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k20z3 in 2008 Si - hit list for 10,000 rpm

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50K views 43 replies 12 participants last post by  mucter  
M
#1 ·
So I've read/searched a lot for info on high-revving all motor builds. Seems there's a lot of info about the k20a2, but nothing definitive about the k20z3.

Now that FlashPro is coming out, that really opens the engine building options for the Si. I'd like to go all motor on my Si and make power up to about 10k. I do not want to go k24/k20, I want to rev, not have low end torque.

I know that on the k20a2 the oil pump is a problem due to cavitation. Is this an issue with the z3's oil pump? If so, will the S2000 oil pump fit on the z3 engine?

I assume that rods/cams are a must for revving to 10k safely. I was looking at the BP Stage 3 cams/valvetrain, but its unclear if they'll make power all the way up to 10k. I don't want a Stage 2 setup, as those seem to run out of breath right before 9k.

Anyone got some useful info on any of this?
 
#2 ·
you can run the s2000 oil pump, but you will need a k24a oil pan

Revving to 10K, you can do with any cams, even stock..

the question is why? The only real reason is because you are making power that high..

Without the right motor and head, you are not going to make power that high...

If you are serious about making power that high, you will need a camshaft that can sacrifice some tq for peak power.. Most cams on the market will make power up high but not that high...

Also it is said that the OEM pistons should not be revved after 9000 RPM, same with rods..

A block like the one you are describing, is going to be assembled by top nothch Ksereis engine builders.. There are only 4-5 people/shops that can do it right every time

If you are not planning to spend around $7000-$8000 just on the block and another $3000 for the head + cams + manifold + header, just dont worry about it and so something else..

A lot of people want this 10K RPM 300whp k20 motor, but it is basically a pipedream for 99.99999999% percent of them..
 
M
#5 ·
The reason I want to do it....

For the experience? It will be fun as hell. Why do we modify anything on our cars. Just because I don't want to get a k24 and swap my block, doesn't make me illogical or foolish. I know that I'd lose low end torque, and I don't care.

I want something that makes its power between 8k-10k. I know that the stock motor won't make any power past 8500, thats why I'm asking what parts I'd need to CHANGE it to be like that. I understand that I'd need rods, pistons, etc. I'm just trying to find out, what rods and pistons, if any, are made to handle that kind of abuse.

Are you sure that the k24 oil pan will mount up properly in the Si chassis?

I didn't ask for a 300whp k20. My goal isn't a power number, its a driving experience. I want the engine to make power to 10k, I want to be able to rev it up there relatively safely. Thats my goal. Period. Money is not a concern, but I want to do as much of the work with my own 2 hands as possible. I've built several D and B series engines in the past. I enjoy engine building.
 
#6 ·
One question. How streetable will that motor be revving to 10k? To pull something like that off you will definetly need a S2000 oil pump. Nobody is telling you to use a k24 bottomend. With that you definetly wont see 10k rpms unless a piston shoots from the block. You will need to do some reading and searching man. What is this car going to be used for? Is is going to be a track/weekend or a daily man?
 
M
#7 ·
As far as the k24 block is concerned, yes I know that revving that to 10k would be foolish. I was just referring to the fact that everyone seems to be doing a k24/k20 setup now. It seems that high revving engines aren't cool anymore and I think thats a shame, yeah sure, 8000rpm is high or whatever, but really as far as Honda's are concerned, 8000rpm is passe. Everyone's obsessed with low-end torque now. The Sti's and Evo's have made all the Honda guys have boost envy. I want the experience of the old-skool LS-VTEC builds that revved to 10k, but i want it in my Si.

