andywear87

i have a 89 gt with stock bottom end with b cam roush 180 heads gt 40 lower and hogan sheet metal upper 70 mm tb 24lb injectors and calibrated 76mm mass air. the car ran fine when i had the gt 40 upper and every since i put the box upper on it just is always loading up and has a lot of predetonation and runs really rich and doesnt have much power is this caused buy the box upper?

67mustang302

If the plenum on the upper is huge, then it can cause all sorts of problems. And since it was fine before, but sucks after, there's about a 98.8% chance that's what caused the problem. BTW, that was one of the 92% or so of statistics that are made up on the spot, but you get the idea. Switch it back, and see if the problem goes away...it's almost a garuntee it will

5.0stanger

Those box style intake are made more for forced induction. By putting that on you shortened up your runner length and velocity of the incomming air, probably really hurting your bottom end torque. Switch back or get a blower.

jperz89lx

yeah i agree, the sheetmetal uppers are made for a s**t ton of air movin thru em, other then that your set up sounds pretty good so far, keep up the good work

andywear87

so if im going turbo or supercharger in near future would you keep this intake on or would you go with like a systemax 2

67mustang302

You could put the GT40 upper back on and keep the box until you get a turbo, then put it back on

jperz89lx

yeah keep the sheetmetal for turbo, you'll be glad you did

Silver88T

i bought a cartech box style upper and now i have to make a 2 inch spacer between the tb n upperto get my intake tube that comes off the super charger to reach the tbit kinda sucks butt hole... i was gonna buy an egr spacer but my tb is 80mm so id still have to make a venturi out of it so im jus gonna make my own venturi to get my 80mm tb to the 75mm upper intake hole and defeat the spacer problem, kinda extends my plenum but i guess u gotta do what u gotta do unless ne one has ne other great ideas pm me

5.0stanger

^^get a smaller TB...

andywear87

will the box upper make that big of a difference when i put a turbo on? also if anyone has an afrtermaket intake they would like to trade for it let me know what they got.