Support Team Shaun_E Posted October 9, 2013 Support Team Share Posted October 9, 2013 No I haven't gone over to the dark side - the Duratec motor is still firmly planted in the engine bay. However, I have a colleague who has built a Hayabusa powered 7 type car which has failed IVA on noise. I know a couple of members have got Hayabusa car's through SVA/IVA and was hoping for suggestions on how to get the noise down. The car has a decent size silencer and a standard Hayabusa air-box but it's obviously not enough. The car measured 104 dbA and has a 10750 max RPM. Needs to get down to 99 dbA. Thanks, Shaun Link to comment Share on other sites More sharing options...
robmar Posted October 9, 2013 Share Posted October 9, 2013 what rpm do they test at for the IVA? and how do they test? luckily I never had to go through that for my conversion... rob Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted October 9, 2013 Author Support Team Share Posted October 9, 2013 The limit is 99 dbA 0.5m from the exhaust at an angle of 45 deg @ 3/4 of the "maximum power" RPM. In my colleagues case thats about 7875 RPM I think although he's not sure exactly as he didn't present the car for the test. I think it is likely to be exhaust noise as the airbox is completely under the bonnet. Didn't Darren get his 'Busa through SVA? Link to comment Share on other sites More sharing options...
robmar Posted October 9, 2013 Share Posted October 9, 2013 how do they define max RPM - is it from a book/lookup? guess if it was a prog ecu maybe they could either lower limit, or do something fancy at that rpm I would fail at that RPM easily rob Link to comment Share on other sites More sharing options...
Simon.Rogers1 Posted October 9, 2013 Share Posted October 9, 2013 I think from those figures its going to be doable but very marginal. I seem to get lower readings at events in the busa than the K but under IVA conditions with all that tarmac around it will be tough. I think I would be 102- 104 ish. I guess he has a CAT also limiting length of silencer? I would go for the ECU and limit revs. Link to comment Share on other sites More sharing options...
Jason Plato Posted October 9, 2013 Share Posted October 9, 2013 I would put a bung up the exhaust Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted October 9, 2013 Author Support Team Share Posted October 9, 2013 Max RPM is something you complete on the IVA form - I think my colleague may have shot himself in the foot there! Maybe he could adjust the max RPM (claim a mistake)? The bung is a good idea - is it Merlin who sell them? Link to comment Share on other sites More sharing options...
robmar Posted October 9, 2013 Share Posted October 9, 2013 how do they do emissions test with the bung 🤔 "I only ever rev mine to 10K, honest" - is what I tell the noise testers 😬 rob Link to comment Share on other sites More sharing options...
Violet Elizabeth Posted October 10, 2013 Share Posted October 10, 2013 Speak to PDQ motorcycles. http://pdq1.com/ They know stuff. Link to comment Share on other sites More sharing options...
Dutchy Posted October 10, 2013 Share Posted October 10, 2013 Hi Shaun, I know mine failed on noise initially. It had a rear exit exhaust fitted with 2 silencers, normal side one and also a rear one. It's currently not fitted to the car. It would need repacking and may be a bracket welded on the rear basket but it free for use over the winter! Blatmail me if you want to discuss more? Steve Link to comment Share on other sites More sharing options...
the_village_idiot Posted October 10, 2013 Share Posted October 10, 2013 Why not just buy some massive bike exhaust, fabricate some pipe to make it a second rear exit and set it up just for the test? It doesn't matter how terrible it looks (provided it's safe) as I doubt it would be on for long :) Link to comment Share on other sites More sharing options...
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