Which Engine Should I Choose?

        I enter this debate with much trepidation, few Triumph subjects are as heated and varied as to which engine is best. After reading every single bit of Triumph literature I could get my hands on and many telephone calls to those who have raced & modified Spits almost since before I was born (no really!), I can with reasonable certainty give a good account as to which engine is best for which purpose.

        Here is a small list of the usual reasons you hear for choosing various engines and a short explanation of each. A rev limit for each is provided as it seems to be a much requested figure. These are limits which relate to avoiding mechanical failure NOT avoiding high wear rates so its still not terribly clever to sit on a motorway at 5500 Rpm all day.

The Early 1147cc Mks 1&2 Engine: 6000 Rpm Standard, 9000 Rpm full race

        The 1147cc engine is obviously rare and so far fewer tuning bits are available for it, its reliable and took the Le Mans Spitfires to a creditable 134 Mph with over 100 Bhp from the tiny engine.
The car completed the 24 hours at an average speed of 94.7 Mph. For this purpose special 8 port aluminium cylinder heads were cast, if you can find a genuine one of these you are a lucky chap! To the best of my knowledge there are no reliability problems with this engine.

    A high revving engine, lower Torque and Bhp than 1300 or 1500.

The 1296cc Mk3 Engine: 6000 Rpm Standard, 9000 Rpm full race

This is usually the first choice for the full race brigade. It has the lightest internals, the camshaft runs in bearings and still a short stroke. Perfect for spending some time at 9000 Rpm.

Note that the Herald version does NOT have cam bearings. Again no problems with reliability

High revving, lower Torque than 1500

The 1296cc Mk4 Engine: 6000 Rpm Standard, 9000 Rpm full race

This has heavier internals than the 1300, bigger inlet valves and larger big end bearings.

Unfortunately it hasn't got cam bearings.

High Revving, lower Torque than 1500

The 1296cc Mk4 Engine (from FH-25000) 6000 Rpm standard, 9000 Rpm full race

As the Mk4 1300 above but with a recessed lip at the top of the bores, this allows a sort of big `o` ring in the cylinder head gasket which improves the chances of a good tight seal.

High Revving, lower Torque than 1500

The 1496cc 1500 Engine: 5500 Rpm Standard, 6500/7000 Rpm full race

Long stroke, no cam bearings and the block top cylinder recesses.

        This is the tricky one, dreadful blow up lump or a misunderstood badmouthed high torque engine perfect for easy street driving? Triumph faced a dilemma in the face of US emissions requirements strangling their engines with not enough cash to fund a new engine. In the end they just increased the crankshaft stroke to its maximum capacity bringing the engine to 1496cc.

        This means that for any given Rpm the pistons are moving faster up and down than on any of the other Spitfire engines, this equates to more stress. I spoke to the Triumph Tune Spitfire guru TERRY HURRELL, who personally owns a 120 Bhp 1500 as a daily driver.

He put it simply and clearly:

"If you want to win races with a screamer engine go for the 1300, if you want a good Torquey road car get a 1500".

        His 120 Bhp 1500 has so far completed 60,000 miles in a manner probably not approved of by Triumph (in other words thrashed to within an inch of its life) while putting out nearly 70% more power than standard.

        Its still going strong, I think that about wraps this old debate up. I must add that his 1500 managed that in no small part because it was rebuilt properly and tuned with the correct components. If you do the same you can have a reliable 1500, his other big tip was that "An oil cooler is a must, especially on the 1500". Also use good quality oil & change it with filter every 3000 miles. Do that and your happily away for a good 100,000 miles of fun.

Not a Spitfire Engine please!

        Originally I was going to make this a Spit engine only guide but due to the number of Spitfires going around with everything from Fiat Twin Cams to 5.7 litre Chevy Small Block V8s (I believe the name `small block` to be the American sense of humour at work!) I thought a small section on transplants would be useful.

Why should I use a different engine?

        If you don't care about originality and you're faced with rebuilding and modifying the stock engine at great cost you could think about a transplant. It can be tempting as you can pick up a low mileage alloy block 4.6 Litre Rover V8 for less than a rebuilt & modified Spitfire engine. The cost factor isn't really as good a motive as it might have first appeared. By the time you have uprated the suspension, brakes, drivetrain & chassis to cope the total cost can be high.
Inserting an engine which as standard produces as much Bhp as a race prepared Spit engine can be the easy option. The more radical you go the more expense and more engineering flair you will require. Of course if you have too much money you can pay people who are professional engineers to do a lot of the work for you. Deduct suitably large sums from your bank account before proceeding.

