Improving Performance

Discussion in 'Tech/Mech General' started by OddSocks, May 11, 2014.

  1. OddSocks

    OddSocks Read Only Funster

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    Not wanting to hijack someone elses thread, I'll start a new one.

    I have a 1990 Mercedes 208D with an Autotrail body.

    Very underpowered. From what I have read the 5th gear was all but useless. But a previous owner has installed a turbo and intercooler and it has helped no end. I can make it up most slight inclines in 5th gear, but a steep hill is still 3rd gear territory. (Or 2nd!!)

    I used a dose of RedX fuel system cleaner in my last tank. On todays run, and tankful later, it went most of the journey in 4th gear (I was on winding A roads, too slow for 5th) but I was amazed at how well it went, almost didn't have to change at all, just ran in 4th! More torque at low revs and happy on slight hills.

    I have checked the air filter and it is almost new.

    What else can I do to tweak performance? Bear in mind I am a total novice!

    Apart from the little things I can do for myself - with your guidance, of course - I was also thinking of this vortex exhaust system which jezport posted about. If it can add the slightest oomph I would think it money well spent. Do you think it will work?

    What other little jobs should I be doing to help bring some life back in to the old girl???
     
  2. funflair

    funflair Funster Life Member

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    Hi

    Its never going to be a flying machine you know. If the turbo was done right with the fuel pump and injectors uprated that will be making a big difference already.

    I have no experience with the Vortex system so dont know if that will help or not.

    Martin
     
  3. veevee

    veevee Funster

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    This will sound like a silly idea, but make sure your tyre pressures are at the correct inflation as all the little improvements add to a larger one.

    About 18 months ago on a serious recommendation from someone I respect for their technical ability, started using only premium diesel fuel. After a couple of tank fulls there was a difference. We now use only premium diesel on our 3 vehicle, all very different and driven differently too, premium has had two major benefits for them all.

    Lower fuel consumption which pays for the extra cost of premium fuel.

    The engines on two of our vehicles have around 50,000 miles each and they definitely sound quieter and smoother since using premium fuels, plus the emissions are better too.

    I think these super fuels don't just have an affect on the engine, but also clean up the exhaust too, found that to be particularly the case on buying or low mileage older MH.

    Two other things. Make sure you change the engine oil and filter, it is generally agreed that diesel engines re-act well to oil changes.

    Change the fuel filter too, this can affect power outputs too. There may be a small pre-fuel filter, these are often overlooked.

    Good luck
     
    Last edited: May 12, 2014
  4. Bellini

    Bellini Funster

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    Your Mercedes diesel donk will be able to run with new vegetable oil.

    Veg oil has a higher calorific value than diesel and, when I'm using it in my 300Tdi Land Rover 110 at roughly 30% mix, it makes a welcome difference.

    You'll find the engine smoother, slightly more powerful and a little quieter.

    And new veg oil is around 80p/litre at the moment.

    Besides that, just make sure your mechanicals are all A1.

    Udo (Merc 410 base) is massively slow, but it really doesn't bother me. I just sit there and relax. If he was quicker, I'd have to use the brakes more to slow down for corners and he'd probably lean more round bends. It's just not the style of vehicle he is.

    But saying that, since I had the rear suspension replaced and strengthened, he does go round corners a lot better and, consequently, I can drive that little bit quicker (and smoother) round them. It's helped journey times but the real benefit is to the smoothness of the journey - less lurching and less reduction in speed round curves.

    So, anyway:

    1. Veg oil. New stuff. Costco do it in handy 20 litre containers.
    2. Drivetrain A1.
    3. Suspension / running gear.
    4. Tyre pressures.
    5. Reduce unecessary weight (if you really want to go that far).
     
  5. fifthwheel

    fifthwheel Read Only Funster

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    I could be wrong but I always thought the calorific value of veg oil was less than DERV.
     
  6. ShiftZZ

    ShiftZZ Funster Life Member

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    May help..

    [​IMG]


    PM Old Mo for the phone number.:Wink:
     
  7. scotjimland

    scotjimland Funster Life Member

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    it is.. but not quite so simple.. it also varies with type of veg oil ..

    google says this

    Diesel fuel 44800 kj/kg

    Oils vegetable 3500 kj/kg

    Calorific Value
    Is nearly equal for all vegetable oils, but 10% less in comparison to diesel fuel.[HI] Because of higher density the volumetric content of heat value is about the same.[/HI]

    http://www.elsbett.com/engl/oil.htm
     
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  8. TheBig1

    TheBig1 Funster Life Member

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    if you found a dose of redex helped, there are far better systems about, which are available through garages. a clean fuel system and engine will always perform better, and the typical motorhome does relatively low miles and slower than most vehicles. soot and other deposits like wax and algae will seriously effect the engine power, so cleaning them out is good for the longevity of the engine too

    i had an old van some time ago that had intermittent power loss when I bought it. we tried various things but were still getting the issue. in the end my old school mechanic dropped the diesel tank and flushed it. you should see the muck that came out. no surprise that lumps of this muck were getting into the fuel line causing issues. after a good clean through and some additive to clean the pump and engine, the problems went away. they used one of the forte products as i recall
     
  9. Bellini

    Bellini Funster

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    Fair enough, but I've always had a noticeable performance boost each and every time I use veg oil.

