[jin1990]

I was planning on doing a K20/24 (K20Z3 Head + K24A2 Bottom End).
I noticed a comment from couple threads I passed through (not verbatim), "why does every dyno graph illustrates power stops before mid8K rpm for K20/24 build?"

Here are some answers I found of why the build does not allow the motor to rev beyond 8 or 8.4K rpm.
http://www.8thcivic.com/forums/bolt-ons-all-motor/82534-just-got-off-phone-doug-hondata-2.html (begin reading statement from silverspoon1996)
Doesn't suffice much to me, I need more concrete reasons why it won't safe rev up to; let say 10-10.5K (w/ ERL S2K Oil Pump) or 9-9.5K (RRC/PRB Oil Pump) rpm. Would it be the issue of rods & pistons not being able to handle up that high of rpm, something?

Any fillers???

I enjoy touge/auto-x (though I'm still an amateur) for it's high intensity. Just this (safe rev) alone is converting me to look away from K20/24 builds.

 

[xander1212]

Yes, concerning the piston rods. Since you'd have an increase of stroke when switching from the K20 to a K24 block, you have more distance the reciprocating parts are traveling. While it may be only a mere few millimeters of distance, that small change can add plenty of stress to the rods (especially when you think just how fast they are changing direction, from the up stroke to the down stroke, and then back to the up stroke and repeat). The stock Types-S/Si oil pump as you may already be aware, tends to cavitates beyond the 9000 rev limit, which is a great way to ruin your block (especially when you have parts moving at that speed). K24 oil pumps can't handle anything above the stock K24 redline for too long until cavitation.

Valvetrain for the K20 isn't a problem since it's made to go past 8000 already. If you really want to ensure your block doesn't call it quits early, you'd look for beefier rods and rod bolts that'll handle the added revs with ease.

F1 engines have super small strokes, which enable them to rev far beyond 10,000 for a comparison.

And seeing as you'd be trying to utilize the most out of the highest powerband possible, you should switch out parts that are made for high rev limits.

 

[jin1990]

hey man, thanks for the knowledge!!!
You just save me a ton of greenbacks.
I been looking into K20/24 build for some months. I'm considering to put the money elsewhere, reducing rotational mass, something benefiting MPG as well as high rpm performance^^

 

[xander1212]

I'm currently doing a turbo frank build shooting for 1,000 hp, so all my parts are forged to get me to my goal. You could build the K20 using lighter internals to make it rev faster and reduce stress if you want. That would one rev-happy, serious engine.

 

[maruipro]

Another cool fact is that revving a K20 to 9000 rpm has a slower max piston speed than a k24 revving to 8000 rpm.

Just food for thought.

 

[xander1212]

Another cool fact is that revving a K20 to 9000 rpm has a slower max piston speed than a k24 revving to 8000 rpm.

Just food for thought.

And, Top Fuel engines have mean speeds ~30 m/s. Damn fast.

 

[jin1990]

Another cool fact is that revving a K20 to 9000 rpm has a slower max piston speed than a k24 revving to 8000 rpm.

Just food for thought.

thanks for the input, I had no idea
I like that extra 1K rpm to keep it in gear a bit longer.
I know power means much, but I enjoy an engine that's elastically responsive w/ a wide band rpm.

 

[jin1990]

I'm currently doing a turbo frank build shooting for 1,000 hp, so all my parts are forged to get me to my goal. You could build the K20 using lighter internals to make it rev faster and reduce stress if you want. That would one rev-happy, serious engine.

what brands would be recommended?
The Si is my DD, so reliability 1st, performance 2nd

 

[xander1212]

what brands would be recommended?
The Si is my DD, so reliability 1st, performance 2nd

Really anything except for Skunk2. Their internals don't really stand up to par with the rest of the competition. Manley, ARP, Drag Cartel, SuperTech to name a few. And of course OEM Honda parts.

 

[bello]

Ok. So question, in order to get the k24/k20 to rev higher to the 9k , u wud need to upgrade the valve train and the oil pump?

 

[jin1990]

Ok. So question, in order to get the k24/k20 to rev higher to the 9k , u wud need to upgrade the valve train and the oil pump?

To get best of both worlds (Displacement & Rev), you would need serious $ to change out more than oil pump & valve train. It sounds good until build becomes more in detail

 

[emancivic]

I rev mine k20/k24 to 8500, its built though.

 

[jin1990]

I rev mine k20/k24 to 8500, its built though.

baller!

 

[jin1990]

Ok. So question, in order to get the k24/k20 to rev higher to the 9k , u wud need to upgrade the valve train and the oil pump?

that is just part of it, but it's safer to......
-Stay w/ K20 86X86mm including Oil Pump, Valve Train, & Mercury (Hg) Pulley for harmonic balance @ high RPM
OR
-Utilized an over-squared like how the AP1 S2K is. Either de-stroke K20 or K24 crank, but this is a lot of $ for an NA setup