4.6 3 valve instead of 4?

[silvermike]

Why did they make a 3 vavle engine for the Mustang? The Mach1 gets more horsepower and torque. Why not the 4 valve? Is it cost? Ho wmuch more could it cost?

[Bama GT]

Why did they make a 3 vavle engine for the Mustang? The Mach1 gets more horsepower and torque. Why not the 4 valve? Is it cost? Ho wmuch more could it cost?

It's more efficient and runs on regular 87 octane. And didn't the Mach 1 have a cast iron block? If so, Ford says the 3-valves aluminum block saves 75 pounds.

 

When it was stock, my 2006 4.6L 3v GT made more power and torque than a stock 2003-2004 Mach 1.

 

Assuming 15% drivetrain loss:

265.89 rear wheel horsepower = 312.81 flywheel horsepower

280.2 rear wheel torque = 329.65

 

What were the benefits of the 4v again??

 

Edited August 8, 2006 by Bama GT

[silvermike]

The 4 valve Mach 1 has more horsepower and torque than the 3 valve GT. They could have used the ALL aluminum 4 valve from the Mustang Cobra. Also there is one more cam per cylinder bank.

[Bama GT]

The 4 valve Mach 1 has more horsepower and torque than the 3 valve GT. They could have used the ALL aluminum 4 valve from the Mustang Cobra. Also there is one more cam per cylinder bank.

If it did have more horsepower and torque it was only marginal. Like I said, my car could've been rated at 310 horsepower and 330 ft-lbs, which is higher than the Mach 1's rating on both counts.

[Moby Vic]

The Mach 1 engine was all aluminum. But a DOHC engine costs more to make than an SOHC engine.

 

The Mach 1 engine was essentially the '99 and newer Cobra engine. The main difference was the cams. The '03 and '04 Cobra engines had iron blocks, but the heads weren't different as far as I know (and of course they had a supercharger).

[NickF1011]

If it did have more horsepower and torque it was only marginal. Like I said, my car could've been rated at 310 horsepower and 330 ft-lbs, which is higher than the Mach 1's rating on both counts.

 

It's generally accepted that the 03-04 Mach 1 4.6 4V's were a tad underrated as well. Realistically, they were probably making more in the range of 325 HP and 330 lb-ft.

 

They were all-aluminum. Aside from some head/cam changes they were identical to 99-01 Cobra motors, save for cast cranks being used in those equipped with automatics.

 

In the end, it boils down to cost. 4-valve heads cost more to produce. That's about it.

[silvermike]

How much more could the 4 vavle cost?

[NickF1011]

How much more could the 4 vavle cost?

 

When you consider economies of scale and the couple hundred thousand 4.6's that Ford builds a year, the additional costs would be substantial with little benefit.

[pro3qtr]

Really simple, I was told:

 

Bore size is way to small for the 4 Valve head to work to its potensial (NA) Spmthing about the valves being shrowded ???

 

Cost was the ther thing I heard

 

I like the new 24V Engine, much easier to work on in the car.

 

Hope to order a 07 real soon and dump my 32V !!! LOL

[dbmstng]

the 03 Mach 1 had an aluminum block, but i believe the 04's had iron blocks. the heads and cams are the same as the 03/04 Cobras, which are different heads than pre 2003 4V heads. the 3V makes about the same power as the Mach 1 engine for less money and on 87 octane thanks to the Variable Valve Timing. Ford could easily exceed the stock power of the Mach 1 engine with a less conservative tune and slightly more agressive cams. i've seen 300rwhp from a stock 3V with nothing more than a cold air kit and a retune.

 

as far as the bore size, that's a problem on the 2V engines, not the 4V engines.

[NickF1011]

the 03 Mach 1 had an aluminum block, but i believe the 04's had iron blocks.

 

Both are aluminum. Only difference between the motors is a slight programming change which yielded a hair more power from the '04 Mach's.

[old_fairmont_wagon]

Something else that everyone's forgetting:

 

The 3V 4.6L Aluminum setup weighs less than the 4V aluminum setup in the MAch 1. That weight savings is worth some power alone.

 

The 3V 4.6L has VCT, which the DOHC 4.6L doesn't at present. That broaden's out the torque curve and makes for a more efficient engine overall. So, when you look at the 4V engine and 3V engine next to each other on a dyno chart (on a computer, the real world manufacturing variations make this difficult on head to head dynos), you slightly more area under the torque and HP curves on the 3V than the 4V dohc.

 

So, in the end, the 3V 4.6L is an overall slightly more powerful engine that weighs less and is more efficient than the DOHC 4V. Granted, we're splitting hairs there as the engines are a virtual dead heat on paper with the weight nod going to the 3V.

[NickF1011]

Something else that everyone's forgetting:

 

The 3V 4.6L Aluminum setup weighs less than the 4V aluminum setup in the MAch 1. That weight savings is worth some power alone.

 

The 3V 4.6L has VCT, which the DOHC 4.6L doesn't at present. That broaden's out the torque curve and makes for a more efficient engine overall. So, when you look at the 4V engine and 3V engine next to each other on a dyno chart (on a computer, the real world manufacturing variations make this difficult on head to head dynos), you slightly more area under the torque and HP curves on the 3V than the 4V dohc.

 

So, in the end, the 3V 4.6L is an overall slightly more powerful engine that weighs less and is more efficient than the DOHC 4V. Granted, we're splitting hairs there as the engines are a virtual dead heat on paper with the weight nod going to the 3V.

 

Well, you also have to remember that all new development on the 4.6 4-valve was pretty much done by 2002-2003 whereas the 4.6 3-valve is still seeing R&D. I imagine if Ford were to re-introduce the 4.6 4-valve at this time that it would receive variable intake cam timing much like the 4.6 3-valve. Doesn't the 5.4 4-valve in the GT500 have VCT as well? If not, it needs it. :happy feet:

[Sizzler]

I think the post above referencing "shrouding" said it all.

 

Some people want more more more. But often, less is more.

 

Too many valves can be too much for a small bore.

 

One larger valve in a small bore will flow better than two little valves that have half their openings blocked by the cylinder wall.

 

Not to mention the complexity of 2 extra cams and associated hardware.

 

Not to mention the weight of 2 extra cams and associated hardware.

 

Not to mention the extra width of the engine caused by 2 extra cams and associated hardware.

 

Not to mention the cost of 2 extra cams and associated hardware.

 

My only question would be, why would anyone WANT a 4V head on such a narrow cylinder?

[NickF1011]

My only question would be, why would anyone WANT a 4V head on such a narrow cylinder?

 

 

Cuz it looks bitchin'!!