    Note that I always buy new veg oil, called SVO or Straight Vegetable Oil. I've NEVER bought the used stuff as I know the calorific value decreases markedly, plus you've got the faff of filtering it.
     
  10. fifthwheel

    fifthwheel Read Only Funster

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    I have run my private vehicles on SVO for years and have used tons (I buy in 1000ltr IBC containers) I find around 10% less mpg and 10% power loss but I am still using it as the price is less than diesel. I was hauling spuds into Scarborough a few years ago at 44ton and called for fuel on the A64. They sold biodiesel then, around Castle Howard there is a steep bank I needed to drop two gears there compared to Derv. Changed back to diesel and back to normal. It was nothing to do with the bio clogging the filters. I also had the same van as the OP about four years ago same year 1990 we went to France and Spain. Bomproof engine but so slow we couldnt wait to sell it. We have a Renault Master minibus I am converting it goes very well but will never be as reliable as the Merc.
     
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  11. OddSocks

    OddSocks Read Only Funster

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    Thanks everyone, very helpful indeed!

    I think I will switch to the premium diesel and see how that goes. Might also run another redX through next time I fill up.

    The air filter was pretty clean when I looked at it. I will look through all the bills that came with and see if I can find tha last service date and what work was done. Will put in new oil and filters if needed.

    Checked the tires. They seems to be over inflated if anything.

    I have 215 R14 C - 40psi front 47 psi rear according to the info plate under the drivers seat:

    However, mine are at 75 and 62 at the front and 75 and 78 at the back when cold!

    This is crazy high! Closer the the pressures in the 185 tyres (Again according to the late under the drivers seat) Why would they be pumped up so high? I should let them down some, huh? lol Is it possible they have become damaged by over inflation? They look like they are in excellent condition, and have very deep treads on them, barely warn!

    I'm not expecting to turn the van into a racer - I knew it was slow when I purchased her. Just want to get the bes out of her that I can, and if I can tweak a few extra miles out of a gallon, then I will!!
     
  12. outkast

    outkast Read Only Funster

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    Redex is definitely a good idea if you are running a diesel, when I got our sprinter I serviced it and added some redex, we took it on its first long run up to Norfolk a few weekends back and ran the rest of the redex through the sytem.

    it now idles smoother, accelerates smoother and seems to have a better power delivery than before :Smile:
     
  13. Sidney

    Sidney Funster

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    I wouldn't rush to put in vegetable oil. I would start by establishing a benchmark - because you don't know how the engine is performing versus the original power plant.

    Two easy tests can be carried out by a garage with minimal labour costs...

    Exhaust analysis

    Compression test

    If the exhaust analysis figures aren't good you can start with a decoke (old style) or call in someone to hook up a Terraclean type of machine.

    If the compression tests are bad on all cyclinders (or one or two) a decoke can help too. If the figures don't go up you have worn rings/bores or valve/stem/follower etc issues but at least you'll know where to start!

    Lastly and as an aside you can always ask an expert regarding the turbo and intercooler. If the intercooler isn't big enough (or poorly positioned) you're loosing valuable bhp as you'll be putting hot air into the engine.
     
    Last edited: May 12, 2014
  14. Bluemerle

    Bluemerle Read Only Funster

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    Using my vast technical experience, my advice would be "chill out" and enjoy it for what it is. A lovely 24 year old square box, over cab motorhome!! It will never be the fastest round the block, so why try!:BigGrin:
     
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  15. fifthwheel

    fifthwheel Read Only Funster

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    The thing is you haven't got the horses in the first place. A previous owner tried to improve power by fitting the turbo can you imagine ours without the turbo. Truck drivers must have thought i was taking the micky I was flat out!! I don't think you can do any more.
     
  16. OddSocks

    OddSocks Read Only Funster

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    :BigGrin: I know you are right! We love our old box on wheels. It really is a great machine. And half the fun of the trip is getting there any way! Just thinking if I could get to the top of that hill with one less gear change, or gain a couple of MPG..... well you know! It's never going to be fast and efficient, but a little less slow might be nice! lol

    There is a hill on the A30 just round the corner from here which is a 3rd gear climb for me - I have never been overtaken by an HGV until I got this camper!
     
  17. TheBig1

    TheBig1 Funster Life Member

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    another option that will help a bit is fit taller tyres to improve your gearing, but your speedo will then be out a bit
     
  18. Bellini

    Bellini Funster

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    Taller tyres will put the engine under greater strain to accelerate and keep momentum up hills.

    You need a goodly amount of torque to overcome that.

    But, you're right. It'll raise the gearing and reduce cruising noise.

    The speedo often over-reads. I found that when fitting taller tyres to my 110 Land Rover, the speedo became more accurate as the error was reduced.
     
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