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Can higher CR improve the Idling? ALL 90

posted by  someone claiming to be Alexander on  Fri Dec 14 00:43 CST 2001 [RELATED]

One friend of mine changed the head on his B230F and cam for more agressive, he's got a power surplus, but engine a little unstable on idle and torq is weak on low RPM. This head has a CR 9.3 if mill down the head to get the CR ~10, will it improve the idling? I've heard something about it, but I'm not shure. Anyway can milling the head be harmful to head, gasket or other parts of engine, I've heard different oppinion about that if CR will not increase 10? which is usual for most B230.

Alexander







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    Re: Can higher CR improve the Idling? ALL 90

    posted by  someone claiming to be Leonard on  Fri Dec 14 02:13 CST 2001 [RELATED]

    The compression ratio will not noticably affect the idle. The cam affected the idle. A "performance" engine is a compromise. He gave up a smooth idle and low end torque and in exchange, got top end power. A different cam profile could make a great idle and low end torque. The cam is the single most important "performance" decision one can make on an otherwise stock engine. Raising the compression will just further cloud the issue unless more modifications are done, porting, exhaust, etc.

    Leonard







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      Re: Can higher CR improve the Idling? ALL 90

      posted by  someone claiming to be Alexander on  Fri Dec 14 02:29 CST 2001 [RELATED]

      Well, let's forget about idle, but will it give me more power?

      And what about milling the head? Is it OK?

      Alexander







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        Re: Can higher CR improve the Idling? ALL 90

        posted by  someone claiming to be Leonard on  Fri Dec 14 15:00 CST 2001 [RELATED]

        How are you planning on raising the compression? One option is to mill the head. This could be done at considerable expense and with nominal gain in power. I don't know for sure what the ratio is now, or what could be achieved, but even if you could get 10 to 1 out of it, it wouldn't show up noticeably in the seat of your pants. What you might find is that it pings because of poor fuel, and then you have the host of problems with that and the fuel injection. The simplest way to get a bit more power is with a different profile camshaft and a good exhaust header. You certainly can get more power, but at considerable more cost. Then the mileage goes down as does the reliability. In short, it is hard to carve a totem pole from a toothpick.

        Leonard






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