4.6L transplanted into a Shelby Cobra 427 S/C

[Shelby Cobra]

New member here, though I've read up on this forum over the past 2 weeks.

Within 3 months I will be purchasing a Shelby Cobra replica and have many choices in engines (4.6L, 302, 351, 390FE, 427FE, etc...). The place that is selling me the Cobra recommended a 4.6L over the larger engines because the are way more efficient, lighter, and run cooler. I've priced engines/tyranny's at car-part.com and the GT runs about $2500, the Mach 1 runs about $5000 and the Cobra being about $10,000.

Here is a 4.6L SOHC in a Cobra:

Here is a 4.6L DOHC Mustang Cobra engine in a Cobra:

My questions are:
- Do you guys truly like these engines?
- Which engine would you recommend? Remembering it's going in a 2300lbs car.
- Is the SOHC built pretty strong? Any weak links?
- Is the DOHC Mach 1 engine built much stronger?
- Do I really need a supercharger?
- Is the DOHC simply a better engine than the SOHC?
- What are the ideal no brainer mods to meet my goals below? (Intake, TB) Cobra already has headers and high flowing side pipes.

Here are my goals with the Shelby Cobra:
- Daily driver (weather permitting)
- Daily commute is 40 miles, so 20+ MPG would be nice
- Occasional 1/4 mile drags, with 12 to 12.5 seconds runs
- Occasional auto-cross

I would think a 250-300rwhp would run nicely in this, wouldn't you?

Yes there are many Cobras pushing 500-600hp and yes it's easy to do, but I want an easy daily driver and I want usable horsepower. Traction can because a big problem in these light cars.

Thoughts and or ideas are appreciated.

Thanks,
Matt

 

[btolenti]

6.8L V-10.....

 

[MachAzure]

For the price I would go with the 4.6 DOHC out of the mach.
It has a forged crank-for the manual version.
The rods/pistons however are still as weak as what is in the SOHC engines.

A 427FE would be cool as well. Big cubic inches and big torque numbers unlike the 4.6.

If cost has nothing to do with it-go with an 03/04 4.6 DOHC cobra engine.
They put out 425bhp and similar amount of torque.
They have forged Manley rods, forged crank and pretty good pistons.
Plus for a couple grand more you could add a few things to put down 600 at the wheels.

And I would definently try to go with the T-56 6 speed.

 

[Shelby Cobra]

Thanks for your response MachAzure (notice I didn't include you, btolenti )

Unfortunately I have a budget and a $20,000 authentic 427FE is out of the question. Not very efficient either. 600rwhp would be just plain suicide in a 2300 pound Cobra for a daily driver. I've ridden in the Cobra with the Cobra engine pictured above with 475rwhp and it was SCARY!

I honestly would be happy with with 300rwhp. If I wanted more I could alway add a supercharger for 150 more right?

What Mustangs come with a T-56 6 speed? Cobra? And what RPM's does it run at 70mph in 6th?

Thanks,
Matt

 

[new22003]

Windsors (302/5.0/351) do not run hotter than modulars(4.6)
Windsors do not get far worse mileage than modulars
Windsors are not drastically heavier than modulars as most people put on aluminium heads and you have all the hardware for ohc's.
Windsors are cheaper to build and buy than modulars
You can carb a windsor if you want
GT modulars are 2 valve per cylinder and cast cranks rods and pistons
Cobra modulars are 4 valve per cylinder and have forged cranks
2003+ cobra engines have forged crank rods and pistons
2003+mach 1 engines are 4 valve per and have a forged crank on manual transmission engines, automatics have cast cranks

A cobra kit will not run hot with a 302/351 if it does the kit is poorly designed.
I got 26 mpg with my 89 5.0 stang
I get 26 mpg with my 2000 4.6 stang its in the gearing
Building a 450 horse windsor is cheaper than building a 450 horse modular

If you have extra money a 4.6 32 valve cobra would be awesome. You will wind up with about the same car though performance wise but will have just spent more money. If you really wanted an awesome car get a 2003 cobra take out for around $10,000 with the factory supercharged engine, 6 speed and wiring, and have a killer cobra. 2003+ cobra engines are very stout and people have made 800 horsepower on the factory engine.

