20 replies to this topic

[mariner]

One of the few pleasures of covid lockdown is reading my collection of Motor and Autocar magazines from the 60's/70's when they had technical editors like Charles Bulmer and Anthony Curtis who could do really in-depth articles .

 

Today I found Anthony Curtis's description of the then new Lotus two litre slant-four engine. 

 

He describes how Lotus used the Vauxhall slant 4 block to speed development while their own cast alloy block was designed. That mixed engine was the LV240 as fitted to the Lotus 62 which won a lot of Club races albeit with John Miles driving it .

 

Then the later all Lotus alloy block engine became big rally winner in the Lotus Sunbeam.

 

However I don't think it ever had much success as racing engine until the much later Espirit turbo engines - I can only think of the Novamotor engines which were done for the Texaco Star F2 cars.

 

As I remember it those engines were no very good and the cars never showed any real promise despite the team and drivers ?

 

Apart from the Lotus 62 and the Texaco Stars were there any other naturally aspirated lotus two litre engines used in acing ?

 

 

[RS2000]

Someone who rallied a Sunbeam Lotus told me that engine's alloy block seemed as heavy as an iron block.

[Gary Jarlson]

Renowned engine builder Chuck Willis, who did my Cosworth BD motors, told me about the time someone brought him one of those  "Lotus things" with the hopes of making it into a "racing engine." It seems that when he just tried to hone the cylinders, the block would distort. He made a stabilizing plate but that was not the complete solution. Years later, I ran into a racer in the Seattle area who was using that very same engine. "We can never get consistent measurements during rebuilds. It's just hope and pray," he said.

[john aston]

Surprisingly perhaps , because by most accounts  it was a pretty horrid car in period , one still sees the occasional Jensen Healey competing in Historic racing . Its problems , apart from the uninspiring styling , were invariably engine related. How we have progressed - here was a sporty overhead cam 16valve which gave 140 bhp - not much more than your niece's 1 litre Fiesta 'three'  in 2020... 

Edited by john aston, 21 November 2020 - 07:25.

[Odseybod]

But the J-H seemed to handle pretty well - at least, based on a ride back to London from Silverstone in "Motor"'s long-term test car, conducted by a certain T. Dron in the wet. Of course, that impression may have been at least partly due to the driver ...

Edited by Odseybod, 21 November 2020 - 10:11.

[RCH]

Someone who rallied a Sunbeam Lotus told me that engine's alloy block seemed as heavy as an iron block.

 

Going a little off topic, that original Vauxhall block was a heavy old thing. Tough though, mine did 30 plus miles, ten stage miles at least, with no water having blown a core plug. Hammered in a new core plug, filled with water and it was good to go. 

[mariner]

Surprisingly perhaps , because by most accounts  it was a pretty horrid car in period , one still sees the occasional Jensen Healey competing in Historic racing . Its problems , apart from the uninspiring styling , were invariably engine related. How we have progressed - here was a sporty overhead cam 16valve which gave 140 bhp - not much more than your niece's 1 litre Fiesta 'three'  in 2020... 

 

Yes, progress in engines has been steady and relentless.

 

Back in the 80's we marvelled at the Cosworth Sierra 2 litre 16 valve turbo giving 200 bhp in high performance road car and 145 mph. 

 

today my very ordinary 2 litre 4 cylinder turbo Mondeo has 240 bhp - 20% more, way better fuel economy and its claimed 149 mph top speed despite its huge size. The Lotus 2 litre engine was up to 301 bhp in final S4 Sport form by 1993.

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The  highest bhp/litre "regular"  road engine is the MB 2 litre turbo , it churns out 400 bhp with reliabilty. To put that in perspective if it had two extra cylinders it would have 600 bhp - same as most Le Mans cars!

 

Of course there is down side. Engine tuning in world of spec. racing and fuel limits means less work for engine tuners . I suspect its the Historics that keep many in business?

Edited by mariner, 21 November 2020 - 11:49.

[BRG]

I have always been a little unsure about the relationship between these Vauxhall and Lotus engines.  The LV220 had its genesis as the Vauxhall motor used in such exotica as the Bedford CF van and the Viva GT.  Did the LV use the Vauxhall crank and rods, even after replacing the iron block?  I was told that these were really tough parts, good for a lot more power. 

