TheRecklessEngineer Posted February 24, 2008 Share Posted February 24, 2008 A friend and I have been trying to work out what makes a V8 sound like this: I had a V8 series a while back with an engine which was a very lucky eBay purchase. It was in bits and a complete unknown - turned out to be a complete monster when bolted together. Masses of power and sounded like the V8 in the vid above, only a but quieter and not quite so lumpy on the idle. In contrast, just been out in a hybrid with a standard rangie engine and it just makes a 'note'. You only really get the V8 growl at high revs and even then no real 'bite'. So what is it that makes an engine sound like this? Carbs vs EFI? Lack of silencer? Wild Cam? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 24, 2008 Share Posted February 24, 2008 I think 80% is in the exhaust and probably 10-15% in the tuning, 5-10% in the induction setup - did yours actually have much in the way of silencing? It's also interesting to compare the soft-ish burble of Nige's 90 (which has a fairly well silenced system) and the 109 which sounds more harsh. I noticed a big difference in sound when I tuned the 109, it definitely got a bit softer after a couple of passes with MSTWeak3k. I'm wondering if letting Nige loose to tune it a bit more might bring it down further. Mind you, I do only have one small straight-through silencer and a "megaphone" style tailpipe. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted February 24, 2008 Author Share Posted February 24, 2008 I think 80% is in the exhaust and probably 10-15% in the tuning, 5-10% in the induction setup - did yours actually have much in the way of silencing? True...I never did fit a silencer, however the pipe was quite a small diameter so provided quite a lot of silencing. Hmmm...did try this hybrid with no silencer and it sounded bloody 'orrible! Quote Link to comment Share on other sites More sharing options...
Guest diesel_jim Posted February 24, 2008 Share Posted February 24, 2008 Hmmmm..... sounds very tasty at around 1:05mins Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 24, 2008 Share Posted February 24, 2008 A small diameter pipe doesn't provide silencing, it just speeds the gases up. It may change the sound a bit but a silencer introduces resonance & muffling, there are various ways to do it that do different things. A cherry bomb or two would be a good start I'd guess. Quote Link to comment Share on other sites More sharing options...
RRX Posted February 24, 2008 Share Posted February 24, 2008 Take the exhausts off any v8 and it will sounds similar, but a rover v8 will sound alot smoother. also having open carbs will give a very loud induction roar Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted February 24, 2008 Share Posted February 24, 2008 Yes Mr Fridge let me have a tweak at yours Anyway, re the noise Yep, big bore and open pipes do a huge amount of it, then there is the CC of a Hemi and the design of it with adds to it, the induction roar just finsihes off ones "Moistnesss" Even a 3.5V8 can sound similar with no manifolds, but there is still a need for a minimum length pipe, and often too short on an engine that isn't set up for the system will give less power than a stock set up Nige Quote Link to comment Share on other sites More sharing options...
jules Posted February 24, 2008 Share Posted February 24, 2008 Just remove the down pipes and any V8 will sound like that Also be prepared for your ears to start to bleed and get very smoked out from the fumes. Tick over sounds very lumpy and spitfire like which I do like from a V8 but under power sound nice. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted February 24, 2008 Share Posted February 24, 2008 If you get drunk, take some dodgy medication and then listen carefully - the V8 exhaust is actually saying to you - "I want to be a diesel" Les Quote Link to comment Share on other sites More sharing options...
