The BMW

ridr4lif · Post by **ridr4lif** » Fri Aug 26, 2005 5:48 pm

Whats up everyone.

I havent been active on the forum all summer, but i did get work done to my car...even tho its not audio work.

I finally got new Carbs for my 1975 BMW 2002. Motor work that was already done was a 292 degree cam (stock was 264), 9.5:1 comp. ratio piston, cylinders bored 1mm over and honed, whole motor hot tanked and rebuilt w/ new parts.

The carb i had on it was a Weber 32/36, total choke area= 68mm.
New carb setup is Dual Weber DCOE 45's, total choke area= 180mm.

So yea, i burn a little more gas, even tho prices keep goin up, esp. premium.

Ill work on gettin pics up soonish.

TEDD

ridr4lif · Post by **ridr4lif** » Fri Aug 26, 2005 6:01 pm

The first pic is of the old set up, obviously, and the second pic is the new set up not completed. Once my g/f comes to visit me i will take a pic of the finished product w/ the strut bar in place. Let me know what ya think!

Jonathan · Post by **Jonathan** » Fri Aug 26, 2005 6:56 pm

Looks sweet, I always liked Webers. With 9.5:1 compression and a hotter cam you shouldn't need premium gas, unless you milled down the heads or went to a thin head gasket and the 9.5:1 is rated for a stock cyl. head. Dynamic compression lowers with a higher duration camshaft.

ridr4lif · Post by **ridr4lif** » Fri Aug 26, 2005 7:02 pm

Thanx Jonathan!!!

Stock compression was around 8.5:1 i believe, but when i ran it w/ regular, it pinged like crazy. I might be able to get away w/ midgrade, but i dont wanna compromise the life of my motor. I kinda wanna do more compression anywayz, but dont wanna do another total engine rebuild.

TEDD

Jonathan · Post by **Jonathan** » Fri Aug 26, 2005 7:19 pm

Hmm. That car stock should have been able to run regular, BMW lowered compression so that they could run regular fuel during the gas crunch. Maybe the timing had too much advance.

ridr4lif · Post by **ridr4lif** » Fri Aug 26, 2005 7:22 pm

The car stock did run on regular. Sorry i should have mentioned that. After i did all the motor work i had to run it on premium.

TEDD

Jonathan · Post by **Jonathan** » Fri Aug 26, 2005 7:33 pm

Oh, ok. Makes more sense now. Kinda hard to generalize a camshaft, when you talk about overall specs like 292 and 264, the difference is far less than if you were talking about that much of a difference with .050" tappet lift, also have to take the ramps into account. Plus the duration rating varies with manufacturers. Cyl head design makes a difference as well.

Post by **GlassWolf** » Sat Aug 27, 2005 11:51 am

premium on 9.5:1 I'm guessing iron cyl heads.
aluminum should run much higher on premium.. I'm at about 11:1 with 93 octane on my motorwith no detonation, but that's with Indy 440SR cylinder heads (aluminum)

ridr4lif · Post by **ridr4lif** » Sat Aug 27, 2005 1:28 pm

Nope...its an aluminum cylinder head...cast iron block tho.

TEDD

Jonathan · Post by **Jonathan** » Sat Aug 27, 2005 2:15 pm

Maybe the engine builder advanced the cam to improve low end torque a bit, or just gave it a lot of timing to take advantage of the cyl heads. Maybe the heads need hardened valve seats, the extra octane may keep them from heating up as much. It was around 1975 or so until BMWs came with hardened seats from the factory, don't know exact models or anything. Back to the original topic, though :) .