Lotus couldn’t live on Ford engine blocks forever. It needed to build a new motor for its new, upmarket cars. This is the story of the 16-valve engine that would go on to produce record-breaking specific power output.
Maybe Colin Chapman had an inferiority complex. He thought his cars were the acme of technical sophistication, and if people were niggled at some of there shortcomings, that were their problem. But as Lotus grew in age and stature, the kit-car jibes started to hurt. The company was in Formula One, for heaven sake. Surely it could build its own road-car engines without using a superannuated cast –iron Ford block.
So Lotus began its journey upmarket, which would result first in the wedge shaped elite, then the Eclat, the Esprit and the Excel. All were to be bigger cars the Elan and the Europa that marked the end of the kit-car days – which meant a bigger, more powerful engine. Lotus was about to become its own engine builder for the next three decades.
Back in the late sixties, Jensen Motors was feeling the pinch, too. To survive it needed to move downmarket, and American then-owner Kjell Qvale saw an opportunity for a low-cost Jensen sports car in the USA. A deal was done with Donald Healey, the Jensen-Healey project was born – and here, for Lotus was the perfect fit. If Jensen could buy significant of the new unit, the whole idea would become more financially viable.
Even before Jenson came on the scene, Lotus had sketched out what was needed. The engine would have twin overhead camshafts. The size would be about two litres, over square bore/stroke dimensions as had worked so well in the Ford-blocked twin-cam. And the engine had to embody the latest technology that befitted a Lotus creation.
Such as? The block and head would be of Aluminium, with removable wet cylinder liners. The camshafts would be driven by a reinforced rubber-toothed belt – such a system had won a Design Centre award for Vauxhall in 1967 – and they would activate four valves per cylinder. Here, in the making, was Britain’s first full-production 16-valve four-cylinder engine (because the Ford-Cosworth RS1600 engine, the other candidate, was hardly quantity produced)
However, when the project began back in 1966, it was far from given that the engine would be a straight four. Lotus looked at the 60-degree and 120-degree V6’s, too, and dismissed them as too tall or too wide. Which leads the four-cylinder’s other distinctive design feature, the fact that it sits inclined at 45 degrees to the cars nearside. There were two reasons for the: it helped keep the bonnet line low, and the design would lend itself to doubling up as a V8. For what? A future supercar? A race engine? Chapman had long harboured a desire to race at Indianapolis with his own power unit, and here could be the answer.
So a straight four it was, and Steve Sanville, then Lotus’s chief recruited Ron Burr from Coventry Climax to get the project underway. Burr’s work on the four-valve-per-cylinder v8 and stillborn flat-16 Formula One engines stood him in good stead for the new cylinder head, and that’s where he began.
Enter Vauxhall. Chapman, Sanville and Burr discovered at the 1967 Earls Court motor show that Vauxhalls 2.0-litre slant-four (that Design Centre winner) proved, surprisingly, to have exactly the same bore centres as Lotus’s own proposal. It was easy to adapt the head to fit the Vauxhall block, and getting the head running would speed-up development.
Lotus’s embryonic hybrid engine fired up in July 1968, and soon gave 220bhp on its Tecalemit-Jackson fuel injection. Dubbed the LV220 (Lotus-Vauxhall and the power output) it went racing in the Lotus 62 Europa –look alike sports-racers with considerable success. The project was now know internally as the 900-series and the LV200 was given the number 904-there were no 900 to 903 numbers.
A 147bhp road going version, durability-tested in various Vauxhall cars and Bedford vans, became 905.
These early Vauxhall –block engines didn’t have the Vauxhall 1975cc capacity, despite their common 3.75in bore. That’s because they had a fractionally longer stroke Lotus-made crankshaft (a tidy 2.75in instead of 2.72) to stretch the engine to more race-competitive 1995cc. The same went for the first Lotus block unit in sand- cast aluminium, the 906 race engine which still kept the Vauxhall based terminology as LV240. Thereafter, the engines used standard Vauxhall nodular cast iron crankshafts, but the production die-cast blocks held wet liners, who’s fractionally smaller bore brought the capacity back down to 1973cc.
