Adding a supercharger to a 300GD
I was having a think about how to overcome the lack of 300GES' available in my budget and one thought was to get a 300GDS and have a play with the rather sluggish engine.
I've read a few posts here about people adding a turbo but was wondering if anyone had given any though to a supercharger?
And if I was going to embark on such a project if there were any issues, like compression ratio adjustment, which I'd need to think about. Fitting will obviously be a bit tricky but there should be plenty of room and it's amazing what you can do with a bit of angle iron and aluminium scaffold tube :wink:
Anyone any suggestions?
I presume you are talking a 463 as they never made a 300GES 460 to my knowledge. But going to a 300GDS due to a lack of 300GES in your budget? Usually its the otherway around. 300GESs were, at least when I was hunting for one a few years ago, more common and cheaper than 300GDSs
Adding a turbo to an old engine is risky... and expensive. It would be cheaper to buy a turbo out of a sedan and swap the entire engine.
Well a turbo is just an exhaust driven supercharger...
I guess there is more black art in picking turbos for an engine but it is all down to air flow which is same thing as hp.. you only need to worry about surge which are down to compresion ratios and charts.. but as a rule.. a 3 litre diesel turbo will work on any 3 litre diesel to similar hp. Similar rules on Supercharging but need to play with getting good enough multirib belt system in instead of messing with your exhaust .. but exhaust will be too small for the flow after 20% raise in hp/flow .. so you may well end up redoing it..
The tricker bit to me (as I have not fully examined this bit yet.... :lol: ) is the fueling and timing.. on an old mechanical injection pump you just turn up the max fuel delivery until it smokes (well an exhaust temp gauge is really required) which is a bodge as part load fueling is no doubt well messed up.. but you are not in part boost that much .. and your EGT gauge warns you about this. Timing is left alone.. but you will run out of fuel delivery so need bigger injection pump (and injectors?) so upgrades are minimal.. I would guess 6-8 psi... which as pressure ratio of atmospheric 14.5 psi gives 25% absolute max more power at 80% efficency.
Then there is reduction of engine compression ratio by changing piston/questionable spacer head gaskets (timing issues and double the failure points).. most just tune to EGT and smoke without getting inside engine .. and there is normally enough on the table from OEM tune to let you get 50-100 % more if you know what you are doing, have EGT, smoke and a suitable robust engine.. but suitably robust engine is all guess/rumour .. and entry into the bell curve of failure.. OEM like to keep well to the edge of the bell curve.. if you want more then you must accept failure is a possibility.
Then intercooling becomes a fair certainty at over 6-8 psi.. all depends on engine compression ratio and ambient temperatures..
It is a whole kettle of fish... which I am dancing around the outside of (done 100% more power on petrol cars with turbos/intercooler/ECU so it is much the same). Easier option maybe Sprinter engine... all done by OEM so no failure bell curve to consider (Merc engines are not cheap to blow up :shock: :cry: .. unlike some reliable cheap Japan based manufacturers :wink: ) .. All Good Clean Smoky Fun :)
I do not know why, but only petrol engines seem to ever have supercharged, probably down to performance / horsepower .
Diesels appear to agree better with turbocharging, its "free" for a start, does the higher compression ratio in a diesel produce more exhaust gases to harness with a turbo?
PS
I agree with your assessment that by and large a 3 litre diesel is a three litre diesel,
I tried to tell a somewhat thick step father in law this-- when he could not get the origional fit air filter for an imported Japenese diesel -- but what did I know :roll:
The w463 300GD is a 6 cylinder....
D'oh! my bad ... so it is. That can't be the only difference between the 460 and the 463 diesel, I hope the others aren't quite so obvious. :oops:
Hi You will not find a 463 GD with a five cylinder engine... they are all six cylinder..the same engine as in the W 124 car.. fuel delivery is by a mechanical inline pump without electronics.. my last 463 was with aturbo and intercooler (an aftermarket mod) supplied and fitted by TB Turbo in Lancaster... cruising at 70mph gave me 27/28 mpg @ 3200rpm much lower than without the turbo...there is 463 LWB in Cornwall for sale at GBP 8000 with auto G'box.
