I have a new engine installed (Aluminator) and I'm running a Whipple 2.9 with the stock 3.5" pulley pushing 21 pounds of boost. Heads are ported and have "stage 2" Comp cams. Intake is a JLT RAI with 110mm MAF housing and Accufab 100mm single blade TB. Exhaust is Kooks 1 3/4" long tubes with 3" collector and Kooks 3" o/r x-pipe which necks down to 2 1/2" into Spintech mufflers for the Roush side exhaust. The mufflers have the input and output on the same end for the side exhaust. I'm pretty sure the restriction of the mufflers and side exhaust is why boost is so high with the stock 3.5" pulley. My mechanic and tuner say I have two options given that the side exhaust stays and we are tuning for 93 octane pump gas. Either we can stay with the 3.5" pulley and 21 pounds of boost and pull timing on the tune to stay safe, or back boost down with a 3.75" pulley.
According to superchargersonline.com and gettorq.com which carry the 3.75" pulley, they say it won't fit under the stock hood without a k-member spacer kit. The pulley should only be 1/8" higher than the stock pulley. Is clearance really that tight? If so can the hood be ground out a little to provide an extra 1/8" clearance? The side exhaust and stock hood stays so I need to find a solution that keeps these. Yes, I know there is a lot more potential power there if I go with a better fuel, better exhaust, and/or more boost, but at this level I have more than enough power.
What should I do? Keep the 3.5" pulley and pull timing? ...or drop boost by switching to a 3.75" pulley? ...or something else?
According to superchargersonline.com and gettorq.com which carry the 3.75" pulley, they say it won't fit under the stock hood without a k-member spacer kit. The pulley should only be 1/8" higher than the stock pulley. Is clearance really that tight? If so can the hood be ground out a little to provide an extra 1/8" clearance? The side exhaust and stock hood stays so I need to find a solution that keeps these. Yes, I know there is a lot more potential power there if I go with a better fuel, better exhaust, and/or more boost, but at this level I have more than enough power.
What should I do? Keep the 3.5" pulley and pull timing? ...or drop boost by switching to a 3.75" pulley? ...or something else?