'05 gt head flow numbers

Has anybody else seen these. Looks like they are finally getting serious about the GT. But they only flowed it at 25" instead of 28" so not sure how much better 28 would be. From corral.net

STOCK Ford GT heads @ 25"
Lift Int Exh
.05 42 39
.10 85 88
.15 126 136
.20 166 171
.25 200 193
.30 228 207
.35 248 217
.40 261 225
.45 271 230
.50 279 234
.55 285 236

Has anybody else seen these. Looks like they are finally getting serious about the GT. But they only flowed it at 25" instead of 28" so not sure how much better 28 would be. From corral.net

STOCK Ford GT heads @ 25"
Lift Int Exh
.05 42 39
.10 85 88
.15 126 136
.20 166 171
.25 200 193
.30 228 207
.35 248 217
.40 261 225
.45 271 230
.50 279 234
.55 285 236

STOCK Ford GT heads @ 28"
Lift Int Exh
.05 44 41
.10 90 93
.15 133 144
.20 176 181
.25 212 204
.30 241 219
.35 262 230
.40 276 238
.45 287 243
.50 295 248
.55 301 250

that's what it would be with a covnersion factor of 1.058 but they really should be flowed on a bench at 28" to get the real numbers.

Sad thing is that the 05 GT also only puts down 266rwhp

Far from a stock LS1 and closer to a LT1 in a car that weights in at 3500lbs.

Might be nice heads but they don't translate to HP.

Bret

Wow :bow: just shows you that flow numbers dont mean everything.

yes but as far as a bolt-on modder is concerned, the rest should be easy

what rwhp would you expect from a well tuned engine with 300cfm heads?

Do you mean Mustang GT? There is a Ford GT which puts down a lot more power than the Mustang GT.

Yep , went back and checked. Those are on the Ford Gt, with the blown 5.4 not the Mustang Gt. They said the gt heads dont flow like that :D . But the GT heads are almost identical to the '00 Cobra R heads.

Yeah, big difference between the Ford GT and the Mustang GT. :D

Good numbers. This part amazed me the most...

.35 248 217
.40 261 225
.45 271 230
.50 279 234
.55 285 236

It maintains about a 20cfm difference over 0.150-0.200" of lift. That's amazing. No wonder they make 650-some horse. :bow: to Ford on these monsters.

Any word if they're available to the public? A set of these would go over REAL well on a Lightning. :death:

Any word if they're available to the public? A set of these would go over REAL well on a Lightning. :death:

You could get the Ford GT's motor as a crate motor, but that'll cost you 40g's :eek:.

Bret:
actually the do translate to power!


first off its a 300hp 4.6 Liter. I mean, not exactly a 5.7 there:p


2nd; that thing is very choked up. If you look in the intake duct there is some white honeycomb paper that is a horrible restriction. Just a few ponies there.

3rd: man do they love boost. 5 pounds of boost = 400hp! not too shabby for a 4.6 liter.

in the end, there is no replacement for displacement.

Are those the heads they use on the 5.4 3 valve? that thing makes impressive power, espeically concidering how low it was "designed" to rev for the F-150

Yes put those on a larger engine or one with an intake and cam and you will see big power just like the LS1. The sad thing is that the Ford is only 280 inches though! They need another 70 inches like the LS1 and then they would run much better!

Those flow number are from the Ford GT(aka GT-40) not the mustang GT. Its a blown 5.4 not the 4.6 :)

The heads off of a Ford GT (NOT a Mustang GT) are 4-valve heads. Has to be a totally different casting than the 3-valve heads going on the Mustang GT. Going to venture a guess and say that, since they're going on a $150,000+ sports car, they're probably CNC'd, maybe even touched up by hand, no expense spared, etc.

This is sort of off topic, but does anyone have a flowchart for the 3.6L Ferrari V8 they put in the Modena? They are 5-valve heads and I would be quite interested to see what kind of air they can move.

sorry, thought this was about the mustang GT.

both heads are pretty good imho

Well that explains it then.

