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I know there are a few people in this forum who have had diesel engines chipped. As I recently started a thread on tyre selection, with regard to speed ratings, I wondered how many of the people, who have had their engines chipped, then thought it necessary to upgrade the cars tyres to deal with the increase in performance?
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It is unlikely that chipping will increase performance so significantly as to require uprated tyres.
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Not needed in my case. Tyres were already rated over and above the performance of the car in standard and enhanced tune.
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jumping on board this one... has anyone any personal experience of results (performance improvement and effect on MPG) from chipping an A3 tdi 130, please?
gracias
EH
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Whilst I was involved in the thread I have mentioned, during which time I received conflicting opinions about using tyres with a lower speed rating than the original specification, I did a search on the the Michelin UK web site. We have a C5 2.2 HDI Exclusive, for which Michelin recommend W rated tyres (same as the 3.0 V6 actually, which is a fair bit quicker), whilst for the 2.2 HDI SX they recommend H rated tyres. Now the tyres on the Exclusive are R16 whilst on the SX they are R15, otherwise the cars are virtually the same technically. Would a change of tyre profile normally require a step up in speed rating?
I know that chipping of C5 2.0 HDIs has been mentioned in this thread and they would have been fitted with H rated tyres (I think). I also believe that chipping takes the power output up to about the same as the 2.2 HDI. Has anyone with a modified C5 2.0 HDI thought it necessary to upgrade the tyres? I assume it was necessary to tell insurance companies about modifications, has anyone any experience of insurance companies mentioning tyre spec. as a result of increased performance?
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I doubt they will worry about tyre speed ratings.
Really, would you drive at 130mph even if you could?
My insurance company were fine about a chip-in-a-box.
The 2.0 HDI is a gem when chipped. I wouldn't go back. Any future replacement has a lot to live up to. My standard size (but replacement tyres) Michelin Energy E3a are good with the extra torque and power, but it is slightly easier to wheelspin when in a hurry when its wet. Stopping is fine though.
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Thanks for that SeeFive, it is reassuring to hear you say what your experience has been with your C5 after chipping the engine. I felt that W rated tyres were rather over the top on our 2.2 HDI, which is why I raised the matter in my earlier thread in Technical Matters.
I contacted my insurance company to check their opinion and the underwriter that was consulted said that, as long as the speed rating of the tyre wasn't exceeded, there wouldn't be any problem. However, several of the forum members didn't agree with that and said I shouldn't fit tyres of a lower speed rating than the original specification. I feel that if H rated tyres are good enough for a 2.2 HDI SX, then they are good enough for our car. As you say, I am never going to get near to 130 mph.
I believe that they fit the W rated tyres to the Exclusive because they have the same tyre size as the 3.0 V6.
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Does anyone know if the 2.2 HDI can be chipped and, if so, what kind of power and torque increases can be expected?
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I would have thought the top speed on many diesel cars is limited by revs rather than bhp. As most chips don't up the rev limit, the top speed should be pretty much unaffected. The advantage will be torque, and therefore acceleration (and an increase in bhp as a result of the increase in torque).
My concern would be the transmission, as some of the chips I've seen advertised claim 20-30% torque increases. That's a lot to ask of a transmission system.
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I understand the 2.2 when chipped is superb. See www.psi-motorsport.com/turbodiesel/pdf/pdf.php?sel...n for the chart for the box sold by www.dieselchiptuning.com who I bought my box from. They said I would be able to return it if I didn't like it. Sounded like a challenge to dislike it if I could. Now I remove it before it goes into the garage, drive 500 yards down the road to the supermarket, open the bonnet and put it back.
The gearbox in the later 2.0 HDI and the 2.2 is a newer design and able to stand more torque than the older one with reverse below 5th gear.
I'd give it a try. The only thing is that I change my oil twice as often. There is sometimes a little more smoke at around 60-70 mph in 3rd gear. Otherwise, no problems!
Try it - what can you lose?
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SeeFive, can I ask what you remove the box for?
Ours is an automatic and one of the early versions, so I don't know if it would be suitable from what you say.
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Depends on the gearing, a lot of diesels do have relatively close ratio gearboxes but if you've a tall top gear for economy top speed will be restricted to power not revs.
With my gearing, at 4500rpm I'd be doing 145mph which just ain't going to happen.
Clutches are slightly more susceptible to increased power, VAG clutches in particular. Transmissions should take the extra 20-30% comfortable, they're usually over-engineered. However, there are notable exceptions so check out HJ's car-by-car breakdown and the car forums if you want more information.
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I reported a tyre company in Reading to Trading Standards once for trying to fob me off with V-rated tyres for my 325 BMW. When I queried this, the fitter asked me when I was ever going to drive over 130mph. At the time I worked for a company near Munich...
El Dingo.
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V rated tyres are limited to 149 mph, not 130 mph, which applies to H rated tyres.
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> V rated tyres are limited to 149 mph, not 130 mph, which applies to H rated tyres.
Correct (although 240kph is the actual limit, being really pedantic). For the complete range of speed ratings in a nice graphical layout, and with tabular explanations below, visit www.tyresave.co.uk/tyrspeed.html
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