Re: Re: Re: Re: Re: Benefits of higher compression

Posted by Ron on June 27, 2004 at 02:41:59 from (69.179.4.15):

In Reply to: Re: Re: Re: Re: Benefits of higher compression?. posted by Neil on June 26, 2004 at 22:45:49:

Lots of good info.

A couple more points. While I come from the same school, I've learned over the years that it's usually far more cost-effective to replace an engine with one that has a larger displacement than get into boring and stroking the old. This is more true with car/truck engines where certain engine families have a range of displacements. Some tractors do to. Example: I can buy and rebuild a 454 Chev and swap it into any engine bay a 350 came out of for less than just the cost of a custom 350 stroker crank and machine work. And the bigger engine will always be more reliable than the smaller one.

Some tractors also present these swapping possibilities. Olivers are especially good. I realize than some sanctioning bodies have rules that preclude such swaps.

Actually there are some engines where boring results in huge overheating problems. Siamised cylinder engines already have cooling issues due to no coolant flow between adjacent cylinders. Boring them is usually not done. Most tractor engines are wet sleeve designs and most tractors have enormous reserve cooling capacity so they are good candidates for boring.

I agree with your statement about the 10% inprovement in general but there are other factors. I can shave the head of an inline 6 tractor engine for say $400. Because they are usually low compression engines, I can pick up 10% easily. To get a 10% increase with a bore/stroke might cost 10 times that $400. Lastly, there are about a dozen factors that enter into engine performance. They must all be balanced. For example, with a bore/stroke, the intake and exhaust systems must be modified to increase flow. This can get mighty pricey depending upon the exact situation. The one big advantage of compression ratio increases is that because they increase efficiency, they often produce excellent torque gains with no other modifications though some engine builders in some situations will run a longer cam to help eliminate the dreaded low-rpm part-throttle knock.

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• Re: Re: Re: Re: Re: Re: Benefits of higher compres Neil 08:37:31 06/27/04 (0)

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