Any 2Gs with Evo Pistons?

[shredwin]

I just purchased this Evo pistons down slowboys, they are used but look in good shape plus I got a good deal. I believe they either came off the Evo 8 or 9. My question is if there are any 2Gs out there with these piston? If your one of them please tell me if your pleased with them or if they are not worth it. Im in the process of rebuilding my motor and im just curious since im still wating for my stuff to be done at slowboys. here is a pic of the pistons.
<a href="http://s74.photobucket.com/albums/i252/shredwin/?action=view&current=Evopistons.jpg" target="_blank"><img src="http://i74.photobucket.com/albums/i252/shredwin/Evopistons.jpg" border="0" alt="Photobucket"></a>

 

[shredwin]

Friend, I wasn't worried about your response. I was worried about someone doin more damage than good. Which delta488 suggests. You can't put Evo pistons in the same way you put dsm pistons. without putting the maximum capable strenght in question.

Yeah I dont wanna any damage either thats why im asking all this question that are probably stupid for you guys... but I get it now so Its all good, thanks again

 

[1timehondalover]

The offset on the pin in the Evo piston should be very near identical to the offset in a DSM piston.
I don't understand all the commotion over turning the pistons around. The valves are oriented the same in both engines so there is no need to modify the valve reliefs. The engines both rotate in the same directions (which would dictate wristpin offset) so the pistons should not be turned.

The only difference (that matters in this thread) between the 2 engines is which side the timing belt is on.
As long as your marks on the pistons point towards the bell housing and not the T-belt you're golden.

 

[shredwin]

The offset on the pin in the Evo piston should be very near identical to the offset in a DSM piston.
I don't understand all the commotion over turning the pistons around. The valves are oriented the same in both engines so there is no need to modify the valve reliefs. The engines both rotate in the same directions (which would dictate wristpin offset) so the pistons should not be turned.

The only difference (that matters in this thread) between the 2 engines is which side the timing belt is on.
As long as your marks on the pistons point towards the bell housing and not the T-belt you're golden.

Thats what I was told at slowboys, but why did gixrman point his EVO piston towards the timing belt side? here is the link below with pics:

http://www.dsmtuners.com/forums/cylinder-head-short-block/244184-can-anyone-help-me.html

 

[delta448]

The "commotion" about turning the pistons around is because some are worried about the valve reliefs. The DSM valves are oriented opposite with respect to the piston valve reliefs, when the piston is installed with the offset toward the correct side. The reliefs for the intake valves are larger than the reliefs for the exhaust valves. This is the only difference with the Evo 8 pistons, the bottom end is identically assembled, except for the piston valve relief positions.

In Gixrman's thread, the pictures clearly demonstrate the correct offset orientation with the dot towards the T-belt, and you can clearly see the intake valve reliefs on the exhaust side of the piston. The clearance of the valves will depend on the amount the head/deck has been shaved, the diameter of the valves being used, HG thickness and the maximum lift of the camshafts. I would suggest that if there is any doubt, to:

1) secure the bottom end so #1 & 4 are locked at TDC
2) use 4 pieces of soft clay, place them on #1 and 4 pistons (DSM intake valve sides of the 2 pistons)
3) with the T-belt off and the head held by a couple of finger tight bolts, rotate the intake cam slowly
4) do not continue to turn the cam if there is binding
5) remove the head and inspect the thickness of the clay, this is your valve clearance

The DSM head's exhaust side should not be a concern with these pistons because of the larger intake valve reliefs on the pistons lining up with the exhaust valves.

 

[shredwin]

The "commotion" about turning the pistons around is because some are worried about the valve reliefs. The DSM valves are oriented opposite with respect to the piston valve reliefs, when the piston is installed with the offset toward the correct side. The reliefs for the intake valves are larger than the reliefs for the exhaust valves. This is the only difference with the Evo 8 pistons, the bottom end is identically assembled, except for the piston valve relief positions.

In Gixrman's thread, the pictures clearly demonstrate the correct offset orientation with the dot towards the T-belt, and you can clearly see the intake valve reliefs on the exhaust side of the piston. The clearance of the valves will depend on the amount the head/deck has been shaved, the diameter of the valves being used, HG thickness and the maximum lift of the camshafts. I would suggest that if there is any doubt, to:

1) secure the bottom end so 1 & 4 are locked at TDC
2) use 4 pieces of soft clay, place them on #1 and 4 pistons (DSM intake valve sides of the 2 pistons)
3) with the T-belt off and the head held by a couple of finger tight bolts, rotate the intake cam slowly
4) do not continue to turn the cam if there is binding
5) remove the head and inspect the thickness of the clay, this is your valve clearance

The DSM exhaust side should not be a concern with these pistons because of the larger intake valve reliefs on the pistons lining up with the exhaust valves.

