I have been gradually working towards doing some upgrades on my VVC engine. Actually a total rebuild, an issue I have asked advice on in the past. In the interim, I have been thinking about ways of improving the midrange torque of my engine (unmodded vvc on an S2 111s) Spending money fiddling with the internals doesn’t make huge sense at the moment, as I will likely go to 1.9l, however, I have been thinking about replacing the standard manifold. I have a larini backbox. Is this a reasonable option?
Of the available options, which manifold will be likely to help improve torque in the midrange, bearing in mind that it would be a component I would like to carry over when the engine is rebuilt. Options seem to be:
Piper
Janspeed
EBD
Eliseparts
The latter 2 seem to get the best feedback, but the EBD seems to be better value for money. Also, which size, as most manufacturers seem to make a smaller and a larger bore manifold.
I will also be considering throttle bodies and an airbox, which obviously can be carried over. Sorry if the above seems rather badly worded - sleep deprivation is setting in.
Of the manifolds you describe I’ve only had the Janspeed big bore, EBD big bore stepped and several 2bular ones.
Last Saturday at Donington was the first time I used the 2bular JV5 and was really happy with its results, easily the best of the bunch. Very broad midrange, not peaky and powerband is from 4 to 8K.
Unfortunately the straight through design while not being awfully loud (96db @5K, 1/2 meter), proved to have a pitch the microphones didn’t like and I was blackflagged due to noise.
Jim will make one exactly like this but using the standard layout so it can be used with whichever backbox you want, so obviously the Larini would fit.
I’ll email you some plots so you can compare. I’ve tried to keep it comparable, the changes are only due to manifold design and intake length, and even then you can follow the trail. Engine is exactly same spec.
Unfortunately the straight through design while not being awfully loud (96db @5K, 1/2 meter), proved to have a pitch the microphones didn’t like and I was blackflagged due to noise.
Are you sure that was the cause?
Pitch only effects the frequency - and you can have both a low frequency and a high frequency noise producing the same amplitude, which is the measure of noise.
Don’t know exactly why, but to all who heard it, at Doni or before at Knockhill, it sounded sweet, certainly no louder than others.
But mine would set off the microphones.
They showed me the graphs later, my car was clearly measuring more… in the instrumentation that is.
But not to the common human in the pit lane.
Some exhausts seem to be like this.
Anyway, I’ll be sporting something definitely quieter next time. So quiet it’ll sound like a Std S2
This one I have now would work great for racing only.
pitch probably isn’t precisely the right word to use - what do you expect from a mexiscot ??? -
From reports by peeps watching from pit wall, Uldis exhaust didn’t sound as loud as some of the others that managed to stay on track… and at static test it seemed to pass.
However, the meters read dBA - which you prolly know is a weighted reading in attempt at simulating the response of the human ear (biased in the 500Hz-10000Hz range) and its most accurate for sounds around the 40 dB area (i.e. pretty quiet) so its perfectly plausible that the ‘pitch’ (wrong word but its what Uldis used to try and explain so i’ve used it as well)… of his exhaust under engine load and at high(ish) revs generates higher intensity (watts/m2) inside the weighted dBA contour. THis won’t neccesarily mean its actually ‘louder’ but it will mean he’ll get black flagged.
this is because two different 90 dB sounds won’t have the same ‘loudness’. On the dB scale 40dB at 1000Hz sounds about as loud as 30dB at around 4000Hz to the human ear (that’s technically around 6 times quieter in absolute terms). So to the dBA meter if Uldis zorst had lots of mid-range (1kHz-5KHz) at higher intensity then I can see the possibility of him getting a big score on the meter however, the next guy with an exhaust full of <1Khz and >10KHz which is actaully LOUDER might well escape.
Ohh and another thing… when things get louder the human ear starts to respond ‘flatter’ (that’s why Bass dissapears first when you turn the volume down on your car stereo)… so the discrimination applied by a dBA meter becomes more important… and more of a disadvantage in overall ‘loud’ envirnments.
mainly I have a big interest in Audio Engineering but have also done lots n lots of work with music recording and live gigs over the years… spent quite a lot of time with environ’mentally’ (unsound) health people telling me the sound was too loud… its why i’m nearly deaf now
Rox, I understand there is dbA and dbB, and I thought the latter had a narrower frequency range (closer the thuman ear?). Is it definately the A range they use and am I making any sense at all?!
BTW, at the end of the day I heard the marshalls talking over the radio that it was the worse day they had noise wise in a long time.
Rox, I understand there is dbA and dbB, and I thought the latter had a narrower frequency range (closer the thuman ear?). Is it definately the A range they use and am I making any sense at all?!
BTW, at the end of the day I heard the marshalls talking over the radio that it was the worse day they had noise wise in a long time.
Ian
IDG
There is also dBC… but dBA has the ‘narrowest’ range and is biased in the range 500Hz - 10KHz the other two are flatter over a wider range and as the sound gets louder the dBB and dBC get more representive of the response of our ears, but i’m pretty sure most noise meters use the dBA scale.
Do you think the marshalls were making comment based on what they heard or on what they saw on the noise meters ??
[quote
Do you think the marshalls were making comment based on what they heard or on what they saw on the noise meters ?? [/quote]
Rox et al,
As I organise race meetings and track days at Donington I know the staff quite well. I went to see them to see if I could get to the bottom of a certain northerner’s noise problems. The noise man (yes there is one who’s sole job is to monitor noise levels) works off a trace produced at the start of the pits straight and remote microphones out on the circuit. There are also mics in four of the local vilages which report directly to the council all traces over 54dBA (often these are aircraft). I was told it was the worst day for noise in some time (for a supposed ‘quiet’ day), not because there were one or two outrageously noisy cars but because there were so many marginal ones giving an overall ‘noisy’ day. I understand that there were fourteen separate violations recorded on the day… any one of which could lead to problems with the local council if the circuit cannot produce evidence of having taken action to correct the offence. In a way they were quite kind to us…
Regrettably noise is an issue we must all come to terms with.
With full disclosure on house sales you’d have thought it would be a non-issue over time, as seller would have to state they lived within a certain range of a noisy thing, therefore negating any complaints.
Regrettably noise is an issue we must all come to terms with.
Yep, the bullet must be bitten, sooner rather than later, cos this won’t go away. Silencing a car to meet the requirements may mean losing a few bhp, but surely that’s a small price to pay!
[quote
Do you think the marshalls were making comment based on what they heard or on what they saw on the noise meters ??
Rox et al,
As I organise race meetings and track days at Donington I know the staff quite well. I went to see them to see if I could get to the bottom of a certain northerner’s noise problems. The noise man (yes there is one who’s sole job is to monitor noise levels) works off a trace produced at the start of the pits straight and remote microphones out on the circuit. There are also mics in four of the local vilages which report directly to the council all traces over 54dBA (often these are aircraft). I was told it was the worst day for noise in some time (for a supposed ‘quiet’ day), not because there were one or two outrageously noisy cars but because there were so many marginal ones giving an overall ‘noisy’ day. I understand that there were fourteen separate violations recorded on the day… any one of which could lead to problems with the local council if the circuit cannot produce evidence of having taken action to correct the offence. In a way they were quite kind to us…
Regrettably noise is an issue we must all come to terms with. [/quote]
cheers 83man
ps T-shirt arrived and i’ve got it on just now many ta’s…