The 4.6L 3V is still worse than a LT1.

Well that explains it then.

The 4.6L 3V is still worse than a LT1.


is that 1 or valves?

in any event, they make more power than the LT1 stock with 20% less displacement . and like i said, under 5lbs of boost they make make an additional 100hp. they also have that stupid, i want to call a paper cat, in the intake duct crunching it for 5-10hp. motor i saw dynoed 309hp i think. 315hp out of a 4.6 liter...not too shabby.

the DOHC 4.6 are where its at though. my understanding is people go pretty damn fast on stock castings in those things

Still go back 10 years look at the first Northstar. Smoother, more power, more TQ, same cubes. 320hp in the XLR version.

A LT1 gets about the same RWHP as a '05 GT with less TQ. Once you get in the car HP per L means squat.

The cranks in those 4.6L's leave a lot to be desired as well they snap like twigs were a LT1 crank is pretty dam tough and essentially a 50 year old design.

Maybe I'm just bitter because we don't have F-bodies anymore and the Ford pony car doesn't come close to living up to the concept car appeal. Well that and a bunch of drag racing series and organizations to race Mustangs and we have close to nothing.

Bret

in any event, they make more power than the LT1 stock with 20% less displacement . and like i said, under 5lbs of boost they make make an additional 100hp. they also have that stupid, i want to call a paper cat, in the intake duct crunching it for 5-10hp. motor i saw dynoed 309hp i think. 315hp out of a 4.6 liter...not too shabby.

The Cobra's run 12psi. Not 5. I'd be ashamed of myself if I was only making 400hp with 12psi. In the end, the only thing Mustang guys can argue is "horsepower per liter" or some other nonsense like that. From the factory - they have trouble keeping up with a 10 year old f-body. If we're going to talk about modifying Mustangs vs. Camaro's & Firebirds - it boils down to this: if you have enough money, you can make any motor do anything you want.

The Cobra's run 12psi. Not 5. I'd be ashamed of myself if I was only making 400hp with 12psi. In the end, the only thing Mustang guys can argue is "horsepower per liter" or some other nonsense like that. From the factory - they have trouble keeping up with a 10 year old f-body. If we're going to talk about modifying Mustangs vs. Camaro's & Firebirds - it boils down to this: if you have enough money, you can make any motor do anything you want.


1. last i heard they run 8, stock.

2. i'm not talking about a cobra, they are not blown GTs. thye are 6spd manual IRS DOHC 4V blown forged motors with reduced compression. a GT is none of those.

3. mustangs have a lot of advantages on camaros and vice versa. they both suck. pick your poison:)


4. mutang guys, at the end of the day they have a factory supercharged car. infact take "factory supercharged" out of there and they still have us beat ;)

Still go back 10 years look at the first Northstar. Smoother, more power, more TQ, same cubes. 320hp in the XLR version.

A LT1 gets about the same RWHP as a '05 GT with less TQ. Once you get in the car HP per L means squat.

The cranks in those 4.6L's leave a lot to be desired as well they snap like twigs were a LT1 crank is pretty dam tough and essentially a 50 year old design.

Maybe I'm just bitter because we don't have F-bodies anymore and the Ford pony car doesn't come close to living up to the concept car appeal. Well that and a bunch of drag racing series and organizations to race Mustangs and we have close to nothing.

Bret
bret. i'm not comparing mustang vs camaro. i'm just stating their heads make power.

1. last i heard they run 8, stock.

I stand corrected.

bret. i'm not comparing mustang vs camaro. i'm just stating their heads make power.

I know they can make power, throw enough boost at something and it can make stupid power.

Hell a 2.2L Ecotec can make 975-1000hp with 30psi!

I have nothing against Fords, hell the 302 motor is a great drag motor (with Victor heads and a Dart Block) but I still can't get that GM out of my head.

