Stroker conrods

[caterpillar]

jepp! stenparners piston,will not(???) fit ,BECAUSE they will go over 3mm over the deck of block.....THAT was strange.....only in 81mm too....i have ordered by JE...

[auditude]

There was good article about dialynx 2.5 litre engine, with very good dyno results.

This might be the link, but it is down for me right now:

http://www.sls.wau.nl/fstolp/magazines/AudiDriver/500bhp.htm

[Jamo]

well if you use 30mm tall pistons from eurospeck = hondas je pistons, you need 159mm long rods, if you use 32,8mm tall orginal pistons 155,5mm long rods is close.


Your math is wrong: 95,5 stoke is up and down, so its blockheight-piston compression height - (95,5/2)


236-32,8=203,2
95,5/2=47,75
203,2-47,75=155,45

and then add to lenght that you want to be deckheigt clearance, 0,7mm is my opinion. Orginal does not come so much over deck, newer measured it.

but if you use different pistons all this is wasted.

So are you saying here that the original pistons dont have 0mm clearance but come 0.7mm over the deck height? And this is o.k?

[Jamo]

we may have language prob here, technical terms are allways hard.

155,45 long rods would be EVEN to deck and my opinion is that 0,7mm over deck is good, that would make rod 155,45+0,7mm BUT that would make compratio higher than orginal, becouse it does orginally go just 0,1-0,3 over deck, this is just memory, not an actual measurement.

But alllllllways measure everything your self, do not drust anybody, it is your engine, and believe it or not the truth is NOT in the internet.

I have so many times got "race" or quality parts with so many wrongs that I dont trust any measurement that i have not made my self. Its cheaper that way.

Same goes for the calculations,

[AnLe]

No, I don't know does the orginal piston come over deck, if calculated from the dimensions, it does not, but the squish area is raised, but no more than 0,3mm, but it is so small that it does not change compression rate, but makes squish area better.
The reason I liked to around 0,7 over the deck is that squish area works even better, and when the gasget is 1,6 thick it gives 0,9mm clearance.
Feel free to google squish area it the term is unfamiliar. I'm no expert on the subject, just something I picket up long the way.

[AnLe]

So are you saying here that the original pistons dont have 0mm clearance but come 0.7mm over the deck height? And this is o.k?

No.

Stock goes very close to deck level, and if it goes over, it is just the squish area part.

proof:

stock: 220mm block height
86,4mm stroke
144mm rod
32,8 tall piston.

86,4/2=43,2
43,2+144+32,8=220

[Jamo]

Just as I figured every calculation I do comes out at 32.45 compression height I need for the stroker at 236mm AAT block height to get 0 squish.

I want to know the effects of running S2 compression height of 32.8 giving 0.35mm into the squish is a no no or would that be good?

[AnLe]

Just as I figured every calculation I do comes out at 32.45 compression height I need for the stroker at 236mm AAT block height to get 0 squish.

I want to know the effects of running S2 compression height of 32.8 giving 0.35mm into the squish is a no no or would that be good?

I don't know how the comprate comes out, but there should be no prob. gasget is 1.6mm thick so the piston will not hit head.

Is is good ? dunno, must ask someone that knows, I dont think there is any problem, but what conrod are you using? What is cr?

[Jamo]

CR will be 8.5 - 8.7 dependant on my final calculations rod 155.8 in length.

[AnLe]

erm, I did write little too fast, 0,35 over deck should not be a problem.

Ok, so you have 155,8 rod and orginal pistons, that makes 10,04 of an compression rate, thats more than one unit more than orginal, I would not recomend that.

[Billman]

erm, I did write little too fast, 0,35 over deck should not be a problem.

Ok, so you have 155,8 rod and orginal pistons, that makes 10,04 of an compression rate, thats more than one unit more than orginal, I would not recomend that.

Now that you in the number what pistons should i take in order to have 8,5 CR with diesel block and crank and 158mm 23mm rods?

[Jamo]

erm, I did write little too fast, 0,35 over deck should not be a problem.

Ok, so you have 155,8 rod and orginal pistons, that makes 10,04 of an compression rate, thats more than one unit more than orginal, I would not recomend that.

No not original pistons, original piston compression height. The dish will be made with more cc on to

[AnLe]

jamo: ok!

Bill: calculate your sefl

[Billman]

@AnLe

[Mark Halligan]

So are you saying here that the original pistons dont have 0mm clearance but come 0.7mm over the deck height? And this is o.k?

Jamo

from an old thread

http://www.s2forum.com/forum/showpost.php?p=43503&postcount=39