CRXR

Ok so am wondering what would be the maximum piston comp ratio to run with a 95mm stroker crank on a b18b block...

I currently have a build b18b block with forged internals but not exactly sure on the comp ratio of my current piston cause i bought the engine build from the start.

Would like to stroke it to 95mm so i can get to atleast 220whp without having to switch to a b20 block...current power is 205whp with blox type c cams, no pnp, build head, flat valves, stock 81mm bore, 89mm ls stroke.

Iam guessing the comp ratio is between 12 and 13.1 to make 205whp on a lsv

Was running a S2 pro series im with a 65mm tb but am going to switch to a Ultra Series IM & a 70 or 74mm tb...Also got a good deal on some Buddy Club stage 4 cams for 300, so i might switch to those.

My goal is simply 220 to 230whp. Would like more but i know id have to switch to a 84+mm block

whitesihatch

Do you have e85 readily available?

CRXR

Yes am currently using e85...Am just more worried about the piston to deck height.

93egSLEEPER

You can (and will) reach your goals w/o doing a stroker setup or B20 block and save yourself a ton of money.

Slowsleeper has a 82x89 w/ cast ITR pistons making 240whp. I think I sent that to you in a PM a few weeks back if I'm not mistaken. You must just be set on running a stroker setup.

Local guy has an LSV making 219whp on a dyno dynamics (which is stingy in our area reading 5-7% lower than others) w/ this setup:

81.5x89
wiseco 12.5:1 pistons on eagle h-beams
Portflow CNC head
Skunk2 pro2 cams
S2 alpha header
S2 ultra street w/ 70mm alpha tb
RDX injectors
3" SRI w/ Vstack

Keep in mind this same car did a "dyno day" on a dynopack and made 228whp when it was 95 degrees out.

Another guy I sold my old M22 cams to has a 12:1 82x89 LSV w/ stock port head making 212whp tuned at Kaizenspeed. With head work he could easily unlock another 10whp.

If you really read into what I am saying, the power you are looking for isn't hard to get. And it definitely does not take a 95mm stroke w/ customs pistons/rods.

And just for emphasis...
https://honda-tech.com/all-motor-nat...hread-1583606/

CRXR

Ive read all the setups on there...all those numbers vary with different dynos, temperatures and elevation ..but didnt really see many 95mm strokers and not really set on it just considering all possible options.

So far i know that am getting a s2 ultra street with a 74mm tb, so that am set on cause i sold my s2 pro series im and my stock itr im recently.

I currently have blox type c cams which pretty mild at only 268 intake/264 exhaust...so that needs improvement...buddy of mine said i can try his bc4s to see if i can reach my goal. So possible upgrade.

Also have a choice of getting a 85mm sleeved built block with 13:5.1 cp pistons that a buddy of mine is selling for 1000.

220-230whp is the current goal so i can spank up some bolt on k20s but 250+whp later would be nice

Chugger

Couple ways to skin a cat with a 95 crank 1 involves stock pin height pistons and short rods others require raised pins and diff rods. All depends on what you want longevity, compression, etc etc.

93egSLEEPER

A 13.5:1 85x89 will make well over 250whp if built properly. Look up black_dc4's build. He uses an ITR crank and makes 260+. A poorly setup 85x95 will be nothing but a disappointment and a headache/money pit unless you plan on racing it competitively on the weekends and have the time/money to devote to it. Is that in the plans/budget? I definitely wouldn't make it street car/dailyish driver. I like to keep it simple, but that is me. You may think I need to drop it or not be a dick, but I'm trying to HELP you reach your goals the EASY way...and save you a few bucks.

My opinion so far? The ultra street on an 85x95 setup is not the right choice if you follow through with it. Even on an 85x89, again my opinion, it is not optimal.

It is your car, your build and your money. At the end of the day do what makes you happy.

CRXR

These plans are just for a weekend racer not a daily.

No worries my friend all opinions welcome.

So what intake manifold would you recomend for a 85x95?

93egSLEEPER

Skunk2 ultra race, or something of that caliber

CRXR

Well noted thank you and i might just be going that route soon when all my parts sell

1HGEJ2

iTrader: (1)

which rods can i buy to use a 95mm crank (eagle) in a b18c motor

Chugger

Rod length depends on piston comp height.

CRXR

Well brian crower does sell the complete stroker kit but it aint cheap.

Well stock ls rods are 137mm and b16 are 134mm except for the b16b which are 142mm.

I am 10yrs into the honda game and now is when am finding more of an interest in building a honda lol been to much into my old mr2 turbo. I have the knowledge, skills and tools to do all this...just never really put time into trying until now.

CRXR

What i really would like to know is when using a stroker crank does the piston and rod travel farther down in the block?

It would make more sense to me if that is what is happening instead of traveling more up and messing with piston to deck clearance.

