long rod stroker problems

[jbeaton9292]

Ok so i have a motor that i was gonna do 2.3l stroker but now have decided a 2.0 is better for my needs i had only got the pistons and block machined so no hige loss i was reading u can do a longrod stroker which is just a 2.0l i was thinking this is cheaper than starting fresh being pistons are not cheap so i set out to find some rods i cant find any 156mm rods for a 6 bolt

So here is my question does anyone know where i can find some of these 156mm rods in 6 bolt please help or make suggestions any help is good

 

[white92talontsi]

Well idk im not seeing how it will lower compression i would see lower compression if i used stroker piston standard rods and standard crank

Then I would suggest before building your engine to read on how everything inside an engine works.

Here is a 2.3 stroker piston on a 88mm crankshaft and 156mm rods. the pistons are advertised as 9.0:1.

As you can see since we used a piston designed for a 100mm stroke then losing 12mm of stroke we lose a lot of compression. The compression ratio is listed in the bottom left.

 

[jbeaton9292]

Yes i see that but u can change your cr with alot of factors the pistons are measured 9.0:1 in the perfect scenario the hg thinckness the cams porting in the head ect.ect. can change compression correct?

Im not saying your wrong as im still pretty new to this stuff but i was sure all that plays a role in the actual compression numbers

 

[white92talontsi]

Yes i see that but u can change your cr with alot of factors the pistons are measured 9.0:1 in the perfect scenario the hg thinckness the cams porting in the head ect.ect. can change compression correct?

Im not saying your wrong as im still pretty new to this stuff but i was sure all that plays a role in the actual compression numbers

Yes, all that stuff does change compression, Minimal changes though. The number 1 biggest factor that determines compression is the stroke.

 

[jbeaton9292]

Yes, all that stuff does change compression, Minimal changes though. The number 1 biggest factor that determines compression is the stroke.

Ok so camming porting bigger exhaust all them small changes is gonna make a normal effect or close to it which regardless less compression the more boost i can shove through the motor and being the better rod ratio higher revs as well without as much sacrifice

 

[white92talontsi]

Ok so camming porting bigger exhaust all them small changes is gonna make a normal effect or close to it which regardless less compression the more boost i can shove through the motor and being the better rod ratio higher revs as well without as much sacrifice

I have no idea what you were trying to say right there. You can do as you please, I told you what the differences are and you can choose whatever path you like.

 

[lasthope05]

You should not lose any compression. Are you taking into account the 4g64 block as a 6mm taller deck height? With stroker pistons and the 6mm higher offset the pistons would sink in on a standard 4g63 block. Using a longer rod(156mm) the offset would be rebalanced and the pistons would be back to zero deck(or close to it). Your not increasing displacement or changing CR but instead changing rod ratios and piston side loading.

Im not exactly sure what you are trying to say..

 

[white92talontsi]

I guess you guys just don't get it.

A 2.3 liter piston was designed for a 100mm stroke.
Put said 2.3 stroker piston on a 88mm stroke crankshaft and you lose compression.


It's really simple.

 

[lasthope05]

Im trying to understand what you are trying to say but, we are compensating the extra stroke of the crank for longer rods. The wrist pins on stroker pistions are 6mm higher(lowering the piston) to take into account of the extre 6mm stroke increase up top with a 100mm crank in a 4g63 block. 6mm longer rods are used in a 88mm crank in conjunction to stroker pistons that are 6mm "shorter" to bring the pistons back closer to zero deck in a 4g63 block.

 

[jayson427]

So if it's a stock crank how can it be a stroker? It just a long rod motor right?

 

[white92talontsi]

Im trying to understand what you are trying to say but, we are compensating the extra stroke of the crank for longer rods. The wrist pins on stroker pistions are 6mm higher(lowering the piston) to take into account of the extre 6mm stroke increase up top with a 100mm crank in a 4g63 block. 6mm longer rods are used in a 88mm crank in conjunction to stroker pistons that are 6mm "shorter" to bring the pistons back closer to zero deck in a 4g63 block.

It does not matter what you do as far as moving the wrist pin up and using longer rods as it is not changing the stroke. You still have a total of 88mm of stroke in a long rod 2.0. Now put a piston on that rod that was designed for a 100mm stroke.

Really simple.

So if it's a stock crank how can it be a stroker? It just a long rod motor right?

Correct, a long rod motor is just that. A long rod motor. Stroke does not change.

