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Old 08-03-2005, 11:43 PM   #12
2milehi
Scooby Specialist
 
Member#: 81633
Join Date: Feb 2005
Location: Dillon, CO
Vehicle:
'98 RS-T
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Quote:
Originally Posted by O2wrx
wot switch or not the fuel still puddles and the nitrous backs up in the manifold. You can have a nitrous backfire if you need to peddle the car. Wet single fogger systems will have nitrous backfires no if's and's or but's.

This is really common on the GT40 intakes and such with the long runners. If you get off the gas your throttle plate closes and the fuel starts to puddle and then hits that hot cylinder when the intake overlaps. Thus creating a nice explosion that will blow the upper intake apart.
I'm new to the Subaru club, but I have backpedaled 10s of times on a V8 in a '70 Duster drag car. The intake is wet since I am running a carb and with a nasty cam with tons of overlap (5" Hg at 1000 RPM), there was NEVER a nitrous backfire. I have see multiple cars in the same situation with no backfires and ALL of those cars have had a WOT switch. Occasionally there is a nitrous backfire with the plastic intakes (from other manufactures) that blow up and winds up on the 'net.

I have seen one engine backfire (SAAB 1/4 miler with a ton of nitrous being shot in). Driver was doing a burnout and needed the spray to turn the tires in the water box. Driver got the tires partly heated and the turbo kicked in. Engine stalled and the driver attempted to restart (oil to the turbo) and BOOM!!!!!!!!! This car did not have a WOT switch.

Backfires "usually" happen when an engine goes lean.
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