Pushrod engines, why?

[Mensan]

Originally posted by Mallard:

 

However, I don't think the Ford Mod DOHC motors are good because of size/packaging, valvetrain inertia, and cost.

And here is a very good point:

 

I never made mention of a particular make or engine. I just would like to know why we are so stuck on pushrod engines.

 

Once again, arguments are flawed.

 

Nitrousbird, didn't you just create a thread on how much rotaries suck? And now you are saying that what makes an engine better is how much power it makes in comparison to its physical size? Pick one, because those statements are contrary.

 

Also, if torque is what matters then why aren't you guys arguing in favor of inline engines? How many of you run inline 8 cylinders when its obvious that they would make a shitload of torque? What about diesel engines? They make FAR more torque than gasoline engines. If that is what matters then why don't we see any of you running them?

 

The 1968 427 pushrod engine made 390 BHP. The same engine in SOHC form made 657 BHP from the factory. It weighed in at 5 pounds more than its pushrod counterpart.

 

427 info

[Mallard]

Originally posted by Mensan:

And here is a very good point:

 

I never made mention of a particular make or engine. I just would like to know why we are so stuck on pushrod engines.

True, I just brought up the Mod motor because it's probably the most common DOHC V-config. engine that's built for performance.

[recklessOP]

listen to one of these and you'll forget all about pushrods... graemlins/leghump.gif

 

http://www.rsportscars.com/foto/01/360modena00_engine.jpg

[Dave1647545494]

Ford 427 V-8 Engines

 

427 "W" (4V)

1968 427 SOHC "D" (8V)

427 SOHC "L"(4V)

1964-68 427 "Q" (4V) 1963-64

427 "M" (8V) 1965

427 "R" (8V) 1963-67

427 "W" 1966-67

Engine Type 8 cylinder

90 degree,

Overhead Valves (OHV) 8 cylinder

90 degree,

Overhead Valves (OHV) 8 cylinder

90 degree,

Overhead Valves (OHV)

 

Displacement 427 cu.inches (CID) 427 cu.inches (CID) 427 cu.inches (CID)

Maximum torque 460 lbs./ft. @ 3,200 RPM

 

515 lbs./ft. @ 3,800 RPM (4V)

575 lbs./ft. @ 4,200 RPM (8V)

476 lbs./ft. @ 3,400 RPM (4V)

480 lbs./ft. @ 3,700 RPM (8V)

Maximum Horsepower 390 BHP @ 5,600 RPM 616 BHP @ 7,000 RPM (4V)

657 BHP @ 7,500 RPM (8V)

410 BHP @5,600 RPM (4V)

425 BHP @6,000 RPM (8V)

Firing Order 1-5-4-2-6-3-7-8

(Number 1 cylinder on right bank, nearest radiator) 1-5-4-2-6-3-7-8

(Number 1 cylinder on right bank, nearest radiator) 1-5-4-2-6-3-7-8

(Number 1 cylinder on right bank, nearest radiator)

Bore & Stroke 4.232" X 3.784"

(107.59 mm X 96.03 mm) 4.232" X 3.784"

(107.59 mm X 96.03 mm) 4.232" X 3.784"

(107.59 mm X 96.03 mm)

Compression Ratio 10.9:1 12.01:1 11.6:1 (all 1963-64)

10.0:1 (Mercury only)

11.0:1 (most 1965-67)

Oil Pressure (hot) 35 to 60 lbf/in2 35 to 60 lbf/in2 35 to 60 lbf/in2

Mains cross bolted cross bolted cross bolted

Carburetor Holley 4150 (4V)

automatic choke

Holley 4150-C (4V)

Holley 4160 x2 (8V)

Holley 4150 (4V - "Q" series)

Holley 4150-C (4V - "W" series)

Holley 4160 x2 (8V - "M" & "R" series)

all automatic choke

 

Size of Carburetor 710 cfm (4V)

780 cfm x2 (8V)

 

Fuel premium gas super premium super premium

Intake Manifold aluminum (thru 12/1968)

cast iron after 12/1968

aluminum aluminum

Valve train hydraulic lifters solid & adjustable lifters solid & adjustable lifters

Intake 2.082"-2.097" 2.235"-2.265" 2.022"-2.037" (low riser intake before 3/15/1963)

2.082"-2.097" (low riser intake 3/1963-64)

2.185"-2.195" (all medium & hi riser intake)

Exhaust 1.645"-1.660" 1.938"-1.968" 1.645"-1.660" (all low riser intake)

1.723"-1.733" (all medium & hi riser intake)

Distributor single point

vacuum advance dual point

mechanical advance

Transistor ignition option: single point mechanical advance

dual point

mechanical advance

Transistor ignition option: single point mechanical advance

 

Spark Plugs Autolite BF-32 Autolite AG-2 Autolite BF-32

Long Block Weight

in lbs. 675 680 590 (4V-1967)

600 (8V-1967)

 

 

way to compare like engines the cammer has 2 points more compression electronic ignition dual quads solid lifter (bigger) cam

 

put the same induction ignition compression and cam in a regular 427 and it makes the same power

[Mallard]

Originally posted by recklessOP:

[QB]listen to one of these and you'll forget all about pushrods... graemlins/leghump.gif [QB]

Put it in a car the price of my Protege and I will.

