1G Wiseco HD2 for EVO 4-9 in to a 6 bolt

[mikellinos]

Hi all, I want to share some useful info with you guys.

Last year I had a bad batch of fuel and I melt a piston. My engine is a 6 bolt, 2.0 long rod with 9.4:1 compression, custom JE pistons 0.02” overbore and 272 kelford cams. The car was running great for 2 years at 26 psi boost with 93 octane pump gas (98 in Europe) until that one day… The piston on cylinder 2 melt and also caused damage to the block, fortunately the cylinder wall cleared with 0.06” overbore.

This time I decided to go with off the shelf set of pistons and lower my compression ratio to be safer, I end up with Wiseco HD2 6669M865. This particular piston is advertised as an EVO 4-9 but I found only 2 websites where they said that will also work for DSM engines and EVO 1-3. The piston has offset pin and asymmetric skirt, so I thought the valve relieves will be identical and can work in both engines, my bad I didn’t ask first and I just ordered them. BTW is my first time I ordered from Wiseco and I had the worst service… no need to go in to details now.

The pistons arrived and the valve relieves weren’t identical, smaller for the exhaust and larger for the inlet. So if you use that piston in to a DSM engine the valve relieves will be opposite, will have the exhaust relieves under the inlet valves. After a LOT of searching I couldn’t find out if they going to have enough clearance (piston to valve) for the inlet valves but I found few posts that people used EVO 8 pistons in a DSM and they worked, some they flipped the piston around but I didn’t want this because then the offset would be on the wrong side and same with the skirts. Wiseco told me if they don’t clear then I can fly cut the valve relieves but that will remove the coating. Anyway I decided to move forward and I will find out.

Finally the pistons work just fine, I checked today the clearance and it is ok, 0.157” piston to inlet valve. This clearance is with Mitsubishi MLS head gasket 4 layers, kelford 272 and the piston protrudes 0.006” above the deck and my current compression will be 8.8:1.

I hope someone can find the above info useful.

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[DSMPT]

There is no offense but I should tell you that the Wiseco 669M will NOT work properly for early 4g63. This is because the 669M have asymmetric skirts and valve reliefs. It is not only about valve relief size. You should think about the thrust side, too. On EVO 4-9 4g63, the major thrust side would be on intake side, so you probably see that your pistons have wider skirt on intake side and narrower skirt on exhaust side. but it has to be opposite on DSM's early 4g63. So if you would flip the pistons, the valve reliefs would be opposite but if you wouldn't flip, the piston skirts would be opposite. It "can" run while the valve clearance is fine but it's not ideal, not recommended especially if it's a serious race engine. If I were you, I would get a right set for DSM 4g63.

 

[mikellinos]

There is no offense but I should tell you that the Wiseco 669M will NOT work properly for early 4g63. This is because the 669M have asymmetric skirts and valve reliefs. It is not only about valve relief size. You should think about the thrust side, too. On EVO 4-9 4g63, the major thrust side would be on intake side, so you probably see that your pistons have wider skirt on intake side and narrower skirt on exhaust side. but it has to be opposite on DSM's early 4g63. So if you would flip the pistons, the valve reliefs would be opposite but if you wouldn't flip, the piston skirts would be opposite. It "can" run while the valve clearance is fine but it's not ideal, not recommended especially if it's a serious race engine. If I were you, I would get a right set for DSM 4g63.

i don't agree with you, maybe i didn't explain good. The piston right now in my engine has the wider skirt where it should be, at the major thrust side which is the exhaust side, and the narrow skirt at inlet side. So the skirts are in correct sides, same goes with the offset of the pin. What is opposite are ONLY the valve relieves, i have the exhaust relieves under the intake valves but they are wide and deep enough and they clear the valves just fine. The clay at the pictures is the exhaust relief under the intake valve.

 

[1990TSIAWDTALON]

I have seen that damage more than once and they were all from too much timing not bad fuel. I don't know anything about the occurrence but bad fuel doesn't melt aluminum. I mean no harm, just saying from experience.
Was it #3 cylinder? Both motors I have seen, that was the cylinder and the same spot, right near the end of the valve relief.
Do you happen to have a log from when it went down? I'd be interested in seeing what happened.
I respect Hiroshi's opinion on this, get the correct parts or you will risk doing it all over again. It's just opinions.

 

[DSMPT]

i don't agree with you, maybe i didn't explain good. The piston right now in my engine has the wider skirt where it should be, at the major thrust side which is the exhaust side, and the narrow skirt at inlet side. So the skirts are in correct sides, same goes with the offset of the pin. What is opposite are ONLY the valve relieves, i have the exhaust relieves under the intake valves but they are wide and deep enough and they clear the valves just fine. The clay at the pictures is the exhaust relief under the intake valve.

