Discussion
joust said:
Will I need any, or does having the cats in keep me under 98??
J
J
Joust, get some! I was MILES over at Donny without cats. Cats did bring it down a bit but never enough for Donny or Bedford IMHO. RobP is the expert on this I would think as he had the first set of tail pipe silencers from me.
Actually - I was just packing the car up to go to Donny (Monday session) when Mike_p alerted me to this post.
Last time out at Donny I was going past the mic in 4th gear at 5000 rpm and was fine all day long (Roush exhaust, cats in, standard tail-pipes). However if you open up in 3rd and bounce off the rev limiter you will be well over 102dBA. Other factors which can give you high readings are air temp, wind direction and distance frorm mic. Can't do much about the first two but you can about the third
so stay over to the right hand side of the track. Now all of this might sound as if you're deliberately gaming the noise limits, but actually, using higher gear and torque is pretty well the best and fastest way to drive an M400 (unless of course you'll actively trying to over-take at the time).
Bye bye
Last time out at Donny I was going past the mic in 4th gear at 5000 rpm and was fine all day long (Roush exhaust, cats in, standard tail-pipes). However if you open up in 3rd and bounce off the rev limiter you will be well over 102dBA. Other factors which can give you high readings are air temp, wind direction and distance frorm mic. Can't do much about the first two but you can about the third
so stay over to the right hand side of the track. Now all of this might sound as if you're deliberately gaming the noise limits, but actually, using higher gear and torque is pretty well the best and fastest way to drive an M400 (unless of course you'll actively trying to over-take at the time). Bye bye
All,
RobP seems to have the noise thing at Donny licked without the tailpipes, and with cats in, we have recorded 98dB static at 4500rpm (several cars). So on a static test, they should be OK. Kevin (GTO 400) tried a set of tailpipes and on his meter went from 103dB to 96dB (IIRC), so they definitely work. Kevin was less cats for his track-day. Seems that the cats do have a big effect (cf washy miles over to RobP being OK at Donny). We have yet to do any power checks with the tailpipes, but as they're acoustic and don't massively up the backpressure, I don't expect them to lose and power - we know that Joust WITH cats saw 430bhp and washy WITHOUT cats saw 428bhp - ditto Ash at 425bhp. So the cats don't seem to affect power, and I wouldn't imagine the tailpipes do either.
I'm ordering up some more tomorrow, so I expect them in late next week, or early the week after.
Sorry for the delay in replying - work pressures etc. You know how it is....
YellowShed
RobP seems to have the noise thing at Donny licked without the tailpipes, and with cats in, we have recorded 98dB static at 4500rpm (several cars). So on a static test, they should be OK. Kevin (GTO 400) tried a set of tailpipes and on his meter went from 103dB to 96dB (IIRC), so they definitely work. Kevin was less cats for his track-day. Seems that the cats do have a big effect (cf washy miles over to RobP being OK at Donny). We have yet to do any power checks with the tailpipes, but as they're acoustic and don't massively up the backpressure, I don't expect them to lose and power - we know that Joust WITH cats saw 430bhp and washy WITHOUT cats saw 428bhp - ditto Ash at 425bhp. So the cats don't seem to affect power, and I wouldn't imagine the tailpipes do either.
I'm ordering up some more tomorrow, so I expect them in late next week, or early the week after.
Sorry for the delay in replying - work pressures etc. You know how it is....
YellowShed
gizard said:
Hmm, Mine seems to have got a lot louder recently - I get my noise meter out when I get the car to see....
I was half a sleep earlier that doesn't make sense at all!
Mine has always had it's Kats in. I should be getting it back on friday and I'll see if I can get a reading with my sound meter.
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