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Old 04-28-2016, 08:52 AM   #428
Matt@Cosworth
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Join Date: Dec 2015
Drives: blue - Cosworth SC stage 3.0
Location: Northants - UK
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Quote:
Originally Posted by weederr33 View Post
Matt talked about it briefly (he's very secretive lol) a few pages back. Basically Cosworth determined that 280-290 hp (at the crank) is the recommended output for a stock engine. BUT, if you've read any other threads in the FI section, you will quickly find out that that is not always the case. Some people can go much higher than that, while others blow the motor on a CARB-tuned engine. Of course, Cosworth has done a megaton of research so that's why I feel pretty confident with them.

The supercharger itself is good for about 380 hp. But that would require a built motor and a specialized pulley set which Cosworth will hopefully release.
as weederr33 says really
the main issue is that the stock rod being sintered is a bit of a lottery
some folks may go bang - some may not all depending on how far you're pushing it
our stress analysis on the parts showed a certain cylinder pressure level was safe so we developed our tune with cylinder pressure measurement to even up all the cylinders and then dialed in the minimum of boost required to achieve this pressure level with optimised cam timing spark, fuel etc

now if you want to push on with the stock rods then you can of course just press on and machine up a smaller SC nose pulley you can go about 10% smaller before you run out of room and this gives another 0.1bar boost pressure and our tune will just about accommodate this

more than this will need a larger crank pulley to get the ratio you need and ideally you'd resize all the other pulleys too so you don't overspeed the water pump for example
now I'm experimenting with a small increase on the crank pulley to avoid changing everything else and this should result in about 0.9bar of boost and 330-340Bhp
obviously we're into a custom tune here and the need to go SD instead of MAF and possible consider a aftermarket airbox at this point too
it would also need larger injectors / fuel pump / better clutch etc

Last edited by Matt@Cosworth; 04-28-2016 at 09:07 AM. Reason: stuff
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