If it was me Id build a 351. You can build a 450 horse 351 for pretty cheap. If I won the lottery Id do a 2003+ cobra engine.

Do not price parts at carparts.com

A used 4.6 cobra can be had for $2500 you can get the whole package of engine trans and wiring for under $4000.

Try ebay or http://www.stangparts.com or http://www.karkraft.com

 

[Jackie Chan]

as much as i hate to say it....i would go with a 302 or 351.

or buy a used PI 4.6 2v and get cams and headwork done. that would be good for 300+ to the tire

 

[krly79]

I personally would go with the 351 or something like a 347 stroker, because you can build the same power with them that you can with a 4.6, only you can do it cheaper. It would also have more potential...of course I'm a believer in "There's no replacement for displacement." You could go with a 302 factory roller and stroker it to a 347 all roller setup, that would be nice and cheaper. Then you could run a carb or fuel inject it....OH! Did I mention it would be cheaper?

 

[BETTERBULLITT]

Go with a forged 4.6L block (Maybe Stroker) from VT engines and then later when you are bored with the 280-300 hp, throw a blower on there for 450-500 HP.. That's what I would do..

http://www.vtengines.com/46gtLB.htm

 

[KaPPaBaLL]

all i have to say is. that mofo looks gooooood

 

[Shelby Cobra]

Thanks for all the replies. Keep them coming.

When you say a 351 can be built cheaper, help me out here. You saying as building it myself? Or having an engine shop do it?

What do you recommend. Me searching around the junk yards or buying a rebuilt engine off he internet? Please provide web addresses. THIS place charges $8900 for a 351w THIS place charges $6400.

Sorry for the noobness questions. I come from a chevy background and have rebuilt a 406 small block and a 427 bigblock with my dad about 15 years ago, so I'm a little rusty. I can't count on my dad to help because he is a die hard chevy man and would never touch a Ford.

 

[new22003]

Thanks for all the replies. Keep them coming.

When you say a 351 can be built cheaper, help me out here. You saying as building it myself? Or having an engine shop do it?

What do you recommend. Me searching around the junk yards or buying a rebuilt engine off he internet? Please provide web addresses. THIS place charges $8900 for a 351w THIS place charges $6400.

Sorry for the noobness questions. I come from a chevy background and have rebuilt a 406 small block and a 427 bigblock with my dad about 15 years ago, so I'm a little rusty. I can't count on my dad to help because he is a die hard chevy man and would never touch a Ford.

I could easily build a 350 horse carbed 351 for around $3000. Find a 351 block at your local salvage yard have a machine shop clean and bore it. It wouldnt be Fuel Injected for that price of course but can be made so for another $1000

P.A.W. http://www.pawengineparts.com/ has complete 351 forged longblock kits that sell for $1795. This includes all parts needed for the longblock (heads, crank, block, pistons rods crank, cam, etc etc) about all you will need is external stuff like harminic balancer, flywheel, valve covers, oil pan, timing cover and intake and carb or fuel injection. The machine work is completed and really all that is required is assembly which anyone can do. If you got this in a 10:1 compression and chose the right intake 350+ horse would be no problem. I cant imagine that a local machine shop would charge too much for assembling this

P.A.W. also sells a 351 stroked to 427 cubic inches for $2995 for the longblock kit. That would be more power than you would ever need.

I honestly think your best bet if you want to stay fuel injected and get decent gas mileage would be to find a wrecked 5.0 stang. You would then have the engine transmission wiring and various other parts. You can often find wrecked stangs for $1500.

Depending on the mileage of the engine you can just freshen it up. Having a 5.0 shortblock freshed up can be done yourself for under $500 and for under $1000 by a local machine shop including parts. Get something like the holley or edelbrock performance kit for the 5.0 including cam heads and intake for around $2200 and have a 350 horse engine.
http://store.summitracing.com/partdetail.asp?part=HLY-300-501-1

So
$1500 wrecked stang
$1000 machine shop
$2200 performance package (cam,heads,intake)

So for $4700 you can have a 350 horse engine, wiring, fuel injection, transmission, rear end and various other parts.

Even ford motorsports has 385 horse 351 crate engine with aluminium heads for $4900. again you can find this at P.A.W.

