Ok so I'm not actually thinking of doing this, but figured i would put my idea up for scrutinizing by other corolla nuts hehe.

 

Does a 3k crank fit into a 5k? Assuming it does, when you did drop it in you would have a stroke of 6mm less correct?.

 

Now i know what your thinking. "what is he thinking? it wouldn't work because your combustion chamber would be too big, cos of the piston being at 6mm lower at tdc"

soooooo, the obvious answer would be to shave the top of the block 6mm.

 

Hahaha, now i know what your thinking now, "what an idiot"

But think of it this way, if you pulled it off, you could have a 5k with a bore of 80.5mm plus however much a 60" boreout would add in mm, and a stroke of 66mm

 

Have it Balanced, add a massive cam, pair of sidiez, custom dizzy/advance curve ect

 

Would it create a super high rpm monster or just a shit 5k? if done well?

 

 

p.s. don't hate tooo hard please, its early in the morning hehe

Ella likes this idea, but thinks your possibly been getting too close to some sort of chemicals again mr jack...

So you want to build an oversquare motor to get it to rev?

 

Forget it. Put a hayabusa engine in, getting close to your capacity anyway and it rolled out of the factory built to rev it's tits off.

 

Plus - the claim is that K blocks hit a harmonic at 8000+ revs with reasonable consistency. Balancing wont rectify that.

If you were to put in a 3k crank and shave the block 6mm the pistons would be sticking out the top of the block at TDC. :y:

Edited August 28, 200917 yr by Felix

Plus - the claim is that K blocks hit a harmonic at 8000+ revs with reasonable consistency. Balancing wont rectify that.

 

 

can you explain this some more philbey?

 

we used to turn my old 4k (now jacks engine) somewhere in the vicinty of 8-9000RPM on a daily basis

 

yes i know absolutely no mechanical sypathy, but shit man it sounded sweet when we made her sing like that...

yep, till it finally died from f@$ked valve stem seals it reved clean past 8, up to 9

sometimes cold rofl. and it wasnt balanced

 

If you were to put in a 3k crank and shave the block 6mm the pistons would be sticking out the top of the block at TDC

 

huh? if it 6m shorter then the 5k crank then why would it stick out of the block?

Edited August 28, 200917 yr by Captain_Fantastic

can you explain this some more philbey?

 

we used to turn my old 4k (now jacks engine) somewhere in the vicinty of 8-9000RPM on a daily basis

 

yes i know absolutely no mechanical sypathy, but shit man it sounded sweet when we made her sing like that...

 

I am glad I was a loooooonnnnnnggggg way away from that car when you were doing that :y:

Redo your maths Captain.

 

As for your motor revving 8-9 daily, unbalanced, I would have to put forward my doubts about the accuracy of your tacho.

 

Anyway, I just put forward the claim made in the faq on building a tough K engine. Although it is anecdotal only.

ran like that for 7 years since it was built. easily pulling up to 9, i had it at 9500 once getting 2nd instead of 5ht at the local race track.

Still ran sweet aside from carby issues was the only thing.

wish i hadnt f@$ked the valves by being a noob now :y:

 

As for your motor revving 8-9 daily, unbalanced, I would have to put forward my doubts about the accuracy of your tacho.

i would agree, but this is on 3 differnt tachos, two stock tacho dash clusters and one after market tacho (unsure of make)

 

edit: stroke in a 5k is 73? and in a 3k its 66? I'm confused?

Edited August 28, 200917 yr by Captain_Fantastic

lol i didnt believe it much when i first got the car but was checked with several tachos.

 

poor thing was given a lot of hell and it stood up to everything i gave it lol.

huh? if it 6m shorter then the 5k crank then why would it stick out of the block?

 

Well the 3k stroke is 7mm shorter.

 

The pistons travel up 3.5mm less and down 3.5mm less from the crank centerline. :y:

ah yes of course. *facepalm*

wouldnt doubt that the 4k would rev like that. My 5k was unbalanced, and would pull 8000+rpm with ease. Again this was with two different tachos.

yeh 4k's rev hard, mine went crap until about 4500 then pulled all the way to 8000, couple times hit the 9000 mark to keep up with a civic or something

Back to the original question. Read an article years ago in Fast Fours (before it turned shit) about an Appendix J Mini that used this approach to gain more power. They were limited to the capacity they could run so they decided to build a big revving motor. Think it worked ok as long as it was a "power" circuit.