I'm going to start working on a K24 soon and I was wondering what the advantages and disadvantages would be to destroking the motor w/ a K20 crank. Is it useful to have a motor that likes to rev high (maybe to stay in vtec?) or would it be better to not worry about redline and just try and build it w/ the crank it has (hopefully it'll be a TSX mill). Also, I don't actually know much about destroking (as I'm sure you can tell) but when you do destroke a motor, do you necessarily change more than the crank? What else do you swap out? rods? anything? Thanks for the help.

 

Im by no means a genius when it comes to all motor setups. But when you destroke a motor depending on the block height. You will need to run the K20 rods. The K24 rods will be too short if it has the same block height as the K20 motor. What this will do is give you a higher R/S Ratio and allow less sideloading. Creates less stress on the cylinder walls.

I really dont have to much info on the K24 or K20 blocks or heads. But you might have a issue with the mains in the K24 being too small or big for the K20 crank. I doubt it though the way honda makes there parts interchangeable. But that is another issue you might have to address. Also with running the K20 crank which has a smaller stroke but a a longer rod. You might have to notch the block so the rod doesnt hit the bottom of the cylinder wall. When your putting the motor together or whoever would be they would have to check all this out for you and make sure its with spec.

Maybe someone could chim in who actually has specs on both these motors and say if its physically possible to even do this swap. But if everything checks out I dont see it being a problem.

Sal

 

K24 block have a taller deck height than K20 blocks. If you were to destroke a K24 block using a K20 crank you would need a K20 crank (obviously) and some custom length rods (longer than both K20 and K24 stock rods). If you search around a bit you should be able to find info on deck heights and rod legths of the K-series motors. A K24 block destroked with the 86mm K20 crank would have a really high rod/stroke ratio, perhaps too high to really take advantage of.

One more thing to consider is that destroking cuts down the displacement of the motor. K20 crank in a K24 would take the 2.4 liter displacement down to around 2.0 again (stock K20 is 86mm bore and stock K24 is 87mm I believe)

 

What kind of advantages/disadvantages would destroking it bring? I know it's 19.7mm taller than the k20, if that helps anybody. But what are the pluses and minuses of undertaking something like this, instead of just using a k20