Kernow - you have a PM
Aha, I see what you mean now Maxwell :oops:
I'm after a SWB tbh and preferably a manual. As I've somewhere here it is porbably better to wait until the right one comes along than pine for something you can't have. This does not include wanting something you can't afford :D
The SWB was clear but you are really making it difficult.... a 463 300GES in manual.... not many of those about.
Why manual? I had a manual - now have an auto. The MB auto is very smooth and great off-road....
And MB seem to have given up on manuals .. they specialise in Autos and the manuals cannot take much more torque so you are limited.. hence back to Sprinters engine and gearbox as a matched pair.. The V8 will have the same Auto issue .. real rare without the slushbox. Seem off-road on an auto maybe better as there are no "gearchanges" to break traction but give me a manual everytime.. I want control.
Superchargers just have a rev limit ... so you match the gearing with the max engine rpm. They give a more linear response compared to the turbo.. and turbos thrive on exhaust temperatures .. which diesel dump when loaded so they are well matched to turbos; it is a very nice positive feedback loop. Response .. well we are talking about slow burning diesels with the subsequent low rpm limit.. response is more down to fuel type.. but Supercharger will be more linear with less of a torque hump.
Hmm, I'm still undecided but that's me all over. It's been suggested I have a look at Bruce's G which has been for sale since new it seems :wink: but I've not driven a LHD on the LHS of the road and fear it might be a bit wierd.
I hope to see said diesel G at the weekend so I'll be in a better position to comment if I decide to get it. when it comes to ripping the engine and gearbox out to replace with something else, regardless of fuel type, I suppose actually getting a G in the first place is a good place to start.
I actually won the bidding on a nice G on eBay. I wasn't suprised when it didn't reach the reserve but it was pretty much ideal.
Nevermind. I've waited long enough, I won't rush now.
they are out there ;)
I found a '91 300GES Manual for very sensible money. Both myself & my wife HATE autos with a passion & the 460 diesels we tried were way to slow . But we were lucky & found the G we now have, even if meant having to travel all the way to the centre of London from Yorkshire to buy it.
I live in hope!
I'd be willing to travel anywhere if necessary, well almost anywhere.
Hi You missed the manual one sold by Buckalec to Chilipepper just a few weeks ago.both are GWOA members..you never know maybe Chilipepper would consider an offer..it is silver and is still in "G's for sale" as cheap as chips 463 GES rgds Peter
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It is indeed a 463 and maybe I'm looking at a duffer but I can't find a GES for less than £10k for love nor money.
Very sadly, I work in front of a computer all day and live < 3 miles from work so not only can I afford to have the machine off the road whilst playing but it would give me something to do of an evening. I've toyed with the idea of a kit car but I've always wanted a G and I've more recent experience with diesel than petrol. I wouldn't rule out a transplant if only I could find a donor with a V8 already changed to use LPG :D
I had thought that even the earlier 463 diesels were mechanical injection and as such more fuel would be easy to get with a tweak here and a bigger pump/injectors there. Something about a sturdy 5 cyl Merc diesel said "plenty of tolerance" to me.
I would go down the route of a very thick metal head gasket to lower the CR if needed. It wouldn't be a bad thing to do in the course of time tbh.
I would have thought there are pros and cons to the super vs turbo charger debate whichever side you want to be on. I was thinking it would be slightly more unusual for a start. Plus a Supercharger doesn't suffer from lag and a nice, steady increase in power and torque would be beneficial, certainly when off-roading.
There are other Supercharged diesels out there but with the advent of the ECU and variable vane turbos the 'simple' supercharger is simply too expensive to warrant using OEM. They do of course take power from the engine but they give back more than they take but I'm not really after uber HP, just enough to be more interesting.
I've read in several places people going on about how a SC can't really cope with high rpm like a turbo can. It is my understanding that a positive displacement SC runs at a speed proportional to the engine which would mean that the compressed air should stay at a reasonably steady pressure regardless of rpm unlike a turbo which is so inefficient that it doesn't warrant talking about.
Anyway, it was only an idea for a project. It might turn out to be wiser to replace the entire engine as suggested with something else entirely. There are two 5 litre V8 Merc engines on eBay at present. I suppose the standard gearbox would be man enough for the job, providing it fitted, with perhaps a more manly clutch?
It would be kinda cool to have the only supercharged DIESEL G kicking about though 8)