Worst Engine Ever Made?

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Another vote for the slant-four Triumph. Had plenty of head gasket failures on our TR7. Got quite adept at taking the head off and fitting a new gasket. Could never get it to seal for more than a few months at a time. Stupid head bolt/stud arrangement, whoever designed that should have had their pencils confiscated. Had to fit a new short motor as well because the bores were worn out.

Also on the way to work early one Saturday morning, the cooling fan overcame the hold of the viscous coupling tolerance ring and smashed into the radiator before exiting the engine bay bouncing along under the floor before finally doing a pirouette in the rear-view mirror! Had to pull over, rescue the fan and go on to work hoping it wouldn’t boil over (which it didn’t). Spend the afternoon repairing radiator and welding the fan onto the coupling as temporary measure. Was amazing how much power was lost spinning it around full time.
 
What do you guys think is th engine we do the most work on in the MB range? Thats over the last 23 years.

I was going to say some Diesel variant with BluTEC, but BluTEC didn't exist 23 years ago...
 
I did the V8 conversion on a TR7 in my 20's - it was pretty straight forward IMHO.

Well Done!

From memory, there was a conversion kit available at a later date, but at the time it meant finding and fabricating lots of bits and adapters. Also the brakes needed upgrading, etc.
 
Another vote for the slant-four Triumph.

I had a Dolomite 1850 HL and had no problems with the engine in that ... they must have made a few good ones :D Actually I did have one interesting moment when I lifted off the throttle and the car continued to accelerate. After a bit of prodding I gave up and turned the ignition off ... luckily I was on a road where I was able to coast to a stop. The linkage between the two carbs had come undone, and the one that the cable wasn't attached to had gone wide open (it was sprung to do that rather than go fully closed?!).
 
Aside from their sojourn in the RO80, was the ****el Engine, ever used in any other context? Or did it just die a natural death?
As said above, Mazda made a quite successful one until about 10 years ago, emissions killed it as it has a long combustion chamber & also has to burn a little oil. All 4 major Japanese motorcycle manufacturers dabbled but it was only Suzuki that brought a production rotary motorcycle out (as well as smaller scale European manufacturers such as Norton, DKW & Van Veen). It was very complicated & didn't sell very well, in fact Suzuki lost a lot of money. The Citroen GS was originally going to have a rotary engine but they ran out of money during development & Peugeot weren't interested in it when they bought Citroen. So the engine ended up in the Van Veen OCR1000 motorcycle. Rotaries are still used in snowmobiles & chain saws. Rolls Royce even had a dabble with a diesel rotary back in the 1960s.
 
Mazda had several successful and reliable rotary engines right up to 2012 but for all it's positive qualities like smoothness and power they never manged to make it competitively economical on fuel and emissions were also a problem which eventually sealed it's fate. There is talk of a rotary engine being used as a range extender in an electric hybrid vehicle. In that role I imagine it's attributes of being small, smooth and quiet would make it a good application.
It was Audi who proposed a rotary as range extender - possibly due to access to NSU knowledge. Why though remains a mystery. The rotary's smoothness advantage is meaningless in a REx application as without torque reaction to resolve its mounts can be as soft as marshmallow - isolating the gruffest of engines. It's woeful fuel consumption in the context of a 'green' EV is baffling. That only left compactness as a virtue and that could have been sought elsewhere - delving into DKW's 2T experience would have been fruitful in that regard - in all regards!
 
I am (or rather, was) intimately familiar with both engines :)

In the early eighties I helped a friend who had a TR7 with the Triumph engine, replace it with the SAAB engine. The Triumph engine kept giving him grief, and when two exhaust valves burnt he decided he had enough and fitted the SAAB engine instead. It was hard work, the block was the same but the location of ancillaries was different - water pump, alternator, etc - which required fabricating flanges and brackets. But the SAAB engine never missed a bit. He also considered a V8 upgrade, but it was too complicated and too much work, so it didn't happen...
Evidence that the two versions were substantially different...

Ricardo's account in his autobiography of the conception of the two engines doesn't quite chime with Wikipedia's. But Ricardo was known to be a 'self publicist' and Wikipedia for its occasional lapse from veracity - who knows?
 
As well as calamities, there's also been neat detail touches in engines that largely go unnoticed.