CRXR

A Stroker kit is an aftermarket assembly that increases the displacement of a reciprocating engine by increasing the travel of the piston (that is, the piston moves further up and/or down in the cylinder). This is done by using a different crankshaft where the crank pin is moved further away from the center of the axis of rotation of the crankshaft. While this increases displacement and torque it can potentially lower the limit to which the motor can rev safely compared to the stock configuration.


Ok i found this but still hoping that the crank goes further down instead of up and messing with piston to deck clearance.

whitesihatch

When you stroke the motor and utilize standard skirt length pistons, you reduce the rod to stroke ratio.

Your only options are custom piston and rods or the bc kit. Tall deck block etc.

These are ways to cope with the r/s ratio and still have larger stroke. Personally I think you'll have just as much fun with an 89mm stroke eagle 5531 rods and pistons.

But I'm not shooting your idea down.

whitesihatch

Just calculate your mean piston speeds, r/s ratio etc. Not too mention the diameter of your rod bolts. These will all be determining factors of how high you can spin the rotating assembly.

Don't forget about rod angle and the loads in which your cylinder walls will face from the angle and distance your piston will have to travel.

This is why I advise getting 1:6 rod to stroke ratio or better to get in the high rpms.

1HGEJ2

iTrader: (1)

i want use a eagle 95mm crank with wiseco or cp 86mm 13:1 pistons with darton sleeves. so i need the rod lenght :-/

Chugger

I would run atleast and i mean atleast a 5.394 rod with a 95mm crank i am running 5.531 length rods in my setup.

212mm deck height
137mm rod length
95mm÷2=47.5

47.5+137=184.5
212-184.5=27.5mm thats your comp height for the pistons

so something very close to that range for comp height

27.5mm= 1.08in

hope this helps

whitesihatch

Good info chugger. I agree 100% with you.

1HGEJ2

iTrader: (1)

thank u !
@ chugger..whats ur setup?? so i need unique pistons? are all stroker crank with b17/b18ab/b20 rod width??

JRCivic1

Be careful there... some important information is missing for ordering custom pistons.

Chugger's information above is basically for illustrative purposes... to get you in the ball park... and to help you understand basic theory here. Not every B18 stock block has a deck height of 212mm... I have measured quite a few "virgin" blocks that are more like 211.6-211.8mm. Also, you may want to sit in the hole a few thousandths in order to keep the proper quench area and not be even with the deck surface, which unfortunately, is what his calculation would do.

Discuss your plan with whoever is ordering your custom pistons... and get your block measured. Otherwise, if you use an arbitrary measurement like 212mm and it turns out to be shorter, the only simple fix will be to order a custom headgasket that is thicker to fix your goof... otherwise, valve to piston contact will be a real danger.

If you truly understand the basics that chugger presented above, you can use a compression calculator to help tweak the numbers and get the specs that you desire.

Honda B-Series Compression Calculator by ZealAutowerks

From here, you can alter the install height to find the proper depth of the piston in the hole. Using a stock thickness head gasket, a quench area of .037-.040" is optimum, which means that you will need to have the piston about .010" deep in the hole.

If you didn't want to use a custom piston, the only stock length rod choice that even comes close to working is a B16A rod at 5.290" (134.37mm)... and with the exception of having a rod ratio that is mathematically less than ideal, they will work just fine... assuming you use a .045" thick headgasket since the pistons would sit proud about a thousandth. Depending on the school of thought, some would say that rod ratio doesn't matter, and some would say that this engine just won't rev really high because of the low rod ratio. But since you are in Germany and getting custom parts may be challenging, it is a viable option.

Good luck.

1HGEJ2

iTrader: (1)

yeah the deck height of 212mm is my problem. i want a 86mm darton mid engine. i will sleeve at first and then measured them. are custom pistons with an other comp height expensive?

jdmconcepts

A couple of things you will need to know when ordering your custom pistons are the deck height, stroke, rod length, cylinder head chamber CCs,gasket thickness, and how much you want to be in the hole if any. Custom pistonpricing varies on what bells and whistles you want for example, moly side sits? Ceramic top coating? Gas ports? Sleeving the block and measuring the deck height is a good place to start then I would do the cylinder head and get a final cc of the chamber. Then it's time to plot out your piston design. I'll try to post up the custom piston form we use tomorrow for you.

JRCivic1

All custom pistons come with a premium price... and depending on the Manufacturer, this premium can vary dramatically. There are also options like dome and skirt coatings that can increase the price even more. Construction time also varies between manufacturers, and the time of year in which they are ordered can affect the timeline as well. The good news is that since you are considering a custom piston, choosing a longer rod will be advantageous and this can be incorporated in the piston design.

These details need to be discussed with your builder... or at the very least, an experienced shop.