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Old 08-23-2012, 11:09 AM
paperplane94 paperplane94 is offline
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Location: Los Angeles, CA
Join Date: Jan 2012
Posts: 933
Mein Auto: 1989 525i M20B25
Originally Posted by coolredlich View Post
I have a 1993 521I touring, with the stock chip can I run 87 octane fuel, and would a performance chip give me increased hp and torque as advertised? Thanks
Mister, don't threadjack...

Your engine is an M50. What you need to find out is if it has VANOS or not. The M50TU has VANOS and the M50 does not.

If you have the M50 then Premium fuel is required for best performance, otherwise you will experience knocking.
IF you have the M50TU then Premium fuel is not required since the engine is equipped with knock sensors to compensate for lower grade fuel.

If you do buy a performance chip you MUST use Premium fuel since that is what the chip does. It re-maps the injection for use with Premium fuel only (91 AKI or higher). Otherwise you will not see an increase in HP or Torque.

Byork and I do not have to use Premium fuel with our stock chips because we have the M20 engine. It was made to be used with 87 as stated above.

Last edited by paperplane94; 08-23-2012 at 11:10 AM.
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