 

In parallel, there was the Vauxhall Chevette HS and HSR which used a similar DOHC 16 valve engine also based on the slant four base.  There was a problem in rallying when DTV were found to be using the Vauxhall head in their Gp4 rally cars and had to change to a Vauxhall head.  Presumably the road car (homologation special) used a Vauxhall head, but the rally team used the Lotus one to save time and effort developing it?  What block did this engine use?  The iron one or an alloy one, and if so was that the Lotus block?

[Myhinpaa]

I have always been a little unsure about the relationship between these Vauxhall and Lotus engines.  The LV220 had its genesis as the Vauxhall motor used in such exotica as the Bedford CF van and the Viva GT.  Did the LV use the Vauxhall crank and rods, even after replacing the iron block?  I was told that these were really tough parts, good for a lot more power. 

 

In parallel, there was the Vauxhall Chevette HS and HSR which used a similar DOHC 16 valve engine also based on the slant four base.  There was a problem in rallying when DTV were found to be using the Vauxhall head in their Gp4 rally cars and had to change to a Vauxhall head.  Presumably the road car (homologation special) used a Vauxhall head, but the rally team used the Lotus one to save time and effort developing it?  What block did this engine use?  The iron one or an alloy one, and if so was that the Lotus block?

 

Blydenstein never used an alloy Lotus block in any of their cars, as far as I know. The first car to use the Lotus head was Old Nail from the '72 season onwards.

That was by then a 2.2 litre from a 2 litre block in 8 valve configuration, after the 16 valve conversion it was gradually enlarged up to 2.6 litre capacity.

The car used a Tecalemit Jackson fuel injection system both before and after the the Lotus head conversion.

 

The debacle over the use of the Lotus head on the early Chevette HS was due to a rule change for '78. Before then alternative cylinder heads could be homologated

for use on the original type block in Gp.2/4, providing there were available at least 100 kits. Such did we get a 24-valve Stratos, 16 valve Corolla/Celica, BRM Avenger etc.

The Chevette was homologated with reference to the Vauxhall head (meant for the HP Firenza) but from the beginning it used the Lotus head on a Vauxhall cast iron block.

 

So when the '78 season started Vauxhall continued to us the Lotus head due to the non-availability of the base homologated head. This did slide a bit and they got away with

it on quite a few rallies, Sweden, Mintex, Circuit etc. Allegedly Ford with the help of Graham Robson in an article in Autocar drove this issue to the attention of the FIA.

He visited Shepreth before writing that article and was welcomed and shown around the workshops by Bill Blydenstein and Gerry Johnstone. 

 

So at scrutineering in Portugal the proverbial hit the fan proper. A very few heads had been produced by Vauxhall before, but GM being the way it is/was it would take a long time

to get the correct heads in production, Jensen Healey did a few too. But after Portugal it was Cosworth who was chosen for the main batch, there wasn't much choice with the very limited amount of time available, and the quality required. Vauxhall/WBB could not put the whole rally programme on halt for a variety of reasons.

 

There might have been some privateer Firenza and Chevette specials for hillclimbs and sprints using the whole Lotus engine but there's no info of any official WBB built cars. (?)

 

Lotus had three different cars they used to test their prototype, (iron block first) 16 valve engine in, a Victor FD VX4/90, a Viva HB GT and eventually a Bedford CF!

The latter was the car they used to road test the first alloy block version, allegedly. There might be some more details in Tony Rudd's book, "It Was Fun"

 

Source : http://www.lotusespr...evelopment.html

 

Vauxhall never experienced the same problem as the Talbot team did with seized cranks etc. During certain times it was a big problem, it was not totally unknown for the engine to

seize over night in parc fermé even! Russell Brookes experienced this at least once and had to push the car out to where they could get a tow rope to a service van/chase car. 

Then towing it down the road to see  if they could free up the engine again.... When Russell first tried to let out the clutch the rear wheels locked up!

 

Not sure if they got that engine going again at all on that event. They (Phil Davidson) must have got over this problem somehow, the engine proved reliable (enough) eventually.

[mariner]

In his article Anthony Curtis mentions that the Vauxhall iron block was very strong as was the iron crank. Supposedly the  block would take 9,000 rpm ( not sure how GM knew that?). Lotus used the Vauxhall iron crank in early production at least.

 

It's interesting if the alloy block was weak because it followed DFV practice in having a very substantial alloy lower main bearing cap ladder for strength.

 

Novamotor claimed 275 bhp for their ace version of the Louts engine. As Lotus got 240 bhp quite quickly for the type 62 this doesn't seem unlkely but I guess by then BMW had raised the F2 bar to about 300 bhp .

