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V8 exhausts and crankshafts


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#1 Roger Clark

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Posted 11 January 2021 - 18:32

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!



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#2 Ray Bell

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Posted 13 January 2021 - 21:45

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.



#3 blueprint2002

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Posted 14 January 2021 - 06:05

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.



#4 Pat Clarke

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Posted 14 January 2021 - 09:32

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



#5 Roger Clark

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Posted 14 January 2021 - 09:32

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. 



#6 blueprint2002

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Posted Today, 01:06

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.