I have long been under the assumption that oil squirters sole function is to cool the bottom of the piston which seems reasonable. How and why would the 1G squirters need to be modified to do this given the basic premise of their function with a set of Evo pistons? Seems logical if it hits the bottom of the piston it is doing it's job. Some builds I have done on other motors have removed the squirters entirely. Does anyone have direct experience with putting Evo pistons into a 6 bolt block and what precise actions were taken in regard to this oil squirter issue?

/brox

on a recent 'flipped evo parts into a 1G' project i did, the 7 volt motor I used had the 93-94 squirters, which lined up fine without clearence issues. a small pipe bender would do the needed job if to pull the outlet back some

So is this more a clearance issue rather than a where it hits the back of the piston issue? Seems to me where it hits it is of little consequence as long as it does hit it.

I'll take a look at it tonight and figure it out I guess.

/brox

If it is hitting, there is something wrong.

I only thought that going the stroker setup (100mm stroke) is where you get the piston skirt hitting the squirter. I solved this by bending my existing squirters slighty and then later replaced them with evo8 items which didn't require and bending.

I know different brand pistons have different length skirts.

As for factory EVO pistons, they should pretty much be the same as the VR4 ones?!?!

I did not look thru the hold thread but maybe it will help

click

The piston skirt shouldn't be any reason to relocate or modify the squirters as far as I can see.



Skirt on the Evo piston is much shorter and given the factory stroke I can't see how this would be an issue of interference. From searching, I assumed someone was making a claim that the squirters were improperly squirting onto the piston but I find that to be hard to believe given my understanding of how the oil cooling works in that instance.

I did have one more question and maybe someone can answer this one for me.



This discoloration is obviously from heating of the rod during the boring process to fit the larger pin in place. The heating looks fairly minor but for anyone who has had 1G rods bored out before in this manner, was this also present on your rods? Seems to me more care could have been taken in cooling the boring machine to keep the heat from doing this. I am marginally worried about the heat treating and how it will affect overall strength but not incredibly.

And one last thing. I have seen many pistons crack or loose part of a ring land, ahem...Subaru...and have inspected these broken parts for more answers as to why. Well when I got my 1G pistons back, I got a possible answer as to why the factory pistons seem to be able to take so much abuse.







They are really well cast. The casting is incredibly dense compared to many pistons I have seen. Some factory cast pistons I have inspected have literally had swiss cheese holes within the cast, a result of fast cooling I suspect or possible impurity. The three 1G pistons I have that came back broken, were all of the same internal quality and even though the fracture had exposed 360 degree on them I found no such disformation or pockets within the casting. In all honesty, Very impressed. When people argue about insane HP stock bottom end builds, point them to pictures of the piston 'internals' and maybe they will understand. Especially once compared to the Subaru cracked pistons I have seen.

Comparison so you don't think I'm blowing smoke. This is a 2.5 Factory STI piston with a busted ring land. Look at the pores.



That is all.

/brox

The discoloration on the small end of the rod is from the machinist putting the small end of the rod in their rod oven to make the small end bore size grow larger so they can fit the wrist pin in. Stock wrist pin is not full floating type..

See I would have thought it was heat transfer from the boring process itself. But that makes sense.

Well I am on a 5 day wait for two of my piston ring sets so I will have to test the interference squirter theory in a few days I suppose.

Thanks for all the replies guys.

/brox

Quoting grocery_getter:
The discoloration on the small end of the rod is from the machinist putting the small end of the rod in their rod oven to make the small end bore size grow larger so they can fit the wrist pin in. Stock wrist pin is not full floating type..



I was always under the impression that the wrist pin for the stock setup was press fit, not shrink fit. /ubbthreads/images/graemlins/confused.gif

Or is this just an alternate method that some machinists use?

Ask the guys over at thedsmgraveyard.com They do evo9 pistons on 6bolt rods, they call it a frankenstein setup. They should be able to help you out on the squirter issue.