In this 907 form, further developed in road going Vauxhalls and now rated at 140bhp, the engine entered production 1972 for the Jensen-Healey. Ex-BRM chief engineer Tony Rudd oversaw this process, which was problematic because the die-cast head wouldn’t let oil return quickly enough to the sump under certain g-force conditions. Oil was accumulating around the valve gear with nowhere to go, starving the oil pump, but the problem was solved by redesigning the oil drainage system.
Come 1974, and Lotus had its own elite in to which to slot its own engine (uprated first to 155, then to 160bhp), followed by the Eclat and Esprit, which helped offset the pain of Jensen’s 1976 demise. But there was plenty more evolution to come, the first visible example of which was 1979’s 2.2-litre version for the Chrysler Lotus Sunbeam.
Chrysler UK’s competition department wanted a ford-challenging rally weapon but lacked the engine to do the job. The Lotus fitted the bill perfectly, and represented another sales opportunity. The extra capacity came by means of the longer stroke (3.00in) version of the Vauxhall crankshaft, and it soon showed up problems with blocks strength cured by belling-out the block’s base to accommodate a wider, tougher main bearing ladder. In road guise this engine designated 911 made 155bhp; in the rally cars, with 240bhp, it won the 1980 RAC Rally and the 1981 manufacturers’ title.
So with the 911 as our representative lets look more closely at the engines architecture. Most obvious, apart from the ribbed aluminium castings made by Aeroplane and Motor of Birmingham is the 45-degree slant. Then you notice the sandwich between the sump and the crankcase, one of the first production engine instances of a main bearing ladder. It takes the place of five separate bearing caps and makes for stronger assembly. Rover’s K-series engine is one of many that have since used such system.
On the blocks offside, below the carburettors, a separate housing contains the eccentric-lobe oil pump with the distributor on its rear end, both driven by a shaft from the cambelt. It’s a neat and simple solution. Talking of pumps, Lotus had learned the lesson of the old Ford based twin cam engine and the 900 series has a conventional, separate from mounted pump. No longer would mechanics have to remove the cylinder head to release the entire front cover with its integral and leak prone water pump.
The removable wet liners are cast iron in most 900 engines, located at the bottom and sitting slightly proud at the top, the better to nip the head gasket. The last 912 engines however had aluminium liners with Nikasil coating and no nip; we’ll discover the 912 identity later.
And so to the head. Twin camshafts and shimmed bucket tappets sit above combustion chambers to shallow to be true hemispheres. The angle between the exhaust valves is just 38 degrees, the idea being to keep the chamber compact (for a high compression ratio) without resorting to domed pistons- which are ideal for neither gas flow nor emissions, because pockets of unburnt hydrocarbons lurk around the edges. A compact combustion chamber also has a smaller surface area and hence better thermal efficiency because less combustion heat is lost to the cooling water. The spark plug sits right in the centre of the four valves.
The camshafts each sit in a separate removable, carrier on to which ribbed cast aluminium cam covers are bolted. There are no bearing caps; instead the camshaft is inserted from the front. Finally, there is a different flywheel depending on the engine capacity. Tony Rudd, worried about the long-stroke 2.2’s vibrations, devised a flexible dual-mass flywheel that effectively damped them out.
There is another major variant in this engine family. It involved a turbo charger, and as the 910 it reached the public in 1980 in the Lotus Esprit Turbo. At last, the performance lived up to the looks.
Graham Atkin was the man in charge of the turbo project. The idea was to create lots of low down torque, but both he and Esprit development engineer Mike Kimberley had a hard job in persuading Chapman that this was a better idea than chasing revs. It paid off; Lotus ended up engineering turbo installations for seven other clients on the strength of the Esprit’s attributes.
“We have a standard for measuring turbo lag,” the late Tony Rudd told me in 1989. “You drive at 40 per cent of the maximum speed, say 60mph in fourth so the engine is in a steady state. Then you put your boot in and measure the time to indicate 90 per cent of the rated boost. More than one second is unacceptable.”
