EJ22 Turbo pistons

[drivemusicnow]

Originally Posted by OBI

Here's something you obviously dont know. Unless you are sleeving your motor you can forget about 3.6-3.8 displacement. The eg33 block can only be bored out to .50 mm as per factory manual, any more than that and the cylinder walls will get to thin. So let me do the math for you, max bore size you can get the motor to is 97.395 x 75 bore is 3.353cc which is not much difference from the stock 3.318. I hope you havent payed yet lol.

Yeah... I read that and was like wtfmate?

Pistons themselves cannot dictate displacement unless you bore the engine out (read OBI's comments). The other way to increase displacement is to create a longer stroke which requirse a new crank.

[TomsSVX]

i decided not to comment at all

Tom

[SilverSpear]

Originally Posted by drivemusicnow

Yeah... I read that and was like wtfmate?

Pistons themselves cannot dictate displacement unless you bore the engine out (read OBI's comments). The other way to increase displacement is to create a longer stroke which require a new crank.

That would increase torque at the expense of top speed if the current compression is still the same.

As for as I know, Alfa Romeo's engines are designed for a longer stroke, this is why their engines have a higher torque than other cars.

Not entirley true....
One can always lower the gudgeon/piston pin height, rework the cyl head and gain a few mm of stroke this way.(I did this on a Ford 302 Jetsprint boat motor that we couldn't afford a stroker crank for!! ) The other alternative is offset grinding the crank, again, good for a mm or two. In my personal experience with Subaru Engines over the years, I have realistically doubled the overbore limit that the book recommends, (i am NOT saying this is OK to do and you will have NO probs!!), I have bored a EA82 Turbo out to .75mm and the factory limit is supposed to be .25mm!! This was my own vehicle, I came across the stuff cheap and machined my case to suit the bits I had. I then disconnected the fuel cut and drove it @ 11Psi, (std is around 7), on std Everything except Dumpipe for 35000kms!! Never had a drama....
I could go on and on about engines I have done WAAY oversize, but again, I am not Recommending it, Just my 0.2 Cents worth!
There MANY ways to get your SVX pumping, I believe the best, (cheapest, most effective, most 'bling value' ), is the Twin intake setup.

Cheers

Sixpack Subaru

[OBI]

Originally Posted by Sixpack Subaru

Not entirley true....
One can always lower the gudgeon/piston pin height, rework the cyl head and gain a few mm of stroke this way.(I did this on a Ford 302 Jetsprint boat motor that we couldn't afford a stroker crank for!! ) The other alternative is offset grinding the crank, again, good for a mm or two. In my personal experience with Subaru Engines over the years, I have realistically doubled the overbore limit that the book recommends, (i am NOT saying this is OK to do and you will have NO probs!!), I have bored a EA82 Turbo out to .75mm and the factory limit is supposed to be .25mm!! This was my own vehicle, I came across the stuff cheap and machined my case to suit the bits I had. I then disconnected the fuel cut and drove it @ 11Psi, (std is around 7), on std Everything except Dumpipe for 35000kms!! Never had a drama....
I could go on and on about engines I have done WAAY oversize, but again, I am not Recommending it, Just my 0.2 Cents worth!
There MANY ways to get your SVX pumping, I believe the best, (cheapest, most effective, most 'bling value' ), is the Twin intake setup.

Cheers

Sixpack Subaru

The only way you will increase the stroke is by changing the location of the crank pin, period. all you are doing by what you said is changing the range were the stroke operates at. No increase in displacement will occur like that.

You could bore the cylinders till they are paper thin and he still wont get 3.6 liters.

According to CCR in colorado they wont go beyond the overbore limit on their svx rebuilds because the cylinder walls will get to thin and distort causing premature engine wear. They have rebuilt more subaru engines than anybody else and have the best warranty.

[drivemusicnow]

Originally Posted by OBI

The only way you will increase the stroke is by changing the location of the crank pin, period. all you are doing by what you said is changing the range were the stroke operates at. No increase in displacement will occur like that.

You could bore the cylinders till they are paper thin and he still wont get 3.6 liters.

According to CCR in colorado they wont go beyond the overbore limit on their svx rebuilds because the cylinder walls will get to thin and distort causing premature engine wear. They have rebuilt more subaru engines than anybody else and have the best warranty.

Thats just it.. if they didn't have to warranty them, think they would be willing to bore them out farther?

Anywho, I had been thinking what would happen if you ground down the crank journals to be a much smaller size, however keeping the "outer" edge the same, and taking more material off the "inside" part.

Essentially taking a circle, and by only grinding 340 degrees of it, (the main bearing side of the rod/crank journal), you would essentially "lengthen" the stroke by 2-3 mm. Does this even work?

Like take the stock as "O", then grind it such that it is "o"

Disclaimer, I am in no way suggesting you do this as it will most likely weaken the crank significantly.

[oab_au]

Originally Posted by drivemusicnow

Thats just it.. if they didn't have to warranty them, think they would be willing to bore them out farther?

Anywho, I had been thinking what would happen if you ground down the crank journals to be a much smaller size, however keeping the "outer" edge the same, and taking more material off the "inside" part.

Essentially taking a circle, and by only grinding 340 degrees of it, (the main bearing side of the rod/crank journal), you would essentially "lengthen" the stroke by 2-3 mm. Does this even work?

Like take the stock as "O", then grind it such that it is "o"

Disclaimer, I am in no way suggesting you do this as it will most likely weaken the crank significantly.

Stroking cranks, involves grinding metal away from the inside of the big end, and welding extra metal to the outside of the big end pins. It does extend the stroke, but it removes part of the forged metal grain flow that gives the forged crank its strength. The flow of metal through the main bearings, up through the web and the inside of the big end pins, is cut away This is common practice with slow reving engines, but to do it to a high reving crank like the SVX, would not ensure a long, reliable engine. High frequency torsional vibration would cause cracking.

Harvey.

[SVXelerator]

Mr. Harvey,
I understand what you are saying, from a metalurgical standpoint. Question - how do you explain the popular 350 cu in. stroked to 383 cu in. small block Chevy engines that have been around for years and are taken up beyond the SVX's normal 6500rpm redline rotational speed on a regular basis?
Thanks.

[TomsSVX]

Forged 383 cranks

Tom

[OBI]

Im trying to post pictures of the pistons but im having a some trouble. I already have them in my locker down to 640x480 but i cant attach them to my post, im getting an error when i upload them on the bottom of the type box where it says manage attachments. Can anybody tell me how

[longassname]

[longassname]

it's hard to see for sure but it looks like the top edges are the same height and the only difference is the dish...is that correct?

[oab_au]

There is a lot of clearance volume in that dish, It is at least the same depth as the valve cut-outs in the SVX piston. Looking better.

Still need the cylinder clearance volume, to know what the final comp ratio will be.

Harvey.

[longassname]

Looks to me like they took the same piston with the valve cut outs in it and everything and milled the dish into it.

Originally Posted by oab_au

There is a lot of clearance volume in that dish, It is at least the same depth as the valve cut-outs in the SVX piston. Looking better.

Still need the cylinder clearance volume, to know what the final comp ratio will be.

Harvey.

[SVXRide]

Originally Posted by longassname

Looks to me like they took the same piston with the valve cut outs in it and everything and milled the dish into it.

How about a pin-side view to see if the piston compression height is the same? The centerlines of the pins don't look like they're identical (but then that could just be due to the washing machine's lid not being perfectly flat )
-Bill