HEADS

[Doppleganger]

I need to know what Type heads are in the new GT 40? Is it the 4.6L cobra or the 5.4L Navigator heads. We are constructing a monster and we may need to buy an intake from the GT 40 to fit our application.

[Ron Earp]

The closest thing will be the navigator 5.4L DOHC heads. But, these are not exact Ford GT40 though, as I am sure you probably realize.

Many people have done 5.4L DOHC head swaps on Ford Lightning motors which ends up with a motor that is similar to the Ford GT40. However, the Ford GT motor wears a screw type blower, not a roots design as on the 4.6L Cobra and 5.4L Lightning motor. Therefore, that is another big difference.

The closest thing you could probably build using "bolt on" parts would be to use a Lightning iron 5.4L block, Navigator 5.4L DOHC heads (check Lightning swaps for this procedure, there is a fair amount involved), and a Kenne Bell screw type blower in place of the Ford OEM Roots style. Power output will be higher than the Ford GT if you run any sort of boost on it (> 8psi) as folks routinely make over 550 rwhp and over 700 ft/lb rwtq with these combinations.

[Tom B]

[ QUOTE ]
The closest thing will be the navigator 5.4L DOHC heads. But, these are not exact Ford GT40 though, as I am sure you probably realize.

Many people have done 5.4L DOHC head swaps on Ford Lightning motors which ends up with a motor that is similar to the Ford GT40. However, the Ford GT motor wears a screw type blower, not a roots design as on the 4.6L Cobra and 5.4L Lightning motor. Therefore, that is another big difference.

The closest thing you could probably build using "bolt on" parts would be to use a Lightning iron 5.4L block, Navigator 5.4L DOHC heads (check Lightning swaps for this procedure, there is a fair amount involved), and a Kenne Bell screw type blower in place of the Ford OEM Roots style. Power output will be higher than the Ford GT if you run any sort of boost on it (> 8psi) as folks routinely make over 550 rwhp and over 700 ft/lb rwtq with these combinations.

[/ QUOTE ]

Ron,
If one wanted to enhance the performance of the Ford GT, with pulley changes, who would you recommend? Using what products?

Thanks,

Tom

[Ron Earp]

I'm not sure anyone makes a "kit" yet, but I am sure they will and they'll charge a fortune for what is basically a Lightning/Cobra pulley kit. Maybe we should do this before someone else does....

John Coletti from SVT (now retired I think) indicates that the Ford GT fuel system can handle more hp, he was quoted a couple of times in Muscle Mustangs and Fast Fords when he personally delivered a GT for them to wring out on the strip - and that they did, to good effect producing some high 10.xx timeslips if I recall.

Anyhow, the motor is what we would call understressed, that is, it is built for consumers and carries a warranty. So like the SVT Ligtning and Cobra motors (the supercharged ones, the early SVT motors had some issues) they can handle a fairly good increase in power.

Plus, the GT wears a Lysholm supercharger, not a Roots blower as my truck does, and it can produce more boost than it is now doing without making all that much heat. It is a more efficient design, more expensive too, but peanuts in the Ford GT price. Ford has those set at 12psi, I'd certainly think 16psi total boost or a little more would be in the realm of possibility. I don't know the pulley sizes on the GT, but I'm certain that one of the Lightning/Cobra performance places would jump at a chance to make a set, if they haven't already. I run a mild 4lb increase on the Lightning and we're at 410hp and 503 ft/lb of torque (wheel numbers) - I've got a 8lb+ increase pulley to that we'll run soon and see what she will do. I'm sure the Ford GT will respond well to boost increases!

[Tom B]

Ron,

If you decide to make something, let me know as I'm ready to get started.

Tom

[Mark Worthington]

Beware modifying a GT with a pulley swap. Yeah, the engine can dish out the power but the Ricardo transaxle was designed to a specification of "up to 650 hp." I think going from 12 to 16 psi would put you into the 650+ range.

[Ron Earp]

Good point.....that would be an expensive bang!!!!!!

[Doppleganger]

Ron I have a few questions for you. First off, I have a lighting as well. I have a 5lb underdrive pulley, plus a smaller blower pulley on mine plus electric fan, kenne bell throttle body, JLP Flip chip, mafia chip, open air kit and denso plugs. I only dynoed at 384 rear wheel hp. 493 FPT. I am guessing you have newer lightning that me. I have a 2000 is this a correct assumption?

