Carbon Cans - pops/bangs and residue
Discussion
After 5 days of enormous popping and banging from the cans on the Tuscan, I am continuing to notice a dirty white dusty deposit left on the rear/rear wings of the car at the end of each long driving day. A couple of quick questions therefore for those more technical than I;
- what is actually causing the loud pops and bangs? I had assumed "unburnt" fuel was passing through hot exhausts and vapourising, but not sure this is correct - and if it is, does a lot of popping and banging equate to a poor engine not using fuel correctly?
- is this dust potentially vapourised "unburnt" petroleum?
Noticed the noise even more as the Octane rating on the fuel increases - 98 RON in France v loud!
- what is actually causing the loud pops and bangs? I had assumed "unburnt" fuel was passing through hot exhausts and vapourising, but not sure this is correct - and if it is, does a lot of popping and banging equate to a poor engine not using fuel correctly?
- is this dust potentially vapourised "unburnt" petroleum?
Noticed the noise even more as the Octane rating on the fuel increases - 98 RON in France v loud!
Mine pops & bangs all the time as well - believe you are right in the concept of unburnt fuel! Nothing to worry about as almost all Tuscans do this - especially if you have uprated cans (mine as the CCC's).
I use Optimax in mine as well - some say yes and some say they use regular........maybe this adds to the vocal bursts????
Some say that on a dark evening when the zorsts go pop....a flame can be seen
I use Optimax in mine as well - some say yes and some say they use regular........maybe this adds to the vocal bursts????
Some say that on a dark evening when the zorsts go pop....a flame can be seen
Mustang Baz said:
dealmaster said:
Some say that on a dark evening when the zorsts go pop....a flame can be seen
I can confirm this to be true - happened this past week during dusk so am now a little wary of putting in any octane boosts (track days etc) as I could blow up!
Has your Tuscan had a De-cat MB.?
The pops and bangs are as a result of unburnt fuel igniting in the headers. I have learned that the S6 is batch fuel injected rather than the more involved/expensive/desirable sequential fuel injection......I say desirable as it would lead to less fuel consumption (slightly), better low end performance and would enable mapping specific air/fuel mixtures per cylinder. How ever the trade off would be the loss of the pops and bangs, unless one was to dial in over fueling during deceleration. Motec for example supply such ECU replacements and I have been told that they will interface with the existing TVR ECU so that the dash controls and displays are retained, however I believe getting these ECU's set up is the major cost part of the exercise.
yzf1070 said:
The pops and bangs are as a result of unburnt fuel igniting in the headers. I have learned that the S6 is batch fuel injected rather than the more involved/expensive/desirable sequential fuel injection......I say desirable as it would lead to less fuel consumption (slightly), better low end performance and would enable mapping specific air/fuel mixtures per cylinder. How ever the trade off would be the loss of the pops and bangs, unless one was to dial in over fueling during deceleration. Motec for example supply such ECU replacements and I have been told that they will interface with the existing TVR ECU so that the dash controls and displays are retained, however I believe getting these ECU's set up is the major cost part of the exercise.
Is the pops and bangs not the product of the valve overlap that the Speed Six/ AJP 8 run? With unburnt mixture entering the exhaust manifold because the exhaust valve is still slightly open when the mixture enters the cylinder, or am I barking up the wrong tree?
nsparey said:
yzf1070 said:
The pops and bangs are as a result of unburnt fuel igniting in the headers. I have learned that the S6 is batch fuel injected rather than the more involved/expensive/desirable sequential fuel injection......I say desirable as it would lead to less fuel consumption (slightly), better low end performance and would enable mapping specific air/fuel mixtures per cylinder. How ever the trade off would be the loss of the pops and bangs, unless one was to dial in over fueling during deceleration. Motec for example supply such ECU replacements and I have been told that they will interface with the existing TVR ECU so that the dash controls and displays are retained, however I believe getting these ECU's set up is the major cost part of the exercise.
Is the pops and bangs not the product of the valve overlap that the Speed Six/ AJP 8 run? With unburnt mixture entering the exhaust manifold because the exhaust valve is still slightly open when the mixture enters the cylinder, or am I barking up the wrong tree?
