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Discussion Starter #1 (Edited)
Hi all

Been reading up alot, especially LotusElise , Lotus and K20actr.J threads

Also been digging through the internetzzz and looking at different possible k20 stroker combinations/kits.


Please dont talk about k24 cuz that's not an option I want to pursue.

So....

the standard stroker kits in the market today are...
(crank stroke, rod length, piston height)

BC > 92mm crank, 140mm rods and by reverse calculating from 212mm deck height, 26mm pistons

TODA > 90.7mm crank, 138mm rods (from website), and by assumption 28mm pistons (not sure about this, anyone can confirm?), leaving a deck height of 211.35mm

ZRP > 93mm crank, 135.5mm rods, 30mm pistons, achieves 212 deck height

InlinePro's rods + f22c1 crank + stock pistons > 90.7mm crank, 136.65mm rods, 30mm pistons, achieves 212mm deck height

clockwise motion > 92mm crank, 139mm rods, 27mm pistons, achieves 212mm deck height

not putting rod ratios down as i forgot how to calculate and realllyyyyyy dont wna go find it and do it over again

SO!

136.65mm rods dont exist except for these ads

https://www.part-box.com/bw-billet-4340-rod-set-h-beam-honda-h22-l-136-65mm-4pcs-4-epr-027-01

https://shop.marmotorsport.com/4340-epr-h-beam-rod-honda-h22-13665mm-long-arp2000-bolts-4633-p.asp

which are listings for a H22 rod (by divine grace the rod journal sizing matches the f22c1 and the wrist pin just so happens to be 22mm LOL)

however the bridgeway site http://www.bwcrank.com/product.php does not have this particular item number. unless i email and ask haha.

Dont know where inlinepro are getting their rods from hmmmmmm but I am operating on the assumption they are 136.65 as they mention f22c crank and stock k20 pistons on their item description


the thing that the sets all have in common is their high price tag.

I know and understand that you have to pay to play, but sometimes we wanna feel good that we have managed to get stuff at a good price.
BC, TODA, clockwisemotion are all big money purchases even before thinking about other stuff like cams etc.

Out of all the options I still quite like the idea of a stock honda OEM crank, so the f22c 90.7

it's either
a) 90.7 crank, 136.65 rods (inlinepro or bridgeway email), stock 30mm pistons, 212mm deck height, and call it a day, just like K20actr.J

or

b) 90.7 crank, 139mm rods, and 27mm pistons. this will result in a 211.35mm deck height, 0.65mm off from stock.
Ian from clockwise has been v helpful and mentioned their pistons are designed for tight clearances and will be relatively noiseless in DD usage even though it is 2618 alloy.

Car will see 98% street driving, it's my DD for work/life. Rev to 8.5k
cams will be one of toda a3, prayoonto 2, prayoonto 3 (advise pls? leaning toward toda a3 based on K20actr.J experience)
i will be running a k20z2 block without oil squirters.
i have j37 tb, rrc intake mani, but am limited to stock fd2r exhaust diameter.
hope to see the engine last for 100,000km or for as long as i own the car.

What do you all think? especially Lotus, LotusElise, K20actr.J and whomever has had experiencing with stroked motors. (thanks in advance Marko and Markus)

Welcome discussions,suggestions, advise, flame


cheers

Marko if you see this I hope your k22 elise is destroying everyone haha
 

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Arouse the DAMPFHAMMER!
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...looking at different possible k20 stroker combinations/kits.
You only look for stroke variation to increase displacement? Or does it include other options like having something BlackNDecker suggested?

Those you have mentioned, F22C forged/milled/hardened crankshaft with 90.7 mm, the 92 and 93 mm billet/milled/hardened crankshaft from BC, ..., ZRP. All these decrease rod-stroke-ratio (R/S ratio) from 1.51 down to 1.48, which is far from 1.62 of the 86 mm stroke. The R/S ratio is pretty sensitive to chances, e.g. a 27 mm piston height on a 86 crank changes R/S ratio by +3/100 to 1.65. But what does it mean?

