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Location:
Brisbane, Australia
Registered:
May 2004
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 4AGE smallport maximum compression on stock pistons
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Sun, 12 September 2004 04:42
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I'm sure this question has been asked before, but I did a search and came up with plenty of threads, but nothing answering my question. 
I'm going to have the head shaved, and my cams reground to 264 degree duration, 8.1mm lift. I'd like to know what sort of compression I can run before I have valves touching pistons. I'd like to be able to run 12:1 compression.
As the title says, the engine is a smallport 100kw 4AGE.
Thanks in advance. 
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Location:
Adelaide
Registered:
July 2002
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Re: 4AGE smallport maximum compression on stock pistons
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Sun, 12 September 2004 05:23
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reground??? YIKES
get sum billets man they're not THAT expensive
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Location:
NSW, East Coast
Registered:
July 2003
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Re: 4AGE smallport maximum compression on stock pistons
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Sun, 12 September 2004 06:14
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| Hunty wrote on Sun, 12 September 2004 15:23 |
reground??? YIKES
get sum billets man they're not THAT expensive
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I agree, i have a link to a pic of what happens to re-ground cams, when i find it ill email it too you. Try wade cams in melbourne.
Steve
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Location:
Brisbane, Australia
Registered:
May 2004
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Re: 4AGE smallport maximum compression on stock pistons
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Sun, 12 September 2004 06:22
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Fair enough... I'll look into getting some new cams instead. Thanks for the info.
Still need to know what my limits are for shaving the head. I'd love 12:1 compression. 
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Re: 4AGE smallport maximum compression on stock pistons
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Sun, 12 September 2004 07:01
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running compression that high
you'd want to be using 98octane fuel
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Location:
Brisbane, Australia
Registered:
May 2004
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Re: 4AGE smallport maximum compression on stock pistons
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Sun, 12 September 2004 09:47
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Yeah, I've only ever used 98 octane (BP Ultimate) in this thing... I had the timing advanced while on the dyno, so it's kinda 'tuned' for 98 octane anyway.
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Location:
Sydney
Registered:
September 2004
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Re: 4AGE smallport maximum compression on stock pistons
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Mon, 13 September 2004 03:36
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With that compression I'd be worried about pinging if your still using the factory computer.
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Location:
Brisbane, Australia
Registered:
May 2004
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Re: 4AGE smallport maximum compression on stock pistons
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Mon, 13 September 2004 12:54
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Thats where a bigger fuel pump and a malpassi come in.
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Location:
Sydney
Registered:
September 2004
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Re: 4AGE smallport maximum compression on stock pistons
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Mon, 13 September 2004 23:31
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A bigger fuel pump and more fuel pressure won't be enough.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4AGE smallport maximum compression on stock pistons
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Tue, 14 September 2004 03:55
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I'm thinking that's a bit of an ambitious head shave... remember it's going to screw with your cam timing a little bit too... but then you'd be fixing up your cam timing because you're changing cams.. right! 
Also, 12:1 is doable, but it's not going to be happy with factory timing/fuel. As a guide, the old group A 4AG's ran 12:1, 300ish cams, rechipped (in Japan) factory ECU and made ~195hp on Avgas.
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Location:
Kings Langley, Sydney
Registered:
July 2004
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Re: 4AGE smallport maximum compression on stock pistons
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Wed, 15 September 2004 02:59
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is there any info on these old group a 4ag's
are these the same ones that they used at bathurst in the early 90's!!
i want one 
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