GT500 Engine Similarities to FGT


Awsum GT

GT Owner '05 & '18
Mark IV Lifetime
Sep 17, 2005
3,894
Central California
Great stuff gentleman. Now I am armed with answers for the next car show. For the non-gearheads like me, this is dumbed-down just enough to understand. Thanks again... :thumbsup
Really... We can print out a cheat sheet and hand them out to those that ask questions :)
 

PeteK

GT Owner
Apr 18, 2014
1,255
Kalama, WA
Horsepower is an imprecise measure of rod strength. Manley cites approximate HP in the catalog image, but caveats that with some of the other variables.

For our engines, being significantly undersquare, rpm may be more of a limiting factor than hp. For such a long stroke design, the 6,500 rpm redline is remarkable and generates insane piston speeds.

The stock rods seem to handle 800 hp ok. We've seen enough Whipples and TTs with stock bottom ends. But while 800 hp at under 6,500 rpm may be ok, far less hp may result in rod failure at over 6,500 rpm.

Boost is another tricky variable. Keep in mind that our stock blowers use 80 hp at full boost. A big Whipple will need well over 100 hp. So, a big Whipple motor needs to make well over 900 hp to put 800 to the output shaft and 7xx to the wheels.

The GT500 websites are full of broken and bent rod photos.

View attachment 37761

BTW, that's an I-beam, but I can't say for sure that it came from a 5.4 GT500.

And, who's to say the rod was too weak for the hp? Maybe the tune was to blame. Or over-revving. Ford was comfortable enough to put the same (or similar) rods in the 5.8 and put a factory warranty on 662 hp.
That picture of a bent rod shows that it failed in compression and buckled. IMO, most likely due to detonation, but also could be due to overboosting or too advanced timing (both of which generally lead to detonation) That was not due to excessive RPM, which would have caused a failure in tension, making the rod stretch or break.
 

PeteK

GT Owner
Apr 18, 2014
1,255
Kalama, WA
Last week, I picked up the SAE book on the FT and GT40--great book, can't put it down! (it is a bit pricey at $90 for a paperback)
 

Indy GT

Yea, I got one...too
Mark IV Lifetime
Jan 14, 2006
2,435
Greenwood, IN
That picture of a bent rod shows that it failed in compression and buckled. IMO, most likely due to detonation, but also could be due to overboosting or too advanced timing (both of which generally lead to detonation) That was not due to excessive RPM, which would have caused a failure in tension, making the rod stretch or break.
Pete is absolutely correct. The bent rod is definitely a compression failure as stated. Failure analysis to the trained eye can tell you a significant amount of information about the failure mechanism.

Although I agree the bent rod is a compression failure, I do not think it is likely the result of overboosting, advanced timing and/or detonation. To be sure these conditions are bad for the piston/rod and do lead to spikes in compression loads transmitted through the rod. However, the extent of the bending to me implies a “time function” failure as it takes some amount of time to bend a rod in that shape. Detonation is a very short duration, high impulse event. Detonation blows holes in the tops of pistons or breaks away pieces of the piston around the circumference. Unfortunately we are not afforded a good view of the top of the piston. And although detonation or over boost could begin the column buckling rod bending event, the engine would start shaking so badly it is unlikely continued engine use could be made to achieve the bent level shape shown in the photograph.

My guess is hydraulic lock where the combustion chamber gets filled with a liquid (oil or coolant) which is uncompressible.

Last week, I picked up the SAE book on the FT and GT40--great book, can't put it down! (it is a bit pricey at $90 for a paperback)
Being a technical person, I thought you might enjoy the papers in this SAE book.:thumbsup
 

Indy GT

Yea, I got one...too
Mark IV Lifetime
Jan 14, 2006
2,435
Greenwood, IN
Twobjshelbys originally posted the below question to Scott in the thread
http://www.fordgtforum.com/forums/showthread.php/30419-FGT-Weather-Sensitivity/page2

Hi Scott

I asked a similar question in the tire topic too. Over there it was about how the great amount of work on the Goodyears influenced the decision to use the same tire on the GT500

Here the question is similar. How much info sharing was done between the two teams on superchargers? The FGT used a different one, but underneath the engines were quite similar (yeah, I know, but at least for displacement and probably similar heat generation). Were design considerations on the FGT then leverged into the GT500?

Thanks!
Hi Tony,

Leveraging the FGT work, especially powertrain was SVT's intent, but I do not have first hand knowledge of the level of transfer to the GT500. I was not involved on the project and did not keep tabs on it. Mark McGowan may know.

Scott
Glad its a help. 10-4 on water injection. I am sorry, I don't have the detail intake temp data for you.

