47 replies to this topic

[Roger Clark]

The early Climax FWMV engines had 2-plane crankshafts and a convoluted exhaust system that ended in two megaphones over the gearbox.  This was apparently to allow pipes from cylinders in opposite banks to be linked to the benefit of gas extraction from the cylinders.  In 1963, Climax produced a single-plane crankshaft, initially at the request of Ferguson who were planning to fit a V8 in their front-engined P99.  The first single-plane crank appeared during practice for the Belgian Grand Prix in Bonnier's Cooper.  Its first race appearance was the Dutch Grand Prix in Gurney's Brabham.  I have never seen a photograph of the rear of Bonnier's car but slender, low-level megaphones.  Apparently the single-plane crank made the linking of exhausts unnecessary.   

 

Climax found that the expected vibration problems with a single-plane crank did not materialise and we are told, by Walter Hassan among others. that all new engines from autumn 1963 onwards had single plane cranks.  Many early engines were converted to single-plane cranks.  during 1964 and 65, Team Lotus cars often had low-level exhaust and it was common then and now to refer to those as having single-plane cranks and the high level exhausts as 2-plane cranks.  Apart from those few 1963 races in Gurney's car and the rare and brief appearances of the 32-valve engine in 1965, I can't recall seeing a Brabham-FWMV with low level exhausts and never a Cooper so fitted.  

 

I know that none of these three teams were flush with money at the time but is it really possible that they continued to use two-plane cranks to the end of 1965 - or did they continue with high-level exhausts even when they were no longer necessary?  Simon Hadfield once told me that FWMVs in historic racing all use single plane cranks and those that I have seen don't link the exhausts.  Were they doing the same in 64-65?  If so, descriptions  such as "Clarks car had a single-plane crank while Spence had an old 2-plane crank" must be doubtful.

 

My tired old brain aches even more when it comes to BRM.  They also started with 2-plane crankshafts  and changed to single plane in 1963.  It appears that they adopted linked exhausts at the same time, although the linkage was underneath the engine, so not normally visible.  Is it really true that Climax dropped linked exhausts when they changed to single plane cranks while BRM changed to linked exhausts at the same time?

 

To make matters worse, I believe that some H16 engines had linked exhausts on the bottom bank but not the top!

[Ray Bell]

Sorry to see you've had no responses here, Roger...

 

It's certainly an intriguing little issue. I'd imagine that exhaust scavenging efficiency couldn't be at the top level with crossover exhausts on a flat plane engine.

 

Repco, Cosworth and others tend to appear to agree.

[blueprint2002]

The early Climax FWMV engines had 2-plane crankshafts and a convoluted exhaust system........

To some extent, my initial post in the thread entitled “Racing V8 Engines”, in the Technical Forum, has briefly discussed single-plane and cross-plane crankshafts and their respective impact on the engine and on the complete car.

But your post views the matter from a rather different angle, which brings out additional aspects.

Coventry Climax V8

As you have pointed out, contemporary accounts and photographs seem to indicate that the single-plane engines were used almost exclusively by Lotus (mostly for Jim Clark), with the exception of one or two early examples in Brabham/Cooper cars.

Perhaps the chief advantage of the single-plane crankshaft is that each bank of cylinders becomes, effectively, an independent four-cylinder engine, and its exhaust system can be configured accordingly: 4-into-1 for best performance. With this in mind, it would be counterproductive to cross-connect the exhaust of the two banks together, and it doesn’t seem possible that this could have been done. To my mind, an engine with a low-level, 4-into-1 system on each side must have a single-plane crankshaft; one with the pipes from both sides meeting and blending above the gearbox, equally, must have a cross-plane crankshaft. (This is for engines where ultimate performance is essential).

I am no historian, so cannot reconcile this with the statement that most of the later engines were single-plane, perhaps someone else has access to data that might clear this up.

 

BRM V8

The BRM P57 appears, from contemporary photos and cutaway drawings, to have had either low-level individual stub pipes terminating below the rear wheel centreline, or the more obvious “Pan Pipes” which were also individual, rather longer, and swept upwards and backwards. Certainly, neither of these expedients was ideal from the performance aspect, and it wasn’t surprising that BRM redesigned the engine to address this, and at the same time integrate it with the chassis.

The P61 used an early version of the single-plane engine, with the induction ports at the top, inside the V, and the exhaust ports outside the V. With this arrangement, a 4-into-1 system on either side was naturally provided, the header pipes routed between the tubes of the subframe that carried engine and rear suspension.