On to my other post. We are trying desperately to build my neighbors lighting with lincoln navigator heads, however he wants to put twin superchargers on his, I told him he is crazy it will be too much of a headache.
You were saying that lots of people have done the DOHC swap on a lightning we want to know who builds the intakes for this swap or where we could fine out who makes these intakes, or will be have to build our own?
Thanks for you help.
Kyle

[Ron Earp]

Kyle,

Mine is a 2004 and they seem to put down more power than the 99-00 trucks as you probably know from the Lightning boards. Yours is still strong though, no doubt, but what MAF are you running? The early cars benefited from a larger one there for sure. I am assuming you are not running a stock air meter, but if you are you'd get benefit from getting a larger one. How much boost do you run? How is your A/F ratio?

As far as I know you have to fab your own intake for the DOHC swap. There is someone who has a thread on their twin turbo DOHC Lightning here:

http://www.svtperformance.com/forums...d.php?t=190281

I don't know much about it, but I think I would talk your friend out of that. Tell him to get a Kenne Bell blower along with the others usual bolt on and you can have 600-700 rwhp and 700+ rwtq for much less trouble than a twin blower setup with DOHC heads. People make a lot of power with the 2V heads, ported, with cams, with a lot less trouble than the DOHC setup. People do them, for sure, but it looks to be a pain in the ass.

Ron

[Twehttam]

Just remember, when you build a Lightning, to upgrade those rods. [img]/ubbthreads/images/graemlins/smile.gif[/img]

And re: the GT, I'd definitely love to see the aftermarket community come out with a few more modifications - that 5.4 shouldn't bee too hard to work on. [img]/ubbthreads/images/graemlins/wink.gif[/img]

[Tim Kay]

Thought I'd pass a little unsolicited info hear.

My one and only friend has an '04 Lightning and simply had the boost raised, took a trip across the desert and on the way broke down. The symptom was the feel of several cylinders not firing, no major catastrophic noise. Turned out to be all the head bolts stretched [img]/ubbthreads/images/graemlins/crazy.gif[/img]

That's all I know, just thought it would be of some interest [img]/ubbthreads/images/graemlins/wink.gif[/img]

[Mark Clapp]

Tim, I'll be your friend. Although some think my head bolts were stretched at birth. [img]/ubbthreads/images/graemlins/grin.gif[/img]

[Tim Kay]

Thanks Mark, made my day. But I'm warning you my mom makes me wear that shirt that says 'does not play well with other' [img]/ubbthreads/images/graemlins/shocked.gif[/img]

[Ron Earp]

Tim, could be he didn't get a good tune on that motor and it let go. Simply putting a pulley on, while that is basically all anyone says, is only 25% of the story. The rest lies in dyno work and changing the MAF tables etc. to arrive at proper A/F. There is plently of fueling capacity in the truck (and the GT) to make a lot more power but cranking the boost with a pulley and nothing else is a receipe for disaster.

Most people don't run much more than 14lbs or so without doing some other upgrades. The valve springs are only good for about 20-22lbs, after which the boost will blow and hold them open - not good. 22lbs of boost on a circle over 2" in diameter produces good pressure!

The serious Lightning freaks use the Lysholm screw blowers and run 20-25lbs of boost with upgraded rods, ported heads, etc. and make big numbers that start with 7s and 8s. And, for the money, it isn't that expensive for a 10s truck as it can be done with the cost of a truck and under 10-12k $. MM&FF got their GT in the 10s with slicks, I'm sure much more can be had with increases in boost etc.

R

[MK -IV J6]

[ QUOTE ]
Beware modifying a GT with a pulley swap. Yeah, the engine can dish out the power but the Ricardo transaxle was designed to a specification of "up to 650 hp." I think going from 12 to 16 psi would put you into the 650+ range.

[/ QUOTE ]

Mark
Where are you getting that number from? I've heard that it is duty rated at 750 hp.

Best

[RaceDeck]

I have heard that the ignition computer on the GT will self correct and that you are still very safe at 15-18 lbs of boost?, has anyone heard anything on a perfomance exhaust? or other items? I am looking in to building a custom race seat with exact tracks ( non moveable ) so that I can fit with a helmet on....I do not have the stomach to go the gurney bubble route

[Mark Worthington]

[ QUOTE ]
Mark
Where are you getting that number from? I've heard that it is duty rated at 750 hp.

[/ QUOTE ]

Jim, I got that number from an engineer who was on the GT suspension development team. I suspect that's the "OEM" duty rating and that, in the real world, you could put more hp through it and it would probably hold together as long as you don't use slicks to do 6,000-rpm clutch drops.

[Howard Jones]

Tim, I'll be your friend too. I live in the SF bay area. How about you?

[MK -IV J6]

I agree I think it would stand up to use but not abuse.
Best

[Tim Kay]

Gee Howard, Thx, I'll take every friend I can get [img]/ubbthreads/images/graemlins/grin.gif[/img] You're stuck with me now.

I'm not so far from you. I am down here in the inland empire (San Bernardino) So Calif.