The R/S ratio is first just a key number, calculated by rod lenght / stroke lenght. Second it tells you about the kinematic of the crank assembly, which is basis for force and tension calculation for the block designer. As a thumb rule, the lower it is, the more side load piston put down on the liner, which tells us something about the mechanical efficiency of the block. There is much more to know, but enough as for an overview. Third it tells us something about the piston acceleration and speed at a given engine speed. This tells us something about the VE capability concerning engine speed. The lower R/S ratio, the higher the VE capability. Drag Racers know this and reach with there 108 mm crank highest VE levels I ever seen. They even need 38 mm intake valves and 550 ccm big block-like sized ports to get the air hunger of these feeded.

Seems like the lower it is, the better? Yesno, as forces of e.g. at the rod bolts increases with a sligth power to 2 character for a given engine speed piston height and block height. What we can say is, the lower it is, the more left the VE curve increases, but also the recommended maximum engine speed for a given crank assembly and rod bolt specification.

For an DD I personally would prefer more an forged crank than an billet type. Billet type cranks have a strong to quality bounding of the base material, as the structure of the metal is homogenious and only cutted. Torsional vibrations and impacts at misshift, knocking, pre-ignition and so on can lead to broken crankshafts. Forged cranks has an inhomogenous structure with a strong enforcement at critical areas as the filament structure has a higher density there by nature of the process and if done right, key word is notched impact strength. Of course highly qualificated shops like Winberg understand to handle and to prove the basic material and support the racing industry with great success. But, the longer it should run in hours at a certain load profile, the higher small failures came up and risk an engine damage. So finally all depends on what you aiming for and of course your budget.

Concluding, for me a 90x86 or an 90x90.7 are the most alluring crank assembly setups, respectively between and down to stock bore size 86x86 or 86x90.7, when it comes to DD with a lot of miles on the clock.

Markus
 

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Arouse the DAMPFHAMMER!
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To your question in the topic. Of course you can order any size you want to have. A customized billet crankshaft is about 4000 $ and 30 weeks of delivery time. In my few no option for just a DD engine.

I personally work on a concept of an 90x78.5 engine for Bonneville land speed record. Seems to be 370 [email protected],000 rpm at sea level are possible with a fully moded concept. I spoke with Reg Cook, a 9 times Bonneville winner, who prefers the Nissan SR20 engines more because of the lower included valve angle, giving a better combustion design. He is a strong supporter of engine speed is just limited by the capability of the valvetrain. All his inline 4 engines are 86x86 (Nissan SR20, Honda K20) engines.

So, no need to destroke for higher engine speed? Yesno, as valve size is strongly bounded to bore size, as well as piston shape and dome volume. The question is, does the engine breathing at Bonneville, which has a normal atmospheric pressure of 0.89 bar instead of 1.01 bar at sea level, need a smaller valve size to keep air velocity of the intake runner high? I didn't answer this question yet at full satisfaction.

Finally, to try to answer your question. Are those needed or do they make sense? If you need a K20 stamp on the block for to be legal -> maybe, but stamps can be stamped. If you need more torque down low, maybe, but it cost you a lot more as bulding a 87x99 engine. If you need more power, maybe, but done the 86x86 setup right you can reach almost every power level of an 86x9X at same costs. So finally only torque can be a real argument for a stroked K20. And here we come to your budget which rules if it is worth to do. If you already are willing to spend 2,500 $ into the crank assembly, why spend it into an 89x86 or 90x86 engine like BlackNDecker recommended it. For me it makes most sense too. Only challenge is the head gasket durability...experience there increases at the fab shops and the head gasket suppliers. De-shrouding your valves would be an improvement for the head and a smaller port-throat-ratio would help to improve head flow where many aftermarket parts on induction side works best too.
 

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Discussion Starter #5
Thanks BlackNDecker

Since I'm not sleeving the block, I dont think 90mm would last. I did look into it but the walls are really gonna be very thin on stock sleeves
Spoke to my engine builder he suggested max 88 on stock sleeves.

Hi Markus, thanks for the input as well as the technicalities on R/S. I rmb reading something about safe max piston speed, which should be below 5000 feet per minute. I did a lot of reading on R/S but this was last year and I only rmb the issue on low R/S and increased wear on liner due to sideways force. thanks for the tuition.

with regard to stamping
Yes i can easily stamp a k24, but the block heights are still different and can be measured out, unless I have special mounts made to make the engine sit lower.


