I’ve got an 88 325 (super ETA) and I’m looking to either tear it down and rebuild it, or buy a 2’nd engine and rebuild that, in the near future. I want to build a bored and stroked motor and would like to confirm that I’ve got the correct parts and processes in mind.
I’ll start out explaining my performance expectations: I’m looking for 220WHP, >200WTQ, and good NA reliability. I also don’t want to have to rev over 7000 RPM.
I’m looking to buy:
• MM 86mm high-compression pistons (obviously I’m planning to bore out my cylinders to 86mm)
• 135mm forged H beam rods, or E36 M3 135mm rods
• E30 325i head
• MM dual valve springs
• 1mm oversized valves
• MM valve guides and seals
• 272/284 cam
• Peened rocker arms
I’ll reuse my 81mm SETA crank, but replace all the bearings and fasteners of-course. I plan to port, polish, & port match manifolds to the 325i head (and will send it out for machining to take the larger valves). As the icing on the cake I’m putting together an ITB system as well. My intension is to use a MSII computer to take care of fueling and spark duties.
Q- What compression ratio is appropriate? I was hoping for 10.5:1 but I’ve read here in the forums that may be too high for normally available premium fuel, would polishing out hot-spots in the combustion chamber allow me to run higher compression?
Q- Are the H beam rods worth the $$
Q- Is a high capacity oil pump worth the $$
Q- Am I missing anything?
I suppose I could do without all the valve-train goodies, but it’s my feeling that the head is what really keeps the cork on my engine. I may do everything but the head work as a 1’st step and see how I like that before I spend all that money on my top end.
I’ll start out explaining my performance expectations: I’m looking for 220WHP, >200WTQ, and good NA reliability. I also don’t want to have to rev over 7000 RPM.
I’m looking to buy:
• MM 86mm high-compression pistons (obviously I’m planning to bore out my cylinders to 86mm)
• 135mm forged H beam rods, or E36 M3 135mm rods
• E30 325i head
• MM dual valve springs
• 1mm oversized valves
• MM valve guides and seals
• 272/284 cam
• Peened rocker arms
I’ll reuse my 81mm SETA crank, but replace all the bearings and fasteners of-course. I plan to port, polish, & port match manifolds to the 325i head (and will send it out for machining to take the larger valves). As the icing on the cake I’m putting together an ITB system as well. My intension is to use a MSII computer to take care of fueling and spark duties.
Q- What compression ratio is appropriate? I was hoping for 10.5:1 but I’ve read here in the forums that may be too high for normally available premium fuel, would polishing out hot-spots in the combustion chamber allow me to run higher compression?
Q- Are the H beam rods worth the $$
Q- Is a high capacity oil pump worth the $$
Q- Am I missing anything?
I suppose I could do without all the valve-train goodies, but it’s my feeling that the head is what really keeps the cork on my engine. I may do everything but the head work as a 1’st step and see how I like that before I spend all that money on my top end.
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