[Mensan]

Originally posted by GAS,GRASS,OR ASS:

way to compare like engines the cammer has 2 points more compression electronic ignition dual quads solid lifter (bigger) cam

 

put the same induction ignition compression and cam in a regular 427 and it makes the same power

12.0-10.9=1.1...I guess that's close to two. The carbs are a gimme. You can have that one. So let's use the single 4v option, which nets 616HP. Other than that, show me where you can do a cam swap and add an igition and add 226 HP. Have you researched this engine at all? Do you know why it makes more power(hint-PORT SHAPE/ANGLE)? Do you really think that having overhead cams hurts performance? Instead of arguing for arguments sake, do some research. Find out about OHC engines, and what their weaknesses are. I'll wait. Post your results.

[recklessOP]

Originally posted by Mallard:

Put it in a car the price of my Protege and I will.

i didn't say buy one... tongue.gif

 

did you miss the ALMS race at midohio?

[recklessOP]

Originally posted by Mensan:

Find out about OHC engines, and what their weaknesses are.

shut up, they have no weaknesses...

 

http://www.zilvia.net/f/images/smilies/bowdown.gifhttp://www.steeda.com/store/-catalog/enginecooling/4VheadLG.jpg

[recklessOP]

redface.gif

[Mensan]

Originally posted by recklessOP:

shut up, they have no weaknesses...

 

http://www.zilvia.net/f/images/smilies/bowdown.gif(Your pic)

Those are "C" heads...They do have weaknesses... tongue.gif You want a multi-port head.

[Guest riggs867]

the LS2 isn't even on sale yet...

Hasn't the LS2 been in full size Chevy / GMC trucks since 1999?

[Mallard]

Originally posted by recklessOP:

did you miss the ALMS race at midohio?

Nope! I was there. You ran by me while I was sitting on in the Esses...twice.

[Nitrousbird]

32V SBC PUSHROD heads. Yeah, they make those for the LT1 too.

 

Originally posted by Mensan:

Nitrousbird, didn't you just create a thread on how much rotaries suck? And now you are saying that what makes an engine better is how much power it makes in comparison to its physical size? Pick one, because those statements are contrary.

Where did I EVER make a reference to the size of the rotary?? I never used that in any sort of discussion for or against it. I mean you can make a 1.5L 4-banger make more power on boost than a stock LS1 (as an example), and be smaller....but that's kinda apples to oranges. You are comparing a 4.6L DOHC modular Ford to an LS1....using it's smaller displacment as some sort of stretch of an example of it being superior. Yet, even though it displaces less, the ENGINE IS PHYSICALLY BIGGER. Who cares what the displacement is?? How is its smaller displacement an advantage when the motor is physically bigger/heavier??

 

And folks, why are you all using the LS2, which isn't easily available yet, as an example when you can easily use the LS6....a PROVEN engine that has been available since 2001, makes the same power, and is sold in crate form as well.

[Guest Ponyfreak]

I hate to tell you guys but the NHRA cuts your nuts if you try to push the envelope and develope something with technology and finally starts winning races. 500ci hemis are there cause they were there years ago. They cannot make any more usuable power as it is. The only difference between runs is the settings adjusted for optimal traction. That is it. If they could get larger tires, they would not have a problem running 3 second 1/4 mile times.

 

Now look at racing where technology is not hindered. Look at the history of the indy/CART/formula series race cars over the last 50 years, and what they currently run engine wise. In the early late 50's early 60's most were still running pushrod engines, frontmount nonetheless. As the years went by rearmount engines became more popular, as did the OHC, until one day all the pushrods were phased out.

There is a reason for this. Go read.

 

 

Pushrod engines will never rev as high as OHC engines with simlular materials. With proper intake, cam, and head design you can never get as much power out of the same ci pushrod engine as you can OHC/DOHC engine. Even with the addition of extra parasitic drag of the extra cams/sprokets.

 

Now onto another point:

 

STREET CARS need torque and low rpm hp. Simular sized OHC and pushrod engines can do this very effectively. HP for HP and TQ for TQ both can be engineered to perform this function equally.

 

Pushrods are cheaper to make, mainly due to poorer quality materials that they are made from(cast iron), and less complex valvetrain. Made from the same materials the OHC would weight slightly more, DOHC even more. Most of the time DOHC are made from all alum construction which add to their cost and weight.

