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Thread: Stroke Ratios. 4age vs 7age

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    Default Stroke Ratios. 4age vs 7age


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    Just doing a bit more study. I know people bad mouth wiki all the time but I cant help that its such a user friendly source.

    http://en.wikipedia.org/wiki/4AGE#4A-G_.2816-valve.29

    The link goes on to say the of the A series engines the 4age is the most race bred being over square bore/stroke. And the 7afe loses this to it economy style set up keeping the 81mm bore seen in the 4 series but increasing the stroke from 77mm to 85.5mm making it very much under square.

    It doesnt say this but by my mind a heavily under square bore/stroke ratio means that the piston has to travel further than its over square 4age counterpart? Im not sure if im right or not. This would mean the what the 4a lacks in displacement make up for in top end power due to a high rpm favoured set up leading to it screaming passed the 7 series with ITBs wide open .

    I know the 7age set up is mainly for torque but in doing that is the top end scarficed?

    Anyone out there who has driven a decent 4age and or a decent 7 series please share your thoughts.

    Cheers,

    -Jamehij

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    add ITB's and decent cams to a 7a and ull hav no problems in the top end with the added torque lower down

    also remeber on wikipedia they are refering to the 7afe as a stock pos...not the "improved" 7age version

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    I agree with delazy, if you look at the bore/stroke ratios of the ZZ engines you will see they are way under square and yet they still have a highish rev limit and max power made at a high rpm.
    My website: SQ Engineering - 4AGE and 3SGE upgrade/replacement parts

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    Cool so you can tinker with the power curve quite alot by selcting approprite cams? What kinda rpm can they see safely? Modded of course. That of the 4age?
    Yea the extra torque looks very appealing.

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    it just depends how much you wanna spend, i'm sure it could rev out very closely to a
    4age. i've decided to go 7age as i've found a 4age head and 7a blocks are piss to find at the wreckers, give it a rebuild with some goodies and it should be sweet

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    yeah cams and intake tuning can shift the power curve around, as for your second question see here:

    http://www.ae86drivingclub.com.au/fo...ead.php?t=1308
    My website: SQ Engineering - 4AGE and 3SGE upgrade/replacement parts

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