Confused about the GT Engine...

Agranado · Jul 6, 2004

Hey everyone.

Ever since I heard about the new 2005's being released this October, all I can do is scour the net for new bits of information regarding it. I've found alot, but one thing that I dont understand is this:

the 4.6L 3V v8 OHC engine.

I dont know much about engines (although I have become more and more interested these last few months in cars) but I have heard about SOHC and DOHC engines. How does the new GT engine compare to those two? Or other engines out on the market right now?

Thanks alot,
Alex

Agranado · Jul 6, 2004

P.S. - Sorry if this question's been tackled before... I just stumbled onto the forum today.

thanks again,
Alex

RandyB · Jul 6, 2004

The new 3V is a SOHC design. It trades a little bit of performance potential(DOHC 4V) for more compact dimensions and a lower cost to build(SOHC). What it gives up in valve area it tries to make back with Variable Cam Timing and Charge Motion Control valves. I think it's a winner all the way, and I currently own one of the DOHC 4V Cobras('98).

numenor27 · Jul 6, 2004

like randy said, the 4.6 3v has a single overhead cam

SVTdriver · Jul 6, 2004

It basically breaks down to a SOHC with an extra valve. But 96-98 Cobra performance on regular unleaded not premium.

DBMSTNG · Jul 6, 2004

if the rumours are true, the 3V will put out more power than any of the DOHC N/A Cobras.

shadowland2000 · Jul 6, 2004

It will be around 300 HP +/- 5 HP. 99-01 Cobras are 320.

TomServo92 · Jul 6, 2004

shadowland2000 said:
It will be around 300 HP +/- 5 HP. 99-01 Cobras are 320.

The rumor that DBMSTNG alluded to is that the 300HP is underrated. Muscle Mustangs & Fast Fords magazine has stated that clandestine testing of '05 test mules has yield approx. 290HP at the rear wheels. That puts it well above the 300HP at the crank that Ford has been advertising (and above the 320 for 99-01 Cobras).

351CJ · Jul 6, 2004

RandyB said:
The new 3V is a SOHC design. It trades a little bit of performance potential(DOHC 4V) for more compact dimensions and a lower cost to build(SOHC). What it gives up in valve area it tries to make back with Variable Cam Timing and Charge Motion Control valves. I think it's a winner all the way, and I currently own one of the DOHC 4V Cobras('98).

Don't forget that the 4.6L 3V is about 60 lb lighter than the 4.6L DOHC, 4V Cobra / Mach 1 motor (both with aluminum blocks). Those DOHC 4V heads are not only physically HUGE but they are VERY heavy too.

All indications are that the 05 Stang, 3V motor will really perform. I remember an interview with on of the team Mustang engineers where he said the following:
"If there is one thing we got right of the 05 Mustang, it is the GT motor."

SVTdriver · Jul 6, 2004

351CJ said:
Don't forget that the 4.6L 3V is about 60 lb lighter than the 4.6L DOHC, 4V Cobra / Mach 1 motor (both with aluminum blocks). Those DOHC 4V heads are not only physically HUGE but they are VERY heavy too.

All indications are that the 05 Stang, 3V motor will really perform. I remember an interview with on of the team Mustang engineers where he said the following:
"If there is one thing we got right of the 05 Mustang, it is the GT motor."

Where did you find the weight of the engines? 60 lbs is a lot of weight. Considering the cobra was also all aluminum.

shadowland2000 · Jul 6, 2004

I highly doubt that the single cam will out-rev the twin cam, which is a major factor in horsepower.

Obviously a twin cam is a superior design, cost not considered. The advantage of this new engine is it runs on 87 and is cheap to build. Sometimes technology doesn't make something better, it just makes it alot cheaper to make something almost as good.

351CJ · Jul 6, 2004

SVTdriver said:
Where did you find the weight of the engines? 60 lbs is a lot of weight. Considering the cobra was also all aluminum.

99-01 Cobra DOHC, aluminum block = 521 lb.
99-04 GT SOHC 2V, iron block = 530 lb.
05 GT engine SOHC 3V aluminum block = 460 lb.

The weights on the 1st 2 engines came from a discussion on BON several years ago. Info was given by someon who re-builds mod motors. Also similar data on a engine swap data web site. 05 engine weight per Ford's press releases that said it weighs 70 lb. less than the iron block 04 engine.

As I said, those DOHC engines are huge, there's a lot of extra aluminum in them and you have an extra cam, 8 lifters, 8 rockers, 8 valves in each head. It all adds up to the DOHC heads weighing 30 lb more, for each head.

SVTdriver · Jul 6, 2004

351CJ said:
99-01 Cobra DOHC, aluminum block = 521 lb.
99-04 GT SOHC 2V, iron block = 530 lb.
05 GT engine SOHC 3V aluminum block = 460 lb.

The weights on the 1st 2 engines came from a discussion on BON several years ago. Info was given by someon who re-builds mod motors. Also similar data on a engine swap data web site. 05 engine weight per Ford's press releases that said it weighs 70 lb. less than the iron block 04 engine.

As I said, those DOHC engines are huge, there's a lot of extra aluminum in them and you have an extra cam, 8 lifters, 8 rockers, 8 valves in each head. It all adds up to the DOHC heads weighing 30 lb more, for each head.

