Noob Question of the week (M3 pistons)

[Technician]

i am in the process of rebuilding my motor for my S50 B30.
E36 M3, 3.0lt

i am finding it increasingly difficult to find the correct pistons and the M3 piston are any where from 16k upwards.

heres the Noob question-
(my knowledge of pistons is very very limited)

i have heard through the grape fine that the 2JZGTE pistons fit (Supra 3lt)
the stock bore is 86mm, stroke 86mm, pin diameter 22mm

i have also read on the net that the opel super boss pistons also fit
the stock bore is 86mm, stoke 86 mm, compression 9.5:1

the stock M3 3.0lt is 86mm bore and 85.8mm stoke.


now i understand that the distance from the pin to the top of the piston needs to be the same, in order to get the clearance and compression ratio the same.

second question, do the 3.2lt pistons fit? (E36 or E46)
the stock bore 86.4mm
will it fit on the same crank and rod?

i am trying my best to get all my info together before i go ahead.

any help or advice will do.

and YES the build thread will be up in time.

 

[Peertjies]

I dont know anymore than you do but what i do know is that my buddy has a zooped up opel superboss and he fit the m3 piston into his machine...but unfortunately he burned them. I think his boost is a bit too high for those pistons. Dunno know if that helps in any way but it might be nice to know.

 

[moranor@axis]

part numbers for the 3.0 and the 3.2 are the same e46 has different part number

 

[Technician]

part numbers for the 3.0 and the 3.2 are the same e46 has different part number

the part numbers seem to differ??

E36 3.0lt -35.965mm, part #11251402390 (0)
-36.365mm, part #11251402393 (+0.4)

E36 3.2lt - 36.365mm, part #11251405264 (0)

 

[Fordkoppie]

From what i have seen, the s50b30 has a very complex combustion chamber in the piston and i doubt that you will be able to get something else that would be the same. AFAIK the superboss piston crowns are almost completely flat.

Now the shape of the dish in your s50 piston combined with the shape of the combustion chamber in the head is one of the most thermodynamically efficient ones on the planet. If you change anything, you will lose specific output. Then there is the issue of clearance. You wont be able to turn the engine on an engine stand and move the valve timing in the same manner as the Vanos would, so you run a real risk of smashing the valves into the pistons if you fit differently shaped ones.

It really is a pity that it wasn't flat, because then your options would have been very wide.

See what is available overseas from the likes of VAC motorsports for example

 

[Technician]

@ fordkoppie,
i thought about that as well.

here is my current piston- my own piston from the M3:rollsmile:


here is a top of a 2JZGTE piston

now without measuring they dont look far off?

 

[moranor@axis]

part numbers for the 3.0 and the 3.2 are the same e46 has different part number

the part numbers seem to differ??

E36 3.0lt -35.965mm, part #11251402390 (0)
-36.365mm, part #11251402393 (+0.4)

E36 3.2lt - 36.365mm, part #11251405264 (0)

when i search the part numbers on Realoem they come up the same on teh coupe and the 4 door :bangdesk:

 

[Alister ///M]

:idea: get 11:1cr pistons from vac for 10k and save 6k :rollsmile:

 

[Technician]

:idea: get 11:1cr pistons from vac for 10k and save 6k :rollsmile:

Why 11:1?
The standard compression is 10.8:1

will going to 11:1 not require more to be changed?

---

a new noob question for this week?

notice on the VAC website it says 11:1 is for high performance pump gas?
surely you will need to change the rods or head gasket or even the fuel supply or management if playing with the compression?

 

[Fordkoppie]

:idea: get 11:1cr pistons from vac for 10k and save 6k :rollsmile:

Why 11:1?
The standard compression is 10.8:1

will going to 11:1 not require more to be changed?

I would also opt for the 11:1 items. It is not that far off the 10.8:1 and here on the highvelt we can surely benefit from slightly more compression. Also the b32 was much higher, so i am pretty sure it would cope

 

[Technician]

thanks guys-
i have been in contact with Burgy@ProjectShift to get me some prices.

ill keep you posted.

i think if i get the M3 pistons for a good price ill stick to it rather than changing to 2JZGTE pistons.

 

[Andy1GP]

:idea: get 11:1cr pistons from vac for 10k and save 6k :rollsmile:

Why 11:1?
The standard compression is 10.8:1

will going to 11:1 not require more to be changed?

I would also opt for the 11:1 items. It is not that far off the 10.8:1 and here on the highvelt we can surely benefit from slightly more compression. Also the b32 was much higher, so i am pretty sure it would cope

+1

E46 is 11.5:1

I don't think 0.2 increase will cause any issues. Run slightly higher octane and smile away

 

[Nukleuz]

Im Also in for new pistons. A new set for me is sitting at R 9045.00