Scott
With an appreciative nod of recognition to our esteemed Team Member mostly associated with our GT’s suspension, Scott says he does not have first hand knowledge on the engine development topic to adequately answer the specific FGT/GT500 engine architecture program carryovers. Although I was not on the Team, my interests lie in this arena and I have over the past 10 years talked to a number of Ford engine development members and will try my best to address some of twobjshelbys questions regarding parallels between the two engine programs.

There was a fair amount of technology transfer between the supercharged 5.4L engine in the MY2007 GT500 and the FGT. Many of the same engineers worked on both programs. Obviously the overall engine architecture (supercharged 5.4L displacement) is common, including the intake charging with an integral water to air intercooler. The engine blocks are significantly different as are the block materials (initial GT500 was cast iron, FGT cast aluminum). Engine development of the GT500 engine actually started before the FGT program was finished. For those with a deeper technical interest, our FGT owners are indeed lucky that Ford allowed the engine designers the time and effort to chronicle the FGT engine design (to the best of corporate disclosure limits) in Society of Automotive Engineers (SAE) technical paper 2004-01-1252.

Some of the more noticeable differences between the two 5.4L engines are:

• Dry sump engine lubrication system with an external oil pump (FGT) vs typical wet sump oil pan on the GT500.

• The cam drivetrain was redesigned on the GT500 engine to reduce engine width for packaging requirements on the narrower Mustang engine bay.

• Forged steel Mahle connecting rods along with Mahle pistons were used on the GT500 while the FGT got Manley billet machined rods with Mahle pistons. If you have ever seen one of the connecting rods in our FGT engine, they really are a work of art. Believe we owners owe gratitude to Mr. Coletti for being a staunch supporter of a bullet proof engine design in our cars when a significantly lower priced rod option was proposed, could have been used and was ultimately rejected. Both engine programs utilized a relatively new purchasing logic of procuring an entire piston assembly (piston, connecting rod, wrist pin and circlips) from a vendor which was supplied to the Romeo engine niche line for assembly. This new process reduced complexity, improved quality/integrity and reduced system cost. Also the forged Mahle GT500 rods used a “fracture cap”design to center and align the removable connecting rod cap for assembly onto the crankshaft pin. The FGT Manley rod caps were fully machined to tolerances much tighter than those obtainable with a fracture cap design.

FGT piston assembly3a.jpg

FGT Piston/Rod Assembly, Note structurally superior rod design, shot peened surface for enhanced fatigue life and dished low compression piston for supercharged intake charge.

GT500 piston assembly1a.jpg

GT500 Piston/Rod Assembly.

• A “Roots” type supercharger was used on the GT500 engine while a “Lysholm” screw compressor was used for the Ford GT engine. Both compressor designs are twin rotor, positive displacement air pumps, but the Lysholm design utilizes a screw rotor design with tighter internal clearances which has been shown to be more efficient in terms of obtained boost pressure per unit of input horsepower and also lower compressor exit temperatures (less engine thermal load) than a similar Roots multi-lobe rotor design.

• Cooling water enters the side of the GT500 engine block which was a carryover from the production 5.4L engine design architecture. On the FGT 5.4L engine, cooling water enters the front of the block and uses a reverse direction water pump for increased coolant flow.

• A single fuel injector per cylinder was used on the GT500 whereas the FGT engine has two dedicated fuel injectors per cylinder.

• Cylinder block oil return runs terminate above the oil pan joint face on the GT500 engine. The same oil return runs on the FGT engine mate to return passages in the oil pan for near zero “windage” (crankshaft spinning thru the returned oil).

• The FGT engine has a structural windage tray for added block rigidity.

• The production GT500 engine used a cast iron cylinder block until 2011 which differs from the aluminum block used on the FGT engine. After 2011 the GT500 block changed to aluminum with a metallic sprayed bore material for the rings to contact. The FGT aluminum block utilizes steel sleeves for each piston to travel within. This new GT500 block shared the same basic design feature of the preceding cast iron design block.

• Because of the availability of high pressure front vehicle cooling air as the car was driven, the GT500 crankshaft harmonic damper was a less costly elastomeric damper. The FGT 5.4L powerplant due in part to its buried mid-engine location and thus higher operating temperatures used a more expensive, multi tuned viscous harmonic damper.

• And finally the GT500 engine block had open bulkhead windows while closed bulkhead windows were used on the FGT engine for added stiffness.

As to the temperature drop across the supercharger intercooler, I would estimate it to be in the 100-130°F range.

Hope this answers some of your questions.
 

Specracer

GT Owner
Mark IV Lifetime
Nov 28, 2005
6,470
MA
Good stuff Bill!
 

Cobrar

GT Owner
Mark II Lifetime
Jun 24, 2006
3,940
Metro Detroit
Nicely Done!! ;- ))
 

twobjshelbys

GT Owner
Jul 26, 2010
5,332
Las Vegas, NV
Awesome info! Thanks.
 

