M10 engine used by Lotus for racing?

[BarrettN]

I've been talking with someone who has a "race" engine - they were talking quickly enough that it was tough to keep track if  everything I remembered was related to this engine. From what I pieced together, it's an M10 engine that was used by\in a Lotus, the name Coventry Climax was mentioned as was Meras (I couldn't hear that part well - might be a name that sounds somewhat like this) - possibly it was used in Formula 500 racing (or the team that used it was involved in it, if not this engine) - reportedly it has 58mm(!!) DCOE Weber carbs and dynos out at 180hp.

 

The engine would be part of a package deal that might happen - anyone that can point me to or tell me more about this engine, that would be much appreciated. I really didn't want to reveal how ignorant I am about this, my part of the conversation was a lot of "a-ha" and "really"!?

 

Hopefully someone here can educate me so that I can negotiate from a point on understanding - I'm not as interested in this engine, at least at this point, as I am in the other items in the package deal - but maybe that changes when I know more about it.

 

Barrett

[73touring]

Possibly Chevron,. Lester Owen still or untill recently builds engines for them in the UK.  I think his standard race engine is approx 225bhp about 25k a build I think.  As for the coventry climax that's been the basis for quite a few engines the engine in the Hillman Imp (The mini beater)

[Mike Self]

2 hours ago, BarrettN said:

the name Coventry Climax was mentioned

The Coventry Climax engine was/is a twin cam four cylinder, about 1.5 liters that was originally built (in England) to power a fire pump (!) and was adapted by Lotus (and other manufacturers) to power race and street cars.  It shares nothing in common with a BMW M10 except that they're both OHC 4 cylinder engines.

 

I wasn't aware that Lotus ever put an M10 in a factory-built car, but I'm no Lotus expert.  However, engine swaps in race cars by private owners run the gamut so there may well be a Lotus powered by an M10 engine somewhere...

 

mike

[Preyupy]

The original “FW” series Coventry Climax engines were single overhead cam, non cross flow, alloy block. They were as small as 750cc and were used in stationary water pumps.  They were discovered by racers to be very light for the HP they developed. The engines were also used on a BEARCAT outboard boat motor.  They were expanded to 1100cc and became the engine of choice for a modified race car class that was under 1100cc.  It was then expanded to 1220cc for use in the 1959 Lotus Elite and also used in the under 1300cc racing classes. There are some that run as large as 1460cc and are very common in vintage racing in Lotus XI and Lola Mk1 in F Modified.  
 

Coventry made its 1st purpose built “race” engine called the FPF.  This was an alloy block DOHC cross flow, dry sump, 4 cylinder engine. They came in 1.5 liter, 2.0 liter. 2.5 liter and 2.7 liter (This was designed for Indy car racing). 
 

As far as a Lotus with a M10 BMW engine there were a couple of Lotus 23B sports racers built by the factory that used the M10 instead of the Kent Ford based “Lotus Twin Cam”. This was done when the class rules moved the engine displacement up from 1600 cc to 2000 cc.  The 1600 cc BMW did not make as much power as the Lotus Twin Cam and weighed about 20 lbs more but the Twin cam could not be enlarged to 2 liters and with the increase in displacement the BMW made enough more HP to offset the weight difference.  The direct competitor to the Lotus 23 was the Elva Mk7 and they came with a number of different engines depending on what class you were running.  The majority of the last 25 -30 cars came with the BMW M10  as well as the 3 GT160 coupes ( one actually ran at LeMans in 1964) 

[BarrettN]

It's looking like I'll be going to look at what all is included in this package deal, when I figure out what all it is I'll let everyone know. Thanks everyone for the help, knowing at bit about all this I can do some research and figure out what it's worth, and where it belongs to be in the right hands. 

[Preyupy]

I think what you misheard in that conversation was “Nerus” this was a company that was building M10 engines for racing and they had a 2 stage dry sump system that worked in the sports racers. They also were the 1st ones to actually build a 2 liter M10.  In 1964 BMW only made 1500, 1600, and 1800cc engines.  At that time the 1800 was a “long stroke” design that used the 1600 bore (84mm) and a 80mm stroke instead of the 71mm used on the 1600.  They figured out they could over bore the block to 89mm, that is a 5mm overbore!!  It wasn’t until 1966 that BMW started making a 2 liter 89mm bore, 80mm stroke and started casting the blocks with enough cylinder wall thickness so there was room to go past 89mm.  This is also the same time they started making a “short stroke” 1800 using the 89mm bore but using the 71 mm stroke from the 1600.  
 