 

 

Basically if you wnat cheap hp get a pushrod engine.

 

If you want more hp ci for ci get a OHC designed engine.

 

Here is my personal choice that I ride with:

317 cfm intake @ .500 lift

267 cfm exhaust @ .500 lift

http://mark8.org/users/ponyfreak/web/heads/headpics%20003a.jpg

[Mensan]

Originally posted by Nitrousbird:

32V SBC PUSHROD heads. Yeah, they make those for the LT1 too.

 

Where did I EVER make a reference to the size of the rotary?? I never used that in any sort of discussion for or against it. I mean you can make a 1.5L 4-banger make more power on boost than a stock LS1 (as an example), and be smaller....but that's kinda apples to oranges. You are comparing a 4.6L DOHC modular Ford to an LS1....using it's smaller displacment as some sort of stretch of an example of it being superior. Yet, even though it displaces less, the ENGINE IS PHYSICALLY BIGGER. Who cares what the displacement is?? How is its smaller displacement an advantage when the motor is physically bigger/heavier??

 

And folks, why are you all using the LS2, which isn't easily available yet, as an example when you can easily use the LS6....a PROVEN engine that has been available since 2001, makes the same power, and is sold in crate form as well.

I was talking about this argument. You just mentioned previously that what counts is the physical size/weight of an engine:

 

 

Originally posted by N2Obird:

Who cares about cubic inches, when that 4V motor is physically a FAR larger engine than an LS1??

 

Why are people stuck on "it makes x HP per cubic inch??" It's the ACTUAL PHYSICAL SIZE OF THE MOTOR THAT COUNTS!!!

I assume you meant in relation to the amount of power it makes (HP to weight ratio; and also packaging). Let me know if I am wrong.

 

I also did not use the 4.6 as a reference in my argument. I am talking about the configuration of an OHC engine as opposed to their pushrod counterparts. We can sit here all day long and talk about the advantages of specific engines. You just proved to everyone that there are 4V heads for SBC engines that are vastly superior to the 2V heads. This was another point I brought up earlier. The 4V heads have more capability. I feel the same way about OHC engines. With the availability of lighter materials, I think we will begin to see smaller packaging and more power out of smaller displacement.

 

FWIW, Chevrolet also has a 4.6 DOHC car. It has just as much potential, if not more, than the 4.6 Ford engine. Chevy decided not to put it in any cars, and that has been to the detriment of an excellent design.

 

This is not an engine/brand name war. I would like everyones opinion on the DESIGN of modern engines. So far, no one has been able to sway my opinion on OHC engines, and you have provided me with another example of my point that the 4V heads are vastly superior.

 

[ 03. August 2004, 11:26 PM: Message edited by: Mensan ]

[AngryBMW]

El Camino > Eli.

-Marc

 

 

*Way to much shit to read right now...

[Mallard]

Originally posted by Ponyfreak.:

Now look at racing where technology is not hindered. Look at the history of the indy/CART/formula series race cars over the last 50 years, and what they currently run engine wise. In the early late 50's early 60's most were still running pushrod engines, frontmount nonetheless. As the years went by rearmount engines became more popular, as did the OHC, until one day all the pushrods were phased out.

There is a reason for this. Go read.

Pushrods are cheaper to make, mainly due to poorer quality materials that they are made from(cast iron), and less complex valvetrain. Made from the same materials the OHC would weight slightly more, DOHC even more. Most of the time DOHC are made from all alum construction which add to their cost and weight.

In the 90's Mercedes-Benz came back to Indy and won...with a pushrod engine. They used a rules loophole for pushrod engines, but I think that proves that they have the rpm capabilities.

 

Also, the LS1 is all aluminum. Cheap materials...huh? They're not cast iron anymore.

[Mallard]

Originally posted by Mensan:

FWIW, Chevrolet also has a 4.6 DOHC car. It has just as much potential, if not more, than the 4.6 Ford engine. Chevy decided not to put it in any cars, and that has been to the detriment of an excellent design.

The Northstar is also a 4.6 DOHC and I think it proves that they can be put into compact spaces. (Anything that fits in the back of a Fiero HAS to be tiny tongue.gif ) There is also a lot of potential with boost on these engines (http://www.chrfab.com/)

 

Since an engine is just a large air pump, of course 4V will flow better then 2. The faster and easier an engine can pump the air in and out, the more power it will make. With a DOHC engine you get the advantage from 4V heads, VVT, and because intake runner design is not hindered by a pushrod. Can a pushrod engine overcome these hurdles? Maybe. GM has a way of using VVT on a pushrod engine. That design was shown about 2 years ago. Intake design? With all the CFD programs out now every company is getting better at optimizing flow. GM also has production ready 3V heads for the LS2 which allow the engine to rev to 7000 rom, and Nitrousbird showed the 4V aftermarket heads.

