ok so a few years back i had a built 2.1L engine failure. i never came to a conclusion what caused it,after that i just put in back my stock block and drove it.

now i want to build the engine again, so i weighed the connecting rods, they are all different weight. mind you i didnt build the engine myself, it was built by someone else.

the engine failed during the tuning session, the guy who built the engine also email tuned it. the engine didnt even last a 1000 miles.

so to cut the story short, i today measure the con rods and the diffrence is huge!

now my question is, could the diffrence in weight of the con rods have contributed to a failure? like the rotating assembly may have not been balanced because of the weight diffrences.

i noticed during the 3rd gear tuning pulls that as soon as it went to 8000 rpms and on to 9000 rpms my steering would vibrate alot, maybe the engine was causing this?

specs of pistons:

manley I bean rods:
piston one: 708 grams
piston two: 721 grams
piston three: 723 grams
piston four: 714 grams

from what ive read, there should be no more than 4 grams of diffrence.

so should i balance the rest of the pistons to the lightest one?

 

That looks significant, but depends on how it was checked.

My last set i balanced within .5 grams of each other. While it is still subjective to if that was the cause of failure?

If you mind telling us the nature of the failure?

Connecting rods should be balanced with checking both reciprocating weight and rotating weight.

Like this:








How much is very subjective, guess it depends on what you will accept
I have seen so called balanced assemblies that had parts over 10 Grams different so I guess this is "acceptable" to some.

I balance to .5 gm per end & .5 total rod weight if possible.

You need some sort of arbor to find the center of the bores to weigh them correctly
The rod also has to hang level.

Hope this helps

 

I stopped buying used rods for the most part. first thing I do when i get them is weigh them. even eagles are matched to with in one gram. a lot of rod sets being resold at this point are mis matched sets. those weights are too far off to correct. especially not by lightening pistons. do you have any clue what 15 grams of aluminum looks like? I will give a hint. a nickel weighs 5 grams.

the weight difference DID NOT contribute to the engine failure.

 

yes it has definitely helped! i didnt weigh the rods like you have, i dont have that jig.

i just put them on a scale and note down the numbers. i have another set of manley I beams with me and they all weigh within 5 grams, dont know what happened to these sets.

 

this was one of the things i thought caused the failure, there can be so many reasons.

my other theory is, i didnt have a kiggly oil regulator on my setup and revving to 9000+ rpms may have caused the failure because of oil starvation in the pan.

or maybe the guy just built a lemon engine.

 

The stock oil pump works above 8400rpm? I have heard it start to cavitate exactly at 8400rpm.

 

is there an aftermarket oil pump for evos to hit 9000 rpms?

to be honest iv'e never heard or read about this, nor did the guy tell me about this. if there is a after market/diffrent oil pump that needs to be with a 2.1L then its the builders fault for not letting me know.

i always thought that these 9000+ rpms on builds were achived on stock oil pump, but with either a oil regulator like kiggly or a baffled/high volume oil pan to stop the pump from starvation and keep oil in the pan.

can anyone else chime in and confirm that the stock oil pump can not work properly at 8400 rpms?

 

Just make your own.

Just make sure the rod is level.

 

While i cannot speak for all that run up to 9k RPM, i would think most run a larger oil pan, Kiggly HLA, and some sort of crank windage tray like the Cosworth or Tomei units....as a minimum to survive with a stock oil pump at that level.

English Racing does make a Underdrive Oil pump gear, but it is expensive for what you get. To add i would only install this gear if you're doing a fresh build, this is because you have to Degree your Cams back to Spec with a Adjustable cam gear. If not your cam timing will be off as much as 2 Degrees.

I am still testing it now myself before i promote its usefulness.

The best Option for that much RPM is a Dry sump system, they are very spendy$$$$