Ive read an old article in GM HighTechPerformance where they removed the small walls located right behind the throttle ports on the intake plenum. They claimed almost 4 tenths improvement in the quarter mile with just this mod. This test was done on a completely stock 89 IROC 350 with only the air intake baffles, and the MAF screens removed. They also had airfoil on the throttle body. My 350 89 Corvette has similar intake mods (airfoil, open filter lid and K&N filter) and was wondering if any of you have any hard before and after track numbers. The claim of 4 tenths seems high, but if i can gain 2-3 tenths that would be great! Thanks in advance.

 

there will be no sotp gain and assuradely no four tenths in the quarter. maybe four one-hundreths . on a completely stock engine it won't make much of a difference. but that added with the other free mods might all add up to be a tenth. and may be worth more than that when you put headers and port your intake and port your heads
Andrew

 

If you do all the free mod's you'll get more than a tenth, on a 350 tpi anyway, but no way just porting the plenum got 4 tenths, even if you do the all out porting. If you port the whole intake tract you could see that kind've change or better depending on the amount of work.
John