Well, the engine that I am getting is the 3.0. However, I planned to also pick up a spare 3.2 to tinker with, since they are quite easy to find for cheap. The idea was to put the 3.0 head on it.
If you say there will be no benefit, do you recommend I just stick with the 3.0?
If it is not the cams, does the 3.0 make the same power because it revs higher?

The main thing I am wary about is Wikipedia stating that it has poor low end torque, though I wish it was put in perspective. Is it poor in comparison to the 3.2, M103, etc.? The engine will be replacing a 2.6 M103, so I am hoping it will at least be a noticeable upgrade.

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Irony.cc

My 3.2 has the 3.0 head, and it is a manual, and only makes 180hp at the back wheels, which I feel is about 50hp short, but it has numerous problems that I intend to eventually fix.... I honestly expected AT LEAST 220HP, like most guys seem to get, but mine should be more, as it's a Manual.... 180 almost made me cry...

What is the reason for identical output even though there is a 200cc capacity increase?

What are the numerous problems?

Cylinder 5 and 6 have oil injection, exhaust is modified, as in not as good as stock, catalytic converters are still feasable, air filter is crap, and hot air induction, and tune is not complete to my liking.

There are other things too.... like total 24 degrees timing at WOT due to oil injection.... etc etc etc....

Oil injection as in burning oil in those cylinders? If so, you run a real risk of burning the motor down due to poor octane rating in those cylinders and a slight increase in compression ratio.

In any event, don't expect good numbers if the motor is in such a poor shape and state of tune.

Tuning mostly EFI Vs CIS. . And the 3.2 generates its peak power at lower RPM with increased torque.

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1993 190E 2.6 Sportline

There are a lot of small differences between the 3.0 and the 3.2. The 3.0 had a flat top piston and the 3.2 has a slight dish. I am almost positive that the compression is different. and Valve guide size. Cams. Injection sysem. Intake manifold timing. etc etc.
Most improvements in engines are towards a cleaner combustion burn and better tq curves for daily drivers and peak hp is not very important.

Found this tidbit, maybe Subaru pistons would work for an M104 AMG crank swap as M104 pistons are apparently too tall for a Subaru, this infers that Subaru ones are shorter.

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Impreza GC8 EZ30 turbo 6MT - Subaru Impreza GC8 & RS Forum & Community: RS25.com

Old 01-08-2017, 11:46 AM
JBLmusic
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After a lot of research which pistons can I use to my engine stronger and not to pay 3k$ I found two cars with vary similar pistons.
One of them was SAAB turbo. When I went to the SAAB spare parts near my town I realised that the SAAB pistons are vary huge.
I just said: What a massive piston wow!!!
I was inspired from these crazy guys from Sweden Tune my car
The another piston that is close to my size was Mercedes 3.2 streight 6 from E124. 89.9mm piston , 22mm piston bolt, vary close piston high.
Yeah vary close but not enough. When I measured the piston I saw that in Botom TDC the oil ring will be in the piston bolt area on the block.
We really do not want that.
I mean that we do not have to see the oil ring thru that hole in BDC.



Than after more more research I found that on 3.0 engine the same age M103 and M104 the pistons are with size 88.5mm STD
But they have 1-st and 2-nd oversize 88.5+0.5mm and 88.5+1mm which is mean that I found closer size piston with 89.5mm.
Only 0.3mm bigger than Subaru EZ30 STD size piston.
I bought 6 brand new kolbenschmidt pistons +1mm oversize.
Than I needed to modify the bigger skirt of that huge piston. Than re-drill the cilinder block and than install one piston to see what is happened.
I calculated the CR and made dish into the piston with 13cc volume.
Meanwhile I had to decide the son rods. The idea was with 6pcs from STI EJ257. But the size is totaly different.
The lenght, the big hole thickness, the piston bolt diameter.
I changed these 3 diamensions. Made the bottom side thinner with 2.5mm (1.25mm each side), Made the lenght +0.5mm from 130.5mm STD size of EJ257 con rod to 131mm.
That length was enough to hide the oil ring from the hole at BDC. And finaly the piston bolt diameter of STI con rods is 23mm and I needed 22mm. I bought BMW 22mm
bushes and you can see how it is installed on the pictures.