4/6 vs invader vs liquifire engines

[Teherr]

I uploaded some interesting pics of heads, cylinders, and bottom end engines. 
the heads left to right - invader, liquifire, 4/6
cylinders - same as above
bottom ends - no pistons 4/6, one piston liquifire

all 3 heads are different.  invader and liquifire cylinders are the same.  bottom ends are the same.

I am rebuilding a second 4/6 motor.  First one is mounted into chassis for oval racing - did light port work.  I was told by two diff sources that the 4/6 is capable of nearly 10,000rpm's and upper 90's in HP with full porting and tuned pipes.  Aaon was one source and said they can do the porting for about $800 and race pipes for another $800.  The other source was mid west collector who is putting a 4/6 motor into a ski-doo RV chassis.   I have a good liquifire chassis that I am thinking of placing the 4/6 motor for vintage oval in mod class. 

[Interceptor398]

John Deere heads had a larger dome ( lower compression ) and the later year Liquifire's had an advancing ignition similar to the LTD.  Many Deere owners first mod was Invader heads. A 4/6 motor can make those numbers but be prepared to spend some piles of money.  You will need to have the crank welded to hold up at that high RPM.

[sprocket]

Do what you like but stock rods will not handle 10,000 Rpms especially in oval racing the stock rods at best will handle 9250.  I agree weld the crank put good bearings on & I'd put different rods on it if you are planning on spinning this engine 10,000 Rpms. Figure out what cc you want in the heads before just choosing a stock head, you can take any stock head & have it machined to your spec or your likings, remember though you win tech tears you down if found cheating you go from 1st to last. Read the rules you're racing in. John Deere used Kawasaki but Kawasaki never used John Deere.
* Example John Deere will be DQ'D for using the 4/6 cylinders in any class including Mod  reasoning for it John Deere never used 4/6 cylinders. All it takes is having a tech person ask a guru in John Deere land and the out come won't be in your favor because those gurus know their Deeres

[Teherr]

sprocket,

yes, you make a good point about not being able to run a liquifire with 4/6 engine in any class.  I suppose I have to put the 4/6 motor in 4/6 chassis to be able to qualify to race it.  and thanks for the advice on crank, bearings and rods.