 

[jbeaton9292]

Im trying to understand what you are trying to say but, we are compensating the extra stroke of the crank for longer rods. The wrist pins on stroker pistions are 6mm higher(lowering the piston) to take into account of the extre 6mm stroke increase up top with a 100mm crank in a 4g63 block. 6mm longer rods are used in a 88mm crank in conjunction to stroker pistons that are 6mm "shorter" to bring the pistons back closer to zero deck in a 4g63 block.

Im with u here but regardless this thread was not made to start an argument

 

[lasthope05]

It does not matter what you do as far as moving the wrist pin up and using longer rods as it is not changing the stroke. You still have a total of 88mm of stroke in a long rod 2.0. Now put a piston on that rod that was designed for a 100mm stroke.

Really simple.




Correct, a long rod motor is just that. A long rod motor. Stroke does not change.

You are not changing stroke but rod angle. 2.4L 4g64 with 100mm crank has 12mm more stroke then a 2.0l 4g63. That 12mm extra stroke comes 6mm up top towards the deck and 6mm at the bottom of the bore. Thats all.

Stroker pistons are standard pistons with a shorter 6mm pin location to take into account of the -6mm shorter deck of the 2.0l 4g63 block and by using them in a 88 crank with 6mm longer rods to bring the pistons back to zero deck. It doesnt matter what happens on the lower end.

We are not changing stroke. Just rod/stroke ratio making it more ideal for higher reving/less side loading.

Please explain otherwise and inform me of anything different instead of saying it wont work because I would like to learn.

Im with u here but regardless this thread was not made to start an argument

Sorry. I'll end this here.

 

[white92talontsi]

Im with u here but regardless this thread was not made to start an argument

You guys really are clueless. Now I realize why I never come on this site anymore.

You are not changing stroke but rod angle. 2.4L 4g64 with 100mm crank has 12mm more stroke then a 2.0l 4g63. That 12mm extra stroke comes 6mm up top towards the deck and 6mm at the bottom of the bore. Thats all.

Stroker pistons are standard pistons with a shorter 6mm pin location to take into account of the -6mm shorter deck of the 2.0l 4g63 block and by using them in a 88 crank with 6mm longer rods to bring the pistons back to zero deck. It doesnt matter what happens on the lower end.

We are not changing stroke. Just rod/stroke ratio making it more ideal for higher reving/less side loading.

Please explain otherwise and inform me of anything different instead of saying it wont work because I would like to learn.




Sorry. I'll end this here.

Ok, now your starting to get a little aggravating. A 2.3 liter piston is designed for a crank that has 100mm of stroke. The compression height of the piston as well as the dish are made to work with the 100mm crank.


If you take that piston and put it on a 88mm stroke crankshaft you are losing 12mm of stroke that the 2.3 piston was designed around and you will lose compression.

Here i'll even do this for you.
Manley 2.3 stroker piston.
607005C-4 Compression height is 1.130" with a dish of -22cc on a 150mm rod

Manley 2.0 Long rod piston
617005C-4 Compression height is 1.130" with a dish of -12cc on a 156mm rod

Now tell me, why does a 2.3 stroker piston have a different part number than a 2.0 piston for a 156mm rod?

Both the above pistons are rated at 8.5:1 in a DSM and both are 85.5mm

 

[bastarddsm]

Jesus. Your all wrong, a 2.3l piston has a dish that is about 9cc bigger than a similar piston for a 2.0l

MITSUBISHI - MITSUBISHI 1988-92 ECLIPSE / TALON / EVO 4G63 21MM PIN - JE Pistons

Compression ratio is calculated as CR = (Clearance volume + Swept Volume)/Clearance volume.

A 2.0 has a swept volume of about 499cc. A 2.3 is 567cc. The clearance volume consists of the chamber volume (47cc), head gasket volume ~6cc, The piston dish volume, and the crevice volume (~1cc).

So if you run JE 8.5 to 1 pistons for a 2.3 (22cc dish), in a 2.3 you get a compression ratio of (22+47+6+1+567)/(22+47+6+1) = 8.46 to 1

If you run JE 8.5 to 1 pistons for a 2.0 (13.2cc dish) in a 2.0 you get (13.2+47+6+1+499)/(13.2+47+6+1)= 8.42

Now if you run JE 8.5 to 1 pistons for a 2.3 (22cc dish) with a 2.0 crank and long rods you get (22+47+6+1+499)/(22+47+6+1) = 7.6 to 1

You see, with a stroker motor your swept volume goes up, so the clearance volume must go up to keep the compression constant.

