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Choosing an engine for your Cobra

by Myles Douglas-Withers. Created 11 July 1995
Last updated:

January 1996:

  • Gary Walsh added some more info about the Rover V8 engines.
November 1995:
  • More about big block Ford V8's sent to me by Ryan Mahood from the USA.
  • More about Chevrolet V8's sent to me by Mike Cobine and Matt (ttxs@mcia.com) and Rob Koeppel.
  • More info about Jaguar engines.
  • Mention of turbine engines in the exotica section.

One of the first decisions that a cobra builder must make is to decide what engine to use. The choices are varied and revolve around the following issues :-

  • How authentic do I want the car to be ?
  • How much will I use the car ?
  • How much money do I have ?
  • How fast do I want to go ?

American V8 Engines

Generally speaking these lovely beasts fall into two groups: small and large ( not getting too technical I hope ! ). Small block V8s range from (approx) 220 to 350 cubic inches and big block V8's range from 390 to 460 cubic inches ( for europeople: there are approximately 60 cubic inches in a litre ). There is some overlap ( the biggest Chevrolet smallblock is 400 cubic inches ) and also 'specials' available from the aftermarket that go right up to 600 cubic inch monsters.

Most where developed in the late 1950's and have changed little since, the power outputs specified by the manufacturers are wildly optimistic, actual output is probably about 70% of the claimed figure. When buying one for your Cobra avoid anything from after the mid 1970's since this is when power robbing anti-smog modifications were made.

Features of the American small block V8

  • Authentic
  • Widely available.
  • Cheap to buy, rebuild and tune.
  • Strong, reliable and simple to work on.
  • Lovely noise and enough torque to pull down small buildings
  • Well served by the aftermarket.
  • Can be reasonably economical.
  • Not too difficult ( or expensive ) to achieve 1 horsepower per cubic inch capacity.

Features of the American big block V8

  • Authentic
  • Cheap to buy, rebuild and tune, but generally more expensive than smallblocks.
  • Very strong, reliable and simple to work on.
  • Huge noise and enough torque to pull down large civic buildings.
  • Well served by the aftermarket.
  • Fuel economy is not a strong point ( who cares ? ).
  • Not too difficult ( or expensive ) to achieve 1 horsepower per cubic inch capacity.
  • Needs strong drivetrain components.

Ford

The advantages ( in addition to those above ) of Ford V8's are :-
  • Highly authentic.
  • Availability of 'real' cobra parts such as valve covers and sumps.
The disadvantages of Ford V8's are :-
  • Not built by Chevrolet.

Here is a list of what is available:

  • 221 cu. No reason to use this.
  • 260 cu. Fitted to some early cobras, better to choose the 289...

  • 289 cu. This is the most common and successful cobra engine.

    Don Mathieson from NZ runs one of these in his ALMAC Cobra. He rebuilt it and uprated the valvetrain, inlet manifold and carburetor. In this mild state of tune he gets 250 hp at 5000 rpm measured at the wheels.

  • 302 cu. Larger version of the 289, except the rare "boss" 302 which is a completely different block. Check out late model Mustangs that use this engine, with EFI and 5 speed manual transmisson.

  • 351 cu. Two types available according to which plant they come from. Cleveland or Windsor.

    The 351W ( Windsor ) is a long stroke version of the 302 and is interchangeable with it. The 351C ( Cleveland ) is a completely different block. It is physically bigger and preferred for performance applications.

  • 352 cu. First of the big blocks and first of a family of engines known by their factory nomenclature: "FE". All of the FE engines are interchangeable ( you will find more in the list that follows ) and all have the letters FE cast into the block.

  • 360 cu. A member of the FE series ( see above ).
  • 390 cu. A member of the FE series ( see above ).

  • 427 cu. Two types are available.

    The common one is yet another member of the FE series. The other type is the rare and desirable "side oiler" 427, a completely different engine built with performance in mind and fitted to the original 427 Cobras. There is also a monstrous SOHC version, see exotica section below.

  • 428 cu. Largest of the FE series.

  • 429 cu. Two types are available.

    The common one is the first member of another series ( not an FE ) of what are basically truck engines. The other type is the extremely rare and desirable "boss" 429, a completely different engine built with performance in mind and fitted to a few rather quick Mustangs.

  • 460 cu. Larger version of, and interchangeable with, the 429 "truck" engine.

Chevrolet

The advantages ( in addition to those above ) of Chevrolet V8's are :-
  • Semi authentic - Shelby's first choice.
  • Not built by Ford.
  • Cheapest and widest range of aftermarket parts.