~Streetability. My only stipulation for streetability is it must run on pump gas. We have 92 octane here in Oregon, so it would need to run on that. I think the max compression I can get away with here is about 12.5:1... so if I'm not going to be able to pump enough air into the cylinders to make power with a stage 3 cam, then I guess I'm screwed. But I'd like to try. The F20C revs to 9200 stock, so it can't be that far fetched to make a K20Z3 rev a little higher. If I can see an increase in horsepower up to at least 9500 I'll probably be happy. I don't care if i have to do rods, pistons, valve train, stage 3 cams, oil pump, etc.... I just need knowledge from people with experience.

I'm fully aware that I'll end up with a lopey idle, and or pathetic low end torque that makes it a pain in the ass for a daily driver. I only drive 3 miles to work every day. So I don't really give a shit about that. I want to build the car to have this type of power.
 
E
#15 ·
mucter said:
...I'm fully aware that I'll end up with a lopey idle, and or pathetic low end torque that makes it a pain in the ass for a daily driver. I only drive 3 miles to work every day. So I don't really give a shit about that. I want to build the car to have this type of power.
Click to expand...
You remind me of myself when I was 19: Cammed big-block hot rod that drank fuel like water, ran like crap around town, and was louder than it was fast. In the end, I practically gave the car away and bought a pickup truck instead.

Why are you so hung up on this rpm-thing? You will spend a million bucks to build it and only drive it 6 miles each day? Why don't you just try the usual bolt-ons first and see how you like it? I know a lot of people with big-hp cars that are very exciting to drive but cannot say that I have ever seen one with a 10K rev limit. That goal seems arbitrary to real-world performance. Just my opinion.
 
#12 ·
Yes, it exists.

IPS, Inlinepro and a few others have revved to 10500+ with different combinations both in k20 and k24a blocks.

I recently did a motor for a friend of mine with k24a block and s2000 crank. The k24a block height is very close to a s2000 block height, so it is not hard to imagine a s2000 motor revving to 10K.

here's back from 2006

IPS k10

Image



then

KXV

Image



crate motor

Image



From what I understand, the specs are proprietary, but it does show you what is possible as far as the powerband and RPM
 
M
#18 ·
I understand what you're saying. One of my other cars is a 2009 TSX.

I guess I'm just wanting to do something different. Even if it doesn't make any sense to everyone else. But it seems I may be thwarted simply by not having easy access to race fuel, which is a big problem. All of the people revving these engines to 10k+ are only doing it in race cars. Ughh...
 
#25 · (Edited)
You need

Custom crank
Custom rods
Custom pistons
Custom Header
IPS K10 cams or better
Quality Intake manifold (built to suit)
Quality head work and valvetrain
S2000 oil pump or dry sump setup
High quality clutch and flywheel combo

enough money to build 2 incase it doesn't last long...

Probly want a K24 block with a really small crank and some real long rods... You should try and get in touch with one of the builders Nikos mentioned. This kind of motor isnt built with off the shelf parts, every part needs to compliment the rest of the build. There for it is best to have someone who knows what they are doing spec out all the parts and assemble the motor to there specs and tollerences...

Your part may just be installing it when it arrives.
 
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#28 ·
jon v is on point man. That motor would have to be custom. You can't just go pick this up and pick that up. Something like that would be best left to the pros man unless you are one. No harm ment by that man.

I have a suggestion man, look at the Toda Stroker Kit. No it's not a 10k rpm package, but the specs of the kit is close to the Civic Mugen RR setup. It should go to 9k if, I'm not mistaken. It could be reliable.

Here's a clip of it. http://www.youtube.com/watch?v=PlAST5cgw4s

Toda products: http://k20a.org/forum/showthread.php?t=34175&highlight=Toda+Stroker+Kit
 
#32 ·
A 2.2L w/ s2k pump should do it. It won't make that much more power up top but here's a 2.2 doing 9,500 and aren't a bunch of ppl n/a ppl running 9.000rpm with stock pumps.

Don't know how valid this dyno is but seems like it's alot of peak for what it is.

Image
 
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#36 ·
I use IPS pistons and rods in most of my motors but the best comes with a price and patience. Rods at cunningham take 16 weeks to be made.