2112

Blue/white 06'
Mark II Lifetime
I have seen detonation cause valve train components (springs, retainers and valves) to fail and pieces of valve dropping into the cylinder, preventing full stroke to TDC and bending a rod.

Not saying that is what happened in the picture tho.
 

w.a.nelson

GT Owner
Mark II Lifetime
Feb 29, 2008
891
Asbury, NJ and Bourne, MA
+ 1
 

SMOKDU

GT Owner
Dec 17, 2011
404
Great stuff. Do you what rod bolts were used .? ARP? And is the valve train different?
 

GKW05GT

GT Owner
Mark II Lifetime
May 28, 2011
2,553
Fayetteville, Ga.
Thanks Bill good info.
War Eagle!
 

PeteK

GT Owner
Apr 18, 2014
1,255
Kalama, WA
I have seen detonation cause valve train components (springs, retainers and valves) to fail and pieces of valve dropping into the cylinder, preventing full stroke to TDC and bending a rod.

Not saying that is what happened in the picture tho.
I won't say that detonation CAN'T cause valve failures, but my experience is that it tends to put holes in the pistons, breaks rings and lands, and hammers the bottom end (rods and crank and bearings). Valve failures usually occur when the cam wears down, opens up the valve clearance, which causes the valve to slam into the seat instead of being "gently" lowered onto the seat by the closing ramp profile of the cam (I lost a Porsche 914 engine that way). Also, very worn valve guides will cause the valve to hit the seat at an angle instead of flat on all around its face, which can lead to valve seat recession, the valves not closing completely, and burned valves. However, I've seen some engines with really worn valve guides that still ran okay.

Either way, if the valve head drops into the cylinder, the results can be as you describe. And as Indy surmised, hydraulic lock also will bend rods, which is a fair bet for that rod.
 

2112

Blue/white 06'
Mark II Lifetime
Heck, Competition Cams can and will blame detonation for the immediate failure of their roller tappets (in a pushrod engine) if it makes it your fault and not theirs. :lol
 

Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
Bill,

Thank you for another great post that adds much to the knowledge base.

I get asked this question from time to time. Yesterday, while talking about parts scarcity and expense, one guy told me I could "just drop a GT500 5.4 in it." lol.

I'm going to make a PowerPoint slide that lays out the differences you cite in side by side bullet layout.

Here are a few more data points:

The GT uses a mechanical throttle linkage to operate twin seventy-millimeter throttles. The GT500 uses drive-by-wire technology and twin sixty-five-millimeter throttles.

The GT twin fuel injectors are rated at 32 pounds per hour each. The GT500 single fuel injector is rated at 47 pounds per hour.

The GT valve lift is 11.2 mm intake and 11.5 mm exhaust. The GT500 valve lift is 10.1 mm intake and 10.9 mm exhaust.

The GT supercharger boost is about 12 psi max. The GT500 supercharger boost is about 9 psi max. (Surprising to me that rated hp difference is only 50. The difference in boost alone should give more than 50 hp).
 

TO AWSUM

Ford GT Owner
Mark II Lifetime
Jul 4, 2007
1,382
Niceville FL
Thanks Bill. I'm often asked at car shows if the pickup, GT500 and FGT engines are the same engine since they are all 5.4Ls and have told them about the differences in the block, connecting rods, pistons, oiling, etc. I also got my info from the engine builders. Now I have it in writing. Great write-up.

Xcentric, When you finish the PowerPoint presentation, could you send me a copy?
 

Specracer

GT Owner
Mark IV Lifetime
Nov 28, 2005
6,470
MA
Also I wish I had more detail beyond my memory, but didn't the ~2011+ GT500, finally use a head that was very close to the GT heads?
 

Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
Also I wish I had more detail beyond my memory, but didn't the ~2011+ GT500, finally use a head that was very close to the GT heads?
Cylinder heads and crankshaft are the same, according to this article: http://web.archive.org/web/20080222195547/http://www.windingroad.com/features-page/ford-engines/

EDIT: The SAE technical paper 2004-01-1252 states that cylinder head castings were slightly different to allow more coolant flow around the exhaust valves.
 
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Vince H

GT Owner
Mark II Lifetime
Jul 23, 2012
2,375
Southern California
Wow Bill you may not have been on the design team but your write up is superb. Your recollection is staggering.

Vince H
 

NorthwoodGT

GT Owner
Jun 12, 2009
1,100
Michigan
I'll have to carry this link with me when I go to car shows. Just love the guy that asks "what size engine is that?" when you tell them it's a 5.4 many times I have gotten the response "oh, that's the same engine that's in my F150 since they are both 5.4s" I just have to walk away silently which isn't easy for me to do! great illustration and explanation. too bad Ford didn't keep the Manleys in the early pre-production Shelby engines. I had a few of those and those Manleys are a piece of art! they should have used Manleys in the 2013-14 5.8 engines in the Shelbys.