As far as value for an original “Nerus” BMW it is not very much.  I seriously doubt that the block is original as there was no way to even go 1 oversize because the cylinder walls were to thin.  The chance hat a race engine from almost 60 years ago has not needed a rebuild is virtually 0.  The cylinder heads they used were 118 and the ports were very small and when they opened them up to basically the size of a stock 121 head (again this did not happen until about 1966) they did not live very long because they cracked.  The engines were mounted in the cars at about 12deg instead of the 30 deg tilt n the street cars so the intake manifolds are different to keep the carbs level as well as the oil pan pickup is in a different location.  Basically other than a piece of BMW history there is nothing on a original engine from back then that anyone would use in a car any longer.  The dry sump system uses the early gear type oil pump and then has a external single stage scavenge pump that is driven off the stock internal pump. Everyone in vintage racing around the world are running 3 stage external dry sump pumps, 2 liter blocks and heads ( 121, E12, E21, 1.8 ) and all of the modern cams, rockers, rods, pistons etc. 

[Preyupy]

Just now, Preyupy said:

I think what you misheard in that conversation was “Nerus” this was a company that was building M10 engines for racing and they had a 2 stage dry sump system that worked in the sports racers. They also were the 1st ones to actually build a 2 liter M10.  In 1964 BMW only made 1500, 1600, and 1800cc engines.  At that time the 1800 was a “long stroke” design that used the 1600 bore (84mm) and a 80mm stroke instead of the 71mm used on the 1600.  They figured out they could over bore the block to 89mm, that is a 5mm overbore!!  It wasn’t until 1966 that BMW started making a 2 liter 89mm bore, 80mm stroke and started casting the blocks with enough cylinder wall thickness so there was room to go past 89mm.  This is also the same time they started making a “short stroke” 1800 using the 89mm bore but using the 71 mm stroke from the 1600.  
 

As far as value for an original “Nerus” BMW it is not very much.  I seriously doubt that the block is original as there was no way to even go 1 oversize because the cylinder walls were to thin.  The chance hat a race engine from almost 60 years ago has not needed a rebuild is virtually 0.  The cylinder heads they used were 118 and the ports were very small and when they opened them up to basically the size of a stock 121 head (again this did not happen until about 1966) they did not live very long because they cracked.  The engines were mounted in the cars at about 12deg instead of the 30 deg tilt n the street cars so the intake manifolds are different to keep the carbs level as well as the oil pan pickup is in a different location.  Basically other than a piece of BMW history there is nothing on a original engine from back then that anyone would use in a car any longer.  The dry sump system uses the early gear type oil pump and then has a external single stage scavenge pump that is driven off the stock internal pump. Everyone in vintage racing around the world are running 3 stage external dry sump pumps, 2 liter blocks and heads ( 121, E12, E21, 1.8 ) and all of the modern cams, rockers, rods, pistons etc. 

 

You can used the Nerus valve cover, it’s a interesting piece  of history but about the only thing of value on that engine. 

[BarrettN]

It'll be interesting to see what it end up being, reportedly whatever it is it was freshly rebuilt before it was stashed away. It'll probably be until next month until I get a chance to go look at everything. 

[Lanny Clark]

Oh no. I have a Nerus engine that I have been saving for  my 1600 project. It was in an 1800Ti wrecked in the 70's.

[BarrettN]

14 hours ago, Lanny Clark said:

Oh no. I have a Nerus engine that I have been saving for  my 1600 project. It was in an 1800Ti wrecked in the 70's.

Interesting that it was in an 1800ti, based on that is sounds like someone figured out how to work around the difference in the mounting angle of the engine. 

[dirving]

     Don't mean to infringe on the original post. Might be interesting to see this Ginetta. Was at Limerock this years Vintage Festival. Sweet car. M10 powered.

[Preyupy]

All sorts of different engines were run in Sports Racers back in the day. There were no homologation rules, the classes were strictly based on displacement. A lot of cars were delivered with one engine and converted at some point to a different engine. Some were even delivered without any engine and the 1st owner got to pick which engine was used. For instance all but 2 of the Elva Mk8 chassis were built at the factory with M10 BMW engines, one of the 2 had a 215ci Buick V8 installed as the 1st engine the other one has had a number of engines including a Ford Capri V6, Buick V8 and it currently has a BRM 2 liter V8 F1 engine in it. 

[TobyB]

Quote

Might be interesting to see this Ginetta. Was at Limerock this years Vintage Festival. Sweet car. M10 powered.

I approve of their airbox!

 

t

 

[bimbill]

Also the nifty distributor housing that allows the distributor to be mounted horizontally vs. vertically.  I assume for bodywork clearance on the sports racers.

[Preyupy]

Yes most of the sports racers use that distributor housIng otherwise the cap would be sticking out of the bodywork.  I have a couple of them in my spares collection. That engine also has the modified front timing cover with the relocated water pump that allows the engine to be mounted closer to the bulkhead behind the driver, it actually pumps the water into the engine through one of the freeze plug holes under the header.  Also notice how the engine is much more upright than they way it is mounted in the street cars.  That is an Elva Mk7 I would have to check the chassis number but it might have been one of the cars originally built with the BMW engine.  A lot of the early cars had BMW engines fitted later in their life. 

Edited September 30, 2020 by Preyupy