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Performance Volvo Cars A forum for those interested in any Volvo performance car from any era, FWD, RWD and AWD! |
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Tesco Super 99 or 97 OctaneViews : 7186 Replies : 87Users Viewing This Thread : |
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Aug 22nd, 2007, 16:05 | #81 | |
S60 R
Last Online: Aug 2nd, 2019 11:43
Join Date: Oct 2004
Location: United Kingdom
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Quote:
My T5 is M reg so my handbook may be slightly outdated as to the information/advice contained within. Although I did say "For the B5234T5 Volvo recommends 98 RON lead-free petrol for the best performance, but will run on any fuel with an octane rating of 91-98." So going with Volvo's information the 850 T5 can run on 91 RON, which is something I would not do, however there are certain countries that have poor quality petrol so Volvo and other car manufacturers I pressume have to a cater for those countries and detune the engine for a world wide market. As Volvo states that 91 RON fuel can be used, why do owners suffer from detination or knocking and worst case senario bent con rods? I think Volvo would be comprimising themselves re litigation if the vehicle could not be driven spirited using a lower RON fuel after stating in their handbook you the T5 can run on such a lower rated fuel. So another question arises, what causes the knock? A fault or failure in the sensors, ECU, fueling, timing not able to change to appropriate conditions or is it the fuel? This is one of those subjects where the more you think you are learning something you suddenly realise more questions are being raised than answered! |
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Aug 22nd, 2007, 17:21 | #82 |
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Last Online: Feb 18th, 2011 10:28
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To answer why some owners suffer from this, you have to find out what the spec of the car is really. Perhaps it's a sensor fault, or perhaps the map they use has been taillored to what they expect?
If it has been changed from the manurfacturers spec and not been looked after then you will always have a risk of stressing engine components. Most of the cars that appear to suffer with this have still got distributors, and would not suffer if they were full sequential injection systems. You also need to remember that some of these cars are 15 years old with 150000 on the clock, which volvo or not is a lot of miles, and things start leaking, corroding and generally break down. I'm not saying that you should use one type of fuel or the other, I am saying however that a standard spec car should run on normal unleaded without any of the problems, in the country that the car was designed to be used in. But just don't expect to get 240 bhp on asda unleaded. You also have to consider , especially after recent events, whether the fuel is quality controlled enough to worry how it would affect the car's engine. FWIW I agree if you are going to chip your car then you like the power so why use anything but super or v-power or Ultimate? You don't have to but why would you pay for the chip and not get all it has to offer? I'm not trying to butt in and cause/cure any arguments, I just felt that maybe for the less knowledgable I could maybe explain why different fuels effect the engine in different ways.
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Aug 22nd, 2007, 17:35 | #83 | |
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If you read back through some of my posts ive explained what knock is and what causes it.
also heres some basic background on how you car detects knock. On the t5 engine fitted to the 850's etc, you have 2 knock sensors fitted on the front of the block. they are nothing more than a microphone tuned to the resonance frequency of you engine. when the fuel burns you shouldnt get any noise, however when it explodes you get knock. this is like hitting the engine with a spanner, it will vibrate at its resonance frequency like a tuning fork. the amplitude of this is proportional to the amount of knock. also knock isnt just knock, there is varying degrees of knock. imagine drawing a line on the floor by pouring out some fuel etc, imagine setting fire to it and watching the flame work its way alone (this is a normal burn), however image as it gets to the end the rest of the fuel explodes - this is knock. so depending on how much of the fuel explodes will affect the knock readings. so as you can see from that when applied to an engine, and engine\ecu can see knock starting to happen, say for example as boost pressure is increasing. knock normally dosent just happen suddendly and blow the engine up!!! Quote:
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Aug 22nd, 2007, 19:03 | #84 |
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Exactly , which is why I doubt that when things go wrong inside an engine it wasn't running right in the first place and it would be wrong to blame one component or fuel.
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Aug 22nd, 2007, 21:37 | #85 |
diy bhp
Last Online: Apr 7th, 2011 19:38
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hi all, only read first and last page of thread... oh how it changed
i always ran my T5 on v power but got sick of a shell ripping people off with daily price hikes. VP is 6p a litre dearer than tesco's (96p)where i am. iv gone back to tesco's 99 and i get an extra 10-15 miles from a £25 fill, 90 miles to £25 VP and 100-105 from T99. for my car there is only a very slight,if any performance loss, altho i had to slacken my MBC off as i was hitting CUT constantly after setting it up for VP. wierd how everybody has diff opinions on power and economy from T99 to VP huh. wayne
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auto 96 T5 tweaked n ratted |
Aug 22nd, 2007, 23:49 | #86 | |
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Surely where and how you drive makes the biggest difference though. And it would have to be in the same temp and weather surely to be accurate. Which is why I thought the fuel test link for the BMW was pretty good. I can't quite keep of the go pedal long enough to be bothered with what fuel gives the most MPG, but I do know that super makes it 'feel' faster and smoother, so I'm just enjoying being able to afford to fill my car up (just) before the global activists start on cars in their bid to save the world, and Brown ups the tax yet again.
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Aug 24th, 2007, 20:40 | #87 | |
Rubbing son is racing....
Last Online: Jan 18th, 2017 14:26
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Location: London
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Quote:
Thanks for your comments, well this thread seems about dead now but was originally about fuel octane availability/usage in performance cars in general, but if its modified turbo engine answers you’re looking for then no I would not as it would put me at a disadvantage using an underpowered engine on a track day. Regarding modified ECU’s controlling such engines though and their capability to cope with a lower octane without detonation well I guess that’s for the individual tuner to answer, the chip in the other thread obviously can’t and is sold as such, so I can’t see why it’s been used as an example. It might also be worth considering the advancement in engine control on vehicles post ME7 as these can normally cope easily if the tuner is any good, if not then limp mode comes to mind, either way not engine destruction IMHO. Cheers
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Aug 24th, 2007, 22:01 | #88 | |
Roary The Racing Car.
Last Online: Jul 18th, 2014 09:00
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Funny how no tuner even those that advocate use of 95RON for hard driving are willing to put down in B&W, 95RON use is guaranteed. Yet, its blah blah this, and blah blah that. Not very convincing if you ask me for someone trying to work out if they should or should not use 95RON no matter what... thats my honest opinion of this all. cheers |
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