Lacking the money for fuel injection, Lotus decided to blow through the Dell’Orto DHLA carburettors rather than sucking through them. That way, the latent heat of fuel vaporization gave a degree of chargecooling. “We had to put pressure on the seals on the throttle spindles and make sure the fuel line pressure went up as the boost built up”, said Rudd. “High speeds used to knock holes in the pistons’.
With its Garrett AiResearch T3 turbo charger, the Esprit’s 2.2-litre engine gave 215bhp in final high compression form, but the days of carburettors were numbered. Pressures on emissions forced Lotus to adopt Ac-Delco electronic fuel injection and with a water-cooled charge cooler it helped the turbo motor to a mighty 264bhp. “It’s the highest specific output of any production engine,” said a proud Mike Kimberley at the 1989 launch.
As you’d expect, the turbo engine had a further strengthened block and bearing ladder, modifications carried through to the normally aspirated 2.2 litre, 912 engine in the Eighties. The first cars had dry-sump lubrication, too, but this was abandoned in 1983.
Today Quorn Engine Developments is this engine family’s centre of expertise. Technical director Ken Snailham is frank about its faults: “the head breathes very well and it’s an engine that wants to rev and rev, but the block can’t cope. It’s too long, not rigid enough and there’s nothing really to locate the tops of the liners. We use a top deck plate when we build race engines.
“Racers over rev them-more than 8500 rpm is a problem- and they come back in with the bearings running on their edges. The iron crankshaft is strong though, and its more rigid than a springier steal one.” And the engines certainly produce power with up to 400 bhp possible from a turbo.
But what of the V8? Projects 908 and 909 were development v8’s, one of which was seen in 1984’s Lotus Etna concept car. But the idea was abandoned for two reasons: turbocharging the four cylinder was a cheaper solution, and a major US client for the engine pulled out. Could it have been General Motors? Lotus later designed 16 valve heads for the Chevrolet LT5 small-block V8 as fitted to the Corvette ZR-1, so perhaps it didn’t die entirely.
The four-cylinder did, though, in 2001 its final incarnation was in 2.0 litre form, charged cooled for the Esprit GT3 and delivering 243bhp.
Now the Esprit has gone too. Will Lotus ever build its own engine again? We’ll have to wait and see.
If you are the author of this document, please contact us as we would like to give you full credit of this excellent article.
Maybe Colin Chapman had an inferiority complex. He thought his cars were the acme of technical sophistication, and if people were niggled at some of there shortcomings, that were their problem. But as Lotus grew in age and stature, the kit-car jibes started to hurt. The company was in Formula One, for heaven sake. Surely it could build its own road-car engines without using a superannuated cast –iron Ford block.
So Lotus began its journey upmarket, which would result first in the wedge shaped elite, then the Eclat, the Esprit and the Excel. All were to be bigger cars the Elan and the Europa that marked the end of the kit-car days – which meant a bigger, more powerful engine. Lotus was about to become its own engine builder for the next three decades.
Back in the late sixties, Jensen Motors was feeling the pinch, too. To survive it needed to move downmarket, and American then-owner Kjell Qvale saw an opportunity for a low-cost Jensen sports car in the USA. A deal was done with Donald Healey, the Jensen-Healey project was born – and here, for Lotus was the perfect fit. If Jensen could buy significant of the new unit, the whole idea would become more financially viable.
Even before Jenson came on the scene, Lotus had sketched out what was needed. The engine would have twin overhead camshafts. The size would be about two litres, over square bore/stroke dimensions as had worked so well in the Ford-blocked twin-cam. And the engine had to embody the latest technology that befitted a Lotus creation.
Such as? The block and head would be of Aluminium, with removable wet cylinder liners. The camshafts would be driven by a reinforced rubber-toothed belt – such a system had won a Design Centre award for Vauxhall in 1967 – and they would activate four valves per cylinder. Here, in the making, was Britain’s first full-production 16-valve four-cylinder engine (because the Ford-Cosworth RS1600 engine, the other candidate, was hardly quantity produced)
However, when the project began back in 1966, it was far from given that the engine would be a straight four. Lotus looked at the 60-degree and 120-degree V6’s, too, and dismissed them as too tall or too wide. Which leads the four-cylinder’s other distinctive design feature, the fact that it sits inclined at 45 degrees to the cars nearside. There were two reasons for the: it helped keep the bonnet line low, and the design would lend itself to doubling up as a V8. For what? A future supercar? A race engine? Chapman had long harboured a desire to race at Indianapolis with his own power unit, and here could be the answer.
