316 cdi remap is it worth doing - Motorhome Forums, Motorhome Discussion, Motorhome Chat

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post #1 of 7 (permalink) Old 16-11-2015, 13:19 Thread Starter
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316 cdi remap is it worth doing

i have been thinking of getting my rapido 992mh 316cdi remapped has anybody had it done and was it worth doing.
not looking for more power but a bit better mpg would be nice
cheers
frank winder
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post #2 of 7 (permalink) Old 16-11-2015, 13:37
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The chances of improving your mpg with a remap are fairly remote.

Basically a remap (note NOT a rechip) will increase the engines torque and BHP to better suit the way your engine is used. the major problem being that if you have extra power available its VERY tempting to use it and that will impact on your mpg figure.

I would suggest that you see if you can modify your driving style a bit in order to reduce your mpg.

Look much farther ahead so you can anticipate what is going on so you do away with braking and accelerating unnecessarily. Likewise dont zoom up to traffic lights, lift off much earlier and try to NOT come to a halt as pulling away from rest uses much more fuel than if you are still moving. DONT accelerate hard, use a light right foot and slowly build up speed through the gears.

Dont think cruise control will give you the best mpg either, it wont. The reason being that you set the speed and CC will use as much power as possible to KEEP you at that speed, knock it off when you come to a hill and left your speed bleed off a little, you wont notice any difference in the time it takes to get to your destination but you will notice an improvement in mpg.

Keep your speed down. The difference in mpg between 50 and 60mph really is amazing. Air resistance increase by the square of your speed and its air resistance is huge on a motorhome. Some years ago I had a hymer b544 on a FIat base. One day on a loooong downhill section of a French motorway I tried an experiment. If I knocked it out of gear at about 60mph I could actually FEEL the MH being slowed by air resistance, once I got to about 50 the speed stayed the constant (even though on a slight downhill slope) I tried it a couple of times with the same result. That convinced me to cruise at about 50 rather than 60. Over a months holiday I really noticed that I was not having to refuel so often.

Use as little throttle as possible, and stay in as high a gear as possible WITHOUT having to use too much throttle. When on a long straight slowly lift your foot off until the speed drops slightly. If you have a constant mpg readout on your dash look and see how much just a tiny bit of extra throttle makes your mpg fall of a cliff!!

Dont carry anything that you dont need ESPECIALLY on the roof !!! If you have your fresh water tank full thats about 100Kg or another passengers worth of weight!

It is truely amazing just how much of an impact the above tips can have on your consumption.

I ran an Autotrail 4 tonne beastie on a 316CDI Sprintshift base and regularly got 29-30 mpg. By going much over 50 it dropped to 22-23 !! Yes really!!!!!

I never felt the 316 CDI was anything other than more than adequate when it came to power, and the mpg figure was acceptable especially when taking into account its size.

What sort of mpg are getting at present???

Andy

Its not the destination that matters.

It's who you share the journey with (even if like me, itís in a caravan!)
I am very fortunate to have Mrs Plodd to share mine with

Last edited by Mrplodd; 16-11-2015 at 13:55.
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post #3 of 7 (permalink) Old 16-11-2015, 17:10 Thread Starter
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thanks for the info andy
at the moment we get about 22/23 mpg at about 55/60mpg so will try a run at 50mph next time we go out
cheers frank
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post #4 of 7 (permalink) Old 16-11-2015, 17:23
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Hi Frank

That sounds about right mpg wise, drop it down a bit and I am sure you will see a disproportionate improvement.

Please let me know how you get on as I would be interested (as I am sure would others)

I rather like just bumbling along these days (so long as I am not holding others up) I try to enjoy the journey as well as the destination so 50 mph is pretty much my norm now with the shed tagging along behind.

My car gives me 50 ish mpg when on its own, if I am really careful I can get over 60 !! but it drops down to the high 20's whilst dragging the shed along at 50 !! so no different to the MH really.

Andy
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Its not the destination that matters.

It's who you share the journey with (even if like me, itís in a caravan!)
I am very fortunate to have Mrs Plodd to share mine with
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post #5 of 7 (permalink) Old 16-11-2015, 21:29
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I too towed a tin tent and found that the fuel economy was terrible when towing. Now the tow vehicle is a Land rover Defender with the ford 2.4 engine which has the aerodynamics of a three bed semi in a gale. I remapped the Defender using a specialist tuner who only tunes Landrovers and the outcome was I got better fuel economy when towing. Pre remap it worked out using an app on the iphone at 23 mpg at 60 mph on the motorway, this was towing a twin axle. Solo was not much better at 29 mpg but then I would be at the national limit of 70mph. With the remap using the same app I get a return of 25mpg when towing and about the same solo as the extra torque available gets used The difference I noticed was that any hills that I used to drop down into 5th or 4th were now done in 6th gear as the extra torque the remap supplied was enough to maintain my forward speed. This meant that the revs were down around 1800rpm going up the hill instead of 3000rpm in a lower gear. Now another point to consider when remapping any vehicle is that often the remap puts the engine outside its operating norms, usually the engine gets hotter quicker due to the increased load and fuel being burnt in the compression cycle. On the Defender I just didn't get a remap I also had to change the intercooler to a larger one along with stainless steel boost pipes as the boost pressure was higher than standard because of the remap. All in the remap made the Defender more drivable as there was a marked increase in the available torque, plus my right foot just got heavier using that extra torque that just blew any economy gains out the window.

HTH Brian.
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post #6 of 7 (permalink) Old 16-11-2015, 23:21
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Just remembered a quote from the workshop foreman when I was serving my time:

BHP is how fast you hit the wall..........Torque is how far you take the wall you've hit with you.
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post #7 of 7 (permalink) Old 17-11-2015, 06:00
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Quote:
Originally Posted by lorryman100 View Post
Just remembered a quote from the workshop foreman when I was serving my time:

BHP is how fast you hit the wall..........Torque is how far you take the wall you've hit with you.
Yes I remember that one, it's a good way to express it.

As for the 316, I think I read it's the same engine as the 311 & 313 and already mapped to give the extra power, but that might be the earlier ones.
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