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Discussion Starter #1
I should know the answer to this, kinda imbarised to ask, but what determines the maximum rev limit for a block before you start spinning bearings, breaking shit, ect... im doing my n/a build soon and was hoping to see at least my new rev limiter, which will be 8600 if i remember correctly from the jdmshit program... is this reasonable for race situations? reaching 8600 every now and then... will reving it this high mess anything up? anybody on here revving an h22 that high or close, or more for that matter? and what can you do to stop from spinning a bearing, will rebuilding the block with new oem parts be enough? thanks guys
 

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Discussion Starter #2
btw, my head will be able to handle up to 9k rpm if not a little more... incase anyone was wondering... block will have ge rods and type s pistons, and a full regasket and new bearings and stuff
 

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really? thanks man, i was worried cause my first bad trouble with my prelude was my old engine, which i missed a shift (actually downshifted instead of upshifting) and probably hit somewhere around 10,500 or 11,000rpm and spun a bearing really badly... didnt cause trouble till about 10k miles later, so i was never sure at what point the bearing spun... so 9k will be plenty for me, thanks for the helpful info
 

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98Vtec said:
stock crank is balanced to 9k

no it is not.
my stock crank was 160 something lbs out of balance at 8k rpm.


when i come home from work i'll answer the real question if nobody does yet
 

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Rick V said:
no it is not.
my stock crank was 160 something lbs out of balance at 8k rpm.


when i come home from work i'll answer the real question if nobody does yet
i read it on some tech site....

hey...just wondering, how did you measure that. That really bugs me
 

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Discussion Starter #7
so... 8k bad?... im still not clear on this, any other info? cause i get mine to about 7900 daily and it seems ok... so what should i expect to stop at with my new build?
 

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my crank was balanced on a 50,000$ computer balancer that gives you exact weights of each counterweight etc and how much everything is out of balance. then the computer has this robotic arm that swings out and drills or shaves off material to balance everything.

and i actually just looked at it to see if i gave you the right number and i didnt. it was 182 lbs out at 8k rpm. what does this mean? well not much really. could the motor be rev'd to 8k being 182 out? yeah sure. would it seriously reduce bearing life and cause metal fatigue if it was done so regularly? probably so.

in road racing we have a saying, smoother is faster. same thing applies to the motor only smoother (balanced) is better. balancing can only take you so far though. there are other things to take into consideration when you want to rev the piss out of the motor. the big ones are rotating mass, piston acceleration, and piston speed. rod stroke ratio and the angularity of the stroke also play a big factor as well as skirt friction and sideloading. and they are all connected

unfortunatly h22's arent really designed well to rev high. because of its rod stroke ratio there is a fairly harsh angularity from the short rod long stroke. this means there is more dwell time at tdc and bdc and less time for the piston to be traveling inbetween each. this equates into very fast piston acceleration and very fast piston speed's. both of these are no no's for a 10k rpm screamer. it also ='s higher sideloading and skirt friction. in order to really rev the motor it would either need a deckplate welded on to accomodate a longer rod ( more to it then just that) or have to be destroked.

valvetrain mass only add's to the problem. titanium retainers really arent going to produce much more rpm, couple hundred if you really need it. there are a lot more things in the valvetrain that weigh much more like the rocker arms and the cams themselves. the same thing applies to bottom end mass. anything that roatates or comes into contact with something else will slow things down, add more load, stress and friction and reduce the safe limit of max rpm.

so to be perfectly honest and this is only MY OPINION. i would seriously not rev an h22 without any balancing, machining, destroking, or safety measures past 8 grand'ish. its just not what the motor was made for.

next a lot of people will say "why did they make it so shitty". well really they didnt. the motor was designed to make torque. it was designed to lug around a 3000 lb pig of a car. there really is no bad rod stroke ratio. designing a motor boils down to its intended use. an f1 car with a r/s ratio in the 2+:1 range was meant to rev to 12k and make power and its cylinder head was designed to operate like that also as it is a race car. a duramax diesel was designed to make hundreds of ftlbs of torque at 2000rpm to tow shit... im sure you get the picture
 

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nholmes said:
Excellent informative post Rick

:number1 :bow :bow :bow
:stupid

i've seen a video clip that tsuchiya ran the Jun lude upto 8.6k-9k rpm... but it was dumped in tons of money...i'd take Rick's advice, balance the motor b4 you rev that high...
 

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PreludeKing1995 said:
you guys think balancing rods and crank and pistons will be enough work to safely rev to 8200, 8500 on occasions?
Why do you want to rev that high anyway, the h22 stops making power at like 7200...
 

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PreludeKing1995 said:
you guys think balancing rods and crank and pistons will be enough work to safely rev to 8200, 8500 on occasions?

it will be able to handle it if its built right. but i really wouldnt make a habit of it.

soem other things i would think about
1. removing or disabling the balance shafts
2. arp (or aebs) main and head studs
3. dont use the stock rods
4. whatever rods you get use the biggest rod bolt you can get them with.
5. chamfer the oil pasages in the mains
6. dont run your piston to wall clearance to tight
7. dont shave the head, reducing the squish is something you want to stay away from.
 
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