As I understand it, this was none too satisfactory, and sometime in 1964 the P261 appeared, with full monocoque chassis (no tubular subframe) and revised engine. The key feature of this new engine was the cylinder head, with exhaust ports inside the V, and downdraught inlet ports, in between the two camshafts. But with the single-plane crankshaft, each bank still had its own 4-into-1 exhaust system, only they were now located within the V, right next to one another. [This contrasts with the Indy Ford DOHC V8, which had similar cylinder heads, but a two-plane crankshaft; hence the exhaust systems were interlaced to merge two headers from each side, what you might call a 2x (2+2)-into-1 system].

I think there was a kind of interim P261, with the earlier single-plane engine, its exhaust header pipes passing through a neat slot built into each of the monocoque “wheelbarrow arms” that cradled the engine, and then blending into the tailpipe, low down on either side.

The final version of the engine, as described above, dispensed with this lash-up, the monocoque running uninterrupted to the rearmost bulkhead, providing the maximum possible strength and stiffness, while the exhaust system was tucked neatly behind the driver’s head and shoulders, out of the direct airstream.

 

BRM H16

I had no idea of what you have described; thanks for opening up a new area for me to explore. Hope I’ll be able to get a grip on this.

[Pat Clarke]

I recall looking at a CC V8 in a Lotus in the Donington Museum several years ago.

 

It had high pipes and looked as we remember the linked exhausts.

But closer inspection showed the exhausts were not linked, just arranged above the gearbox looking like the earlier system.

 

Pat

[Roger Clark]

Thank you for your replies. 
 

As Ray implies, the Cosworth and Repco engines had single plane cranks so the question of linked exhausts didn’t arise. I don’t know about the Ferrari 158 but I imagine that it also had a single lane crank. 
 

I think it is safe to assume that any FWMV engined car with low level exhaust has a single plane crank. My speculation was whether the reverse is true - does a high level exhaust always mean a single plane crank?  It should be possible to see whether later Brabhams and Coopers still linked the exhausts but I have not found suitable photographs. It might have been easier for space frame cars to build a low level exhaust than the monocoque Lotus. 
 

For BRMs, most of my information comes, as always, from Doug Nye’s three-volume history.

 

In Volume 2 he describes development of the single plane crank in 1963, significantly hampered by deficiencies in parts supplied by Weslake. He quotes Tony Rudd’s report to Sir Alfred after the 1963 Lombank Trophy (page 209): “Both cars were fitted with full 1963-type engines with single-plane crankshafts, coupled exhausts, cast iron oil pumps and integral oil filters.”  

 

In Volume 3, page 203 there are extended quotes from Geoff Johnson, engine designer at the time. “The formula 1 V8 engine had begun life with a two-plane crankshaft and individual exhaust stacks. Later the single plane crankshaft had been designed for the engine, allowing a coupled exhaust system between banks to benefit from the pulsing effect of two cylinders which can increase horsepower”. 
 

I have no sources for what I said about the H16.  We’ll probably have to wait for Volume 4 for that. 
 

I think that most of the pushrod Ford V8s used in the 60s GT programme had linked exhausts. The only exception I know of is the 1966 J-Car but the Mk IV reverted to linked exhausts. 
 

It all seems like a proverbial can of worms, an appropriate metaphor for some of the exhaust systems in more ways than one. 

[blueprint2002]

I recall looking at a CC V8 in a Lotus in the Donington Museum several years ago.

 

It had high pipes and looked as we remember the linked exhausts.

But closer inspection showed the exhausts were not linked, just arranged above the gearbox looking like the earlier system.

 

Pat

 

 

Thank you for your replies. 
 

As Ray implies, the Cosworth and Repco engines had single plane cranks so the question of linked exhausts didn’t arise. I don’t know about the Ferrari 158 but I imagine that it also had a single lane crank. 
 

I think it is safe to assume that any FWMV engined car with low level exhaust has a single plane crank. My speculation was whether the reverse is true - does a high level exhaust always mean a single plane crank?  It should be possible to see whether later Brabhams and Coopers still linked the exhausts but I have not found suitable photographs. It might have been easier for space frame cars to build a low level exhaust than the monocoque Lotus. 
 

For BRMs, most of my information comes, as always, from Doug Nye’s three-volume history.