[Myhinpaa]

The Chevette HS rally engines did tolerate 9000 rpm, but it did shorten the life expectancy of the block if taken to that regularly. 

What usually happened with that block was that the centre main bearing web cracked and the oil pressure dropped to half, it was on borrowed time then.

 

Normally a rev limiter was fitted which was set at 8500, it was possible to disconnect quite easy however...

I guess the drivers would know how to get to the reset button for the tell tale needle, or he had a loyal mechanic to do it. (Sworn to secrecy)

 

The Lotus seemed to have problems with cylinder liners in the early days too (mentioned in the article above) but that was sorted out.

Not sure if the problems the block gave was due to design or production, heat treatment to relive stresses after the casting process is extremely critical.

Especially with an alloy block, if not done properly the material will continue to "move" and make main bearing and cylinder bores/liners etc. go oval.

 

Henri Toivonen's engine seized on the road section after SS19 on the '81 RAC : https://youtu.be/2ZOZhxp9dn4?t=737 (Exact reason not known though)

[RS2000]

Probably from running upside down for a bit, judging by the state of the roof when I stood alongside it in the depths of Kielder!

[RS2000]

Someone else with a Sunbeam Lotus I hill climbed against was selling CF van 2.3 blocks as (the same) Chevette blocks and making a profit. He was a Ford dealer.... 

[Gregor Marshall]

The blocks are strong, but will destroy themselves, like any other, if over-revved for their design for a period of time. The weak point is actually the crankshaft, it needs balancing (it is a V8 design, but only has one crank in the slant four).

With modern technology these engines can now rev to 9,000 all day and produce 350bhp plus in 2.6 twin cam, dry-sump form (with other uprated bits, forged pistons, etc) and money.

I didn't believe it until I saw it myself last week and given me ideas for my Vauxhall version ;)  

[Myhinpaa]

Here's a cutaway drawing and photo of the single crank (!!) version of the Vauxhall V8, the revelation of the even more secret twin crank version intrigues me.....

[D-Type]

Well, I understood what Gregor meant - and I'm technically illiterate!  The crankshaft is the same design as the V8 as the slant four is effectively one bank of the V8.  Hence it needs balancing.

[mariner]

First thanks to everybody for their information on relatively obscure engine..

 

What originally interested me was the almost complete lack of racing success of the slant 4 compared to the first Lotus built  engine , the twin cam.

 

Obviously both were raced in the original Lotus cars in which they were installed but the twin cam won races in special saloons, modsports, sports racers and single seaters in huge quantities.

 

Never happed with the slant 4 . I guess the advent of the Cosworth BDA etc gave similar power in a lighter engine with  all of Cosworth's support behind it.

 

Still 350 bhp from 2.6 litres is amazing. that virtually the same bhp/litre as the Cosworth DFV - it shows what 40 years of tuner development and modern materials  can do. 

[Gregor Marshall]

Well, I understood what Gregor meant - and I'm technically illiterate!  The crankshaft is the same design as the V8 as the slant four is effectively one bank of the V8.  Hence it needs balancing.

I'm glad someone understood me being technically illiterate also!!
The crankshafts they use now are incredible and I was lucky enough to see how they have changed in 40 years and watch a new one on a dyno, with a G rig, really interesting.
My late father beat loads of BDA-powered 'specials', but I also get that the engine wasn't as competitive as it's Ford counterpart, but then nor were any other engines really. 
I would like to see the equivalent Ford and Vauxhall/Lotus engine, using modern technology and know-how, no-expense spared. I think the Ford would just have more outright power, but the slant would have more torque.

[BRG]

 I think the Ford would just have more outright power, but the slant would have more torque.

This was always the case, I believe, and is why the Lotus/Vauxhall engine was so successful in rallying compared to racing.  Torque is vital for rallying as you simply can't achieve the degree of accuracy on a rally stage practiced and perhaps driven just a couple of times, compared to multiple laps of a race track.  At a time when the BDA family of engines had largely topped out, the slant 4 came into its own in both Sunbeam and Chevette. 

[Myhinpaa]

And with a different crankshaft design (?) the Chevette HS engine would allegedly produce 310bhp?? 350+ as a 2.6......

Suddenly what previously prevented that head design from producing same bhp/litre as a BD have been eradicated.