Bret

I know they can make power, throw enough boost at something and it can make stupid power.

Hell a 2.2L Ecotec can make 975-1000hp with 30psi!

I have nothing against Fords, hell the 302 motor is a great drag motor (with Victor heads and a Dart Block) but I still can't get that GM out of my head.

Bret
my point was they flow air well in order to make 300hp on a 4.6L and +400hp under 5lbs of boost

Im not a ford fan, at all. Just dont tell that to the guys at work concidering our racecars are ford based :o

Forgive my ignorance of Ford products, but I am slightly confused: Are the 4-valve heads on the modular 4.6L interchangable with the 5.4L motor used in the Lightning & the GT40? My guess would be no. Is the block the same (i.e., small differences like those between LS1 & LS2 - bore size, sensor location, etc.) or radically different?

It is also my understanding that the modular 4.6L block accomodates 2-valve, single overhead cam heads (older Mustang GT's); the 4-valve Cobra heads; and now, the 3-valve heads on the 05 Mustangs. Yes?

Forgive my ignorance of Ford products, but I am slightly confused: Are the 4-valve heads on the modular 4.6L interchangable with the 5.4L motor used in the Lightning & the GT40? My guess would be no. Is the block the same (i.e., small differences like those between LS1 & LS2 - bore size, sensor location, etc.) or radically different?

It is also my understanding that the modular 4.6L block accomodates 2-valve, single overhead cam heads (older Mustang GT's); the 4-valve Cobra heads; and now, the 3-valve heads on the 05 Mustangs. Yes?


the only thing i am fairly certain of is 4.6 4V to 5.4 4V are interchangeable... i think. i might even be wrong about taht the more i think

Forgive my ignorance of Ford products, but I am slightly confused: Are the 4-valve heads on the modular 4.6L interchangable with the 5.4L motor used in the Lightning & the GT40? My guess would be no. Is the block the same (i.e., small differences like those between LS1 & LS2 - bore size, sensor location, etc.) or radically different?

It is also my understanding that the modular 4.6L block accomodates 2-valve, single overhead cam heads (older Mustang GT's); the 4-valve Cobra heads; and now, the 3-valve heads on the 05 Mustangs. Yes?

I'm not sure on the 3-valve stuff, but the 4.6 will accept both 2-valve and 4 valve heads. The only difference between the GT and the Cobra Blocks (2-valve vs. 4-valve) is the main caps. The GT has 2-bolt mains, whereas the Cobra has 6-bolt mains.

I'm not sure on the 3-valve stuff, but the 4.6 will accept both 2-valve and 4 valve heads. The only difference between the GT and the Cobra Blocks (2-valve vs. 4-valve) is the main caps. The GT has 2-bolt mains, whereas the Cobra has 6-bolt mains.
does ford use an alum block in the NA cobra suff/mach 1 stuff

does ford use an alum block in the NA cobra suff/mach 1 stuff

Yes, all the Mustangs run aluminum blocks except for the 03-04 Cobras.

mustangs!? or cobras?

mustangs!? or cobras?

Cobras are Mustangs! ;)


Yeah, all Cobra's, Mustang GT's, and Mach 1's had aluminum blocks except the 03-04 Cobra's.

Cobras are Mustangs! ;)


Yeah, all Cobra's, Mustang GT's, and Mach 1's had aluminum blocks except the 03-04 Cobra's.
YES BUT ALL MUSTNGS AREN'T COBRAS

i am not here to troll.

an 03-04 terminator makes 370-390 to the wheels minimum. the factory rating is a lie. 425 flywheel is more like it.

a roush 05 mustang gt makes 450 rwhp with 6psi.

a bolton 05 mustang GT makes 345rwhp/332 rwtq with cams.

