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1998 SLK230/2000 SLK230
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Discussion Starter · #1 · (Edited)
I've commenced the conversion of my current SLK R170 to also run on LPG. It's obviously not economic in my case to do this. That's because of the low annual mileage in my hands that would mean it would take many years to recoup the conversion cost based on fuel savings. So why should I be doing this? Well purely for the pleasure of doing it and because I've got the time and interest. I go back decades with LPG conversions and have my own filling facility. I've just purchased a Dacia Sandero which is a factory supplied Bi-fuel model. I've done the maths and for the equivalent cost of a gallon of petrol, the car will do 150 miles! Yes, that IS correct! So I thought "lets go ALL LPG"!
Now my aim is to get this to look as professional as possible. When I've finished, the boot (trunk) area is going to look as "finished" as can be achieved. The lining will be neat and the area as tidy as new. The tank is 50 litres vol and sits perfectly into the spare wheel well.

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The filling point is colour matched to the bumper and flush

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My previous conversion was a liquid propane injection system (Vialle) but this will be a standard gas system. I've found a local installer who would have done the complete conversion for £800. I'm hoping that, because I've done the tank and multi-valve, he'll agree to finish it for, maybe, £600? I'd get the conformity certificate, too, which is a legal requirement and needed for Insurance purposes, too. Watch this space!

David
 

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2003 SLK230
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110 Posts
You will need to retune the ECU ,to accept LPG . These conversions were pretty common in New Zealand , mostly for 6 or 8 cylinder engines , due to loses in power the 4 cylinder wasn't seen as a viable option. I'm sure lots has changed with the start and warm up on petrol , then manual switch to LPG , the reverse for shutting down with the advances in electronics and fuel injection. Purging is the word that comes to mind . Anyway the SLK is an eletronic car , and tuning the ECU takes professional equipment and knowledge. It's a different approach to the modding usually seen on this site , so good luck on the economy side of modding , cheers
 

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1998 SLK230/2000 SLK230
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Discussion Starter · #3 ·
Hood Automotive design Car Vehicle Motor vehicle
Motor vehicle Car Hood Automotive design Vehicle


This is the finished boot/trunk. Neat, eh? There's still some space for a hold-all (or specially designed cases! I'm going to do the whole conversion, myself. There's a slight problem as to where to locate the vapouriser under the bonnet! There doesn't seem to be much space, except behind the left headlight? In the second photo, could the item that I've highlighted be moved?

David
 

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1998 SLK230/2000 SLK230
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Discussion Starter · #4 · (Edited)
It looks like I need to find some space for the reducer (the item that vapourises the liquid LPg before it is injected into the cylinders).I need some help as to how I can move that Brake Vacuum Pump to another location? Has any member got a photo of it? I've got some spare tubing to allow re-connection.

David
 

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1998 SLK230K
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285 Posts
I really can't offer idea of what and where to move, but can bring some different point of view. Mass Air Flow will need readings otherwise the electronics will go nuts (a serious problem with vacuum evaporators).
The SC (sorry I have no idea if yours is Kompressored or not) on the other hand is pushing air against the evaporator might be an issue.
From my experience (Honda 1.8 -1996, "naked" engine) adjusting the idles is a bit difficult (winters in my country are going down to -20°C) for summer and winter, as the engine doesn't "suck" it in. A problem that doesn't exist in high rpm, when the throttle is ooooopen. And in the wide open throttle the SC will push equally to intake and to evaporator exit.
No matter what, how...the correct way of installing the evaporator (pressure reducer you called it) is with the "Diaphragm edge" facing the direction of drive. The brass axle should be in parallel with the wheel axles.
And the coolant inlet is to be taken from the radiator inlet. And usually positioned on top of the radiator for easy bleeding...
This could be well explained by the person you mentioned or not. However it is something I think is worth considering.
 

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1998 SLK230K
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285 Posts
...Wow! is there no end to this?...
Never!
People's greed is beyond one's imagination!
I had something like this https://www.lpgshop.co.uk/landi-renzo-li02-136hp-reducer/ and plenty of space around it.
That thing you selected looks compact, but looking at the valve/filter (90 degree pipe connectors and power supply plug) looks like you really need to measure each step of the way.
Just curious, as I see this kind of design for first time, assuming horizontal and vertical installation is OK, what is that cable attached to the "cylinder" for?
And you probably have a clue, but where you gonna "inject" the gas? Like location.
 

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1998 SLK230/2000 SLK230
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Discussion Starter · #8 ·
That reducer that you've shown is only for up to a 136 bhp engine and my SLK is 196 bhp. The propane gas is fed into the engine through four nozzles, one for each cylinder They are located in the inlet manifold at a position as close to the fuel injectors' I've already done that and I used an M6 tap to thread the hole(s) ready to accept the nozzles. Here's the main kit that I'll be using, less the reducer, of course. https://www.lpgshop.co.uk/4cyl-kit-ac-stag-qbox-plus-obd-r01-red-w01-bf-250hp/ I find projects like this so interesting and I get inspired when it comes to problem solving! I'll get there, I'm sure! :) Thank you for showing an interest ....

David
 

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1998 SLK230K
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285 Posts
I really got the impression you are gonna go for "regular vacuum" not injection LPG conversion.
But now it make sense. So you have the things thought of.
How would you "bypass" the injectors and fuel pump running in vain.
Eventually Lambda control - I see the box comes with software.
It really sounds good.
The plastic pipes were preferred over coppers back in the days. I have no idea is it still like that, but in your case - in a space saving/missing environment could be only option.
 

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1998 SLK230/2000 SLK230
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Discussion Starter · #10 ·
You're talking about decades ago! Things have moved on and everything is fully electronically controlled. I converted my first car in 1976 and I've done many since.

David
 

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1998 SLK230K
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285 Posts
You are right Dave, the car was originally sold in Holland 1996 and 15km later the regular vacuum evaporator with 70L tank and AG gas system "ECU" were installed. And because it is "modern car" - fuel injectors, etc. Whoever sees the regular lpg conversion was certain it will never work properly ... so many myths in lpg conversions. And that is why when you mentioned standard - not liquid injection, wanted to get an idea how you gonna do that.
 
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