E28 M30 B28 Turbo

[Tylor Braun]

Hi guys,

I am new to the Forum. I am looking to turbo my M30 B28 motor. are there any recommendations on what pistons are suitable for a strong build? From what i understand the standard piston size is 86mm, but cant seem to find a set that will fit.

Does anyone on this forum have the specs of the standard piston? Deck height, wrist pin diameter conrod length etc?

Let me know.

Cheers!

[1st 5er]

I'm not a Turbo guy, but... viewforum.php?f=6

[turbodan]

Stock pistons are not an obstacle, with the possible exception of compression ratio. I don't know where the B28 is at but if the stock CR is suitable you can make 500+ horsepower with no issues.

[Tylor Braun]

CR is at 9:1

I am going to fit aftermarket management with GT35 on the stock setup. Once i have the rods and pistons ill pull apart the motor and change the internals. The forged rods and pistons are almost impossible to come by.

Once the setup is complete ill update the post with the power figures of before the internals changed and after. But still have a long way to go.

Thanks for the input

[turbodan]

Well, 9:1 is a little high. If you're looking for enough power to require upgrading internals, that will cap maximum boost well before you reach the limits of engine integrity. The 35R is also a bit large for the 2.8 in stock configuration. Might work with a short runner intake and a suitable cam, though I often advise against raising the rev limit on account of the valvetrain.

On a stock B28 I would go with something like the 3076R. The 57mm compressor would be more efficient on the 2.8 while still offering enough flow to reach 500whp. At those power levels it would be a waste of money to open the motor up for aftermarket components. Sometimes I wonder if that stuff is really an upgrade at all.

I might spring for a set of lower compression pistons. 8.5:1 works well on the M20 but I believe the late M20 variants have a superior combustion chamber design. All things considered though, the most sensible option aside from boosting that motor as is would be to source an M30B35 and dunk in some more displacement. Then your 35R fits like a glove and you get better pistons too. Would be much cheaper than spending money on the 2.8 and far more effective.

[Mike W.]

What would probably be ideal for OP is US spec E12 pistons. They were only 8.2:1 CR. But I don't even have any of them and he's on the other side of the world.

[turbodan]

Indeed, if the 2.8 block was the only option that would work.