3v heads flow 230cfm
96-98 4v flow 249
99-04 4v flow 240
navi's flow 240
00 cobra 'r' flow ~269
06 ford gt flow 310 cfm
06 gt500 300 cfm

a stock 07 mustang gt makes 270 rwhp stock
a stock 99-01 cobra 4v n/a the same
a stock terminator 370-390 rwhp stock
an 06 gt500 425rwhp stock
an 06 ford gt 505rwhp stock

a 4.6l 3v blown runs 10.9 @ 146 mph stock cams.
ported heads,longtubes,oversize throttle body, CAI, mufflers. daily driver in chicago. stock chasis w/roll cage,suspension. full weight car 3500 lbs.

a 4.6l terminator with 12 psi, nitrous longtubes, street exhaust makes 520rwhp with the tires spinning on the dyno. runs 10's. that is a convertible in my car club. the big boys make 700-800 rwhp on the street with a turbo terminator. totally street driven non radical.

an 07 gt500 with whipple low drag charger, CAI, oversize throttle body, tune makes 810 rwhp. go to whipple site and verify. it really does and the drivetrain can handle it. that is totally stock except the noted items.

the same kit has not been tested on a ford GT.

there is some number and facts.

i make 340 rwtq SAE with a near stock truck 5.4 3v. wait until i fab my new intake. the hp is there. later guys.

one last thing. i am an auto. i dump every LT-1 car i have raced. all motor. hard to beat 400 flywheel torque with 5.7 liters. i have never beaten an LS car.

i make 325 rwtq @ 3000, 340.1 rwtq @ 3650 and 300 rwtq @ 4200. not much for a power band right now. i hang through 1st on an LS car.

Holy cow, old thread Batman!

sieey, i was on internet search looking for something and this site popped up. so i commented. later dude. there is no other car that ford boys fear and respect like an LS camaro. they bitch and moan on mustang GT site about not having any power to compete all-motor. so i did this swap to show them it can be done. they still bitch and moan without doing anything about it.

they could learn a lot from you guys. if you ain't got it.... make it.


btw an aussie 5.4 4v makes 388 flywheel hp/365 fltwheel tq.with essentially 03/04 terminator heads.

i never see many fast newer mustangs around here. Alot of fox bodied ones....but most of the fastest have a SBC in em

Yes, same. Not to many fast newer Mustangs. Just Fox's.

The 3 valve 4.6 GT heads arent all that great... I sell CNC ones at work (Livernois Motorsports). In stock form, they arent anything special.

they are just ok. now the new 6.2l boss/hurricane will be another story. i will be dumping this modular for that.

You would love the motor we are dumping in the bosses shop truck;)

Teksid 4.6L block, cobra crank, manley rods, mahle pistons, ported navi heads, custom intake, procharger F1A, FR500 cam kit, etc....this in going into an f-150 with company stickers on the side lol

i have a 4.6 4v laying in the back yard. i will use the heads if i can't get enough power from 3v. those 4v's let a 5.4 get to 525 flywheelhp @ 7200 with mild 224* @ .050 .475" lift cams.

Forget NA with the mod motors - they need boost. Think 620rwhp with just a KB upgrade blower on the cobra motors, we see those every week.

old boss had a 03 cobra. 355 hp to wheels. added long tube headres gained 1 hp. put on larger air intake and chip and smaller pully and got right at 510rwhp. blower effiency about maxed out. installed kenne bell and huge throttle body and will put out over 670rwhp all day long with no change in manners.
did a multitude of swaps after that with a simple plan.
1. kenne bell
2. programming
3. cat back exhaust
4. air intake
never under 625rwhp. and does that number with lower boost numbers than the eaton.

please don't get me wrong i am a chevy die hard, but the 03 cobra in my opinion is the baddest factory muscle car for the money ever. the engine are almost indestructible and you could not buy one done the same for a chevy under $10,000

the lightning with the 5.4 is the next baddest per dollar. add a kenne bell and go like heck.

if you have time check out some of the ford stuff and be amazed at what has been done with the 4.6ltr. just remember the cobra motor is nothing like the mustang motor.