Here is a list of what is available:

  • 262 cu. Mid '70s attempt for fuel thrifty engine, low performance. Little interchangeability.
  • 265 cu. Early engine, no oil filter, no reason to use this.
  • 267 cu. Mid '70s - early 80's attempt for fuel thrifty engine, low performance. Little interchangeability.
  • 283 cu. First of the desirable smallblocks.
  • 302 cu. Rare. High revving, high performance engine. Basically a 283 crank in 327 block.
  • 305 cu. Generally low performance engine but EFI version in late Camaros worth checking.
  • 307 cu. Rare. Torquey but rather limited performance potential.
  • 327 cu. Bored and stroked 283. A good choice.
  • 350 cu. Very common, long stroke version of the 327. Probably the best choice. Also rare 32 valve version, see exotica section below.
  • 400 cu. Bored and stroked 350. Uses a special block, crank balancer and flywheel but still physically interchangeable. Performance potential is limited.

  • 396 cu. First of the big blocks. First of series known as Mark IV's all of which interchange.
  • 427 cu. Bored 396.
  • 454 cu. Stroked 427. After 1990 these became Mark V's which are different from Mark IV's.

  • 502 cu. So called 'crate' motor because it is not fitted to any production vehicles but you can buy one in a crate brand new from a Chevrolet ( around $3500 ). It is a Mark V engine interchangeable with the 454 and makes 445 hp straight out of the box, fit a good quality EFI system and you have nearly 500 hp. One of these I MUST have !!!

Others

Generally, choosing to use one of the less common American V8s will cost you. Parts are more expensive and aftermarket support is much more limited. If you just love to be different here are a few choices :
  • Buick. Engines up to 455 cubic inch. Some high performance, I used to have a 430 cu Buick Riviera with factory dual quads !. Also of particular interest is the aluminium 215 cu engine, more about this in the European section below, since Rover produced far more of these than Buick ever did.
  • AMC
  • Jeep
  • Pontiac. Some big high performance motors ( up to 455 cu ) in Firebirds and Trans-ams.
  • Chrysler. Some lovely big hemi-headed engines up to 440 cu.
  • Cadillac. Monster motors but dated and without much tuning potential.

European V8 Engines

There are a few european V8 engines worth considering if you feel like something different.

Rover

The 3.5l ( 201 cu ) Rover engine is really a Buick engine. It is extremely common in the England and is fitted to 8 out of every 10 cobra replicas. It is available up to 4.2l and has all the advantages of American V8's ( since it is one ) and in addition it is very light. ( Actually it's lightness is a disadvantage in a Cobra because it is lighter than the Jaguar IRS so you tend to end up with a rearward weight bias ). In standard form the output ranges from 130 hp from the de-tuned version fitted to early Range Rovers through 160 hp powerplants fitted to early saloon cars to 180 hp EFI units in later cars. It is comparatively easy and cheap to obtain 220 hp from this engine. Miles mentions that the Rover V8 is available in capacities up to 4.2 litres. However, there are now (at least) two sources of these engines in 5.0 litre capacities. The first is from TVR, developing 340bhp, and the second is from Marcos developing 320bhp. I can't speak for the Marcos engine, but the TVR engine certainly has the right power/noise characteristics for a Cobra...

Daimler

Tiny 2.5l hemi-headed engine used to be very popular amongst UK hot-rodders and drag racers but now rare. Quite heavy and giving around 140 horsepower, fitted to a variant of the Jaguar MkII. Also a very rare 4.5l version fitted to Daimler limousines.

Mercedes

Various aluminium SOHC engines in the 4 - 5 litre range.

BMW

Don't know much about these.

Porche

5 litre aluminium SOHC engine found in their 928

Triumph

Horrid unreliable 3 litre SOHC engine fitted to the Stag. Gives less power than the Rover V8.

6 Cylinder Engines

A straight six engine can be an option for a cobra replica. The AC Ace from whence the Cobra came had such a powerplant, so if you dare to be different, here are some thoughts :

  • Straight six engines make a glorious noise, not everyone likes the 'lopey' V8 sound ( hard to believe ).
  • For a traditional feel, try the Jaguar XK unit, see below.
  • For something completely different, what about a 2.8 or 3.0l unit from a Toyota Supra. This is a superbly smooth injected DOHC aluminium unit. Just pull one out of a low mileage wreck and drop it straight in, it will last and last. Also, it comes with a very nice 5 speed manual attached ( avoid autos ).
V6 engines - see 4 cylinder engines below.

