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cnavarro cnavarro is offline
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Join Date: Oct 2001
Location: Momence, IL 60954
Posts: 1,847
For a REAL turbo race engine, JB cylinders would be a no brainer unless dispacement can be sacrificed for wall thickness. Again, if comparing to stock cylinders, the JB cylinders are light years stronger, as Nickies are too. Even on street turbo engines Nickies work fine. Example in point is running a 92 or 93mm 930 cylinder. We haven't as or yet found a level of boost or accidental overboost that Nickies can't handle (which as of this date is 2 bar). Primarily Chris Carroll of Turbokraft, Inc (Pheonix, AZ) has used a few sets and seen what they can handle. CMW Motorsports also has been using Nickies for their customer builds for almost a year now with excellent results in their n/a and turbo race engines.

Andy, you're spot on. Nikasil does have lower friction. The figures I've seen from improvements on V8 blocks is about 8-10hp. I don't have a comparable figure from 911s, but do have figures from 356/912, 914s, and type 1s from builds done over the past few years and we saw an overall 15% increase in HP/torque and a 100-150F drop in head temperatures under a full load when going from cast iron or biral to aluminum/nikasil. Not all of that can be attributed to just nikasil, but also to the reduction of head temps (and cylinder temps) and a cooler, denser intake charge (n/a engines in all cases).

It would be interesting for someone to take a small 911, say a 2.2t and do a build with cast iron cylinders and dyno it. Then swap cylinders to birals then again to aluminum/nikasil. No other changes would be allowed to keep the figures comparable. This is the same process we used on the 356/912, 914, and type 1s in testing Nickies.

No cylinder can prevent detonation. All you can do is try to keep things cool, and that helps a ton, assuming many conditions including the tune of the engine and other factors. Accidental overboost will do the same thing to the pistons and rings regardless of cylinder choice. It is concievable that under those conditions where severe detonation and overboost along with inadequate fuel delivery, too much advance, etc. could cause the cylinders to split. The JB cylinder will hold up under those conditions far better than a stock cylinder that would most definately split. I've had customers overboost and detonate and the engine had to come apart. One cylinder had to be replaced as there was a hole the size of a quarter in the head at the sealing surface that intersected the cylinder (not flame ringed). Another single cylinder had to be welded to fill in a gouge (caused by the pistons/rings) and then replated. Neither case were in whole caused by overboost or normal operation. In both cases there was too much advance and in one case, bad race gas and in the other, the customer didn't think he needed race gas to run more boost and more advance :-)
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Charles Navarro
President, LN Engineering and Bilt Racing Service
http://www.LNengineering.com
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Old 10-04-2005, 04:54 AM
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