Young bobtail Rhys Posted February 24, 2008 Share Posted February 24, 2008 The best induction roar will be heard from 4 weber 45's. Get some downdraft carbs on a v8 and it will suck loads, and drink alot more fuel! One of the best silencers that I have heard was on an ac cobra. That had some kind of metal plates inside the body of the silencer to refract the noise, therefore silencing it, but does not restrict it so the engine can breath better, and giving greater horsepower. Obviously, if any exhaust system is changed from the stock one the carbs will need re-jetting to suit and a fuel injection system re-mapping, otherwise like said above the engine will infact produce less power. The same rule also aplies for air filter upgrades if you are looking to get the best performace from it. Also to note there is a given optimum exhaust diameter for each engine, exceed that and the engine won't perform very well! Quote Link to comment Share on other sites More sharing options...
missingsid Posted February 24, 2008 Share Posted February 24, 2008 Hmm. Not sure that I agree with all the comments. I have a recording of my mates 289ci Mustang on tickover. It sounds much the same and the same volume but it has a full road legal exhaust. I put it down to a lumpy cam as the motor was tuned for street racing. Cherry Bombs, personally I have hated them from the first time I heard a V8 with them, personal shoice I know. My experience is that lots of people fit separate exhausts for each bank of cylinders. Lots of noise and not always very good at flowing the gasses? My Series 1 has cast manifolds as thats all that fits with a siamese "Y" pipe. the rest is a 2.5 - 3" straight pipe through the PTO holes in the chassis and right at the end a straight through expansion box. Even though there is not a single baffle in the entire systems thing is it's not noisy the "Y" join as per RRC etc. evens out the pulses and helps the motor flow the gasses. Even though it is quiet it will set off car alarms on tickover Quote Link to comment Share on other sites More sharing options...
tacr2man Posted February 25, 2008 Share Posted February 25, 2008 The noise made is affected by a lot of variables which include pipe length , staging of cylinder outlets , cam profile, when the engine comes on cam , type of muffler (baffled or absorbstion) and location of muffler. compare an aston db9 with a Stalwart both eight cylinders. whats good depends on how much hearing damage you caused to yourself as a teenager Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted February 25, 2008 Author Share Posted February 25, 2008 Hmmm...thanks for the replies. Ill do some experimenting with some vapour and see what noises I can get. Quote Link to comment Share on other sites More sharing options...
Shackleton Posted February 25, 2008 Share Posted February 25, 2008 Yeah the idle sounds like a scatter pattern cam or it's equivalent for V8? I'm not pretending to know. I took the pipes off my 3.9 and it sure as **** didn't sound - or pick up for that matter - anything like that lump. But then if thats a Hemi 392 then it's what 6.4 litre? the video is like watching someone driving a V8 pillar box Quote Link to comment Share on other sites More sharing options...
Paul Humphries Posted February 25, 2008 Share Posted February 25, 2008 My old SD1 V8 sounded like that after a mate borrowed it and ripped the rear part of the exhaust system off on a speed hump ! If you want a decent exhaust sound listen to a Merlin engine - a real Rolls Royce version and not the Packard copy preferably in a Spitfire doing a low level fly over. Paul Humphries Quote Link to comment Share on other sites More sharing options...
pugwash Posted February 25, 2008 Share Posted February 25, 2008 or how about an SD1 with a merlin lump? Quote Link to comment Share on other sites More sharing options...
Young bobtail Rhys Posted February 25, 2008 Share Posted February 25, 2008 or how about an SD1 with a merlin lump? Funny you should say that, I have seen one!!!!!!!! Quote Link to comment Share on other sites More sharing options...
pugwash Posted February 25, 2008 Share Posted February 25, 2008 yeah PPC built one a while ago- it's a lovely bit of kit. As to the clip at the start of this thread- i can't say i like the noise at all- it's basically 2 big straight 4s sitting next to each other, which always sounds carp- sidepipes on cobras sound the same and really raen't very muscical. If you really want something nice then get behind something like a GD cobra with underslung zorts- because they are underlsung you can fit a balance bar, and the sound is pure porn Quote Link to comment Share on other sites More sharing options...
Young bobtail Rhys Posted February 25, 2008 Share Posted February 25, 2008 Couldn't agree more with you there. As you say, all you get is the sound of a very lumpy and unbalanced sound as you are only hearing half of the cylinders. A full system will always give that unique v8 burble and crisp bark Quote Link to comment Share on other sites More sharing options...
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