So a straight four it was, and Steve Sanville, then Lotus’s chief recruited Ron Burr from Coventry Climax to get the project underway. Burr’s work on the four-valve-per-cylinder v8 and stillborn flat-16 Formula One engines stood him in good stead for the new cylinder head, and that’s where he began.
Enter Vauxhall. Chapman, Sanville and Burr discovered at the 1967 Earls Court motor show that Vauxhalls 2.0-litre slant-four (that Design Centre winner) proved, surprisingly, to have exactly the same bore centres as Lotus’s own proposal. It was easy to adapt the head to fit the Vauxhall block, and getting the head running would speed-up development.
Lotus’s embryonic hybrid engine fired up in July 1968, and soon gave 220bhp on its Tecalemit-Jackson fuel injection. Dubbed the LV220 (Lotus-Vauxhall and the power output) it went racing in the Lotus 62 Europa –look alike sports-racers with considerable success. The project was now know internally as the 900-series and the LV200 was given the number 904-there were no 900 to 903 numbers.
A 147bhp road going version, durability-tested in various Vauxhall cars and Bedford vans, became 905.
These early Vauxhall –block engines didn’t have the Vauxhall 1975cc capacity, despite their common 3.75in bore. That’s because they had a fractionally longer stroke Lotus-made crankshaft (a tidy 2.75in instead of 2.72) to stretch the engine to more race-competitive 1995cc. The same went for the first Lotus block unit in sand- cast aluminium, the 906 race engine which still kept the Vauxhall based terminology as LV240. Thereafter, the engines used standard Vauxhall nodular cast iron crankshafts, but the production die-cast blocks held wet liners, who’s fractionally smaller bore brought the capacity back down to 1973cc.
In this 907 form, further developed in road going Vauxhalls and now rated at 140bhp, the engine entered production 1972 for the Jensen-Healey. Ex-BRM chief engineer Tony Rudd oversaw this process, which was problematic because the die-cast head wouldn’t let oil return quickly enough to the sump under certain g-force conditions. Oil was accumulating around the valve gear with nowhere to go, starving the oil pump, but the problem was solved by redesigning the oil drainage system.
Come 1974, and Lotus had its own elite in to which to slot its own engine (uprated first to 155, then to 160bhp), followed by the Eclat and Esprit, which helped offset the pain of Jensen’s 1976 demise. But there was plenty more evolution to come, the first visible example of which was 1979’s 2.2-litre version for the Chrysler Lotus Sunbeam.
Chrysler UK’s competition department wanted a ford-challenging rally weapon but lacked the engine to do the job. The Lotus fitted the bill perfectly, and represented another sales opportunity. The extra capacity came by means of the longer stroke (3.00in) version of the Vauxhall crankshaft, and it soon showed up problems with blocks strength cured by belling-out the block’s base to accommodate a wider, tougher main bearing ladder. In road guise this engine designated 911 made 155bhp; in the rally cars, with 240bhp, it won the 1980 RAC Rally and the 1981 manufacturers’ title.
So with the 911 as our representative lets look more closely at the engines architecture. Most obvious, apart from the ribbed aluminium castings made by Aeroplane and Motor of Birmingham is the 45-degree slant. Then you notice the sandwich between the sump and the crankcase, one of the first production engine instances of a main bearing ladder. It takes the place of five separate bearing caps and makes for stronger assembly. Rover’s K-series engine is one of many that have since used such system.
On the blocks offside, below the carburettors, a separate housing contains the eccentric-lobe oil pump with the distributor on its rear end, both driven by a shaft from the cambelt. It’s a neat and simple solution. Talking of pumps, Lotus had learned the lesson of the old Ford based twin cam engine and the 900 series has a conventional, separate from mounted pump. No longer would mechanics have to remove the cylinder head to release the entire front cover with its integral and leak prone water pump.