Jaguar

The Jaguar XK series of engines are DOHC straight six powerplants. First fitted in the 1950's to the XK120 sports car it was then used in ALL Jaguar cars until the mid '80s when the new AJ unit was released. XK engines look good, sound good and are widely available. They are however quite heavy ( the blocks are iron, the heads aluminium ) and need a few special tools to rebuild them. The parts are more expensive than Ford or Chevrolet but are not outrageous. Uprating is expensive but comparable with other less common engines. Engines attached to manual gearboxes are rare and those attached to good manual gearboxes are non-existent. Luckily kits are available to use the Toyota or Getrag five speed transmissions.

Here is a list of what is available:

  • 2400 cc. Rather underpowered, fitted to some early saloon cars.
  • 2800 cc. Bad reputation for eating pistons, avoid this one.
  • 3400 cc. A strong short stroke engine. Good basis for high revving application.
  • 3800 cc. Probably the best choice. About 190 hp in standard form.
  • 4200 cc. Long stroke 'lazy' engine. About 210 hp. Some come with Efi.


V12 Engines

The only widely available V12 engine is the Jaguar 5.3l SOHC unit. In England it is quite a popular choice for cobra replicas but has little to recommend it. Aftermarket versions up to 7.0l are available.
  • It is quite heavy has to sit further forward than a V8
  • It is expensive to rebuild and requires various special tools and skills.
  • It gives around 275 horsepower in standard form and is very expensive to tune.
  • You get the choice of unreliable Lucas fuel injection or performance strangling Stromberg carbureters. Both are ugly and the only option is to fit six downdraft webers at some cost.
  • It is awkward to work on, especially in a small engine bay.

4 Cylinder Engines

You cannot be serious !!.


Exotica

If you fancy putting something really exotic in your cobra, I really look forward to seeing it !. Realise that this is senior league expense and parts may cost 10 to 20 times what the equivalent Ford/Chevy part would be ( for example a set of main bearing shells for a Chevy is approx. 40 ( UK pounds ) but a set for a V12 Lamborghini will set you back a cool 750 ). Furthermore, these engines are not usually renowned for their reliability or longevity.
Still, if you must here are some ideas :

  • Chevrolet ZR1. This all aluminium, 32 valve, DOHC, 350 cu. engine was fitted to a limited number of Corvettes, of which production has now ceased. The heads were developed by Lotus and the engine comes with high performance EFI and a ZF six speed gearbox.
  • Ford 427 SOHC. Probably the least exotic and also the best choice in this list. A powerful rare beast that looks great and performs superbly. Some have already found their way into cobras. These must surely be the king cobras.
  • Ferrari. A range of aluminium DOHC V12 and V8 engines. The V12 engines make a lovely noise, the V8's less so ( they use a different crank/firing order from American V8's so they don't 'throb' ). The V8's are usually transverse mounted in 308 series so gearboxes might be a problem. There is also the mighty flat 12 boxer engine but this may be too wide to fit. Ferrari uses two naming schemes for it's cars, both of which describe the engine. The 8 cylinder cars are named after the engine size and number of cylinders, so a 328 means a 3.2l V8. The V12 cars are given a number that represents the size ( in cc's ) of one cylinder. So the 456 has a 5.5l V12 engine.
  • Lamborghini. Don't know much about these. Range includes DOHC V12 engines.
  • Maserati
  • Cosworth V8. The DF series engines that used to dominate Formula 1 in the '60s and '70s. Various different models - DFV, DFY, DFX ranging up to 4 litres. Apparently these are still popular with historic racers and hill-climb specials. They are still very expensive and for road use you would almost certainly have to change the mechanical fuel injection system to EFI or carbureters. However, will still give around 450 hp when de-tuned for road use.
  • Aston Martin. A lovely 5.4l aluminium DOHC unit that powers the worlds fastest saloon car. Each engine is handbuilt and tended to by an old craftsman whose name appears on a plaque affixed to each block. Prices are outrageous but some do come with a superb ZF five speed gearbox attached. Avoid early injected engines. Latest models have twin superchargers and EFI.
  • Dodge Viper V10. Who's going to be first...
  • Aero engines. Mostly physically too big, I think.
  • Turbine engines. Small turbines from aircraft/helicopters are surprisingly cheap and very compact and powerful. Major challenges include dispersing heat and the exhaust gases. and transmission of the power to the wheels. Turbines are notoriously lacking in torque and slow to respond to power changes, but the sheer pose value of whistling along to the Cobra owners club meeting would make it all worthwhile.


If you enjoyed ( or hated ) this, let me know. If you find mistakes or can fill in more information about anything let me know also.

Myles Douglas-Withers.