Y'all keep talking, just makes me hate 'em more.......LOL
Something doesn't sound right with this whole argument. If what some of you are claiming is true, no new car manufacturer would build an engine with aluminum block and heads. I know they are on a weight savings mandate to improve fuel mileage, but the easiest way to improve fuel mileage is compression, and good fuel. Also, if Lance Smith did R&R the internals from an iron block and install them in an aluminum block, did he blueprint the aluminum block just a carefully as the iron block, did he use new rings, bearings, did he heat the oil, water, engine cycles to the same amount before testing? Did he do this on the same day? Weather the same, barometer the same? Etc., etc., I have to say that with all my years of experience, automotive degree, teaching experience, have I ever heard such an argument that cannot be substantiated with back to back dyno testing in a laboratory environment to eliminate all differences but the material used in the block. A simple gasket mismatch in the intake tract can change the horsepower level on a highly tuned engine, and I have seen 20 hp difference back to back with that situation on the dyno. I have also seen 20 hp difference with spacers turned around differently, or different timing, fuel pressures, different oil level in oil pan, all make differences in back to back horsepower testing to find the ultimate combination. A carburetor not opening fully and not caught when installing on the dyno. I have to call this an argument that I cannot agree with until I see it performed under the same testing environment on the same day with identically prepared engines, and have all the same pulls to break in, all the same temperatures, and same individuals monitoring the testing procedures to verify. JMO, but skeptical to say the least at 20-40hp level. Joe-JDC
This wasn’t just something mentioned in passing, it was something Lance actually advertised with dyno sheets.
“We often have people ask what the horsepower difference is between cast iron and aluminum blocks. It often depends on the engine specs, but here is one that we ran on the dyno in a cast iron Pond block then swapped everything to a Pond aluminum. This is a 482ci, 11.5:1 comp, Stage III Edelbrock heads, and a street solid roller camshaft. Torque was basically the same but hp definitely dropped off on the aluminum. Back to back dyno play is always fun. — at Craft Performance Engines LLC.”
“I think there are several factors. Heat rejection being one, unlike cylinder heads, in a cylinder heat is power. The aluminum will distort more than cast iron under load and rpm, distorted cylinders = ring seal loss. I believe this is the 4th back to back we have done and they are normally 25-40 hp difference depending on engine specs.”
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