300 crank spacings??

[Anonymous]

hey all i am new here i am an aussie

i've just about finished a 700hp build up of a aussie falcon i6

its a standard stroke 246cu in 4.0lt ohc engine feeding a turbonetics t72 with a t78 comp cover and wheel.

now i have been reading on these forums that there is a 300 cu in i6 in the states

now i know that the 250 x flow has the same bore spacings as the ohc engine so does that mean i could fit a 300 crank into the ohc block??

my plan is to fit a 300 cu-in crank with a set of custom h or i beam rods and a set of 20 or 30 tho oversized forged pistons all hosed in an au falcon bottom end (it has a crank girdle and a wider mains caps then all the previous models of aussie falcs)

see at the moment the turbo spools at around 3200 rpm and peak power is made at around 5700-5800 rpm so i'm only really getting 2500 rpm worth of fun. now if i could bump the cappacity of the engine up another one litre or so the turbo should spool at around 2500 or a bit less.

i'd rather bump up cappacity then rev the engine harder as the ford i6 inherrantly is not designed to be revved -due to the fact that the motor is undersquare- which brings me to the next part of the problem.... if i go the 300 cu in crank (which will make the engine undersquare even more) it will not want to rev out to the 6000rpm limit i wish to run so its a catch 22 situation.

also the falcon engine has 12 counterweights on the crank (i know the x-flow had a 7 counter weight) so how many does the 300 cu in item have(same as the x-flow???)

well theres my thoughts on it, please if you have some input to give then do so as any help is always good!

cheers.joe.

 

[StrangeRanger]

The 300 has 4.48" bore spacings. It's an entirely different engine from the 250. I thought there were a few 300s in Oz in some of the older trucks. It's referred to as the "Canadian" engine.

 

[Anonymous]

aw well...

guess i'll just have to look at that anit-lag i was half way thru seting up again.... cheers for the info strangeranger

cheers.joe.

 

[Anonymous]

Nitrous is great for fighting lag...


-=Whittey=-

 

[StrangeRanger]

Yeah, if you breathe enough of it you just don't notice :roll:

 

[xctasy]

Option One: A Wash-your-mouth-out....The latset GM 4200 all alloy 270 hp six used in the GM Olds Bravada truck has a 4.05" stroke, 3.66" lo-deck pistons, and has a Holden Red motor/Falcon I6 bore spacing....to the thousanth of an inch (4.045"). Since it swings in an all alloy block, it is super tough. I'd look at a 28 thou bore out to fit Chevy pistons, and a 150 thou stroke increase from this crank. 4.2 liters.

Not to proud to fight fire with fire, are ya?

OptionTwo: is stealing the 6.5"Astron 80/Sigma/Magna conrods, and slinging them on to the Falcon crank with a 75 thou off-set grind. The wrist pins (0.866")are quite small, as are the crank pins (Jag -style, at 2.048), but it was designed for a vibration prone 2.555 liter four. There is room for a hone out to the 0.9112 the smaller Ford sixes use. You may just get a 300 Ford style 3.985" stroke out of it that way. Altough the hi-po Henry is a thin-wall casting, I'll bet a 53 thou overbore may allow the use of a 1.153" tall ACL piston if you add a steel plate 425 thou thick to the top of the block, like old timer Ken Waggot did to his legandary DOHC 180 cube Holden Grey Motor in the late 50'S. That way, your rod ratio would be bl**dy good. Use an O-ringed copper gasket.

Surely JP's would help you out with a cam longer chain, and a Falcon BA power bulge will help you pack the punch behind bars!


Option Three: is as drastic. Offset grind to a Chrysler crank pin diameter, control the fillet radius to allow some flex, use Chevy 6" rods with 2.0 " journals for a potential 4.03" stroke, use the 3.68 " ACL piston with 1.153" deck. No plate, just good old 258 cubes and 4.220 liters of poke. 6% bigger. Like what a 265 is to a 245, or a 340 to a 318, or a 327 to a 307. Extra swing for greater zing.

Go ahead, make our day with a fat cubed freak! Your'e an inspiration to us all. 34 pounds of punch. Eat 304, 383, 454, and even our own 351's for breakie!

 

[Anonymous]

thanks xecute for that info it has helped out heaps

the 1st option looks to be the best one for me (as much as i'd hate yo use a gm part!!-but i am running a gm delco (or is that dumco??) ecu on it)

but i have managed to get hold of custom cranks in melbourne.

they said they can do a billet stroker crank and a set of billet rods with a set of really tiny pistons (height wise).

the fella on the phone said a 4.5 inch stroke and a set of 6 inch rods with short custom pistons

only down side is that its gonna cost me 8 grand to do - (seems like that nitrious is a better idea tho i couldnt run it on the street as this car is a 100 percent street worrior/show/drag car)

anyone else know know anymore info on the the new gm motor that xecute was talking about?

if anyones interested

atm its a 246 ef 1996 block with the ef crank and rods with a set of acl ea pistons 40 thou oversized (so the block is bored 23 tho to accept the pistons) a set of arp rod bolts blocks been o-ringed as well.

the cylinder head is a 2002 au series 3 one that has been heavily modifeid

i have a billet cam shaft in it with 590 tho lift but it is running 1990 ea rockers and lifters so the total lift is 620tho

custom exhaust manifold and a 8 lt intake plenum with a 700x400 front mount intercooler

its all just about done (i just need to assemble it all now-fun-not!!)

anyhoo cheers.joe.