Hey man I really apreciate you helping me out. Im gonna follow them steps you put on here and Ill see how that works out. My stuff should be ready this weekend but I can't say that for sure since sometimes slowboys takes a while.

 

[1timehondalover]

why did gixrman point his EVO piston towards the timing belt side? here is the link below with pics:

http://www.dsmtuners.com/forums/cylinder-head-short-block/244184-can-anyone-help-me.html

Perhaps he wanted to risk hitting his intake valves on the smaller exhaust valve reliefs?

 

[1timehondalover]

The "commotion" about turning the pistons around is because some are worried about the valve reliefs. The DSM valves are oriented opposite with respect to the piston valve reliefs, when the piston is installed with the offset toward the correct side. The reliefs for the intake valves are larger than the reliefs for the exhaust valves. This is the only difference with the Evo 8 pistons, the bottom end is identically assembled, except for the piston valve relief positions.

In Gixrman's thread, the pictures clearly demonstrate the correct offset orientation with the dot towards the T-belt, and you can clearly see the intake valve reliefs on the exhaust side of the piston. The clearance of the valves will depend on the amount the head/deck has been shaved, the diameter of the valves being used, HG thickness and the maximum lift of the camshafts. I would suggest that if there is any doubt, to:

1) secure the bottom end so #1 & 4 are locked at TDC
2) use 4 pieces of soft clay, place them on #1 and 4 pistons (DSM intake valve sides of the 2 pistons)
3) with the T-belt off and the head held by a couple of finger tight bolts, rotate the intake cam slowly
4) do not continue to turn the cam if there is binding
5) remove the head and inspect the thickness of the clay, this is your valve clearance

The DSM head's exhaust side should not be a concern with these pistons because of the larger intake valve reliefs on the pistons lining up with the exhaust valves.

Why does everyone think that the offset on the pin is opposite on an Evo? The engine spins the same way as a DSM 4G63. The direction of rotation dictates offset. If both engines spin the same way why would the offset be opposite?

There is no need to reverse the orientation of the piston in the bore unless you want piston slap, accelerated skirt wear, and reduced intake valve clearance.

 

[delta448]

Perhaps he wanted to risk hitting his intake valves on the smaller exhaust valve reliefs?

Doubt it. I'd imagine it's because the piston pin offset is correctly located with the piston installed that way. Valve reliefs can be modified rather easily if they are an issue, pin offset cannot.

 

[delta448]

Why does everyone think that the offset on the pin is opposite on an Evo? The engine spins the same way as a DSM 4G63. The direction of rotation dictates offset. If both engines spin the same way why would the offset be opposite?

It wouldn't be. Both engines spin the same way when looking at them from the T-belt.

There is no need to reverse the orientation of the piston in the bore unless you want piston slap, accelerated skirt wear, and reduced intake valve clearance.

Absolutely correct. -Except for how you're viewing the intake valve relief position. You do realize that the Evo VIII has the block positioned with the T-belt on the passenger side and the trans on the driver's side, don't you? You also know that the intake is by the firewall and the exhaust side of the head is by the radiator for both the Evo 8 and the DSM. Now that you're picturing that, in your mind turn the block around 180 degrees so that the T-belt is now on the driver's side as it is in a DSM. Which side are the intake valve reliefs on? Why they're now on the head's exhaust side...

 

[1timehondalover]

I realize all of that.
Call me crazy or forgetful, but last time I saw an Evo crank over the the engine rotated towards the firewall.

 

[gixrman]

Well I feel like people think I just threw this thing together and just giving bullshit advice. I'm just saying that it worked for me take it or leave it. You can do whatever you want, I certainly am not going to tell you that its the best thing to do, or that its better that any other option. Thats the way I installed them and this is how it turned out. The head is stock height, stock head gasket, ARP studs and FP1,2 cams straight up. The motor runs, doesn't knock, ping, or tick. I ran the piss out of it with my 16g and logged over 40lbs of airflow on repeated runs with a good tune. If anyone wants to come see it, or hear it run, there more than welcome to.

 

[shredwin]

Well I feel like people think I just threw this thing together and just giving bullshit advice. I'm just saying that it worked for me take it or leave it. You can do whatever you want, I certainly am not going to tell you that its the best thing to do, or that its better that any other option. Thats the way I installed them and this is how it turned out. The head is stock height, stock head gasket, ARP studs and FP1,2 cams straight up. The motor runs, doesn't knock, ping, or tick. I ran the piss out of it with my 16g and logged over 40lbs of airflow on repeated runs with a good tune. If anyone wants to come see it, or hear it run, there more than welcome to.

