Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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4-1 or 4-2-1?
Bearing in mind mine has got 175bhp with a standard manifold.
What does everyone think
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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what are the current mods?
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Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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Full System
Kent Cams
Super Chipped
Boost Valve
Viper Air
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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unlikely to have gained 25bhp with those mods, what spec are the cams?
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Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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No idea brought the car with the cams in.
Was rollered at 175bhp at 6033rpm
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Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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Any idea which one?
Why is it unlikely to get that bhp from those mods?
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Dave A
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dont want to turn this into a bhp argument thread but 175bhp at 6033rpm
anyway, the standard xe manifold is a 4-2-1 anyway and should be fine for up to 200+bhp
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Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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quote:
Originally posted by Dave A
dont want to turn this into a bhp argument thread but 175bhp at 6033rpm
Explain as it wont be a debate as you will win trust me
Will a 4-1 make any improvement?
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Dave A
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Registered: 10th Dec 03
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quote:
Originally posted by Kiddy_Corsa
Any idea which one?
Why is it unlikely to get that bhp from those mods?
well air filter, exhaust and boost valve may add 2-3 bhp so theres no way cams can add 22 bhp unless they are dialled in with verniers and mapped to suit.
Most c20xe's on tb's get around 180bhp
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Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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Iv got vernier pulleys and they were fitted with the chip and rollered at the same time!
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Dave A
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generally an engine that makes 20ish bhp from cams I would say needed the cams to be quite big.
the bigger the cam, the higher up the revs the power would be therefore I would expect the power to peak at around 7500 rpm.
as a comparison I have just been looking at a graph my mate has on his c20xe with tb's and 270 degree cams, makes 198 bhp@ 7800 rpm. at 6033 rpm it makes 173 bhp.
all depends which rollers it was run on I suppose.
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Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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Would you say that the cams has a degree of around 270 going my your mates or the rollers are not what they could be.
So a 4-1 would be better with a higher degree of cam then?
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Dave A
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the basic rule is:
4-1 less restriction at high gas speeds, more power at higher revs
4-2-1 shorter primaries give better midrange torque but not as effective in higher revs
I would keep the standard manifold if I were you, use the cash to get a couple of runs on a good rolling road to check the air/fuel ratios and cam timing
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Kiddy_Corsa
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Registered: 7th Nov 02
Location: Kidderminster Drives: Astra VXR
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Cheers Dave for your time
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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find a place near you with a dyno dynamics RR. they will give you a good idea of the power its running and the state of tune
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