 

In Volume 2 he describes development of the single plane crank in 1963, significantly hampered by deficiencies in parts supplied by Weslake. He quotes Tony Rudd’s report to Sir Alfred after the 1963 Lombank Trophy (page 209): “Both cars were fitted with full 1963-type engines with single-plane crankshafts, coupled exhausts, cast iron oil pumps and integral oil filters.”  

 

In Volume 3, page 203 there are extended quotes from Geoff Johnson, engine designer at the time. “The formula 1 V8 engine had begun life with a two-plane crankshaft and individual exhaust stacks. Later the single plane crankshaft had been designed for the engine, allowing a coupled exhaust system between banks to benefit from the pulsing effect of two cylinders which can increase horsepower”. 
 

........

Coventry Climax

Pat Clarke’s response indicates that an exhaust system that starts low and finishes high, with both sides nearly meeting above the gearbox, doesn’t necessarily have to couple headers from both sides (as I had always thought). Hence, high level tailpipes near the centreline could just as well indicate a single-plane, as a cross-plane engine. Which, perhaps, was the system adopted by Brabham and Cooper, and on occasion, by Lotus.

This, however, would mean that the header pipes, before they merged into one, each side, would be much longer than those in a system that stays low on either side. This would have an effect on the torque and power curves, in the sense that the peaks would be shifted along the RPM axis, downward seems probable. Hard to say whether those peaks would be higher, the same, or lower; trials might be the only way to find out.

 

BRM

From the context, my guess is that Rudd’s reference to coupled exhausts means the 4-into-1 system, as opposed to the individual pipes per cylinder that the first BRM V8 seems always to have been fitted with.

Accounting for Johnson’s fairly explicit statement is more difficult, except that it appears to have been made about half a century after the events, and memory could conceivably be less than dependable. No disrespect intended, that happens to all of us.

But it’s now nearly 60 years since the time, and we can safely say, from at least a hundred types of racing/high performance fours, used in cars and motorcycles, that the best exhaust system is always 4-into-1 or 4-into-2-into-1. And from several dozen types of racing/high performance V8s, all with single-plane crankshafts, that the same sort of exhaust system (as on the fours) is always fitted on either bank.

It isn’t difficult to understand why. Cylinders 1 and 4 open their exhaust valves 360 degrees apart, as do cylinders 2 and 3. So that, no matter how extreme the exhaust-open duration, they will never be open together. Even the 180-degree separation between, say, 1 and 2, is nearly good enough, because the pressure in cylinder and pipe drops so quickly, after the exhaust valve opens.

On the other hand, the 90-degree separation that is possible with left and right bank exhaust coupled together, is not good enough, because the pressure doesn’t drop that quickly. So even if BRM experimented with such systems, they wouldn’t have taken long to come to the same conclusions as everyone else did.

[Roger Clark]

Pat Clarke's observations match my understanding; that FWMVs in historic racing have unlinked high-level exhausts.  I can understand that; owners of historic cars would want them to look as much as possible like they originally did.  I can't understand why teams in 1964-65 would do the same.  Wouldn't the high level exhausts be heavier and more difficult to install as well as possibly restricting the flow of gas in the tight twists?

 

It is possible that Tony Rudd was referring to a 4-into-1 system but BRM had used such exhausts in 1962.  The first low-level system to replace the vertical pipes appeared in practice for the Monaco Grand Prix and was raced from the Belgian Grand Prix.  Doug Nye says: "The low-level exhaust system was finalised with four-down-and-back primary pipes discharging into a large de-harmonising box. feeding a 2.5inch diameter tailpipe.  The box volume equated tote cylinders since the problem was that two adjacent cylinders fired simultaneously - described as 'port robbing in reverse'.  The downswept system gave an extra 2-3bhp in the 9,500-10,000rpm range.  A megaphone was tried and proved no better."

 

Photographs show that this system was used at Spa and Rouen.  Later in 1962 they adopted another system, with no pipes visible beyond the rear on the engine.  They could have been individual stub pipes. Doug Nye does say that BRM experimented with a cross-over system in early 1963: "they were trying to make a developed copy of the Climax cross-over exhaust system, using tapered pipes..."  this could have been with 2-plane crankshafts.

[Doug Nye]

Presently I just don't have the intestinal fortitude to address this topic - it is something of a moving target on both V8 and H16 engines.

 

Here's a Revs Digital Library photo of a Team Lotus FWMV V8 engine with cross-over linked manifolding...

 

 

And - also from the Revs Digilib - BRM H16 - precious little space for exhaust interlinkage beneath the lower banks.

