Quote:
Originally Posted by -=Jeff=-
SO did you make the H bigger or block it off? I cannot seem to get my head wrapped around the mod you did
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Hi Jeff--
The Corsa does a great job eliminating the common LT-5 resonance or drone under load at 1,800 and 3,400 rpms. What I am hearing is different. It sounds like individual cylinders firing or as I described it a fluttering sound under light/moderate load at about 2,500 rpm. I think certain firing pulses just reenforced themselves at that speed, creating a type of resonance. What I was trying to do was to get the pulses from each bank of cylinders to mix more to smooth out the sounds.
I regret that I no longer seem to have any pictures of the modifications I did on my '93, but I will try to explain them. I first cut out sections around the H pipe about 3”-4” long on the inside of the pipes entering the resonator and removed the H pipe. I had a stainless fabricator box and therefore connect the cut out sections. (FYI, the H pipe on that older Corsa actually intruded into the pipes by about 1/4”, creating a bit of an obstruction in the pipes).
Second, in the pipes aft of the resonator I drilled a bunch of 1/2” holes on the insides of the pipes and similarly had them boxed with welded stainless plates to allow sound mix but not change the exhaust flow. I feel that the modifications were successful in reducing or eliminating the annoyance of the pulsing sounds I noticed. I have no evidence that the modifications change performance in any way.
As Scott noted in an earlier post, if you don't hear such a sound then don't worry about it. Maybe it is just my mind going. But since I noticed it on this system as I had on my older system, I will modify the resonator on this system and see if I can eliminate it. If I ever do the modifications (no one yet seems to have an extra Corsa resonator to borrow or buy) I will take and post pictures of it and report on success or failure. Hope that helped. --Bob