I have a spare here that ill check it with just to make sure.

 

thanks! talk to you soon.

 

the mahle pistons have a diameter at the top of 86.6mm, the bore on the chamber is 87.5mm, there shouldnt be any issues at all.

Also for everyones reference, you can not use stock rods with these pistons. The stock rods dont have a bushing and the small end is too small, by the time you fix that about the stock rods and coat the pins you have bought a set of brian crower rods.

 

That is not something I wanted to hear. I was under the impression we can according to the description of the pistons off science of speeds site.


http://www.scienceofspeed.com/products/eng.../Mahle/pistons/

"Pistons are compatible with factory or aftermarket connecting rods with factory pin size."

"allows these pistons to be direct replacements for the factory pistons with lowered compression ratios. "

I had the pistons installed a week ago. I had the same concern as the original poster, and had to go through some BS to make them fit. I will post a bit more details after my work meeting..

I see headaches coming my way...

 

you'll have this issue with any aftermarket piston, if the pin fits stock rods it's going to be too small for aftermarket rods.. its a trade off.

pm me with what else you had to do to make them fit

 

I didn’t get the oversize pistons, but the 87mm. The cylinder blocks didn’t have any scratches, but still got it honed. I bought the pistons from Scott (dsddcd) because he decided on another route. Anyway, I took the factory pistons and rods to a machine shop to have the Mahle pistons put together. Buddy that work there called and told me it won’t fit the factory rod. He said the Mahle pins are too big for the factory rods, as wadzii mentioned. I was out of town and didn’t want to deal with the stress I told him to do whatever he needs to do. He made it fit the stock rods. Again, I didn’t expect this and luckily I didn’t get charge for the extra work he did. Like the OP, I bought the pistons to be drop-in as advertised.

When I had the pistons installed it wasn’t flush with the block either. My best guess (visually) if I recall would be 1-2mm over the block. Mechanic and I were concerned about it also. However, when we put the head back on and manually crank it, nothing was hitting. Started the car a few days later (stock ECU) and it sounded fine, no CEL. Compression test reading cold was 130, 131, 130, and 135. Does that sound right to you guys?

Anyone thinking about buying the pistons, you have to decide on the rods… factory or aftermarket.

 

130 is a little low for compression, but it depends on which pistons you got and the gauge. How many miles are on it? Did they check the cylinders with a deck plate on the block?

The pistons are not supposed to be flush, they are supposed to come out of the block 1mm, just like factory pistons.

Personally I wouldnt ever use stock rods.. i have seen one too many come apart at the big end of the rod to trust it.

again, this is something you will run into with any after-market piston. There will be install notes included from now on that make not of this.

 

Wadzii where should the compression be at with these pistons? as soon as I save up the money I will be buying these pistons, and now rods lol and get the block bored and honed to 87.25 to fit them. I will be purchasing them from science of speed also, unless I can find them for a bit cheaper elsewhere.

 

I got the ...

enpp-2031 87.0mm 8.9:1
what should the compression be?


I got the head done the same time the pistons were installed. I will ask if they check the cylinders to the block and let you know. Car has 74Km (45k miles).
I wasn’t going to use the stock rods either initially, but I bought a used block and was planning on slowly building it the right way with aftermarket rods/pistons…etc.

 

i know mahle is a good company i just feel alittle let down right now. i hope everything gets figured out with my motor soon. my engine builder has not gotten back to me yet. he said he will get back to my once he has 100% of the info i need to make the next step to making these pistons work for me.