 

 

[url=https://postimages.org/]

 

DCN

[Sisyphus]

I pulled out my August, 1966 Road & Track which had a rather extensive and interesting article on the H16 by Joseph Lowrey.  There is a nice illustration of the layout of the two flat plane cranks and pistons.  The two cranks had their throws 90 degrees out of phase and it was noted each 4 cylinders share a common exhaust manifold (sic).  The was quite a bit of discussion about vibration issues in early running and that 2 plane cranks were being looked at the expense of complicating the exhaust header design.

 

Here's a link to a scan of that article: https://postimg.cc/gallery/448GxXr

 

This was an early article so I imagine quite a bit of development and changes went on in '66 and '67 which I look forward to learning about in Vol 4...

Edited by Sisyphus, 20 January 2021 - 22:49.

[Lee Nicolle]

On production based engines, at least for Nascar 'pan warmers' were tried and proven. But the gains were small and having the engine lower in the chassis was more advantageous.

I have seen them used on speedway sedans but again the gains were not worthwhile.

[blueprint2002]

Pat Clarke's observations match my understanding; that FWMVs in historic racing have unlinked high-level exhausts.  I can understand that; owners of historic cars would want them to look as much as possible like they originally did.  I can't understand why teams in 1964-65 would do the same.  Wouldn't the high level exhausts be heavier and more difficult to install as well as possibly restricting the flow of gas in the tight twists?

Doug Nye says: "The low-level exhaust system was finalised with four-down-and-back primary pipes discharging into a large de-harmonising box. feeding a 2.5inch diameter tailpipe.  The box volume equated tote cylinders since the problem was that two adjacent cylinders fired simultaneously - described as 'port robbing in reverse'.  

Yes indeed the high-level exhausts would have all the drawbacks you mention. Whether or not a loss of power would result is hard to say. The behaviour of such multi-branch systems can be baffling.

Could there be a typographical error in DCN's second sentence, as it is rendered here?  

[Roger Clark]

Yes indeed the high-level exhausts would have all the drawbacks you mention. Whether or not a loss of power would result is hard to say. The behaviour of such multi-branch systems can be baffling.
Could there be a typographical error in DCN's second sentence, as it is rendered here?

Yes - he wrote "The box volume equated to two cylinders since the problem was that two adjacent cylinders fired simultaneously - described as 'port robbing in reverse'."

My mistake.

[Doug Nye]

Excused Roger.

 

DCN

[JtP2]

an interesting photo of the Lotus 25/33. The photo is post the French GP64 and the engine is definately a 2 plane crank. So not all Lotus engines were fitted with single plane cranks as late as mid 64. Mechanics must have been relieved not to do an engine swap on a 2 plane crank engine, imagine having to sort out that spaghetti. The other point of note is the unplated upper radius rods on the rear suspension, long after everything must sparkle from Chapman.

[Roger Clark]

https://library.revs...ion=p17257coll1

 

Hopefully, this links to a revslib photo of Gurney’s Brabham at Monaco in 1964. 

[blueprint2002]

Yes - he wrote "The box volume equated to two cylinders since the problem was that two adjacent cylinders fired simultaneously - described as 'port robbing in reverse'."

My mistake.

"two adjacent cylinders fired simultaneously"?

Not impossible, since two pistons do come to TDC together, in either single-plane or cross-plane engines. Most unlikely, however, because it throws away one of the important advantages of having all those cylinders.

[Pat Clarke]

https://library.revs...ion=p17257coll1

 

Hopefully, this links to a revslib photo of Gurney’s Brabham at Monaco in 1964. 

That exhaust looks very similar (but not identical) to the system I saw on the Lotus at Donington.

 

Pat

[Roger Clark]

"two adjacent cylinders fired simultaneously"?

Not impossible, since two pistons do come to TDC together, in either single-plane or cross-plane engines. Most unlikely, however, because it throws away one of the important advantages of having all those cylinders.

The Geoff Johnson piece that I mentioned earlier says that the firing order of the 90-deg shaft was 1-5-4-8-7-2-6-3; the single plane was 1-8-3-6-4-5-2-7

[JtP2]

"two adjacent cylinders fired simultaneously"?

Not impossible, since two pistons do come to TDC together, in either single-plane or cross-plane engines. Most unlikely, however, because it throws away one of the important advantages of having all those cylinders.

 

Honda big bang engine for CART?

[Macca]

In "It Was Fun!" by Tony Rudd (with DCN), he said he was obsessed with the C-C linked primaries and tried it on his testbed but couldn't get the primary lengths he needed for the BRM V8 when fitted in a car.

