Both of you could stick with 9.0:1 compression 2.0L's and be fine.

 

Happy to assist with your inquiry... unfortunately, it is rather busy on the phones today so I am going to do my best to efficiently answer your question.

There is a delicate balance between components that are designed to handle excessive cylinder pressures and components that are designed to last a long time or promote engine longevity. The quickest killer of engines is cold start up. Forged internals rely on heat to expand to their running dimensions... when they are cold, they are at their loosest tolerances... this is why correct piston to wall clearance and ring gapping is so crucial and actually varies depending on components and expected power output.

Now why am I telling you this to answer a reliability question? Well the reason is that when the piston is cold, it is smaller and actually moves with more slop through the combustion process. When it gets up to temperature, it is fully expanded and has the most stability in the bore but when it's cold, it is sloppy and this slop actually wears out the cylinder bores faster.

For the MOST reliability, you want the least amount of side loading on the pistons during cold start for the engine to last the longest... typically, this also translates to good stability at higher RPM. In my mind, a 2.1 4g64 based engine with stage 1 or NON HD pistons is the most reliable... the reasons for that are the following:
1) you can use the long rod connecting rods (156mm)
2) you can use a full sideskirt piston (non-stroker design)
3) you are using a piston with metallurgy conducive to the least amount of piston expansion during heat up

Those things combined, assuming the engine has been properly assembled, will promote the greatest amount of engine longevity.

Conversely, the least reliable or long lived iteration of engine would be a Stage 2 Stroker engine because:

1) HD piston is more expansive (great piston for high HP but less ideal for middle power engine trying to last a long time)
2) increased stroke but standard length rods impart more piston instability
3) piston sideskirt length is decreased in the stroker piston design which lends itself to less piston stability

Now there are a million engine designs and configurations available and many of them tend to fall into categories of more or less reliable based on those above factors and since the issue tends to relate more to cold start up and not mileage, one cannot predict the life expectancy of an engine. For example, if a guy lives 3 miles from work and runs the most reliable version of engine available and starts it... drives, lets it cool down and starts it, drives and lets it cool down... he might not see a lot of mileage versus another person who builds a higher HP capable engine but his daily commute is 100 miles to work and 100 miles back.

The best rule of thumb is to pick an engine that meets your realistic goals. Simply building a 1000HP engine but making 400HP on it won't actually get you much more longevity (typically) than say building an engine that is suited to your goals and using the LEAST amount of exotic materials and components available.

If you don't know what is best suited to your goals, that is why we are here... and I encourage you to reach out to us (MAPerformance) any time you might have a question so we can help to guide you down the best path possible.

 

You missed the easier rod length on the 4g64 2.2L

4g64 Block, 94mm crankshaft, 159mm rod, OTS Wiseco HD 1.13CH

 

I only mentioned two engines to impart a baseline theory... there are literally dozens of potential combinations available and if you want to take the time to have custom pistons made, or custom rods, there are dozens more on top that that. To the point of the OP's question about reliability, the point to take home is: LEAST expansive piston (this wouldn't actually include Wiseco 1400HD pistons as they are more prone to expansion, although absolutely ideal for higher HP applications), most possible rod length with longest possible sideskirt. I didn't mention 2.1 long rods which would have 162mm rods, for example, because you use a "Stroker" style piston to accommodate the rod length... while the extra rod length does impart less side loading forces to the piston, the piston, itself is more sensitive to side loading so those two factors, in my opinion, cancel each other out.

It is worth noting that many people will have different views and opinions on what is or isn't the most reliable. Given my employ, I have been exposed to every manner of engine iteration and we have built them all. Without going into too much detail, for 4G63/4G64 based engines, we happen to prefer using rods that are designed for use with 6 bolt bearings for the extra bearing area/support... but when you use 94mm Manley cranks with such rods, you have to chamfer the bearings to match the crank journal profile, where the OEM cranks have no such requirement. I will admit, this is a matter of preference... I couldn't, in the nature of full transparency, materialize a back to back test providing concrete evidence of the benefits beyond theoretical mostly due to practicality.

 

By the time they are chamfered there is little more surface area than a normal 7 bolt bearing. Some but not as much as a straight 6 bolt bearing.

General-

There are a few other stroke lengths not mentioned here but since they arent widely available to most it doesnt matter much. Coupled to the fact that what is on the normal shelf for most companies covers 99% of people.

I like the LR2.3 in the 4G64 myself but we have burnt up the crank supply for the time being.

 

So which might be the least expansive piston if Wiseco 1400HD pistons as they are more prone to expansion, although absolutely ideal for higher HP applications)

I do take short drives and some canyon driving but not looking for high HP only about 350-400 whp

 

reviving an old thread :

i'm looking to build a stroker with cams on my evo 9.

my plan is to have the closest compression ratio to OEM with either a 2.3 or a 2.4.

did anyone manage a CR close to 9:1 rather than 10:1 ? what did you use? is it even achievable ?