RE: E30 engine upgrades

[Tom Murphy <Tom.Murphy@xxxxxxxxxx>]

Hello BMW Experts!  		Jeff Roberts asked about hopping up an m20 engine.
	This is what I did with my engine!
I wanted hi power with a streetable tune, which would pass 
pollution tests.  I started with my old M20B25, got a used diesel crank, 
and fitted new JE forged pistons using my stock connecting rods.  If you 
do this, get a crank which doesn't need any journal work, and save that 
money!  My piston maker asked if I would shorten the rods 2 millimeters, 
so that he could make 
pistons with enough room above the top ring.  I said ok, but on second 
thought I wish I had stayed with the stock lenth rod, and put a ceramic 
cap on the piston to keep the rings cooler.  Same money, more power?  
Results: 2.821 liters, CR of ~ 10.2:1.  86 x 81 mm, bore/stroke. 
	The machine shop lightened the rods slightly, (which I liked from 
past 2002 rebuilds), and I smoothed the rods and crank myself (the hot-rod 
books say a lot of oil weight can hang onto rough rods and cranks).  All 
rotating and reciprocating parts were balanced to within one gram(?).
This engine also has a MM lightened flywheel.
	The head got a porting job by Long Island's best, Eric K. (NY).  I 
had my cam reground to a 272 degree spec. (don't know what lift is 
measured!), smoothed and matched the intake runners to the head ports, 
checked for gasket interference (found some), and minimised the throttle 
body central shaft.  I got a good deal on a Stahl header from bmwcca 
member #2, and had it ceramic coated, inside and out.  Then I plunked down 
$ for a Supersprint muffler.
	I coerced a vendor into selling me the adaptor needed for a K&N 
cone filter, but ordered the cone on my own in order to get a bigger one 
than the kits were offering.  I reused the back part of the stock air 
filter housing, cut off the front, and used aluminum sheet to complete a 
heat and turbulence shield,  To get some air packing effect, I cut out 
some of the plastic grill around the headlights and the plastic behind the 
lights. 
	Topping all this off, my last purchase was for a custom Garrett 
Integrated Automotive (NJ-PA) ECU chip.  Redline: 7100 rpm.
	The car runs great, being much faster than my '79 Euro 635, and 
probably faster than a stock E36 M3.  I can floor the gas at 2000 rpm and 
keep it down, with no knocking, flat spots or surging.  Idle is just a 
little bit lumpy, but hardly noticablely different. I still get that great 
'on cam' rush at about 3800-4000 rpms, but don't need to be there for 
power. The supersprint is only a little more noisy, mainly when starting 
off, but a I do have a bit of that header 'rattle' (for want of a better 
word).  No tickets so far (that was then); doing (moderate) street racing whenever I can!
			Murf	'87 328is	'79 635csi	
BMWCCA 79550

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