 

Then it gets very complicated with Owen Organisation politics over the question of whether Bourne or Weslake did research and made 4-valve heads.

 

Richie Ginther suggested reversing the heads so the exhausts would be in the vee and could be linked, and Rudd let him use the new engine in the US and Mexican GPs of 1964 out of fairness, although Richie had now signed for Honda.

 

I remember being surprised to see a photo of Chris Amon in a Parnell Lola-Climax from 1963 with low exhausts, but someone pointed out he had an early flat-crank engine.

 

Then I saw an FWMV in the Donington Collection with the pipes obviously separate: 

 

I don't know all the details of the FWMVs used in historic racing and how many are flat-crank, or indeed how original any of the engines or exhaust systems are, but looking thought my photos I found these:

 

Brabham BT3

 

 

 

  various Lotus 24's

 

And I also found this pic I took at the Revival of one of the earliest GT40s:

 

 

but when Ford did the centre-exhaust 4-valve Indy engine, did they cross-link the headers? The reduced-size engine in the 1966 McLaren that was in the Donington Collection did not appear to have them:

 

I don't have BRM V3 to hand, nor do I have an adequate photo of a centre-exhaust P261, but the cover photo of the April 1965 Motor Sport shows an engine on test and the exhaust headers do not appear to be crossed at all.

 

Paul M

[Roger Clark]

Trying to find more about the Climax engines used by Brabham cars, I came across some information which may be of passing interest.

 

Doug Nye's History of the Grand Prix Car 1945-65 tells us that Brabham bought two MkII FWMVs in 1962, one MkIII (short stroke) in 1963 and one MkIV (ultra-short stroke) in 1964.  It was normal for Climax to update early engines to later specification.  Climax also produced a single MkV in 1964 with the same bore and stroke as the MkIV but larger valves.  It apparently developed 3bhp more than the MkIV.  I don't know where it went but Lotus had two MkIVs and Cooper were already fading by then.

 

The Jack Brabham column in Motor Racing tells us that they changed engines in both cars between practice and the race at Monaco 1964.  He also says that Dan used the same engine at Spa and Rouen and we all know how well he went in those races.  He didn't say whether Dan had an engine change between Monaco and Spa but it would be unusual in those days to change an engine after a single race.  Gurney retired in Monaco with transmission trouble.  Brabham also says that the engine developed 9bhp less when returned to Climax after Rouen than it did before leaving for Belgium.

 

Nothing about which engine he used and whether it had flat or 2-plane crankshaft but I'm sure that Dan Gurney would have had the best available to BRO.

[Pat Clarke]

 

 

 

That is the Lotus I referred to earlier.

Non linked header pipes, but somewhat assymetric.

 

Pat

[Concreteconrods]

I recall talking to one of the mechanics at Hoole Racing a few years ago that they built some new Climax FWMV engines at their Kimbolton workshops. I don't know what crankshaft type they used in those engines.

Edited by Concreteconrods, 22 January 2021 - 10:15.

[Macca]

Having now checked 'Lotus. The Indianapolis Years' by Andrew Ferguson (with DCN), the 4-cam 4-valve Fords did have cross-linked headers.

 

The reduced-capacity version first used by McLaren in 1966 at Monaco did not have cross-linked headers, but when it reappeared for the US and Mexican GP towards the end of the year it had revised exhausts that were now cross-linked.

 

Paul M 

[Sisyphus]

Trying to find more about the Climax engines used by Brabham cars, I came across some information which may be of passing interest.

 

Doug Nye's History of the Grand Prix Car 1945-65 tells us that Brabham bought two MkII FWMVs in 1962, one MkIII (short stroke) in 1963 and one MkIV (ultra-short stroke) in 1964.  It was normal for Climax to update early engines to later specification.  Climax also produced a single MkV in 1964 with the same bore and stroke as the MkIV but larger valves.  It apparently developed 3bhp more than the MkIV.  I don't know where it went but Lotus had two MkIVs and Cooper were already fading by then.

 

The Jack Brabham column in Motor Racing tells us that they changed engines in both cars between practice and the race at Monaco 1964.  He also says that Dan used the same engine at Spa and Rouen and we all know how well he went in those races.  He didn't say whether Dan had an engine change between Monaco and Spa but it would be unusual in those days to change an engine after a single race.  Gurney retired in Monaco with transmission trouble.  Brabham also says that the engine developed 9bhp less when returned to Climax after Rouen than it did before leaving for Belgium.