Yes the more you open up the exhaust the less back pressure you get which in turn releases more un burnt fuel due to valve overlap at low revs. Theoretically you will loose power down the bottom but gain at the top.
nsparey said:
Is the pops and bangs not the product of the valve overlap that the Speed Six/ AJP 8 run? With unburnt mixture entering the exhaust manifold because the exhaust valve is still slightly open when the mixture enters the cylinder, or am I barking up the wrong tree?
I am not by any means an expert, but have read up plenty on the subject through wanting to know more about how to better fuel my S6. Anyway you are quite correct in your analogy. However the pops and bangs can be eliminated using sequential injection with correct mapping by using the throttle/s position sensor/s and calculated engine load. With the ECU configiured to map the values from the right sensors the ECU can be programed to detect when the engine is under load and when its not, hence during deceleration (not under load) much less (in fact a lot less) fuel is injected at the point just before the inlet valve opens as compared with batch or group injection which generally meters in the same amount of fuel regardless of the valve position. The pops and bangs are much less obvious even with a lot of cam/valve overlap with a properly calibtrated sequential ECU map.
Consider modern high powered motorcycle engines, they tend to use a lot of overlap, and its not until you fit free flow exhausts that you get the pops and bangs and this is down to the increased chamber scavenging caused by the drop in back/header pressure. I dont know if its possible to re-jet carbs to compensate....I guess nobody cares to try as its pointless unless the laws/rules dictate you have to, besides the majority of high performance bikes now employ sequential injection as standard. I dont think the european emmissions rules have hit bikes as hard as cars just yet.
It will be quite interesting to see how TVR engines progress, I seriously reckon that the days of the great sounding pops and bangs on the overrun will very soon be lost with new models in the quest to maintain high power levels and still remain on the right side of the emmissions regulations....that'll be a sad day for many.
Cheers
G
yzf1070 said:
nsparey said:
Is the pops and bangs not the product of the valve overlap that the Speed Six/ AJP 8 run? With unburnt mixture entering the exhaust manifold because the exhaust valve is still slightly open when the mixture enters the cylinder, or am I barking up the wrong tree?
I am not by any means an expert, but have read up plenty on the subject through wanting to know more about how to better fuel my S6. Anyway you are quite correct in your analogy. However the pops and bangs can be eliminated using sequential injection with correct mapping by using the throttle/s position sensor/s and calculated engine load. With the ECU configiured to map the values from the right sensors the ECU can be programed to detect when the engine is under load and when its not, hence during deceleration (not under load) much less (in fact a lot less) fuel is injected at the point just before the inlet valve opens as compared with batch or group injection which generally meters in the same amount of fuel regardless of the valve position. The pops and bangs are much less obvious even with a lot of cam/valve overlap with a properly calibtrated sequential ECU map.
Consider modern high powered motorcycle engines, they tend to use a lot of overlap, and its not until you fit free flow exhausts that you get the pops and bangs and this is down to the increased chamber scavenging caused by the drop in back/header pressure. I dont know if its possible to re-jet carbs to compensate....I guess nobody cares to try as its pointless unless the laws/rules dictate you have to, besides the majority of high performance bikes now employ sequential injection as standard. I dont think the european emmissions rules have hit bikes as hard as cars just yet.
It will be quite interesting to see how TVR engines progress, I seriously reckon that the days of the great sounding pops and bangs on the overrun will very soon be lost with new models in the quest to maintain high power levels and still remain on the right side of the emmissions regulations....that'll be a sad day for many.
Cheers
G
yzf1070,
Having read 100% of your reply, I have taken in about 70%, appreciated about 60%, understood about 50%, will remember 40% by the morning...and am likely to talk to the dealer about 5% of it.
That said, I can confidently say I love my Tiv for all its pops and bangs. I love it when it's gone wrong [although then I hate it at the same time] and I love it when its working correctly
Surely this is the joy of owning the mark???
At the end of the day it doesn't really matter what happens with the car, as long as we all love the experience of ownership.
Anyone agree?
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