Mercedes V8 Inlet Manifolds
- Thread starter Oversize
- Start date
- Thread Starter
- #162
Thanks heaps! Hopefully big news coming soon.
The TPS conversion is also now complete. At nearly 12 months turnaround I hope their next one is far quicker, otherwise I’ll be using my CNC company for the work....
- Thread Starter
- #165
At least that all means there’s plenty in the tank of these old girls!
Dropping off my manifold & drawings, plus base materials with my CNC machinist next week. Hoping for a much quicker turnaround!!
I can’t wait to get this finished & start testing!
Dropping off my manifold & drawings, plus base materials with my CNC machinist next week. Hoping for a much quicker turnaround!!
I can’t wait to get this finished & start testing!
- Thread Starter
- #166
Just ordered one of these which is the size they should’ve been in the beginning. It will be tested on both the 560 & 6.9 (with EFI) since in won’t fit under the Kjet & is too big for the stock manifolds even after machining.
- Thread Starter
- #167
Looks like this is what Geoff tried a while ago on a std manifold. Hopefully I can make it work on a custom setup.
I just discovered the 6.9 exhaust collector is the same size as ONE of four Holley 4BBL throats fitted to an Ford XYGT 5.8!! The XY had fairly small exhaust systems fitted to the street cars which was upgraded on the race cars as regulations allowed.
Yet more evidence the 6.9 was choked at both ends... The Euro 560 is just choked on the intake since they’re fitted with Tri Ys.
I just discovered the 6.9 exhaust collector is the same size as ONE of four Holley 4BBL throats fitted to an Ford XYGT 5.8!! The XY had fairly small exhaust systems fitted to the street cars which was upgraded on the race cars as regulations allowed.
Yet more evidence the 6.9 was choked at both ends... The Euro 560 is just choked on the intake since they’re fitted with Tri Ys.
Nice explanation Mark. 
- Thread Starter
- #170
Yes confirmed. The 6.9 struggles to breathe through the 450 throttle plate & 450 sized exhaust collectors. The plenum also reduces flow by about half on the smaller 560.
So it begs the question why Benz designed a unique engine that was later marketed as the fastest 4 door, yet hobble it with an inability to breathe? A lack of sufficient airflow would also slow acceleration of the considerable rotating mass.
I have heard it said the cylinder heads are quite well designed, however looking at them from my perspective the intake tract is too long & has a sharp bend at the approach to the valve. Part of the reason for this is the intake valve is aligned with the exhaust valve for cam activation. They would’ve been better to raise the inlet valve to the top of the cylinder & align the exhaust valve with it. Or better still use a Hemi style head. But that would’ve required 4 cams in a space which was already tight with such a large engine.
For many years I felt that Benz designed components so well it left little scope for performance improvements. Clearly that was an incorrect assumption & the hp/torque gains are yet to be explored.
So it begs the question why Benz designed a unique engine that was later marketed as the fastest 4 door, yet hobble it with an inability to breathe? A lack of sufficient airflow would also slow acceleration of the considerable rotating mass.
I have heard it said the cylinder heads are quite well designed, however looking at them from my perspective the intake tract is too long & has a sharp bend at the approach to the valve. Part of the reason for this is the intake valve is aligned with the exhaust valve for cam activation. They would’ve been better to raise the inlet valve to the top of the cylinder & align the exhaust valve with it. Or better still use a Hemi style head. But that would’ve required 4 cams in a space which was already tight with such a large engine.
For many years I felt that Benz designed components so well it left little scope for performance improvements. Clearly that was an incorrect assumption & the hp/torque gains are yet to be explored.
- Thread Starter
- #171
Another option would’ve been to have inlet & exhaust rockers facing opposite directions to separate the valves vertically but that would’ve required a lot more oil galleries for the lash compensators. Food for thought but not something that could easily be achieved. And unfortunately designing new cylinder heads for these old girls isn’t economically viable.
- Thread Starter
- #172
Another observation is why exactly the highly modded 6.3 couldn’t achieve good hp figures. It can be seen there’s no limiting KJET manifold (the 6.3s standard manifold was better than the later design), big throttles & the exhaust manifolds have been discarded in favour of headers. Could it be a flawed cylinder head design, or did they get the runner length so wrong that internal resonance disrupted flow significantly?? Does the SOHC design prevent high lift & duration, or is the plenum still too small? Clearly something was wrong, but AMG never discovered the answer before they moved onto other projects.
- Thread Starter
- #173
Without clearer photos, it appears they used an early form of mechanical fuel injection & ignition was likely to be similar to other cars of the era. So it’s unlikely those systems contributed to the lower output. I’m still trying to find more info but as predicted it’s extremely hard since it was a task to find evidence of its existence, let alone any other data!!!
Anyone know Erhard Melcher’s phone number lol???
Anyone know Erhard Melcher’s phone number lol???
Ignition was a bigger issue then than it is now.
Jaguar struggled with ignition on their high revving v12 engine. A v12 at 6500rpm is a lot of ignition pules per second!
- Thread Starter
- #176
- Thread Starter
- #177
Yes ignition is far easier with today’s tech!
- Thread Starter
- #179
Well the scanning took far longer than I’d hoped, so I’ve decided to have the prototype fabricated instead to get it completed ASAP. If it works I’ll go back to the scans & have subsequent versions constructed with CAD & CNC machines.
While researching exhaust specialists I discovered they lost their fabricator & reconfigured their business to parts only. During a conversation with the owner I was referred to a great fabricator who’s done custom work on various Porsche’s & V8SCs.
So now I just have to confirm hood clearance, scale draw the intermediate plates, wash the engine/trans & deliver them plus all the other parts for the real work to begin!!
While researching exhaust specialists I discovered they lost their fabricator & reconfigured their business to parts only. During a conversation with the owner I was referred to a great fabricator who’s done custom work on various Porsche’s & V8SCs.
So now I just have to confirm hood clearance, scale draw the intermediate plates, wash the engine/trans & deliver them plus all the other parts for the real work to begin!!
- Thread Starter
- #180
Oh I received the throttle & it was total rubbish. It was cosmetically damaged & the quality was woeful. I ordered a different one from someone else & it wasn’t a lot better. Although we all lament that there’s little aftermarket support for Benz stuff we should be grateful the quality of what is available is generally very good. I pity some of these LS owners that have to be content with these types of substandard parts!
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