 

I must add that many dynos must be overly optimistic, or tweaked!? https://www.britanni...pheric-pressure

 

I've seen BDGs coming with dyno graphs claiming 290bhp + but when put on the rollers installed they fail to get to 260 even, and after much tweaking.

That is not bad going for a 2 litre very drivable engine, but that's far more realistic than what the claimed figures says though.

 

As DTV team manager Gerry Johnstone pointed out when asked about the steadily raising bhp figures being claimed by Ford during '77.

WBB were quite happy then with the genuine 240 they had in the Chevette, and as pointed out above the greater torque makes much more of a difference.

 

Anyway, Johnstone replied : "What is power anyway? Last year I could get you 10bhp more just by opening the test cell door"

 

Partly that was due to ventilation system not working properly, but still.

 

The best 2.3 DTV Chevette rally engines produced at most 250, how to get an additional 60bhp seems completely beyond possible, when limited to MAX 9000rpm. 

 

I'm pretty sure Bill Blydenstein would have agreed to that.

 

Pipo who built the 306 Maxi kit N/A 2 litre engines for the works Peugeots claimed to nudge 300bhp for the late spec engines, but at 11 000rpm...

[Gregor Marshall]

And with a different crankshaft design (?) the Chevette HS engine would allegedly produce 310bhp?? 350+ as a 2.6......

Suddenly what previously prevented that head design from producing same bhp/litre as a BD have been eradicated.

 

I must add that many dynos must be overly optimistic, or tweaked!? https://www.britanni...pheric-pressure

 

I've seen BDGs coming with dyno graphs claiming 290bhp + but when put on the rollers installed they fail to get to 260 even, and after much tweaking.

That is not bad going for a 2 litre very drivable engine, but that's far more realistic than what the claimed figures says though.

 

As DTV team manager Gerry Johnstone pointed out when asked about the steadily raising bhp figures being claimed by Ford during '77.

WBB were quite happy then with the genuine 240 they had in the Chevette, and as pointed out above the greater torque makes much more of a difference.

 

Anyway, Johnstone replied : "What is power anyway? Last year I could get you 10bhp more just by opening the test cell door"

 

Partly that was due to ventilation system not working properly, but still.

 

The best 2.3 DTV Chevette rally engines produced at most 250, how to get an additional 60bhp seems completely beyond possible, when limited to MAX 9000rpm. 

 

I'm pretty sure Bill Blydenstein would have agreed to that.

 

Pipo who built the 306 Maxi kit N/A 2 litre engines for the works Peugeots claimed to nudge 300bhp for the late spec engines, but at 11 000rpm...

 

With all due respect, I know Gerry and I knew Bill very well and I'm sure they would both agree with that the figures that they had over 40 years ago were as good as it gets, but also very reliable and maybe not as optimistic as some other teams.
The best Old Nail engine apparently had 275bhp in 1976 - the best now, with modern technology is over 300bhp and I don't think that is from opening a rolling road door, just 40 years of development. 
Using modern technology, they would also now agree that more power is available - the crankshaft and being a lot stronger and the camshaft profiling being a lot more precise than being grinded originally in their kitchens (to go with the head flowing!!).
Look at all classic cars in modern racing, yes, tyres, brakes, fuel, tarmac, etc make a big difference now, but engines and engine reliability has to be the biggest improvement of all.
Bill very kindly lent me all of his paperwork/research back in the mid 1990s and I was just a spotty teenager, so in no way at all appreciated what I had been lent.
But, even now, I vividly remember reading his 1977 proposal to Vauxhall for a 4WD 2.6 Turbo-charged Chevette to beat Ford and all others; if you want, a Group B car before Group B was thought about and homologated and the reason it sticks in my memory so much, is this is when Mega Bertha was due to race in 1976 (and then 1977), with the proposal being either an 8.1 McLaren Nicholson V8 or a 2.6 turbo-charged slant 4, with the thought of 4WD.
I know my Dad wanted the V8, but the turbo 2.6 would've been a complete game changer in 1977, race and rally and is also why I think Bill went to Nissan after Vauxhall, as he could think about performance and economy and he had a fantastic little turbo-charged Corsa when he passed away.
Back to the Lotus/GM engine though - I really think that with marginal gains, using modern technology, that you would be really surprised with the power now and that they would easily compare incredibly favourably with the equivalent Ford, etc, especially the 2.5/2.6/3.0 Twin Cam Dry Sumps - speak to Mike Taylor at Lotus Bits.