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620 Land Speed Record


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Cast steel not iron yes.  This is a medium strength high carbon steel alloy flywheel.  After spending 2 hours carving on it I realize how well these are cast.  Better than most if not all aftermarket options.  Cutting corners?  Are you kidding me?  Aluminum flywheels are the ones that are banned.  I'll have a custom SFI approved ballistic flywheel blanket, its forward of the passenger compartment, and the floor over the transmission will be both guarded with cage and steel plate.  I may cut even more off of it if we can't run a starter with our arrangement (ring gear and everything around it).  Besides noone of the aftermarket steel flywheels are heavy enough for land speed racing (momentum).  

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I had taken 10 lbs off one of those, and never had any issues with it.

The OS Giken multi-plate set up are very heavy, and not just because of the clutch pieces,

and they are fairly easy to find, since the L6, and RB interchange with your L20B.


+1 on the aluminum crap should be banned. Never seen a used one that wasn't on the verge of falling apart.

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I'm playing a balancing act with weight.  I have a 720 L20b flywheel that weighs one metric shit ton.  I need to find a happy medium between dampening high rpm harmonics and good acceleration.  16 lb flywheels have always been my street solution, but this one is sitting at 21.  The clutch will likely be Chevy or BMW.  The transmission adapter plate will accommodate both transmission bolt patterns.  

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The z car 225mm clutch wheels were cast 21pounds stock. Most L20B 200mm and 225mmand under are 31 pounds. The Z24 uses a 240mm clutch and the wheel is (I think) 21 pounds because of the torky displacement and the already heavier 240mm pressure plate assy.

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Little late but, from DATSPORT Australia.....





Specifications for machining L series flywheels. This spec can be adapted to 4 & 6 cyl fly wheels.It is suggested that the portion contacted by the disc be increased to min 13mm for street use.

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Someone else had asked about windage trays.  Here's what I've started, although I think I'm going to make it bolt into the oil pan.  If I don't, I'll have to make the rest of the pan rail, so the oil pan sits level.  No big deal either way, but sometimes simpler is better.  The oil pan will take days to fabricate, as the straps on the main caps interfere with pan fit.  I could mill them away, but I'd rather deal with the pan and leave well enough alone.  


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If you strap the caps, 2,3,& 4 are the most important.  They're the ones that will move around under stress.  #5 has the whole rear of the block to keep it stable.  Plus you have to machine your caps flat, then line bore/hone because the bores WILL distort after milling.  Build the height to whatever studs you source.  The width should match the caps, or at least be wide enough to not cause stress points at the stud holes.  

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Flow benching the head today.  Manley valves are fitted.  Ported pretty severely but the job is not completed.  Got up to 220 cfm on the intake so far, definitely room for improvement.  That puts us in the 225 hp range if everything else plays along.  25 more to find somewhere.  


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I have a small chamber 1980 head with round exhaust ports that I think I can get closer to the FIA.  These are my training wheels.   :thumbup:

Besides, the flow numbers are pretty good.  Intake to exhaust ratios are very, very good too.  This is the A87 small chamber head that is "no good for performance" according to many.  

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