The removable wet liners are cast iron in most 900 engines, located at the bottom and sitting slightly proud at the top, the better to nip the head gasket. The last 912 engines however had aluminium liners with Nikasil coating and no nip; we’ll discover the 912 identity later.
And so to the head. Twin camshafts and shimmed bucket tappets sit above combustion chambers to shallow to be true hemispheres. The angle between the exhaust valves is just 38 degrees, the idea being to keep the chamber compact (for a high compression ratio) without resorting to domed pistons- which are ideal for neither gas flow nor emissions, because pockets of unburnt hydrocarbons lurk around the edges. A compact combustion chamber also has a smaller surface area and hence better thermal efficiency because less combustion heat is lost to the cooling water. The spark plug sits right in the centre of the four valves.
The camshafts each sit in a separate removable, carrier on to which ribbed cast aluminium cam covers are bolted. There are no bearing caps; instead the camshaft is inserted from the front. Finally, there is a different flywheel depending on the engine capacity. Tony Rudd, worried about the long-stroke 2.2’s vibrations, devised a flexible dual-mass flywheel that effectively damped them out.
There is another major variant in this engine family. It involved a turbo charger, and as the 910 it reached the public in 1980 in the Lotus Esprit Turbo. At last, the performance lived up to the looks.
Graham Atkin was the man in charge of the turbo project. The idea was to create lots of low down torque, but both he and Esprit development engineer Mike Kimberley had a hard job in persuading Chapman that this was a better idea than chasing revs. It paid off; Lotus ended up engineering turbo installations for seven other clients on the strength of the Esprit’s attributes.
“We have a standard for measuring turbo lag,” the late Tony Rudd told me in 1989. “You drive at 40 per cent of the maximum speed, say 60mph in fourth so the engine is in a steady state. Then you put your boot in and measure the time to indicate 90 per cent of the rated boost. More than one second is unacceptable.”
Lacking the money for fuel injection, Lotus decided to blow through the Dell’Orto DHLA carburettors rather than sucking through them. That way, the latent heat of fuel vaporization gave a degree of chargecooling. “We had to put pressure on the seals on the throttle spindles and make sure the fuel line pressure went up as the boost built up”, said Rudd. “High speeds used to knock holes in the pistons’.
With its Garrett AiResearch T3 turbo charger, the Esprit’s 2.2-litre engine gave 215bhp in final high compression form, but the days of carburettors were numbered. Pressures on emissions forced Lotus to adopt Ac-Delco electronic fuel injection and with a water-cooled charge cooler it helped the turbo motor to a mighty 264bhp. “It’s the highest specific output of any production engine,” said a proud Mike Kimberley at the 1989 launch.
As you’d expect, the turbo engine had a further strengthened block and bearing ladder, modifications carried through to the normally aspirated 2.2 litre, 912 engine in the Eighties. The first cars had dry-sump lubrication, too, but this was abandoned in 1983.
Today Quorn Engine Developments is this engine family’s centre of expertise. Technical director Ken Snailham is frank about its faults: “the head breathes very well and it’s an engine that wants to rev and rev, but the block can’t cope. It’s too long, not rigid enough and there’s nothing really to locate the tops of the liners. We use a top deck plate when we build race engines.
“Racers over rev them-more than 8500 rpm is a problem- and they come back in with the bearings running on their edges. The iron crankshaft is strong though, and its more rigid than a springier steal one.” And the engines certainly produce power with up to 400 bhp possible from a turbo.
But what of the V8? Projects 908 and 909 were development v8’s, one of which was seen in 1984’s Lotus Etna concept car. But the idea was abandoned for two reasons: turbocharging the four cylinder was a cheaper solution, and a major US client for the engine pulled out. Could it have been General Motors? Lotus later designed 16 valve heads for the Chevrolet LT5 small-block V8 as fitted to the Corvette ZR-1, so perhaps it didn’t die entirely.
The four-cylinder did, though, in 2001 its final incarnation was in 2.0 litre form, charged cooled for the Esprit GT3 and delivering 243bhp.
Now the Esprit has gone too. Will Lotus ever build its own engine again? We’ll have to wait and see.
If you are the author of this document, please contact us as we would like to give you full credit of this excellent article.