 

Is there anything inherently WRONG with pushrod engine design? Maybe...maybe not. There are many ways to reach an end result and each presents its own design challanges. These could possibly be worked out to prove that either design is equally capable.

 

Oh, and Nitrousbird, I keep refering to the LS2 because it is the state of the art, it is in production, and I had a comparison HP/TQ curve between it and the LS6 that I could post. I think that also shows that there are still gains that can be made in that package.

[recklessOP]

Originally posted by Mallard:

In the 90's Mercedes-Benz came back to Indy and won...with a pushrod engine. They used a rules loophole for pushrod engines, but I think that proves that they have the rpm capabilities.

i've seen pushrod motors that rev past 10k rpm. too bad the valve springs had to be replaced every 100 miles... tongue.gif

 

the engine also cost more than my car...

[recklessOP]

The unique valve gear arrangement made possible by Arao Performance's patented head design (US Patent #5,007,387) allows rev's to over 9000 RPM without use of exotic valve train parts

does anyone else find this funny..?

 

check the price list... graemlins/popcorn.gif

 

[ 04. August 2004, 01:53 AM: Message edited by: recklessOP ]

[SupraGlue]

Phil, the Merc engine used a loophole that allowed it 3.5 liters versus the 2.65 of the OHCs. It had pushrods roughly the size and length of your thumb, which DID compromise port size and shape. Despite this, they were dominant despite the fact that they didn't rev as high. It was probably the pinnacle of pushrod engine design, yet still couldn't have existed without John Menard's lobbying of Tony George (irony, oh irony).

 

No one would ever have dreamed of running pushrods at Indy or in CART at the same displacement as DOHC.

 

I meant to get back to you also on earlier questions you raised. Others have hit on the matter of port size, shape and angle that you can achieve with DOHC that simply can't be done with a pushrod in the way. You can look at what GM did with their SB2 heads to see the gymnastics needed to get bigger ports in there.

 

There is also the issue of valve area. I'm sure someone will claim that 4V pushrod heads are possible, but until we see it in production, we're going to have to give the nod to the DOHC. There is also the matter of spring pressure and valve seat rescession. Two smaller valves running lighter springs will put a lot less force on the valve seat.

 

If you are concerned with torque, you can make your DOHC engine a rocker arm type, thus getting valve lift multiplication from the rockers and a boost in mid range torque if you so desire. Shim and buckets will be happier at hight revs, but at no lift multiplication.

 

So what we are left with from the pushrod advocates is that smaller valves and smaller low angle ports are "better". I am not buying into the cheaper argument. I have priced what high RPM pushrod components cost, and am not impressed, especially when shim and bucket valvetrains can easily live at 8500rpm with only spring upgrades.

 

Believe me, if someone would give me a ser of Arao DOHC heads for my Chevy SBC, they would be on in a heartbeat. (Heartbeat -- get it? tongue.gif )

[recklessOP]

Originally posted by SupraGlue:

There is also the matter of spring pressure and valve seat rescession. Two smaller valves running lighter springs will put a lot less force on the valve seat.

since you brought up wear:

 

a shim and bucket setup would eliminate the rocker arms, as well as any side loading and wear on the valve guides...

 

of course eliminating the rocker arms removes quite a few moving parts, improving reliability and reducing friction in the valvetrain...

 

[ 04. August 2004, 02:19 AM: Message edited by: recklessOP ]

[Dave1647545494]

http://www.dodge.com/magnum/img/magnum_sub_displacement.jpg

 

can't find a better picture the pushrods on the new hemi are layed in at an angle so they don't affect intake runners

[Mallard]

Originally posted by SupraGlue:

Phil, the Merc engine used a loophole that allowed it 3.5 liters versus the 2.65 of the OHCs.

 

I meant to get back to you also on earlier questions you raised. Others have hit on the matter of port size, shape and angle that you can achieve with DOHC that simply can't be done with a pushrod in the way. You can look at what GM did with their SB2 heads to see the gymnastics needed to get bigger ports in there.

Uhh, yeah...I said all of that in my post above. Didin't skew the facts or anything. I wouldn't call myself a pushrod 'advocate,' I'm arguing for the sake of arguing. I live for the 'internet debate,' not the 'internet flame war.'

 

Did I forget anything? OH YEAH!

 

SHUT UP NUTSWINGER. tongue.gif

[recklessOP]

Originally posted by Mallard:

I live for the 'internet debate,' not the 'internet flame war.'

then why are we debating this in the FLAME ROOM! tongue.gif

 

anyone have more info on the merc? i'd like to see some pictures...