Understanding BW race cover physics
Thread Starter
TECH Regular
Joined: Sep 2011
Posts: 431
Likes: 1
From: Washington
Understanding BW race cover physics I've swapped out my standard cover for a race cover. I understand how the valute itself helps with airflow, but looking at the inlet opening to the valute the standard cover is much larger
Is there a phisics difference here, is so can anyone help to understand?
Is there a phisics difference here, is so can anyone help to understand?
Same inlet and outlet? Neither have anti-surge ports?
Found this on theturboforums....
"There isn't a factory "race cover" available for the 71 or 75mm turbos. Let me explain what the race cover is. The S400 with a 80mm wheel (S480) is nothing more than a S475 that is upgraded to the 80mm compressor wheel. The stock compressor cover on the 75mm turbo is remachined to fit the 80mm wheel. This is what is called the standard cover. The compressor cover that everyone calls the race cover is actually the factory designed cover for the 80mm wheel,which is purchased separately from Borg Warner. The factory cover is bigger and does flow better than the standard upgraded cover. The standard cover works fine for 95% of the users out there has most people don't push the limits of the turbo very often. But for racers and such who do push the turbos to its limits every run the race cover will add HP. Now with the 71mm and 75mm S400's, the covers that come on these turbos are the factory designed cover with no other covers offered. I have seen other sellers offer a race cover for these turbos, but these are not a factory Borg Warner design."
Found this on theturboforums....
"There isn't a factory "race cover" available for the 71 or 75mm turbos. Let me explain what the race cover is. The S400 with a 80mm wheel (S480) is nothing more than a S475 that is upgraded to the 80mm compressor wheel. The stock compressor cover on the 75mm turbo is remachined to fit the 80mm wheel. This is what is called the standard cover. The compressor cover that everyone calls the race cover is actually the factory designed cover for the 80mm wheel,which is purchased separately from Borg Warner. The factory cover is bigger and does flow better than the standard upgraded cover. The standard cover works fine for 95% of the users out there has most people don't push the limits of the turbo very often. But for racers and such who do push the turbos to its limits every run the race cover will add HP. Now with the 71mm and 75mm S400's, the covers that come on these turbos are the factory designed cover with no other covers offered. I have seen other sellers offer a race cover for these turbos, but these are not a factory Borg Warner design."
From what I know (very little FYI) is the extra flow comes from a larger A/R just like a turbine housing would. You can see the physical size difference in the photo. Just like other areas of forced induction, the sizes of openings on the pressure side don't affect performance as much as they appear they would. I hope that's an acceptable pseudo scientific explanation.