Also, am putting this up for discussion cuz I wna confirm/dispel any myths about 'no replacement for displacement'

so, to put your words into perspective, the only increase here for the $$$ put in vs a well-sorted k20 is simply more torque at a given rpm? (due to increased piston speed?)


then honestly a well-sorted k20 would probably do the job just fine it would seem???


damnnnn and here I was hoping for more discussion. after seeing k20actr.j build and dyno i got reallyyy hyped up.

oh well hope the above information at least serves to help people doing research on k20
 

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Arouse the DAMPFHAMMER!
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To the wall thickness: 90 mm bore corresponds to 2.0 mm which is race-able.

To the block height: who is able to measure the difference of 231.5 mm vs. 212.1 mm at a sitting and fully assembled engine accurate enough? Not possible without huuuuuge effort.

Power wise a K20 can achieve 300+ hp, I am convinced 370 hp are possible with the right budget. Torque wise engine speed hardly can compete with displacement...so torque is the real advantage of higher displacement. The torque curve sits just higher and get shorten by e.g. rod bolt spec.. Safe piston speed are depending on the last...parts low and high cycle fatigue. Concerning the rod bolt size, if you switch to the wider 24 mm big eye bearing width and use 7/16" bolts you can increase engine speed by 1400 rpm at same rod bolt tension compared to the 3/8" bolt size, when piston and rod weight keep the same. With that in mind, the 86x90.7 engine looks really attractive. BC also overs the wider bearing, but it is a billet crank. I have no experience on those in a DD.
 

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there was once a chap here who did a 89x99 K using a K24 crank in a sleeved k20 block. He seized one cylinder at some point, but it made more than 300HP and more than 300Nm of torque on OEM K20a2 cams.


http://www.k20a.org/forum/showthread.php?t=30078&page=2
http://www.k20a.org/forum/showthread.php?t=53940&page=2

The reason I went with a stroker was that the engine I bought was shagged incl. its crank. I needed a new one anyhow.

Sleeving a block is cheaper than a stroker crank.
The next time, I'd consider doing both :))
89x93mm sounds good, too
 

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Hi man.
Bigger stroke gives more benefits than 89 or 90mm stroke.
Of course bore helps to make hp and more air pTv etc...but no so much as stroke (always at k20..)


If you go to take cc from big sleeved bore think yot must revving at very very high rpms to produce your engine max power....
R/s ratio and piston speed are not issue at 86x90 at 9600-9800.
The issue is that any aftermarket Valvetrain up 9300-9400 its ok but higher the stress of valvetraine starts to measures an operating hours....
With 90.7 crank would produced the same power with k20 crank but at lower rpms
Bigger stroke gives better torque too


I suggest to go with 90.7 crank f22.but honda dont have in stock....
Inlipro rods are 136.5mm length and works perfect with any shelf 30mm c/h piston.
With 7/16" bolts you can rev 9350 and for special times 9550rpm....

Rs ratio its no so important with those rod and perfect k20 lines...as piston speed..and especially at pistons skirts..
I would say to go cp piston...and do not go 88mm bore
Max 87.5mm

F22 crank best reliability,toda that crank use

Inlinepro best value for money.
I never had any issue and will go with same companys k24 rods to new k24 project..

For road race toda a3
For drag pr3
Pr4 with centerfied..
 

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Discussion Starter #9
To the block height: who is able to measure the difference of 231.5 mm vs. 212.1 mm at a sitting and fully assembled engine accurate enough? Not possible without huuuuuge effort.
its either 3 finger spacing or 2 finger spacing from top of valve cover to the wiper cowl plastic. on first glance caveman measurement at least.
 

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The BC stroker kit for the Honda/Acura K Series engine platform incorporates the wider B16A bearing (.935" width) that offers more surface area than the .740" width bearing found in the OEM K Series crank and rod combination. The added surface area increases bearing life, especially at extended rpm.
 

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Arouse the DAMPFHAMMER!
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My 87x93 stroker is still running fine :)
Very good, Lotus :).

