pavorotti
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Registered: 20th Jan 05
Location: west mids
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do these need to be done with cam belt in other words does the cam av to come off to fit these?
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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yes.
btw, i sold the sbd rollers now
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pavorotti
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Registered: 20th Jan 05
Location: west mids
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ok m8 i havent got the doe till friday any way m8? do u think i could get dbilas on first then get the rollers and rods fitted then raise the rev limiter?
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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yeah, no probs with doing that, but you will find u will be revving it to the limiter and then wishing u had a higher limit!
the difference when u first drive it after fitting the manifold will be great(i was smiling for a whole week ) but you will then want more and more and more..........until you have spent £2.5k on an engine build like me
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pavorotti
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Registered: 20th Jan 05
Location: west mids
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so is there much difference after the standard limiter does it pick up speed more or just carry on?
so wen i get rollers and rods done i need to change cam belt at same time yea?
standard cam or?
kent cams would i need a new cam belt to install them aswell?
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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you will need to replace the belt and the belt tensioner, dont bother with cams, i looked down this route and didnt do them, basicly you need to spend loads to get them dialled in right, verniers, mapping etc, for only a small gain (3-8 bhp.)
u would be better off spending the money on getting the head done properly i.e gas flowing it. this gave 7bhp in my engine! i know someone that does it as well for a good price, he's doing a head for me at the moment for my new project.
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pavorotti
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Registered: 20th Jan 05
Location: west mids
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tell me more wabou the gas thing?
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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basicly, it optimses the flow of gasses (inlet air and exhaust) through the head by removing restrictive metal from the throats and passages through the head. helps with getting more air in and exhaust gasses out quicker.
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broster
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Registered: 6th Dec 02
Location: Drives: E39
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quote:
Originally posted by corsa808
you will need to replace the belt and the belt tensioner, dont bother with cams, i looked down this route and didnt do them, basicly you need to spend loads to get them dialled in right, verniers, mapping etc, for only a small gain (3-8 bhp.)
u would be better off spending the money on getting the head done properly i.e gas flowing it. this gave 7bhp in my engine! i know someone that does it as well for a good price, he's doing a head for me at the moment for my new project.
if the heads done then cams will give about 5-7bhp without verniers but with mapping! and to behonest id getr it mapped anyway with cams! will give better gains!
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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but to get decent gains with cams, u will need to pocket the pistons to allow the cams to run at their optimum timing, otherwise the timing will be out, hence you wont get any "real" gain.
read this:
On almost all modern 16 valve production engines compression ratios are quite high to aide combustion for low emissions & the way the compression is kept high is to not to keep piston pockets to a minimum. This unfortunately allows little if any room for increase the opening of the cam at TDC (which is the easiest way to generate extra BHP by using the exhaust gases to help draw in the next charge).
2. The Designers of modern combustion engines are also being asked to make them smaller, lighter, as well as being cheaper to produce. So the room for increasing the cam lift with out replacing the valve springs is usually quite small.
3. Because of the problems mentioned in 1 & 2. The gains are usually quite small for money spent. The way you can attempt tuning your standard engine just by cams changes are.
The last & most often attempted way of fitting an up-rated cam is to use a profile, which is quite mild on acceleration with a mild increase in duration over the standard cam. The problem with this is as stated before, due to the lack of space the new cam profile cannot be timed to its optimum. This will give 1 of 2 similar effects. Either a huge loss in bottom end torque & only a small increase in peak power, over the original cam. This usually occurs if the replacement cam profiles have to be Retarded a long way (to avoid piston contact) because their duration is a lot greater than the standard cams. Or if the new profile is mild enough to fit with only slight retardation the effect is almost the same accept the loss in bottom end torque is not as great & the gain in peak BHP is almost not worth having.
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