I didnt say you were giving bullshit advice. I got my pistons back and compared them to the stock 2G pistons and now I uderstand much better of what you were talkin about. I wish I could see and hear your car run but your all the way in maryland. thanks for the help though

 

[gixrman]

I didnt say you were giving bullshit advice. I got my pistons back and compared them to the stock 2G pistons and now I uderstand much better of what you were talkin about. I wish I could see and hear your car run but your all the way in maryland. thanks for the help though

I wasn't making that reference to you. I understand what dsm-onster is saying and its a valid argument, also about the valve reliefs. I just wanted to post my experience with it and try to help you out and anyone else who was thinking about doing it.

 

[shredwin]

I wasn't making that reference to you. I understand what dsm-onster is saying and its a valid argument, also about the valve reliefs. I just wanted to post my experience with it and try to help you out and anyone else who was thinking about doing it.

The valve reliefs was the only thing that had me worried since i didnt want the piston hittin the valves. But im doing my bottom end just like you said, If it worked for you I dont see why it wouldnt work for me. Ill let you know how it goes, and thanks for the help

 

[xreaction122]

shredwin, any updates on the build? i might be picking up a set of evo pistons and rods next week

 

[projectpat69]

I installed the evo 9 piston, 1g big rod combo in my 90 6bolt and noticed a small .060-.080in. gap when the piston is at top dead center. it seems as though the evo pistons are alittle shorter when comparing them side by side with 2g stock pistons. has anybody else noticed this? i think this will greatly effect my compression ratio, what do you think?>?

 

[94awdcoupe]

I installed the evo 9 piston, 1g big rod combo in my 90 6bolt and noticed a small .060-.080in. gap when the piston is at top dead center. it seems as though the evo pistons are alittle shorter when comparing them side by side with 2g stock pistons. has anybody else noticed this? i think this will greatly effect my compression ratio, what do you think?>?

Finally some one noticed. You are correct. the evo piston has .070 less deck height than 2g pistons. This is nice though so you dont have to worry about running valve cutouts reversed.

I have been running evo 8 pistons in dsm blocks for 3 years now. You want to run them with the valve cutouts in wrong spots. The other option is to reverse them but then you have the greater of two evils. the piston pin offset would be reversed.

Important to note wiseco pistons from evo8 cannot be run in DSM block. You would have to machine exhaust cutout to same size as intake. After market pistons for evo 8 run same deck height as DSM cars. They did not notice the evo runs .070 less deck height.

The compression will still be near 8.8/1. evo 8 piston is flat top design. I think they eliminated dish for better flame propagation. and faster flame speed for smaller timing numbers . less pumping losses.

The evo 8 head is 2cc smaller than DSM. so compression on dsm will be lowered from this 2cc increase. maybe to 8.7

 

[dsm-onster]

Running a piston that doesn't come completely flush to the deck height will null the quench zones in the combustion chamber, increasing the likelyhood of knock.

 

[donniekak]

Running a piston that doesn't come completely flush to the deck height will null the quench zones in the combustion chamber, increasing the likelyhood of knock.

I have built and tuned quite a few engines and the biggest knock problems i have are on engines with decked blocks for this very reason. Making the quench tighter or looser causes knock problems. For engines that have had the block decked usually a headgasket can be selected to make up for the missing materal. If i assembled a block that is supposed to have 0 deck pistons and they sat that far down in the bore i would just get different pistons. Taking the block deck down far enough to make them flush would cause some timing problems with the cams, and render the block unusable for any other setup. Using 2g pistons in a 1g, or evo pistons in a 2g, were an upgrade before the aftermarket stepped in and offered better pistons and rods for not much more than doing machine work for 2g pistons on 1g rods.

 

[toofast82]

So i'm reading that if the piston is not completely flush to deck height, it will be more knock prone.
Also if the piston is not flush, how much of a potential compression loss are we talking compared to the rated 8.8:1? Lets say in a 6bolt
I have a used set of evo8 pistons that I plan on slapping in a budget 6bolt buildup for a spare, but if i'm not going to gain a point of compression, i'll just stick with the stock 6bolt slugs or go with 2g pistons.

 

[dsm-onster]

.07" lower than flush = 1.778mm tall cylinder that is 85mm in diameter added to the combustion chamber (CC) at TDC. This comes to 10cc more volume in the combustion chamber. Adding 10cc to the CC volume at TDC to an 85mm bore 88mm stroke (499.25cc cylinder) at an original 8.8:1CR would lower compression to 7.746:1; lower than stock 1g compression.