i despise add-ons. i come from the old days where we went at all-motor. i cannot expect to equal a 6.0l or larger LS,LT, or anything else with good heads that is too big. but i am going after 5.7l LS.

of course i respect the 03-04 cobras, i have no choice. but i am all motor. Al Papito is in the 625 rwhp rangge with his 5.5l modular. i cannot challenge or even approach that. he has nascar porters doing his work. but i can approach a 5.7l LS with equal mods. that's my definition of fun. this new generation of mustang owner has no idea how to make power, or any of the dynamic priciples. no clue. he thinks a KB and bolt-ons is cool. i hate that crap. they don't know how to get out the die grinder and earn it. even small flow gains from 3 angle, back cut valves,bowl work, polishing, blending, short side, and guide boss work are alien to them.

you guys have them snookered. scared. they compare themselves to 4cyl and 6 cyl cars. "can i beat a G-35" is typical. they can't beat a G-35. hopeless....

damn...I smoked a g-35 with my F-250 deisel pulling a tandem load of gravel

The 3 valve 4.6 GT heads arent all that great... I sell CNC ones at work (Livernois Motorsports). In stock form, they arent anything special.
The Mustang magazines were saying the 3V heads had the best flow capacity out of the box and possibly had more potential than the 4V heads. This was back when they first came out though.

If the magazine say so, it must be true:D

:rolleyes:

why are we talking about fords any way. i thought that web site was junkyardwars.com:D sorry just found this one funny

i have a question for you guys.

what are the unported and ported head flow numbers for

ls1
ls2
ls7

and can you include port sizes before and after porting. thank you. -bill

i think car craft or hot rod has a library of head flow numbers. good luck

i have a question for you guys.

what are the unported and ported head flow numbers for

ls1
ls2
ls7

and can you include port sizes before and after porting. thank you. -bill

http://carcraft.com/techarticles/p104803_image_large.jpg

tack on 100cfm for the LS7 port @ .600

They flow that much? hmmm
my LT1 don't have anything on that

352 @ .600, they can easily do 360cfm in stock form..... and make power. Now ported versions flowing 400cfm can make less power but win the race on the flow bench.

Bret

can you guys help me with the validity of what this guy says?

Take a minute to walk a mile in my shoes you might understand why myself and all the other competent and experienced engine builders are leary about just about 98% of the junk posted on automotive oriented forums. I will include some factual information below from my shop and a few others regarding LS2 cylinder head flow data. I have spent over 150-200 HRS on doing LS2 cylinder head flow analysis alone. Most shops invest about 50-100 hours developing a particular head flow model and program.


this is his post

On certain low valve angle racing heads (less than 12°) you could run 350+ FPS @ 28.0" H20 and not see TQ/HP losses, but the overall port geometry would have to be just about perfect to keep the a/f mixture in suspension and attached to that specific shape throughout the port. On a street/strip small block head like ours, when you start to go over 300 FPS (20.5" pitot pressure at 28.0" flow bench testing depression) you can watch as it will start to induce a premature sonic choke condition on the flow bench with the pitot tube right around the area of the SSR apex. The curtain area should be the choke point, or in other words the curtain area should be where you observe peak local airspeed. If you observe a peak local airspeed anywhere other than the curtain area, you will likely have a problematic cylinder head. When you are flow testing at 28.0" H20, the higher the pitot velocity pressure is above 28" (350 FPS at the pitot tube) and the greater that distance is away from the curtain area, the more power you will lose. Something else that will hinder power is to have a specific area of very high velocity near the SSR apex, or a side of the of the port wall that is in excess of 350 FPS coupled with a significantly slower downstream velocity, that velocity differential will cause fuel separation and will significantly increase your odds of having a sonic choke condition.