The problem is they don't have 8 extra in every head. 3v times 8 cylinders is 24. Which meams it has 8 total rockers/valves/lifters. And yes the engines are huge. But looking at the Ford performance catalog. They do not differentiate between SOHC and DOHC in basic engine dimensions. The only differences I can find are 1 3/8" wider and 3 7/8 taller. Which is likely the heads. I guess I am just having a hard time understanding howan aluminum block is only 9 lb lighter than an Iron block. That just doesn't add up. Even with the larger heads. An iron block is heavy. And while there are extra parts on the cobra motor. The valves are larger which. So the block is the same size. But should be considerably heavier since it is iron. I could be wrong, it's just that I have always thoguht aluminum engines are lighter than the iron ones. And 9 lbs just doesn't sound right.

Rootus · Jul 6, 2004

shadowland2000 said:
I highly doubt that the single cam will out-rev the twin cam, which is a major factor in horsepower.

If they wanted it to, it would. You can build a pushrod Windsor 5.0L to spin 9000 RPM, so I should hope that Ford could tune the 3V to spin to at least 7000 RPM if they wanted. In my experience the limiting factor in a production motor for high RPM potential is not the valvetrain, but the bottom end. The difference in force on the crank, rods, etc between 6000 RPM and 7000 RPM is considerable.

Obviously a twin cam is a superior design, cost not considered. The advantage of this new engine is it runs on 87 and is cheap to build. Sometimes technology doesn't make something better, it just makes it alot cheaper to make something almost as good.

I disagree with the assertion that DOHC is automatically better. It has more moving parts, more valvetrain mass, etc. And it's not clear that it has any significant advantage in airflow for a 4.6L engine. Now, if Ford would just switch to a 4" bore modular, we could have more than enough airflow with a simple two valve design .

IMHO the 3V motor is going to end up being the best Mustang engine to date, hands down. Except for the almighty 5.0, of course...

Dave

Agranado · Jul 7, 2004

Thanks again folks. This has all been a big help.

-Alex

63_Fairlane · Jul 7, 2004

How much do two extra cams, bearings,followers, and associated hardware weigh? 20-30 pounds? The cams, bearings, and mounts could make the difference.

Looked up a few things on www.vorshlag.com ...

A stripped iron 5.0 block weighs 129 lbs.
A stripped aluminum 4.6 block weighs 91 lbs.

A complete DOHC 4.6L head weighs 60 lbs.
A complete iron 5.0L head weighs 49 lbs.
A complete aluminum TFS Streat Heat head weighs 30.5 lbs.

They didn't have weights for the SOHC motors so I used the iron 5.0 for comparison. It looks like the DOHC heads are some some BIG heavy mofos.

351CJ · Jul 7, 2004

63_Fairlane said:
How much do two extra cams, bearings,followers, and associated hardware weigh? 20-30 pounds? The cams, bearings, and mounts could make the difference.

Looked up a few things on www.vorshlag.com ...

A stripped iron 5.0 block weighs 129 lbs.
A stripped aluminum 4.6 block weighs 91 lbs.

A complete DOHC 4.6L head weighs 60 lbs.
A complete iron 5.0L head weighs 49 lbs.
A complete aluminum TFS Streat Heat head weighs 30.5 lbs.

They didn't have weights for the SOHC motors so I used the iron 5.0 for comparison. It looks like the DOHC heads are some some BIG heavy mofos.

I can't find where I stored the info, but I believe that the 4.6 iron block weighs approximately 140 - 145 lb.

The 3V heads are physically smaller and lighter than the old 2V heads. Ford proudly announced this in their press releases when the 5.4 3V was first released. You could probably search fordmedia.com to find the info.

TomServo92 · Jul 7, 2004

Here ya go:

http://media.ford.com/article_display.cfm?article_id=15388

The article states:

With an all-aluminum head, a single camshaft, magnesium cam covers and a clean-sheet design approach, Ford’s engineers have been able to develop a three-valve head that has virtually no weight penalty over the 2-valve V-8 engines. The 3-valve head is actually dimensionally smaller and somewhat lighter than the 2-valve design for the 5.4-liter engine, while offering more rigidity and strength. It also is easier to manufacture, with simpler drilling angles and straight-machined surfaces

“Our innovative new 3-valve architecture delivers the benefits of multiple valves in a much smaller, more economical package than most competitive designs,” said Pete Dowding, manager for Ford’s lineup of Modular V-8 and V-10 engines. “The new 3-valve head is even smaller and lighter than our 2-valve cylinder head.

SVTdriver · Jul 7, 2004

Here's what I found so far.
http://www.modulardepot.com/modspecs.php
http://www.musclemustangfastfords.com/tech/0302MMFF_MixMatch/
4.6-liter SOHC and DOHC
Aluminum block weight (bare): 86 lbs.
Iron block weight (bare): 154 lbs.
Assembled cylinder head weight: 44 lbs.

Now if you assume that the correct weight for an assembled DOHC head is 60lbs. You gt engine still comes in about 40 lbs heavier than the DOHC. Which would mean the 05 engine while lighter. Will not be 60 lbs lighter.

BlackPony2000 · Jul 7, 2004

my understanding that the new 3 valve GT engine eill be all aluminum. which means it will be basically the old 4 valve block with 3 valve heads and rumors are that the new cobra will be going to either a 5.4 liter or a v10 like in the new shelby...makes ya wonder...

Confused about the GT Engine...

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