Rebuilding a 2nd engine for FI

[Don Nguyen]

Hey guys, I have been contemplating going FI for a while now and have been trying to look at my options. I currently have a m50 head and have been thinking of getting a block to mate up with it. This way, i'll have a totally rebuild and fresh engine to throw into my car and at the same time i'll still have the one in the car now as a back up in case anything ever happens. Do you guys think this is worth while? I figure I might as well get a money shifted block and rebuild that since I was planning on changing the pistons, valves, etc anyways. Should I go with a s52 or s50 block? Also should I port and polish the head? Bore out the block more? Any inputs would be great.

thanks.

-Don

[bmwperson]

Figure out the power levels you want and what your goal is.... it helps to figure out what you need to get there.

if you have a head, then just get a 2.8/3.0 shortblock.

Dont bore out anything if you dont have to; keep the cylinder walls as thick as possible.

depending on your goals, its either stock pistons(500-550sh hp?), forged pistons, rods(600hp?)

not sure how much port and polish and oversized valves affect stuff but its probably not worth the extra money....

Tom

[Don Nguyen]

thanks for the input, that's what I have been told too, I just like to have lots of opinions on things and views :)

I have the 2.5 block that goes with the head I could use if needed.

At first with my current engine my goal was to hit 400-450, however, if I was to rebuild this 2nd engine I don't exactly know what kind of resonable power I can make from it and still be reliable enough to run daily.

[Turbo ///M50]

For that kind of power you can simply add a thicker head gasket from Vac Motorsports to reduce compression, so that you can run higher boost to attain 400 or so whp... I'd use the 2.5 block if you have it... that's what I have been using and Im @ 100k @ 8psi for 5 years now. It wasl holding fine till all these people here made me want to up the boost now im going custom..(with a headgasket at the current milage)

Full rebuilds are the way to go if you got the money to blow, and your looking for 500 or more HP otherwise save you money





thanks for the input, that's what I have been told too, I just like to have lots of opinions on things and views :)

I have the 2.5 block that goes with the head I could use if needed.

At first with my current engine my goal was to hit 400-450, however, if I was to rebuild this 2nd engine I don't exactly know what kind of resonable power I can make from it and still be reliable enough to run daily.

[bmwperson]

put a mls on your car, make it simple.. enjoy it.. I spent a year building my car and now anything over 18psi is just lots of smoke... I could have had that for alot cheaper...

[Eric BMW]

Any of the blocks is great. Unless you're goign for some major power (600+rwhp) for a daily driver I think any of the blocks would be more than sufficient for you. It's the engineering fo rthe kit and tuning that really gets you the reliability.

[amdspitfire]

go with your current engine, its a better platform to build off and you can pick up another s52 for ~2k if need be.

[card counter]

Figure out the power levels you want and what your goal is.... it helps to figure out what you need to get there.

if you have a head, then just get a 2.8/3.0 shortblock.


Dont bore out anything if you dont have to; keep the cylinder walls as thick as possible.

depending on your goals, its either stock pistons(500-550sh hp?), forged pistons, rods(600hp?)

not sure how much port and polish and oversized valves affect stuff but its probably not worth the extra money....

Tom

Very good answer but if you decide to use the 2.5 switch the crank to a 2.8
2.5 crank is cast.

[highboostingm3]

Go with an m50 block cause it probably is the cheapest I would think. Like you said, since you have to get new pistons, rods...might as well start with the cheapest cause you have to bore and build no matter what you start with. Make sure it has knock sensors.

Go with a s52 crank though cause it's forged and will give you the most stroke! Then get the rods and pistons accodingly. You can stick with 84mm bore for nice meat between cylinders and still have just over 3.0 liters of displacement due to the stroking which is plenty! :buttrock