There is also a low limit local airspeed that is commonly accepted to be true. This is 240 FPS or 13.14" pitot velocity press when flow testing at 28.0" H20. When you start to go below 240 FPS, you will lose power on any head, especially in the lower RPM range at increased throttle angle. Piston speed and rod/stroke ratio also have an effect on the way a port responds at low RPM increasing throttle angle. On a small stroke motor like ours with a relatively large rod/stroke ratio, that 240 FPS will be way too slow and that motor will lose torque. Torque is obviously important at low RPM part throttle situations.

Also when comparing valve lift to port velocity, low lift flow (meaning anything below 1/2 of the total lift) is relatively unimportant. Think about the valve events in a motor for a moment. From the point when the valve first lifts off its seat until it reaches mid lift, the piston is either going the wrong way (rising towards the top of the cylinder) or it is experiencing dwell near TDC. The piston doesn't begin to move away from the combustion chamber with enough speed to substantially lower the pressure in the cylinder until the valve is nearly halfway open. High lift flow and a relatively low velocity port will make the most power and perform the best on the street or drag strip.




how much if that is true? thanks.

If the magazine say so, it must be true:D

:rolleyes:

More like from Gods lips to my ears. Believe them everytime.

352 @ .600, they can easily do 360cfm in stock form..... and make power. Now ported versions flowing 400cfm can make less power but win the race on the flow bench.

Bret

That's very interesting information. Don't follow the technology but a couple shops around here are getting $8K+ for LS7 head, cam and header packages and making 600 rwhp. Or so they say that's what they get and the heads have "extensive porting."

More "gods lips to my ears" and I believe them every time.

looks like in need FORD GT heads to compete with you guys.

btw a stock gt500 with CAI,oversize throttle body, whipple low drag charger and stock everything else is making 810rwhp. go to whipple to check it out. they saved 60 hp with low drag technology. the gt 500 has ~FORD GT ports.

looks like in need FORD GT heads to compete with you guys.

btw a stock gt500 with CAI,oversize throttle body, whipple low drag charger and stock everything else is making 810rwhp. go to whipple to check it out. they saved 60 hp with low drag technology. the gt 500 has ~FORD GT ports.


More interesting information. I've seen a bunch of LTx cars with stock hyperutetic pistons not do very well at all when the boost went over 6psi. To make 800 rwhp you need some pretty serious boost and out of curiousity I did a little surfing to see if the engine at least had forged pistons as the LS7 engine doesn't.

The very first site on Googel was: http://home.nycap.rr.com/tritonlemon/

The next website on Google talked about the class action lawsuite over cracking intake manifolds.

Never did find out for sure if the Ford GT had forged pistons but found a site that did say they had power forged rods and forged crank. My assumption is they probably are not forged but don't know for sure.

Did however find it a bit amusing the two most popular websites implied a few customers are exactly jumping for joy with Ford. I'm sure Chevy has a few of those running around also but it wasn't exactly what I was expecting.

More interesting information. I've seen a bunch of LTx cars with stock hyperutetic pistons not do very well at all when the boost went over 6psi. To make 800 rwhp you need some pretty serious boost and out of curiousity I did a little surfing to see if the engine at least had forged pistons as the LS7 engine doesn't.

The very first site on Googel was: http://home.nycap.rr.com/tritonlemon/

The next website on Google talked about the class action lawsuite over cracking intake manifolds.

Never did find out for sure if the Ford GT had forged pistons but found a site that did say they had power forged rods and forged crank. My assumption is they probably are not forged but don't know for sure.

Did however find it a bit amusing the two most popular websites implied a few customers are exactly jumping for joy with Ford. I'm sure Chevy has a few of those running around also but it wasn't exactly what I was expecting.

All 03-04 Cobras, Ford GT's, and the new GT500's have forged pistons, mainly because they are all supercharged from the factory. :)

All 03-04 Cobras, Ford GT's, and the new GT500's have forged pistons, mainly because they are all supercharged from the factory. :)

In that case, I'd bet a few of those puppies will probably boot scoot pretty good. The lemon website caught me off guard as I wasn't expecting that to be the first one to pop up. Had to chuckle to myself over that one.

