HPI Muffler results 500HP
10-03-2003, 02:09 PM
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HPI Muffler results 500HP
Tried a set of HPI clamp-ons on a 500hp equiped with Stainless marine dry exhaust.
Results; They do a Great job of lowering the noise levels! The harsh noise is replaced with a deep mellow growl. They do however cost horsepower.
I ran the boat down to get a baseline then put it on the trailer, installed the clamp-ons..took about 5 mins..put the boat back in the water and ran the same course.
Results were a 100-150rpm loss in top-end which resulted in a 2-2.4mph loss in speed. The engine seemed to labor more in reaching top-end so no doubt they are restrictive.
The clamp-on is nice because you can just remove them if you want to run at max speed and loudness...such as a poker run, then put them back on when the wife and kids are on board.
Overall, they do a great job of reducing noise...but if you dont want a power loss with a NA engine look elsewhere.
Personally, I would love this in a switchable system.
Results; They do a Great job of lowering the noise levels! The harsh noise is replaced with a deep mellow growl. They do however cost horsepower.
I ran the boat down to get a baseline then put it on the trailer, installed the clamp-ons..took about 5 mins..put the boat back in the water and ran the same course.
Results were a 100-150rpm loss in top-end which resulted in a 2-2.4mph loss in speed. The engine seemed to labor more in reaching top-end so no doubt they are restrictive.
The clamp-on is nice because you can just remove them if you want to run at max speed and loudness...such as a poker run, then put them back on when the wife and kids are on board.
Overall, they do a great job of reducing noise...but if you dont want a power loss with a NA engine look elsewhere.
Personally, I would love this in a switchable system.
10-03-2003, 10:11 PM
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Chase,
Thanks for the excellent back to back comparison info as I'm considering mufflers on my 525 EFI over the cost of switchable. I'm almost positive HPI claims about a 100-150rpm loss w/ their mufflers which they feel is modest compared to others.
Thanks for the excellent back to back comparison info as I'm considering mufflers on my 525 EFI over the cost of switchable. I'm almost positive HPI claims about a 100-150rpm loss w/ their mufflers which they feel is modest compared to others.
10-04-2003, 04:55 PM
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I think the key words they use are.."in most applications". If you were to look at the design you could see it has to be restrictive. While I was happy with the sound reduction, I bought them due to the advertised no power loss. I would have paid the difference for switchable if I had known about the power loss.
10-04-2003, 07:25 PM
#4
My question is on a physics leavel how could any product quiet any internal combustion engine down with out consuming energy? Sound is the product of energy so it must take more energy to make it go away? Seams esecially so when there is water mixed in with the sound as it adds resistance and drag. And the more drag the more energe requierd, right? Rag's