How much will all this cost me?

        It depends, if you put in an engine of less than 160 Bhp or so then the rear drivetrain can remain almost stock. The brakes & suspension would also require minimal modifications (that is to say straight bolt on ones). Any American V8 engine even if with less than 170 Bhp or so will be too much for the drivetrain as the Torque it produces will be considerably higher than 170 ft/Lbs.

        The higher the output of your engine is the higher the conversion cost will be. If you put in a 350 Bhp V8 (this has been done) you will require to be realistic at least £5000 (not including engine cost). On top of this you will need to have good fabrication & welding skills and a friendly local machine shop. If you are really cunning it may be possible to do a swap for much less than that but in the real world that is probably a good basic estimate for a good job. And more importantly a SAFE car than won't go falling to bits or twisting in inappropriate places.

Which Alternative Engine should I choose?

        If you start from scratch it makes sense to pick the best of the bunch. If you choose the engine there is no excuse for getting an unreliable and expensive motor.

        Weight is crucial, remember that the only reason your Spit is nimble and `chuckable` is that it weighs (in comparison to many) about as much as an empty crisp packet. If you put in a Chevy / Ford / Mopar / Pontiac cast Iron V8 engine in you will loose much of that nimble nature which so endears us to the little car. Here is a rough guide to how much various engines weigh. It does not include transmission or small engine bits like alternators and starters. Also I only had access to very precise figures on the V8 & V12 engines. The rest should be accurate to within about +/- 5%.

        Now I know that it is possible to move the engine so far back that the percentage distribution of weight is better than standard but that does not alter the fact that you have just put 350 Kg of cast iron on a tiny sports car.

        Remember that you will need to obtain a COMPLETE engine & transmission unit. Locating one later can prove to be an expensive operation. Even if you could, putting a Spit gearbox on a V8 or a powerful 4 cylinder engine is just plain stupid.

American V8 Engines:

As we have seen they are very heavy. However they have several big plus points.

1: They are literally bomb proof and should go on almost for ever.
2: New engines & parts are dirt cheap
3: A truly VAST range of cheap race parts are available
4: You can very easily get more than 400 Bhp out of any small block V8 with minimal modifications
5: If you have around £800 to spare you can get Aluminium heads for any US V8. This takes weight down to 205 Kg.
6: If you have too much money you can also get Aluminium US V8 engine blocks. This along with alloy heads makes them about the same weight as the light Rover V8. Bank on at least £2500 for one bare block.
7: The Rover V8 is just a design Buick sold to the UK many moons ago, Rover V8 parts are much more expensive than US V8 parts and due to its smaller capacity will never be as powerful with the same expenditure.

        As a point of note you can buy a virtually complete BRAND NEW Chevy V8 small block engine for £1300, a reconditioned one (with heads too) costs a measly £900 from REAL STEEL in the UK. Those in the US will pay even less.

Rotary Engines:

        These are worth a mention as I was most impressed by a Mazda rotary into Spitfire conversion that Grass Roots Motorsport magazine covered.

        Rotary engines are internal combustion engines that use petrol. That is about where any similarity ends.
There are one or even several triangular rotors in a main housing, there are no camshafts, rockers, cranks, pistons, rods or other gubbins to get in the way. Hardly any moving parts equals spectacular power/capacity efficiency and very low weight.
They also rev up fast and run as smoothly as silk. Mazda now does a Turbocharged version, which with a couple of hundred horsepower which should be interesting!

        The concept is utter genius and was pioneered by a chap called Wankel, there are only two good reasons why it didn't take over the world.

1: They use lots of petrol (25 MPG is the best you can hope for).

2: The problems of sealing the rotor tips to the block walls have only very recently been fixed by Mazda after everyone else gave up. Almost everyone from GM to Rolls Royce tried to fix the rotor tip seals without success. Many owners of the original RX7 angrily tore out the Mazda engines when the rotor seals blew and put in Ford V4s. Oh dear.....