ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Embaressed to be asking this, but does valves make a major difference??
I used to have a punto 1.2 8v but now have a 1.2 16v. Can definatly tell difference acceleration wise, but iv seen like 2 litre 8v and stuff. How does that work?? Surely a more powerful car would need more valves? Also, would a 1.2 16v be more powerful than a 1.4 8v?
A lot of questions i know. Just wondering like 
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Greg_M
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Registered: 2nd Sep 03
Location: Grantham, Lincolnshire
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a greater number of valvae uaually dictates how fast the car is, obviously depending on the engine size also.
there a 4valves for every cylinder as far as i know, a 1.2 16v wold be about the same perfromance as a 1.4 8v, as my 10 12v is 10bhp more than the 1.2 8v engines
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MarkM
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Registered: 11th Apr 01
Location: Liverpool
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Normally 16v Motors are slightly faster accelerating...however they need to be revved to get this acceleration...
8v cars tend to have low down power at low revs...
16v in general tend to accelerate faster...
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ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Basically a bit faster then.
I know its more insurance and i presume its more bhp than standard 1.2
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Greg_M
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Registered: 2nd Sep 03
Location: Grantham, Lincolnshire
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16v is the usual compromise between performance and economy, so ive been told
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AdiSRI
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Registered: 1st May 02
Location: Berkshire
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WEll u have 8/16 v on a 4 cylinder engine and 12/24 v on a normal 6 cylinder etc... so 16v aint a compromise its just wat modern 4 cyl engines have, if u want more valves u have more cylinders.
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Paul_J
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Registered: 6th Jun 02
Location: London
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Basically, the 8v cars tend to be SOHC, and 16v cars tend to be DOHC.
You'll usually find that the power band on a 8v car is in the low revs, so it may feel nippy - but when racing and holding long in gears it won't be.
The 16v cars tend to only really get into their power band from say 3-5.5k rpm, so although you may not get any acceleration if you floor it at 1.5k rpm in say 3rd gear, providing you have it sitting at 3.5k and change so it stays in the power in every gear it'll accelerate pretty quickly.
My car is a 1.2 16v - I had it dyno'd and I'm producing 81 bhp and 95 lb ft of torque.
a 1.2 8v corsa only has 45 bhp!!!
Big difference. But if you are a poor driver like my mum and don't keep it in the power the 1.2 16v can feel very slow (since it has all its power in the power band, anywhere outside of this is very sluggish unlike bigger cc'd cars which pull ok ish even outside the power band)
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AdiSRI
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Registered: 1st May 02
Location: Berkshire
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Yes paul, but the 1.2 8v are SPI thus the low power output, if they were MPI like the 1.4 8v in older SRi's then it would be much closer to yours in power, somewhere around 65-70.
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ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Paul, sorry to sound even more thick. Whats getting it dyno'd?
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Paul_J
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Registered: 6th Jun 02
Location: London
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Also to answer why there's a difference, I feel its to do with timing (may be wrong though)
on a 8 valve car, you have 1 cam shaft - that opens both the air and the exhaust valves...
on a 16v car - you have 2 cam shafts, that one opens the air and one opens the exhaust valves seperately... Different timings - and thus power gains.
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Paul_J
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Registered: 6th Jun 02
Location: London
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quote:
Originally posted by ben_clio_16v
Paul, sorry to sound even more thick. Whats getting it dyno'd?
Put on a rolling road to find out what power it is producing - mine's a 1.2 16v Sxi with cat back exhaust system and I got 81 bhp.
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ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Ah ok, mines just a standard one and has to stay that way till November. How does a rolling road work?
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LukeGSi
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Registered: 9th Dec 03
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quote:
Originally posted by ben_clio_16v
Ah ok, mines just a standard one and has to stay that way till November. How does a rolling road work?
answer is in the question mate.....
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ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Every question i ask on here seems to be stupid.  Just never seen one, wondering what it was like.
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Paul_J
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Registered: 6th Jun 02
Location: London
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You wheels drive against cylinder rollers... (one on each side of the wheel with the wheel sitting in the middle) - they accelerate your car and get the rollers to act as a brake against it. (remember someone saying about water brake? but maybe that was in the old days) - and they work out the power.
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ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Ah right. Cheers Paul, so once i get my own insurance. What is the best way to start off modding the engine, just for a bit of extra power. Wouldnt have a clue where to start to be honest
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LukeGSi
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Registered: 9th Dec 03
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quote:
Originally posted by ben_clio_16v
Ah right. Cheers Paul, so once i get my own insurance. What is the best way to start off modding the engine, just for a bit of extra power. Wouldnt have a clue where to start to be honest
I was only messing fella...to be honest modding a 1.2 lump aint really worth it...go to drilled airbox and panel filter with cold air feed and decent stainless exhaust then concentrate on wheels, suspension etc 
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Paul_J
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Registered: 6th Jun 02
Location: London
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Don't really bother...
Get a air filter (for sound) and a cat back exhaust system for sound and a bit of power...
I dunno about your car but my 1.2 16v Sxi was 75 bhp standard.
You could buy a Dbilas Flowtec Inlet Manifold package (that comes with mapped chip) that takes the car to around 105 bhp, but too expensive imo.
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ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Yeah i'v checked on the Renault website and mine is 75 bhp. How much is the cat back exhaust? Dont an air filter use something stupid like twice as much petrol?
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LukeGSi
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Registered: 9th Dec 03
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quote:
Originally posted by Paul_J
You could buy a Dbilas Flowtec Inlet Manifold package (that comes with mapped chip) that takes the car to around 105 bhp, but too expensive imo.
yeah IMO really not worth it....save and wait till you can get at least a 1.4 16v!!
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Paul_J
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Registered: 6th Jun 02
Location: London
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no offence - why are you on corsasport 
You had a punto, now you have a clio?
Corsa? .... 
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LukeGSi
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Registered: 9th Dec 03
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quote:
Originally posted by ben_clio_16v
Dont an air filter use something stupid like twice as much petrol?
 Think not chap!! Exhaust range from £150-£600 for full custom!! id say def get a one off system from powerflow/ascar (around 300 notes)
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ben_clio_16v
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Registered: 14th Dec 03
Location: London
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Was waiting for that Paul. I know someone who posts on here and was looking for advice a while back about alloys in general. Just stuck around cause seemed like a decent enough forum with some good banter. Unlike some other ones which all seems to boy racer for me. Sorry, i'll be going 
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LukeGSi
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Registered: 9th Dec 03
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quote:
Originally posted by ben_clio_16v
Was waiting for that Paul. I know someone who posts on here and was looking for advice a while back about alloys in general. Just stuck around cause seemed like a decent enough forum with some good banter. Unlike some other ones which all seems to boy racer for me. Sorry, i'll be going
dont be a muppet....50% ppl on here dont have corsas!!! 
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Ian
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Registered: 28th Aug 99
Location: Liverpool
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The number of valves is all about surface area and efficiency and not specifically performance. I suspect there's loads on the web about it, if you need more ask.
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