craig,
i note you are from rmit.....what do you do?? staff or student
andrew
On Thu, 14 Sep 2000, Craig Overend wrote:
> I think Cameron was talking about using the FIA head on a 2.3 or 2.4L.
> The additional 400cc would lower the powerband approximatly 1000rpm
> compared to a 2.0L engine according to my calculations.
>
> The only reasons a Z24 cranked L20B wouldn't rev out is because people
> use rods that are too short and valves that are too small.
> The way I see it you only have one option if you want to use all
> standard Nissan parts for a large capacity L20B.
> An L20B 2.3L 89mm bore x 92mm(Z22) 2289cc using 145.9mm L20B rods and
> KA24 34mm pin height engine with a rod/stroke ratio of 1.59 might be OK.
> Generally a rod to stroke ratio below 1.55 is considered to be bad for
> engine wear and reliability.
> If you wanted a 2.4L then 89mm x 96mm(Z24) 2389cc using 152.45mm
> rods(Z20) and ~27mm piston pin height would give rod/stroke of 1.59 you
> just need to find the pistons to suit.
> I put this info into my engine simulator and I got the following:
> Using 44mm valves, 41mm ID seat and 13.45mm(.530) lift both of these
> engine give a mach index (average airspeed) of 0.5. Meaning that the
> airspeed though the valve on average is at the valve/port maximum value,
> maximizing volumetric efficiency.
> The 2.3L would produce its max HP at ~6059RPM and max TORQUE at ~4767RPM
> if I did my maths right. If the cylinder head port was 74% efficient
> this would require ~43mm ports. This is why I think the FIA head could
> be a good choice. I'd love the FIA actual specs please anyone.
> On the same engine using 42mm valves, 38mm ID seat and 11mm(.434") lift
> results in max HP at ~4663RPM and max torque at ~3099RPM. No wonder it
> dont rev!
> Whack a cam in this head to increase lift to 12.2mm(.480") and you get
> max HP at 5171RPM and max torque at 3811RPM a little better. Any more
> lift than this needs bigger valves and/or seats without sacrificing
> volumetric efficiency.
>
> A nice L18W out to 2.0L 88mm bore x 82mm stroke (1995cc) using 133mm L16
> rods and 34mm piston pin height using 44mm valves, 41mm ID seat and
> 13.45mm(.530) lift.
> Results in 1.62 rod/stroke and a .504 mach index, max HP at 7009RPM max
> Torque at 5471RPM. I think this is what Brad was building but with the
> FIA head? The only downside I see with this engine is the rod to stroke
> ratio could be better with 135mm L20A rods? for 1.65 and the bore to
> stroke improved aswell for less friction. To improve the bore to stroke
> may then require the block be sleeved if possible.
>
> Craig.
>
> Brad HALLETT wrote:
> >
> > Hate to tell you this Cameron, but you will have trouble getting midrange
> > out of an FIA head. They are designed to have maximum volumetric flow
> > meaning a narrow high rev powerband. They really are for maximum rev
> > applications only.
> >
> > Regards
> > Brad HALLETT
> >
>
>
>
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