348 Challenge Non Catalyzed Cam Timing: ECU Cal Change?

There was no challenge ecu. The latest version of the 2.7 motronic was the latest spyder ecu. That had some minor tweek that was used by teams as the challenge ecu. The ecu is sealed and can't be flashed. But they can be openned and eprom replaced with what people whip up as hot chips. We used to copy the 94 ecu spyder eprom chips and retro fit them into earlier year ecus and have a defacto 94 ecu programing. When I raced my 348 I messed with cam timing. It was a pain becuase engine comes out for access each time. So combine going to track under differnt conditions and my inability (newer racer) at that time to run consistent laps within 10ths repeatedly I was unable to prove a superior cam timing with my stopwatch. Your mileage may vary. I don't have a 348 anymore but still tied into the pointy end of the crowd so we have access to "hot chips" if you want to experiment. I have been out of it for a while so I don't know how far they have gone with mapping on dyno with exhaust system changes etc. But if you are sticking to stock challenge stock 94 ecu set up is for you.

 

What exactly did they do to the timing?

Advance intake exhaust or retard the exhaust a couple degrees?

 

To answer your question on timing, yes it will. Tim (aka SoCal1) in the 348/355 section is a good guy to talk to regarding his chips with revised red line and fuel/ignition mapping.

 

I should add, it is assumed that you're running the cat-delete pipes in this config. Based upon my understanding, the cats of the era are quite sensitive to exhaust gas temp, especially given the proximity to exhaust ports in the configuration, and the tweak in timing was a measure to increase cat life, or decrease likelihood of burning them up.

 

yup seen them before... aftermarket chip like what you got from Tim. Before Tim, Before Eric, and before Reiner there was Superchip and a host of others who made their own "hot" chips . The hype was more than the actual performance because rarely was the chip the limiting factor. Chipping was a late 90's thing. When the cars got modified even with the 348 challenge tube exhaust the factory was still using the stock spyder ECU as the latest ECU iteration. The advantage of that ECU was +200RPM limt. Even that radical exhaust was doing almost nothing except making noise because a stock ECU was still being used. Real engine changes would have forced the factory to come up with a race ECU.

 

They retarded the cam timing on the cat cars in order to decrease overlap, so less unburned fuel would go into the cats. The unburned fuel would get burned in the cats, causing them to overheat. Ferrari did the same thing in cat V/S non-cat F40s. Aftermarket chip makers would take this into account. I have seen Michelotto chips for F40s market "Kat" and non Kat.