 

Nothing about which engine he used and whether it had flat or 2-plane crankshaft but I'm sure that Dan Gurney would have had the best available to BRO.

 

Walter Hassan wrote an SAE paper, number 660742, with a significant amount of detail on the design and development of the 4, 8, and 16 cylinder Climax engines for those interested.  The paper is still available from SAE. 

 

There is no info on which teams got what engines but the development of the different marks (9 in total, plus the 16 cyl) is covered--2 valve to 4 valve, stroke length, 90 deg and 180 crank, etc.

[bradbury west]

I looked through my copy of that earlier today in the hope of finding something relevant. It is always a fascinating read. The only point which I thought  perhaps pertinent here was  WH’s assertion that the length of the primary pipes was especially critical in whatever  iteration, including  16 cylinder, so the  various pipe work configurations would or should be critical,  notwithstanding installational or locational complications.

Roger Lund

[blueprint2002]

The Geoff Johnson piece that I mentioned earlier says that the firing order of the 90-deg shaft was 1-5-4-8-7-2-6-3; the single plane was 1-8-3-6-4-5-2-7

The single-plane firing order is the same as that used by Cosworth for the DFV. Their numbering system was: 

Right bank, front to rear, 1 to 4

Left bank, front to rear, 5 to 8.

Would you know if BRM used the same system?

[blueprint2002]

Honda big bang engine for CART?

Assume you are referring to the V8 of around 1994 to 2001. I have little or no information about this; can you point me towards some useful references? Thanks.

But in any case, the first ever big-bang engines, I believe, were Honda two-stroke 500GP motorcycles, around 1988. 

The BRM V8s date from 1962 to 66, much before that. 

[blueprint2002]

Walter Hassan wrote an SAE paper, number 660742, with a significant amount of detail on the design and development of the 4, 8, and 16 cylinder Climax engines for those interested.  The paper is still available from SAE. 

 

There is no info on which teams got what engines but the development of the different marks (9 in total, plus the 16 cyl) is covered--2 valve to 4 valve, stroke length, 90 deg and 180 crank, etc.

Now that is certainly worth a read. Thoroughly professional.

[Macca]

The Honda NSR500 with the Big Bang firing order appeared in 1992; the reasoning was not to get more power but because they had more than they could use at that time and it made the engine more user-friendly and less prone to suddenly breaking traction.

Paul M

[Roger Clark]

Hassan also wrote a pair for the SAE National Powerplant engines, October 31 - November 2 1960.  It also covered non-racing engines.

[dolomite]

Here is a BRM P261 that I photographed at Castle Combe in 2015, which presumably would have the same layout as used in period

[JtP2]

Assume you are referring to the V8 of around 1994 to 2001. I have little or no information about this; can you point me towards some useful references? Thanks.

But in any case, the first ever big-bang engines, I believe, were Honda two-stroke 500GP motorcycles, around 1988. 

The BRM V8s date from 1962 to 66, much before that. 

 

Long time ago. But as remember it the engine was timed so that 2 cylinders fired together and worked like a big 4. It traded off peak power for torque on street circuits where torque was more important out of slow corners. Reading Hassan's book; he always seemed more interested in torque against peak power.

[blueprint2002]

The Honda NSR500 with the Big Bang firing order appeared in 1992; the reasoning was not to get more power but because they had more than they could use at that time and it made the engine more user-friendly and less prone to suddenly breaking traction.

Paul M

Much discussion, in the specialist media, about the way it worked, at the time. The best and most lucid explanation, to my mind, being that by Kevin Cameron, probably in the pages of "Cycle World".

[blueprint2002]

Long time ago. But as remember it the engine was timed so that 2 cylinders fired together and worked like a big 4. It traded off peak power for torque on street circuits where torque was more important out of slow corners. Reading Hassan's book; he always seemed more interested in torque against peak power.

As I understand it, the "Big Bang" engine in racing motorcycles crowded the firing impulses close together over a limited part of the complete engine cycle (i.e. 720 crankshaft degrees for the 4-stroke, 360 for the 2-stroke). By that definition, evenly-spaced firing (of two cylinders at a time) as you have described, is not quite the same thing, though it's perfectly possible that Honda found it convenient to say it was. Or, even more likely, some journalist thought it was, and then the misconception spread.