PI X R^2 X height = cylinder volume

(Displacement + CC volume @TDC) / CC volume @TDC = CR

Displacement / (CR - 1) = CC volume @TDC

Yes, the point of the quench zone is to squish all the fuel/air mix to the center where the plug is so that it is lit and the flame front reaches the outer volume where the fuel/air mix still is before droplets of gas reform. Fast burn. Droplets of gas detonate: start a flame front that collides with the initial flame. Also this quench or squish zones help rechrun the fuel/air mix to keep the fuel in suspension to prevent droplet reformation. And the third thing, is that there is a film of gasoline on the surface of the CC that helps cool the chamber surfaces. Less fuel is needed for this fim and can be burned with an effective quench zone, because the quench zone reduces the surface area of the CC at TDC.

Lower compression ratio than a stock 1g with no quench zones

 

[shredwin]

shredwin, any updates on the build? i might be picking up a set of evo pistons and rods next week

oh yes, its been a while since i've updated on here but the car has been done and running since 11/3/08... all I can say im pleased with it, It still needs a tune but hopefully i get to that sometime soon

 

[94awdcoupe]

Running a piston that doesn't come completely flush to the deck height will null the quench zones in the combustion chamber, increasing the likelyhood of knock.

maybe we should contact mitsubishi engineers and educate them on squish zone?
seriously I believe that every change mistu made to the 20 year run on the 4g63 was to improve overall performance.

I havent noticed less detonation resistance running these pistons. just the opposite if anything.

second your compression numbers are way off as well. 2g pistons have large dish, evos have none. you left that out of your equations.

 

[dsm-onster]

WTF Why are you talking about mitsu engineering? We're talking about doing something the mitsu engineers are not doing: putting evo8 pistons from an evo8 motor that has a different deck height in a 1g/2g block. This causes the piston to sit .07" lower. This removes the quench zone the mitsu engineers engineered into their combustion chamber design.

The math isn't off. ASSUMING the head cc is the same. As I mentioned.

(Displacement of one cylinder + the TOTAL combustion chamber volume )/ the TOTAL combustion chamber volume = Compression Ratio. As I said, assuming the evo 8 head has the same volume, where is the math wrong?

OK. . .The evo8 pistons are flat top. The 2g piston dishes and head gasket volume are 19.6cc. Evo pistons take away the cc of the piston dish, but the gasket is 1.07mm thick. At an 85mm bore, that's 6cc. The evo 8 piston, NOT DESIGNED BY THE MISTU ENGINEERS FOR THE 2g/1g BLOCK, adds 10cc to that 6cc since it sits .07" lower than the block. 16cc total chamber volume. The CR is 8.9 with NO quench zone to fend of knock , things just got worse!

Glad you don't have any issues. Get a tune and push the motor with pump gas. I gues quench zones, which mitsu engineers DID consider, don't count with your current setup. Good job . It's still not a good thing to remove them. The engineers engineered them into the design using their engineering knowledge

 

[94awdcoupe]

WTF Why are you talking about mutsu engineering? We're talking about doing something the mitsu engineers are not doing: putting evo8 pistons from an evo8 motor that has a different deck height in a 1g/2g block. This causes the piston to sit .07" lower. This removes the quench zone the mitsu engineers engineered into their combustion chamber design.

The math isn't off. ASSUMING the head cc is the same. As I mentioned.

(Displacement of one cylinder + the TOTAL combustion chamber volume )/ the TOTAL combustion chamber volume = Compression Ratio. As I said, assuming the evo 8 head has the same volume, where is the math wrong?

OK. . .The evo8 pistons are flat top. The 2g piston dishes and head gasket volume are 19.6cc. Evo pistons take away the cc of the piston dish, but the gasket is 1.07mm thick. At an 85mm bore, that's 6cc. The evo 8 piston, NOT DESIGNED BY THE MISTU ENGINEERS FOR THE 2g/1g BLOCK, adds 10cc to that 6cc since it sits .07" lower than the block. 16cc total chamber volume. The CR is 8.9 with NO quench zone to fend of knock , things just got worse!

Glad you don't have any issues. Get a tune and push the motor with pump gas. I gues quench zones, which mitsu engineers DID consider, don't count with your current setup. Good job . It's still not a good thing to remove them. The engineers engineered them into the design using their engineering knowledge

What your missing is evo 8 pistons sit .070 below deck in evo 8 block as well. So again , your math is off. If you put evo 8 pistons in a 1g block and bolted on evo 8 head you would have 8.8/1 compression. There is a difference between cc of head of evo. it is 2cc smaller. Head gasket is thinner on evo 8 but not on the 9. .035 and .049. 1g/2g is .049. so compression is lowered by the 2cc for evo 9 pistons, and for evo 8 its the same 2cc plus the .014 thicker gasket.

So yes mits did abandon quench zones on evo8/9. running .105 on evo8 and .119 on the evo 9. The dsm factory deck is .065. deck height is top of piston to head clearance.

These type threads would be much better off if people who have actually used the pistons were the only ones replying.