The geometry of the motor is changing with using a longer rod. Research short rod vs long rod on the internet to see the philisophies..

The 99mm crank in the k24a block is good and make power but as you rev up, it becomes more difficult to make power...

That is why people have been destroking the k24a blocks to 96mm, 95mm, 93, 92, 90, 88, 86, and even 82mm , 79mm...

Look at motorcycle specs... small stroke, big bore, high revs

Rod stroke ratio....

The reason why I suggest 86mm is because you already have it.. This motor would not break any HP records, but it would rev to 10K while making power with the right head..

This coudl really become a good turbo motor but for all motor, discplacement is best.

I did a 82mm k24 but had to sell it.. the new owner, has not run it yet..

if you see the spoon motor on your tube that revs to 10K+ is a s2000 cranked k20 or k24 block.

Since you want to put it together on your own and learn, start by maybe messing around with the k20z3 block...

Another point..

On the recent 90.7mm stroke k24a that I did for my friend in greece using IPS partrs, they measured that it would take 1.25 kgs of force to force the crank to do a full rotation which according to previous tests was very very lower comparted to other motors. The low force is a result of the bearing clearances, piston skirt design and piston weight, rod angle/pin position along with pin diameter etc...

So it should be simple.. It is harder to turn a big stroke than a smaller stroke... So at high rpm, it would be easier to turn a 80mm stroke than a bigger one.

Something else to think about

Both the enzo ferrari and the 2010 BMW M5 have the same bore and stroke

92.00 mm × 75.20 mm stroke

Coincidence>? I dont think so :p
 
M
#37 ·
I understand the relationship of an oversquare block vs. an undersquare block and how one is better for revving and the other is better for low-end grunt. That's why the S2000 revs so well, the pistons are like wide pancakes and the stroke is really short.

I know that the K20 is a square block since the bore and stroke are the same. So yeah its not going to rev as well as a f20c.

So basically what you're telling me is that I need to get a k24 block and by putting the k20 crank in it, I'll be creating a slightly oversquare engine due to the increased bore on the k24.

But what I don't get.... is how that'll be more reliable at 10k rpm than just leaving my crank in the k20z3 and putting stronger rods/pistons into it. Just because its oversquare, doesn't change the piston speeds or side loading of the cylinder walls. The pistons will be traveling at the same speed in either block.

Does running a longer rod due to the difference in deck height make the difference? I'd like to understand why that would make it safer in this instance. Because regardless of the rod length, the pistons will still travel at the same speed based on the stroke. It must be the rod angle that makes the difference, because I guess with a longer rod, the angle will be more upright, thus putting less stress on the rods. Is that correct?

Sorry my engine dynamics are a bit rusty.... its been a while since I've built one. That's the whole point of this thread. I miss it.
 
#38 ·
you are right 10K is not as drastic.. I might be talking about 11k+ revs with these combinations

As the cylinder fires, and the piston moves down say, .060", the short rod engine moves the crank MORE crank degrees because of the short rod, and the long rod moves barely at all.

As a result, the long rod pistons "dwells" at TDC longer, and allows the pressure to build up. Obviously at high rpm this is good for maintaining power since the short rod engine would have the piston halfway down its stroke in no time (no push)! Conversely, the short rod engine at low rpms and high loads will not ping and the engine has "leverage" to spin the crank, where the long rod engine "stalls".

Since the piston "timing" is different on the two respective engines they have different characteristics regarding camshaft selection and timing requirements. Also, the shorter engine will "pull and push" the charge thru the ports harder, running out of "breath" at a lower rpm while the long rod engine keeps pulling.
 
M
#40 ·
Yup, that all makes sense. So if I went this way, I have to get custom rods and pistons, there just simply isn't anything in the market that'll swap in to get this done?

I'm not trying to sound impatient. Just asking more questions since you seem to have lots of answers (and I'd probably buy this k24 block from you). :p
 
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