Quoting BarnesMobile:
Quoting grocery_getter:
The discoloration on the small end of the rod is from the machinist putting the small end of the rod in their rod oven to make the small end bore size grow larger so they can fit the wrist pin in. Stock wrist pin is not full floating type..



I was always under the impression that the wrist pin for the stock setup was press fit, not shrink fit. /ubbthreads/images/graemlins/confused.gif

Or is this just an alternate method that some machinists use?



You're both right. /ubbthreads/images/graemlins/smile.gif

Jon, it is a press fit.

Heating the little end of the rod expands it enough that you can just slide the pin thru without having to press it.

By expanding the pin bore of the rod, everything slides together without any force beyond a gentle push.

If you were to press the pin at room temperature, you would probably scratch the pin as it passes thru the rod.

The damaged pin surface would then chew the ever loving dog sh*t out of the piston pin bore, and you'd have big trouble, quick like.

The use of connecting rod kiln is how you would do this job. The small end of the rod is heated up to a temp of no more than 320c or 612F. Applying excessive heat to the connecting rod may damage or distort the connecting rod or piston.

In a non full floating wrist pin application, you don't install a wrist pin without the help of heating the smaller end of the rod. If you can imagine in your mind how you would have handle the piston and the rod and the wrist pin together under a hydraulic press, the process of press fitting a wrist pin down the small rod end would have put deformation pressure onto the piston wrist pin boss under the small end of the rod being pressed down on top of it.

There are actual tool for this. It looks like a small toaster oven. OR you can fashion other ways of providing temperature controlled heating source to do the job.

Andre



Quoting BarnesMobile:
Quoting grocery_getter:
The discoloration on the small end of the rod is from the machinist putting the small end of the rod in their rod oven to make the small end bore size grow larger so they can fit the wrist pin in. Stock wrist pin is not full floating type..



I was always under the impression that the wrist pin for the stock setup was press fit, not shrink fit. /ubbthreads/images/graemlins/confused.gif

Or is this just an alternate method that some machinists use?

Boring process doesn't put that much heat into the rod that it will make the rod beam turn color like that. Maybe if you do it with a dull boring bit, but not normally. The rod is halfway inserted into the rod oven to open up the ID of the small rod end. Each color indicates different temperatures. The spread of the color on the beam is the tell tale of how far of the beam was inserted into the rod oven.


Quoting broxma:
See I would have thought it was heat transfer from the boring process itself. But that makes sense.

Well I am on a 5 day wait for two of my piston ring sets so I will have to test the interference squirter theory in a few days I suppose.

Thanks for all the replies guys.

/brox

I had to run up to the shop today to get a broken stud pulled out of the head and drill a hole in the fuel sender and Cork was there. I brought the Evo piston/1G rod combo so I could break the rod bolts loose as the one oddly missing piece of hardware in my own garage is a good vice.

Cork picked up the piston and said "Look at that ring land would ya." He has an odd way of talking, a style I had mastered while working there. His impressions were that the Evo pistons were probably some of the nicest factory pistons he had ever seen. His actual amazement was in the coating on the skirt which was something he duplicated back in the 60's with a baked on moly graphite. He didn't know what the Evo pistons were coated with but he approved.

He started looking at the rods at this point trying to figure out the build sequence. Best he could see, he figured the rods are forged, then shot peened, then the holes bored, then machined for weight. He found that to be insane for a factory part and was impressed by the entire setup up. his actual words were 'These could probably take almost anything you throw at them. If these break it will be fatigue that does it."

This means jack to you of course, but getting Cork to appreciate any factory parts not from a Miata is hard work. He normally picks something up and finds the flaw in it within seconds. His inspection of the factory mitsubish parts was actually the first time I had seen him not do this.

Back on topic. I think the oil squirter issue may be due not to the skirt but the design of the underside of the piston where the pin holder is located. I am throwing a piston in today to make sure.

/brox