I think you are not understanding well what I meant or I didn't explain myself well, and you missed where I said "It "can" run while the valve clearance is fine but it's not ideal, not recommended especially if it's a serious race engine.".
If you have the wider skirt on exhaust side, then you already flipped the pistons. Which means you now have the valve reliefs and offset on the opposite side.
I have discussed exactly the same thing with my Wiseco rep long time ago (The 669M on DSM 4g63). Because I wasn't sure if the valve reliefs were symmetrical or not. Here is their answer for the question if 669M pistons work for DSM's 4g63.

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[mikellinos]

I have seen that damage more than once and they were all from too much timing not bad fuel. I don't know anything about the occurrence but bad fuel doesn't melt aluminum. I mean no harm, just saying from experience.
Was it #3 cylinder? Both motors I have seen, that was the cylinder and the same spot, right near the end of the valve relief.
Do you happen to have a log from when it went down? I'd be interested in seeing what happened.
I respect Hiroshi's opinion on this, get the correct parts or you will risk doing it all over again. It's just opinions.

Was cylinder #2, i'm almost 100% was the fuel because i didn't find something else, for 2 years i had the car with the same tune and everything was fine, knock, temperatures etc. few times i even checked the pistons with a camera and regularly i inspected the spark plugs because i was using only pump gas. That particular day i fill up the tank from a gas station in a small village, i did a pull with third gear and the car didn't feel the same, idiot me i wanted to try again to see for sure the difference, unfortunately i didn't turn on the log and i did a pull with 4th gear and that was the end...

 

[mikellinos]

I think you are not understanding well what I meant or I didn't explain myself well, and you missed where I said "It "can" run while the valve clearance is fine but it's not ideal, not recommended especially if it's a serious race engine.".
If you have the wider skirt on exhaust side, then you already flipped the pistons. Which means you now have the valve reliefs and offset on the opposite side.
I have discussed exactly the same thing with my Wiseco rep long time ago (The 669M on DSM 4g63). Because I wasn't sure if the valve reliefs were symmetrical or not. Here is their answer for the question if 669M pistons work for DSM's 4g63.

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Dont get me wrong but i still dont agree.
When you see the piston from the front side, the side where should be towards the timing belt in an EVO engine, it has the wider skirt and the inlet reliefs on the left, the same goes with the pin, it is offset towards the left side of the piston, the engine turns clockwise so everything its where they should be, major side is on your left.
Now if you put that piston in a DSM and the front side towards the timing belt you still have the wider skirt and the offset pin correct, towards the major side which is still on your left because the engine again turns clockwise. So the only difference are the valve reliefs.
Please correct me if i'm wrong.

 

[DSMPT]

Dont get me wrong but i still dont agree.
When you see the piston from the front side, the side where should be towards the timing belt in an EVO engine, it has the wider skirt and the inlet reliefs on the left, the same goes with the pin, it is offset towards the left side of the piston, the engine turns clockwise so everything its where they should be, major side is on your left.
Now if you put that piston in a DSM and the front side towards the timing belt you still have the wider skirt and the offset pin correct, towards the major side which is still on your left because the engine again turns clockwise. So the only difference are the valve reliefs.
Please correct me if i'm wrong.

Seems you are confused... What you are saying now is the same as what I said above "On EVO 4-9 4g63, the major thrust side would be on intake side, so you probably see that your pistons have wider skirt on intake side and narrower skirt on exhaust side. but it has to be opposite on DSM's early 4g63".
Please refer the pic below and compare with your HD2 pistons. The piston in the pic is custom for DSM, "based on Wiseco HD2 EVO 4-9 pistons". You see that the wider skirt is on exhaust side (smaller valve relief side) and the narrower skirt is on intake side.

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[1990TSIAWDTALON]

Maybe bad fuel and too much timing but I wouldn't rule out either on the reason for it going down.
As for the parts, I think you have good advice.

 

[1990TSIAWDTALON]

This was from too much timing during a pull at a racetrack. First pull, no shakedown and way too much timing on E85, for example recently. Fresh motor too. Just a good picture of the latest that I encountered and I built the motors. The other motor was not quite as bad, as they let out of the pull. I can't find the picture of it right now, but same exact look in the cylinder. Yours melted all the way thru every ring and beyond. The 2 I have had experience with, 1 went thru the top 2 rings and 1 went down to the top ring and stopped (the one that let out of the pull).

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[mikellinos]

Maybe bad fuel and too much timing but I wouldn't rule out either on the reason for it going down.
As for the parts, I think you have good advice.

Yes something like this could be. Probably my timing was too much but with good fresh fuel didn't knock but with a bad quality fuel didn't need a lot to detonate. BTW the bad happened at 5000 rpm, where i have max torque. In previous logs at that point i usually have about 24 psi boost and 8 degrees of timing.

