over, you are stuck with Ford's 'Authorized' reman's!  Who 'authorizes' those things anyway?  

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1 minute ago, 7Mary3 said:

 

I am not so optimistic. Ford does not understand (or has no interest in) 'crate engines'.  Half the time you can't even buy new replacement production engines after the model year is over, you are stuck with Ford's 'Authorized' reman's!  Who 'authorizes' those things anyway?  

We had a horrible experience with v10 remans from an authorized shop. 3 engines in less than 500 miles. All were under warranty, but a terrible experience.  

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