BMW won’t RPM

Bill Meyer

Bill Meyer

Well-known member
I have a 1995 BMW 318 I autocross car with some issues. Last time out, it didn’t run very well. Lap times were down & it didn’t sound quite right. Found nothing visual so started with the basics: fuel, spark & airflow were ok so on to more serious investigation. Compression test was an eye opener: 200 on 1 & 4, 0 on 2 & 3. Eureka!! As an engineer, it’s obvious the high pressures are creating so much resistance, rpm’s are restricted.
I have a 2 cylinder diesel tractor with similar issues. To get it to rpm, I use a compression release that makes a huge difference. My obstacle here is figuring out how to adapt/install similar technology on the BMW to attain similar results.
Looking for ideas how to facilitate this effort.
Thanks in advance for your insite.
 
I think your theory is flawed. the reason it won't RPM is because the compressions from 2&3 will force the rotation during the compressions for 1&4. since you have 200 and 0, there is an imbalance in the Force. You need to find a way to make balance. Maybe it you drill small passages between 1&2 and 3&4, it will help to balance the compressions closer to 100 on each and then it will RPM more.

This car also sounds like a prime swap for a Chevy LS, since they are the official powerplant for God's Chariot. Any time you use one, you can overcome lack of RPM with greater torques. This will in-turn allow you to identify and replace all the other parts on the car that are made for RPM. this can be an iterous process though, so please be sure you have sufficient financial backing before undergoing this journey.
 
sounds like my SV engine...spins freely, with no plugs............won't roll over fast enough with them.

I do have a 318 with a blown head gasket you can have at fair price, if you come fetch it home....................maybe wed those 2?

SV issue started before today, so if you get a fix let me know, we might work a deal?

ha........................................................................................ha!

Okie
 
Sounds like 2-3 have eloped on a honneymoon. Since both are on the same crankshaft plane, all you need to do is install a camshaft that will allow the engine to fire 2-3 together. Think of the torque increase! :)
 
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Awesome. As a long time reader, first time poster, I never made the connection(s). So obvious. You guys are a lifesaver.
 
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