Thread: 3.5lt EFI day to day fuel economy

Originally Posted by Mercguy

Sounds like you have the situation well under control

The 98RON figures sound quite similar to what I was getting prior to my right bank valve clatter. Now the figures are down a bit, which is unsurprising.

Single biggest improvement I've made was to remove and overhaul the distributor, and do the bee-utey module relocation / shaft modification. I also reshimmed the shaft which made a big difference, and allowed me to get 0.1mm clearance to the reluctor coil, which makes a big difference to spark control.

Other than that, the engine is standard 14CUX 3.9 and runs OK-ish - not bad for 340,000km.

Sure, I could spend money on it, but at these high km's, I have other plans to repower with OM606 diesel.

I had to google that ... Not bad performance for a non computerised low pressure injected diesel. How will you fit a straight 6 under the bonnet though ?

Originally Posted by DoubleChevron

I had to google that ... Not bad performance for a non computerised low pressure injected diesel. How will you fit a straight 6 under the bonnet though ?

I'm not the first one to do it - It's been done before. There are a few tricks to MB engines, like the fact they aren't vertical, ancillaries are not forward of the balancer pulley, bellhousing is very compact, mounting depth is shallow, overall length is not excessive, it's about the same as the v8.

In fact, it's shorter than the M117 v8, and Auto Klugel fitted those to RRC's back in the 1980's....

The OM605 taxi engine would work also. but I like 3.0 litres and not 2.5 of displacement. in fact, if I had my way and could find one cheap enough, I'd drop an OM629 twin turbo commonrail v8 diesel in there... and the 722.9 auto. about 230kW in standard trim.... but that would require an ecu (adaptronic do one for diesel cdi's) because the MB system is locked down harder than goulburn supermax.... it's absurd for an ecu, but the whole interlocking module security thing is a bit OTT.

I had thought about an ML OM612, but they have their own issues, and most of them are black-death EGR related (lack of correct servicing and cheapskate owners) so give them a flick. Plus, in standard trim the 606a is good for a bucketload of torque at idle, and if the pump is tweaked a little, 400 is not hard. with 8mm elements, 400 is easy, and 500 is achievable with turbo upgrades.

and this is on a standard block - no mods, no cams, just IP and turbo upgrades.

Right now I'm in the middle of a gearbox conversion in my 300 coupe, so the RRC will have to wait until I'm done with that. Shouldn't take too long though, plan is to get it underway by xmas.