 

[white92talontsi]

Jesus. Your all wrong, a 2.3l piston has a dish that is about 9cc bigger than a similar piston for a 2.0l

MITSUBISHI - MITSUBISHI 1988-92 ECLIPSE / TALON / EVO 4G63 21MM PIN - JE Pistons

Compression ratio is calculated as CR = (Clearance volume + Swept Volume)/Clearance volume.

A 2.0 has a swept volume of about 499cc. A 2.3 is 567cc. The clearance volume consists of the chamber volume (47cc), head gasket volume ~6cc, The piston dish volume, and the crevice volume (~1cc).

So if you run JE 8.5 to 1 pistons for a 2.3 (22cc dish), in a 2.3 you get a compression ratio of (22+47+6+1+567)/(22+47+6+1) = 8.46 to 1

If you run JE 8.5 to 1 pistons for a 2.0 (13.2cc dish) in a 2.0 you get (13.2+47+6+1+499)/(13.2+47+6+1)= 8.42

Now if you run JE 8.5 to 1 pistons for a 2.3 (22cc dish) with a 2.0 crank and long rods you get (22+47+6+1+499)/(22+47+6+1) = 7.6 to 1

You see, with a stroker motor your swept volume goes up, so the clearance volume must go up to keep the compression constant.

You are right, I am also right as well. The dish is different. the only reason the dish is different is because the stroke is different between the 2 engines.

Stroke plays the biggest role in determining final compression.

 

[lasthope05]

There you go. Thank you. I wanted was some real information about the issue and if it does or doesnt work. I got frustrated because all replys I received were "it wont work because its a stroker piston"..etc As I said I would like to learn if I am wrong and an answer like no it wont work because you dont fully understand or cant explain anything yourself does not help to strengthen your agrument.


Thanks for the math above. This way i will be able to go over the calculation and be better able to understand it better.

 

[bastarddsm]

You are right, I am also right as well. The dish is different. the only reason the dish is different is because the stroke is different between the 2 engines.

Stroke plays the biggest role in determining final compression.

Yes, you just didn't explain it very well. It has nothing to do with the stroke only the swept volume. Notice the JE's I linked to have a bigger dish for bigger bore on the 2.0 pistons?

Essentially a better way to say what you were trying too would be, using a 2.3l piston only puts 2l worth of air in a combustion chamber meant for 2.3l of air, therefore the compression ratio will fall.

There you go. Thank you. I wanted was some real information about the issue and if it does or doesnt work. I got frustrated because all replys I received were "it wont work because its a stroker piston"..etc As I said I would like to learn if I am wrong and an answer like no it wont work because you dont fully understand or cant explain anything yourself does not help to strengthen your agrument.


Thanks for the math above. This way i will be able to go over the calculation and be better able to understand it better.

It certainly will work, and it will probably be a great setup for pump gas. Low compression, with high rev ceiling.

 

[white92talontsi]

Yes, you just didn't explain it very well. It has nothing to do with the stroke only the swept volume. Notice the JE's I linked to have a bigger dish for bigger bore on the 2.0 pistons?

Essentially a better way to say what you were trying too would be, using a 2.3l piston only puts 2l worth of air in a combustion chamber meant for 2.3l of air, therefore the compression ratio will fall.



It certainly will work, and it will probably be a great setup for pump gas. Low compression, with high rev ceiling.

I don't want to argue about it over and over but the reason the dish is different is because of stroke. The 2.0 piston requires less dish because it has less stroke. The 2.3 piston requires more dish because it has more stroke.

That is how piston manufacturers get the compression lower on the 2.3 is by increasing the dish. If they left the 2.3 dish the same as a 2.0 piston dish then the Compression ratio would be extremely high due to the extra 12mm of stroke.

 

[arrowhead]

You are both correct .only stating in a different manner, and hopefully they understand it now.

They may also be confused about cranking comp and static comp.

Cams, will change your cranking comp, but not the static comp.

Decking of block, shaving the heads, thinner gasket or porting the combustion chamber will change static comp.

Porting of the exh or intake runner will not change anything, in the real world.

You are both correct .only stating in a different manner, and hopefully they understand it now.

They may also be confused about cranking comp and static comp.

Cams, will change your cranking comp, but not the static comp.

Decking of block, shaving the heads, gasket or porting the combustion chamber will change static comp.

Porting of the exh or intake runner will not change anything, in the real world.