 

[mikellinos]

Seems you are confused... What you are saying now is the same as what I said above "On EVO 4-9 4g63, the major thrust side would be on intake side, so you probably see that your pistons have wider skirt on intake side and narrower skirt on exhaust side. but it has to be opposite on DSM's early 4g63".
Please refer the pic below and compare with your HD2 pistons. The piston in the pic is custom for DSM, "based on Wiseco HD2 EVO 4-9 pistons". You see that the wider skirt is on exhaust side (smaller valve relief side) and the narrower skirt is on intake side.

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yes we say the same thing, what i didn't understand is why should be a problem. Right now in my engine the wider skirt is on the major side, so this is how it should be. The same goes and with the offset pin, it is towards the major side as well, opposite of the rotation of the engine, so the offset its ok too. My exhaust valves are above the inlet piston reliefs so they have plenty of clearance, i dont see a problem neither here. And my inlet valves are above the exhaust piston reliefs BUT they still have enough clearance, vertical and radial. Im sure nothing is wrong with what i just said. I can post pictures to prove it but i think its unnecessary.

I think the answer that you got from Wiseco was about the reliefs and not about the skirt and the offset, probably with different cams, oversize valves, other head gasket and different bore size, the inlet valves maybe they dont clear the piston enough. Thats the reason i wrote my setup above, i didnt say the 6669M will work with all the DSM setups, maybe they will, i dont know. The answer that i got from Wiseco was that they couldnt tell me if they can work with the DSM engine but sure they work with the EVO engine, they told me if i have clearance problem i can fly cut the reliefs but that will remove their armor plating coating from the valve pocket but will not hurt the piston.

I didnt found anybody who actually bought the pistons, install them and check them. Me i finish today with the installation, i degree the cams, i measured them and they are ok for my setup and i wanted to share this information.

 

[DSMPT]

yes we say the same thing, what i didn't understand is why should be a problem. Right now in my engine the wider skirt is on the major side, so this is how it should be. The same goes and with the offset pin, it is towards the major side as well, opposite of the rotation of the engine, so the offset its ok too. My exhaust valves are above the inlet piston reliefs so they have plenty of clearance, i dont see a problem neither here. And my inlet valves are above the exhaust piston reliefs BUT they still have enough clearance, vertical and radial. Im sure nothing is wrong with what i just said. I can post pictures to prove it but i think its unnecessary.

I didnt found anybody who actually bought the pistons, install them and check them. Me i finish today with the installation, i degree the cams, i measured them and they are ok for my setup and i wanted to share this information.

Basically I said everything in my first post. "if you would flip the pistons, the valve reliefs would be opposite but if you wouldn't flip, the piston skirts would be opposite. It "can" run while the valve clearance is fine but it's not ideal, not recommended especially if it's a serious race engine. If I were you, I would get a right set for DSM 4g63."
This meant how come you risk this on your good build? What if you would want to go with higher lift or/and longer duration more agressive cams or oversize valves? If you have smaller valve reliefs it may possibly restrict your further upgrades. Don't get me wrong, we are just wondering why don't you simply go with the right set from the beginning, and we are sharing our opinions and experiences with you.

I think the answer that you got from Wiseco was about the reliefs and not about the skirt and the offset, probably with different cams, oversize valves, other head gasket and different bore size, the inlet valves maybe they dont clear the piston enough. Thats the reason i wrote my setup above, i didnt say the 6669M will work with all the DSM setups, maybe they will, i dont know. The answer that i got from Wiseco was that they couldnt tell me if they can work with the DSM engine but sure they work with the EVO engine, they told me if i have clearance problem i can fly cut the reliefs but that will remove their armor plating coating from the valve pocket but will not hurt the piston.

I often talk to Wiseco for my work, at that time what exactly I discussed was if the valve reliefs on the 669M are symmetrical or not, because I was thinking to use them on a dsm like you if they were symmetrical. Actually I mentioned everything you mentioned above. Maybe the only difference was the rep knew the engine had the Kelford hight lift cams.

 

[mikellinos]

Don't get me wrong, we are just wondering why don't you simply go with the right set from the beginning, and we are sharing our opinions and experiences with you

My goal wasn't to have a non DSM piston in my DSM engine The reason i ended up with this situation is because i wanted a good off the shelf piston with good features, 0.866" pin and for a long rod engine, 0.06" over bore and a dish volume at about 12cc, that's the 669M piston. From the website where i ordered them, wasn't directly from Wiseco, they had them for the EVO and for the DSM engine, the only thing i regret is that i didn't ask for the valve pockets because I assumed were symmetric. The piston weren't in stock nowhere in the US and because of the covid situation i was waiting literally 4 months for them to arrive. So right now if i want to send them back and get a different set i have to wait 4 months more plus the total cost from the shipping and the taxes (I'm in Europe) will cost me about the half price of what i already have paid for them...