[10kDA]

As I understand it, the "Big Bang" engine in racing motorcycles crowded the firing impulses close together over a limited part of the complete engine cycle (i.e. 720 crankshaft degrees for the 4-stroke, 360 for the 2-stroke). By that definition, evenly-spaced firing (of two cylinders at a time) as you have described, is not quite the same thing, though it's perfectly possible that Honda found it convenient to say it was. Or, even more likely, some journalist thought it was, and then the misconception spread.

Yamaha and Suzuki developed their own, IIRC before the season was out. I had never heard of the CART Honda Big Bang engine but if they were calling their bike engine that, it stands to reason they would apply it to their car engine. It's wise to recall that before, during and after that time frame Honda inserted "spin" into everything they uttered, and likely today as well. Those of us riding other makes considered their "spin" to be just plain "deception".

[Roger Clark]

I have been trying to identify appearances in 1963 of FWMVs with low-level exhausts which I take to imply a flat-crank engine.  The main sources were race reports in Motor Sport and Motoring News, backed up by photographs wherever possible. I am lacking information on some of the smaller non-championship races.  As always, our knowledge of races in this period depend on whether Denis Jenkinson was there.   Gregor Grant's Autosport rarely had this kind of information.  There were more appearances than I expected; I would be grateful for any corrections or additions.

 

Rob Walker   The first appearance of a flat-crank engine was in Walker's new T66 Cooper at the Belgian Grand Prix,  Bonnier practiced the car but raced the older T60, as he did at the Dutch and French Grands Prix. He raced the T66 with low-level exhaust in the British Grand Prix but retired with engine problems. DSJ's race report said that Bonnier switched off when the oil pressure fell but in his German Grand Prix report he said that the car had run its bearings at Silverstone.  Bonnier raced the T60 at Solitude.  The T66 appeared again at the German Grand Prix but with a high-level exhaust.  The Motor Sport report of the Mexican Grand Prix (writen by MJT,  Michael Tee) said "the flat crank engine used at Watkins Glen had been replaced by a normal engine as the timing gears on the latter were not 100%". I haven't found any photographs of Bonnier at Watkins Glen which show the exhausts.  

 

Parnell  Chris Amon's Lola had low exhausts at the British Grand Prix, Solitude, German Grand Prix and Austrian Grand Prix.  He crashed and injured himself in practice for the Italian Grand Prix.  Masten Gregory drove the car at the US and Mexican Grands Prix.  A photograph shows that he had low-level exhausts at Watkins Glen but I haven't found any suitable photographs of him in Mexico.

 

Brabham  The first race appearance of a flat-crank engine was in Gurney's Brabham at the Dutch Grand Prix. He had had engine trouble in practice and the new engine was flown from Coventry and fitted the night before the race.  He raced with it in the French and British Grands Prix.  At Silverstone the engine blew up in a very big way.  The Jack Brabham column in Motor Racing said that he had never seen such a comprehensive blow-up.  DSJ said that the only part salvageable was one cylinder head.  

 

DSJ said that during practice for the Italian Grand Prix: "Gurney turned out in the latest Brabham  with single-plane Climax V8 and Hewland-VW gearbox". I don't think there's any suggestion that Brabham had a new car at Monza but Gurney's usual car was BT7 F1-1-63 and Brabham's was F1-2-63 so DSJ's statement could mean that Gurney tried Brabham's car.  There are many photographs of Gurney in the race showing that he had high exhausts.  Jack drove the old BT3 at Monza; it may be that Brabham wanted both BT7s to be available for Dan Gurney in case of problems on the rough banking - which was abandoned after first practice.  Jack drove a BT7 with low exhausts at the Oulton Park Gold Cup; there is a very clear photograph in MN.  MJT's reports in Motor Sport said that Brabham had a flat crank engine at the US and Mexican Grands Prix.

 

Team Lotus  A bit of a mystery here.  Jim Clark drove a new 25, R6, in the Austrian Grand Prix.  It had a Hewland gearbox - a first for Lotus - and a low-level exhaust.  As far as I know, the appearances of R6 towards the end of 1963 were the only time a works Lotus used a Hewland box during the 61-65 formula.  R6 was a spare car at Monza.  Jim Clark tried it in practice but had problems with the Hewland gearbox.  MN said that the car had a flat-crank engine but there is a photograph in the same edition of a 25 with Hewland gearbox and high level exhausts!  There is also a photograph in Theme Lotus of a 25 with Hewland gearbox and high-level exhausts. The caption says it is 1963. Trevor Taylor drove R6 in the remaining 1963 races but I haven't found photographs showing the exhausts.  R6 became Jim Clark's regular car in the first part of 1964 but by that time it had a ZF gearbox.