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As here. Pistons in a Vortec 5.7l V8. The Vortec has 2 valves per cylinder, in line, slightly angled in their (wedge) combustion chamber. So why 4 clearance cut outs? Because it allowed GM to manufacture a single piston that could go in both cylinder banks without sacrificing the designated thrust face.


When GM wanted a V8 that would end up in FWD applications (eg, Eldorado) they wanted a lighter engine than the previous all-iron construction they had previously employed could afford. The obvious choice would have been to use alloy for the heads but that would have entailed fitting separate valve seats where iron had permitted cutting the seats directly into the head - a feature GM wanted to maintain. So it cast the block in alloy and developed the most minimal iron cylinder heads I have ever seen.

2k19_1.jpg


This engine endured until replaced by the Northstar itself a cleverly designed engine with its US market expectations in mind. Fatally flawed though with a head bolt corrosion problem. The same problem Mercedes would later repeat. Germany with its fabled NIH syndrome wouldn't look to the USA for inspiration - but it could at least cast a glance and avoid repeating its mistakes.

2 strokes 'live or die' by their exhaust design and SI versions can be categorised into three groups depending on the BMEP they operate at. 4, 7-8, and 11-12bar and that is dependent on the exhaust system utilised. The first category is chainsaw/strimmer types where the exhaust has to silence, reduce the fire risk, and above all be compact. The final category is all out performance demanding an expansion chamber per cylinder.
It is the middle 7-8 bar engines that are closest to road engines (in power characteristics) that employ a 'compact branch manifold' and were the mainstay of outboard motors for decades. Such manifolds only work on cylinder grouping of 3 and 4. So when Mercury produced its in-line 6 cylinder engine, why did it not configure at as 2 triples one after the other but instead had it as 3 twins? 3 180 degree twins with each pairing phased 120 degrees from its adjacent pair. This very slightly complicated the exhaust coupling requiring alternate cylinders to share a manifold. (cyls 1, 3 and 5 shared a manifold, cyls 2, 4 and 6 shared another). 2 triples one after the other would have been simpler.

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The reason for groping the cylinders as 3 twins was that the equal phasing across each twin allowed the sharing of a carburettors. Thus 3 carbs were sufficient and each would flow equally.
That engine was also monobloc ie, no separate cylinder head or vulnerable head gasket. The above picture shows all the castings it needed (the one that carries the 3 carbs also retains the crankshaft). The only additional one is the one that closes the exhaust manifold chest.
Clever design details I think. These engines were beautifully simple and could 'take 6000 rpm all day long'. Or at least until the fuel tank drained...
 
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What do you guys think is th engine we do the most work on in the MB range? Thats over the last 23 years.
OM642? It's been around since 2005, and an awful lot have been sold.
 
Mazda had several successful and reliable rotary engines right up to 2012 but for all it's positive qualities like smoothness and power they never manged to make it competitively economical on fuel and emissions were also a problem which eventually sealed it's fate. There is talk of a rotary engine being used as a range extender in an electric hybrid vehicle. In that role I imagine it's attributes of being small, smooth and quiet would make it a good application.
I had the Mazda RX7 Turbo in the late 80's and it was a very smooth quick engine.
But it dranK more fuel than my current E63 does. Economy wasn't its strong point.
 
Probably not the worst engine, but the one fitted to the Mk2 Lotus Cortina sure liked to overheat and the electrics were on par with Peugeot.
 
I removed the head from an Alfa Romeo DOHC engine... twice. The first time took one month, mind. The Alfa Romeo garage later told me I was mad - they just break it with a sharp chisel remove it in bits...
 
.....this chap is showing how to use a head removal tool:

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I've actually had this tool made.... it tore into the alloy head and stripped the threads....

Just so that you understand, the long iron studs are screwed into the alloy block. The alloy head has 8 long holes for the screws to go through, they are then tightened with nuts at the top.

The alloy head is then supposed to be lifted straight up.... but with the iron bolts corroded into the alloy head, it won't budge.
 
you will be familiar with this video then. ;)
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Suzuki used a rotary engine in one of their motorcycles - the RE5 I think it was.
Also Norton spent a lot of money on one for their motorcycles. I think it went into service with the police for a short while but never made it to the general market.

Edit: what a memory for useless information I have.
I believe Norton raced a rotary engined bike in BSB and GP for a while, with varying degrees of success.
 

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