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Discussion Starter · #1 · (Edited)
Carrillo rods for my 5 Ltr. Countach

Well seeing that the engine is totally apart on the 1984 Countach, I am contemplating replacing the stock rods with aftermarket Carrillo rods. The factory redline is 7500 RPM's bone stock, I don't know how much past this point one could or would do. I have heard from owners of 4 ltr. cars with factory redlines of 8500 RPM's that they have pushed this limit to 9000-9500 RPM's bone stock.

I guess my question is how much of an increase in the redline could one expect with these rods being approximately 120 grams lighter than stock rods and no change in piston weight? My second question is what kind of redline could be expected from the factory heads with no modification to springs or valves?

Are these heads the same or close to the same as the 4 ltr cars? I know the 4 ltr car had higher redline due to a shorter stroke and lighter mass but I don't belive that the heads are that much different between the two engines.

Any Thoughts? Thanks in advance Vic
 

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is what kind of redline could be expected from the factory heads with no modification to springs or valves?
Vic,

Carrillo rods are used in many older engines, but not really for the reasons you mention.

Rpms are determined by several factors none of which have to do with the rods per se, other than lenght (stroke). To keep this simple & basic, the Longer the Rod/Stroke the lower the Rpms, like Diesels...the Shorter the Rod/Stroke the Faster an engine can spin, you can look it up on the web, but the general theory is the Rule of Square.. This is the Basic Concept behind, the longivity of IC Engines!!! In trying to keep from writing a thesis on IC Engine design...the weak points have been found to be - Piston Wieght, Valve Wieght, Valve Spring Strenght, "Rod Bolt Strenght", Rod Lenght, Cam Lift!

I truly doubt any of the complications of engine design and building would apply to your engine that were'nt addressed by the factory.!
 
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