Another option would be destroking it. The F20C crank has the wider bearings, which are perfect for revving higher. I developed two engine concepts for an landspeed: 90x78.5 and 87x84 based. Both concepts achieve the specified flywheel power of >360 hp, the first at 11,500 rpm (375 hp) the second at 11,000 rpm (380 hp). The 2nd concept costs about 6000 € less, but less durable, as some parts are already at safety factors of lower than 1.2.

At a more durable level the 2nd concept still can reach >330 [email protected],500 rpm, the head port flow and the cross sections could be lowered to achieve also more low speed torque. Also VTEC and VTC can be kept for better fuel economy, low end torque and better bandwidth. Cost savings are around 2000 € compared to the landspeed application, but endurance is at least a factor of 10 better if run like applicated :D.

None of these stroker engines will be as much fun as this destroked 87x84 engine, once the bills for the parts are paid.
 

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ZRP now also offers a 148.5mm K-Series rod.
It is 9.6mm longer compared to a K20 rod and 3.5mm shorter than a K24 rod. Sounds to me that it allows to fit a 106mm crank in a K24 block.
It would also come close to fitting a 93mm ZRP crank in a K24 block with suitable pistons.


An other option would be a 86mm crank in a K24 block with even longer rods.

https://www.zrp-rods.com/shop/honda-k20-148-50x22-longer-connecting-rods/
 

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Discussion Starter #14
any updates on the decision making?
My 87x93 stroker is still running fine :)

haha hi Lotus

thanks for asking.

to be honest, i almost sold my car last month, had turbocharged dreams.

have decided to keep the car, will be passing it to a friend 3 years from now when his car is due for the scrap heap.

have also decided on an engine build.

local shops havent had much success with stroker kits and i am not going to risk it on my daily.

going for a tried and tested stock stroke with 87mm mahle and toda a3.

keeping the stock z2 block, so sourcing a k20a crankshaft with the build.

i also found out my head is not an rsp but an rbc, so leaving some power on the table for the build.

the opportunity to obtain an rsp head slipped by my grasp. oh well.




recently i changed the intake mani from RRC + J37 tb back to rbc and j35. engine felt more urgent and my consumption was better. i guess on a stock stock build there's no need for too much flow?????? how does this match up to your engine calculation thingy?

of course, the new build will have the rrc intake mani, port matched to the j37. exhaust is still limited to a decat fd2r exhaust.

toda a3, toda springs, stock tct, mahle pistons, eagle rods (low power build with no NOS), daily use which would see the track maybe once a year.



shop was warning me about not having oil squirters but I'd run B engines without squirters on the track before, and with forged pistons im not worried.


yup, that's the update on my build!



nice to hear your stroker is running well, cant wait for videos of you ripping it up!!
 

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hi LotusElise

what's up my man, thanks for the great number calculation as usual. think i got you and marko confused in my earlier post about engine calculation.



anyway i also wanted to mention that i'm starting a family soon so i really couldnt foray into the stroker thing.


i really wanted a 27mm piston with stock rods and 90.7mm crankshaft

with a 92mm crank it would be flush and same as an 86x86 deck height,
but with the s2k crank i would have 0.65mm lower and means i would have a little more allowance on P-V.

On 12.5 comp pistons i'm not sure how much drop there would be in compression but i am under the assumption it wouldnt drop past 12.0


of course all this is just moot discussion but oh well.
what are we without our dreams, eh?
 

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Arouse the DAMPFHAMMER!
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...i'm starting a family soon....
Great, this will change the game a bit :D. Is it already on the way?

...i really wanted a 27mm piston with stock rods and 90.7mm crankshaft...with a 92mm crank it would be flush and same as an 86x86 deck height, but with the s2k crank i would have 0.65mm lower and means i would have a little more allowance on P-V...On 12.5 comp pistons i'm not sure how much drop there would be in compression but i am under the assumption it wouldnt drop past 12.0...of course all this is just moot discussion but oh well...what are we without our dreams, eh?
We would have been poor in our heart without related passion, dreams are like our power supply. For yours I think to get it more clear you have to define budget, aims and timeframe to work out the sculpture below.

...K24 seems impossible now.
It is not allowed in Singapore anymore?
 
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