For engine parts and longblock kits you will not find a cheaper source than P.A.W. They even have a 521 cubic inch big block ford kit for $3595. I suggest you get the catalog its $5 but its as thick as a phonebook.

You will be out some money and time if you want to go fuel injected but you will have better cold starts and fuel mileage. Carbing it will be cheaper and easier. You can find an intake at a swap meet or on ebay for $100 and give another $200 for a carb and you wont have to do any wiring. If you had a carb and some gearing in the 3.08 to 3.23 range and a 5 speed you should still get decent mileage in such a light car. You also would still have good acceleration and the high gears may help traction.

Here are some of the P.A.W. catalog that I scanned in for you.

 

[WhiteDevil69]

Thanks for all the replies. Keep them coming.

When you say a 351 can be built cheaper, help me out here. You saying as building it myself? Or having an engine shop do it?

What do you recommend. Me searching around the junk yards or buying a rebuilt engine off he internet? Please provide web addresses. THIS place charges $8900 for a 351w THIS place charges $6400.

Sorry for the noobness questions. I come from a chevy background and have rebuilt a 406 small block and a 427 bigblock with my dad about 15 years ago, so I'm a little rusty. I can't count on my dad to help because he is a die hard chevy man and would never touch a Ford.

www.dssracing.com, send them a email with what your goals are and they will send you a quote within a day or two, great company!

 

[btolenti]

I say something like this is right up your alley....the V-10 comment was a joke...

http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=3792

Nice and lightweight, with the aluminum heads, and parts are much more readily available for old windsor blocks than the newer modulars. Plus there is no computer stuff to worry about if you go carburated.

Actually any of the Ford crates would be good, they are just a tad bit more expensive than their Chevy counterparts.

 

[jas142]

Go with the GT engine. For a 2300 lb car, 260 hp is perfect if its just going to be a drivers car(not a race car) Add on a nice sounding exhaust, and you'll be good to go

 

[pony_vert02]

Go with the GT engine. For a 2300 lb car, 260 hp is perfect if its just going to be a drivers car(not a race car) Add on a nice sounding exhaust, and you'll be good to go

I second this motion... great choice for a daily driver.. you could always add bolt-ons for a few extra ponies...

 

[new22003]

I was wondering if you have checked factory five out? You might have as they are the best selling replicas. They have a complete list of parts you will need and you used most of it from a 87-93 stang. You can check them out here. Ive known guys that have built these kits and have done so for less than $20,000 total and run 12's in the quarter.
http://www.factoryfive.com/table/ffrkits/roadster/roadsterkit.html

 

[DJT03GT]

How bout a 500+ HP 427 for 9 grand? still less then 03 cobra motor, and perfect for your car. www.coasthigh.com Looking at all the affordable crate motors for the older cars makes me wish I had a old 5.0

 

[MachAzure]

How about a 5.4L from the lightning or f-150,expedition?

Would have good torque, same hp as 4.6 SOHC and be very streetable.

OR 5.4L DOHC from the navigator

 

[03trubluGT]

I was wondering if you have checked factory five out? You might have as they are the best selling replicas. They have a complete list of parts you will need and you used most of it from a 87-93 stang. You can check them out here. Ive known guys that have built these kits and have done so for less than $20,000 total and run 12's in the quarter.
http://www.factoryfive.com/table/ffrkits/roadster/roadsterkit.html

Factory Five is cheap because of the inferior quality. I was looking at buying a replica a few years back, and I found an article that actually tore the Factory Five car apart. They said that it was one of the worst produced fiberglass bodies that they had ever seen. Just go to www.cobracountry.com and check around. See what used FFs are getting as opposed to a Superformance or something similar.

On the other hand, I was looking at a big block aluminum 460 for mine, but I bought a house instead. That's why I got my GT. Something to play around with until I retire in 12.5 years and they have to write me a $60k check for my sick time/vacation time/holiday that I have accrued.

When I do build my Cobra, it will be with a Mod motor. For now, I'm quite happy with my GT with a few bolt ons (see signature), but my car is also about 3280 lbs. I can't imagine what my car would run like if it was a thousand pound lighter

Matt

 

[Monkie]

as much as i hate to say it....i would go with a 302 or 351.

Or try to get your hands on an actualy 427cid. But if you couldn't I'd get a 351W bore and stroke it and you'd have one bad mamma!