 

Cooper  MJT's Motor Sport report said that McLaren had a flat-crank engine at the US Grand Prix.  I haven't found a photograph.  The same author's Mexican Grand Prix report in MN said that a new engine had been fitted since Watkins Glen.

[Ray Bell]

With the flat plane crank it was still possible to have high exhausts, Roger...

 

It's just that they weren't tied from one bank to the other, as shown in the fourth and fifth photos in Macca's post.

[Roger Clark]

I know that Ray and I think it was quite common from 1964 and almost universal in today's historic racing - as shown in earlier posts on this thread including Macca's.  I thought that flat-crank engines in 1963 all had low-level exhaust.  That is true for most of the cars I mentioned  and I thought that the MN picture of R6 at Monza showed linked exhausts.  It is not conclusive.  I have looked more closely at Jim Clark in Austria and he clearly had a high-level exhaust so it is possible that R6 was always that way.  More photographs would be useful.

[Macca]

1963:-

6312 Bel TCooper T60 zps9cd732e2 — Postimages (postimg.cc)   Bonnier in T-car at Spa (different engine cover): high exhausts

 

6311mex bonniersu6 — Postimages (postimg.cc)  Bonnier at Mexican GP; high exhausts

 

6318 Mex zkil — Postimages (postimg.cc)  Amon in Mexico, low exhausts

 

6317 gregory1963lolamkivclim[1] — Postimages (postimg.cc) Gregory in Mexico, low exhausts

 

6305 USA Brabham (1963) Brabham BT7 Watkins Gl — Postimages (postimg.cc)  Brabham at Watkins Glen - look like low exhausts

 

Copyright of all those rests with the original owners. I couldn't find any good ones of McLaren at the Glen or Gurney in practise at Monza.

 

Sadly I don't have access to all the Autosports, MN's, Autocars or Motors from the 1960s.

 

Here is a photo from 2005 of Sid Hoole's Cooper T66 that I took, showing separate headers:

 

 

Paul M

Edited by Macca, 29 January 2021 - 17:07.

[Roger Clark]

Thanks for that.

 

The Walker Cooper photo is the T66.  I think it is Alf Francis, certainly not Jo Bonnier, at the wheel.  I have found another photo of the car at Spa in Motoring News, a week after the race report.  It shows even more clearly the high exhausts.

 

Thephoto of Amon in Mexico is a Lotus-BRM which he drove in the race.

[Macca]

https://aminoapps.co...1gvm55M4eBadR7e

The picture of car 18 appears to show different intakes so maybe a FWMV, and low exhausts (and rain).

Paul M

Edited by Macca, 29 January 2021 - 21:04.

[Roger Clark]

They look the same to me. It rained during practice for the Mexican Grand Prix. 
 

in reading about this race I found another instance of a flat-crank engine. Maggs borrowed Walker’s after problems in practice. He retired on the eight lap when the bearings went. Was that a particular problem with early flat-crank engines?

[Ray Bell]

Possibly a problem related to a hasty installation?

 

In such an instance it would not surprise me that they'd compromise and use the wrong exhaust system.

[Roger Clark]

Could the wrong exhaust system cause bearing failure?  I asked the question because Bonnier suffered bearing failure at Silverstone.  I think there was another example but I can't remember where.

[Michael Ferner]

I doubt it. Bearing failure is usually caused by oiling problems; the exhaust configuration is about scavenging the cylinders. Not really related to one another.

 

 

On second thoughts, yeah maybe: better scavenging can lead to higher revs, thus more stress for the bearings. Possible.

 

 

 

On third thoughts , no: the 'wrong' exhaust would mean worse scavenging, thus throttling the engine - the bearings should cope easily with that.

Edited by Michael Ferner, 30 January 2021 - 11:47.

[Roger Clark]

Possible, but surely not probable.  We have no suggestion that Cooper fitted the wrong exhaust system.  Even is they did, we know that linked exhausts brought no benefit to a flat crank engine.    I suppose it's possible that the flat-crank had different oiling requirements and Cooper failed to modify theirs.  It's also likely that the engine was tired after Watkins Glen (that's why Walker changed it).

[Ray Bell]

I would think that the wrong exhausts, if it indeed did have the wrong exhausts, would have caused somewhat erratic scavenging...

 

Some cylinders would do better than others.