I know Bret follows the engine masters stuff pretty close but Ford whipped some real butt this year at that event with a 434ci limit. If the rumors of a new LS based NASCAR engine are true, that may change in the near future.

But hey...I'd love to have two or three of those Ford GT's sitting in my garage in case one of them got dirty or something. Next to a couple Z06's. Then there is a yaht, a real babe or two to go with the yaht. etc. Not kidding……. this time anyway.

Yeah, the 03 Cobras had serious production issues are first. I belive they shut down the production line due to excessive block shift and bad bearings (as a result). There wasn't time to redesign the aluminum block to take the extra hp so they basicly adapted the Lincoln Navigator's iron bock. Heavier, but easier on the hot roders in the long run (easier to bore... the classic LT1 vs. LS1 issue we all debated in 98-01 or so until sleeving and larger block really became available).

I remember one owner I knew picked up a brand new '03 and traded it in on a Lightning within 2 months... way too many issues. Mostly little things, but the weird one I was suprised an OEM didn't address at the factory was the cruise control "surging". Apparently the car would bounce around the speed set and was REAL choppy in doing so. I have a feeling this was a boost issue, but he swore it was at almost any speed. Did a search online and found others complaining of the same issue. That alone probably cost them a few sales I'd imagine. Add in the wheel hop issues from the IRS that had problems with squat in a heavy, high-hp car... well... I'll pass.

Reminds me of the '99 Cobra delays (head pinging) and the hp recall they needed. (not to mention the sloppy shifter and gutless performance until 3500... I really didn't like that test drive)

Every once in a while Ford puts out a real screamer, but the fact is the Cobra track record over the past decade or so seems like a consistant issue with delivering the whole package.

Personally I don't care if the dials do look like cheap plastic or the outline is short and boxy... I just want solid, reliable hp and a drivetrain to handle it. (which is why my 4th gen has a 12-bolt).

the cranks and some of the internals were made by callies i believe in the 03-04 cobras. the cruise surge was a computer reflash that fixed that.
the cobras in the 03-04 years were nothing like the 99's. they were recalled because the power was no where near rated. most barely got 220 at the crank.. they issued new cams heads and a couple other things to fix that low power.
the 03-04 cars are a very good package and for the power there isn't a whole lot that touch them.... plus there are some serious 9-10 second irs that say bring it on.

do not kill me my blood still runs chevy orange, but that is one bad ask mustang. easy 600rwp for $3400.00

our bad boy 03 cobra convertible runs 10's.

the issue with 03 block wasn't so much core shift of the aluminum although that may have happened. they just couldn't get an aluminum block to live long term. the iron block had nothing to do with the navi. the navi is a 5.4 1" higher deck.

the real issue with the 03 cobra was the lack of exhaust port cooling. it was fixed for 04. all of the 99-03 can suffer port overheating. and taht stupid intake hp issues for 99. just inexcusable. no torque.

the bad boy in our club makes 520 rwhp with two of us in the back seat to stop wheel spin and a set of bad plugs.

I read several places that the bracing from the navigator's iron block was mimicked to help reduce the block instability (I didn't mean core shift, just the block itself "shifting" and flexing... causing cranks and bearing failure). The block was essientally changed to iron then had stiffening ribs added in the same places the truck guys had to increase stength. Time was of the essence I guess.

Can't remember if that was in Fast Fords & Mustangs, or another ford rag I was reading at the time...

ok i'm sorry. you are right. it's a 4.6 block strengthened like our NVH 5.4 for longevity. it can take almost unlimited HP.... that a 4.6 -5 liter can produce on race gas. a lot of guys like the one in our club have higher boost and n2o.

my NVH block is identical to the GT500 block and it's good to only a tested 1250 hp. the 03-04 cobra can go much further.