hello all,

first of all let me thank all of you for all your help. this is my first post, but i've been looking on here for awhile now.

anyway to get to the point i installed a 8lb lower pulley and now at about 4500 rpm and higher i hear a scratching sound coming from inside the hood, from the supercharger i'd guess. is this normal? if not what could it be? thanks in advance for your help.

 

If the "scratching" also sounds like marbles in a can, it's detonation. You may want to have someone with some motor exp. ride around with you to check it out. You definitely do not want detonation!

 

what exactly is detonation?

 

the closest thing i can say the "scartching" sounds like is when you take your nails and scratch a blackboard. dont know if this helps at all. any ideas?

 

scratching a blackboard

The only things I can think this may be is your belt may be slipping or the rotors in the supercharger may be hitting the walls of the case.

200harley you are running a chip, right? Also what belt are you running?

 

yea i'm runnin a diablo chip and the belt is a gates micro-v belt

 

hey 200harley, welcome to the site and congrats on the HD. post pics/build/color when ya get a chance. Hope all goes well finding out the problem

 

I think outnumbered is correct, What your describing sounds like detonation. the thickness of the supercrew firewall will muffel the sound a bit, but I agree you need to have someone you trust, that's good really good with highend moters, hear it. It's not worth harming your engine.

On a side note, how much of an increase of power did you feel with the 8lb change, and does it seem to drop when you hear the noise?

Brian

 

Fixed the problem. it was that the belt was slipping, i put some spray i found in the garage to stop the belt from slipping and it worked like a charm. i'm still thinking the belt i have is too big, imma try to put a smaller one on tomorrow.

thanks for the help.

 

Well good I'm glad you found the problem and a cheap fix at that
Whats the #( size ) on the belt?