Which Performance Exhaust System?
Discussion
Dear T350c owners. My rear exhaust mounting brackets keep failing, the rubber has split again. Does anyone suffer from this. I am also looking to replace the original back box as I believr that a standard T350c doesn't sound as it should, needs to be more aggresive considering the cars performance. Sorry if anyone disagrees.
I have looked at tvr powers individual back boxes at £375.00 + vat, has anyine out their had any moda on eaxhaust systems on the T350c as I need help. Also they supply the main pipea from the cats towards the back boxes in a larger bore which also increases noise level etc.
Finally has anyone removed the cats and supplied the upgrade system. Any help by owners who have had an eaxhaust upgrade will be welcome, and thanking you all in advance.
Please excuse my spelling.
P.S Blew the doors of a Porsche the other day after the owner felt like impressing the bird in his car. Must let these Porsche owners know that we are no push overs.
I have looked at tvr powers individual back boxes at £375.00 + vat, has anyine out their had any moda on eaxhaust systems on the T350c as I need help. Also they supply the main pipea from the cats towards the back boxes in a larger bore which also increases noise level etc.
Finally has anyone removed the cats and supplied the upgrade system. Any help by owners who have had an eaxhaust upgrade will be welcome, and thanking you all in advance.
Please excuse my spelling.
P.S Blew the doors of a Porsche the other day after the owner felt like impressing the bird in his car. Must let these Porsche owners know that we are no push overs.
. All TVRs are goodtrackcar said:
Rumour has it the std T350 exhaust saps about 15bhp .. getting something less restrictive on there is a good move 
I'm sure a less restrictive system will help with power, but surely only with appropriate remapping to release those hidden horses?
Mine has a standard exhaust system and it is most certainly not wanting for power on the track - it seems exactly matched with Tuscan S' and Red Rose Speed Sixes (on very long straights such as Snetterton there didn't seem to be anything in it and around Oulton it easily kept up with a Tuscan S on the hillier sections).
trackcar said:
Rumour has it the std T350 exhaust saps about 15bhp .. getting something less restrictive on there is a good move
I was under the impession Julian that less back pressure had an impact on the valve overlap, ie unspent gasses being released through the outlet valves to early at low revs, only to be evened out at high revs due to the valve being at such high speed the gasses are caught in the chamber. Re mapping i cant see curing valve overlap as the sp6 can not have its valve timing changed unless you have a new cam.
Just my thoughts Julian.. ?
What does re mapping do except change the fuel mixture. ?
Please help as i am not sure.
Mark
Edited by yi8tvr on Wednesday 11th October 16:12
yi8tvr said:
trackcar said:
Rumour has it the std T350 exhaust saps about 15bhp .. getting something less restrictive on there is a good move
I was under the impession Julian that less back pressure had an impact on the valve overlap, ie unspent gasses being released through the outlet valves to early at low revs, only to be evened out at high revs due to the valve being at such high speed the gasses are caught in the chamber. Re mapping i cant see curing valve overlap as the sp6 can not have its valve timing changed unless you have a new cam.
Just my thoughts Julian.. ?
What does re mapping do exept change the fuel mixture. ?
Please help as i am not sure.
Mark
I await a response with interest.
targarama said:
I'm sure a less restrictive system will help with power, but surely only with appropriate remapping to release those hidden horses?
Mine has a standard exhaust system and it is most certainly not wanting for power on the track - it seems exactly matched with Tuscan S' and Red Rose Speed Sixes (on very long straights such as Snetterton there didn't seem to be anything in it and around Oulton it easily kept up with a Tuscan S on the hillier sections).
Mine has a standard exhaust system and it is most certainly not wanting for power on the track - it seems exactly matched with Tuscan S' and Red Rose Speed Sixes (on very long straights such as Snetterton there didn't seem to be anything in it and around Oulton it easily kept up with a Tuscan S on the hillier sections).
I am no mechanic by a long shot Trefor but re mapping in my opinion has only a placebo effect. Changing the dif ratio would have a more dramatic effect as to releasing horses (earlier at least) on track.
The only down side to dif changing is whine and top end slower, but who goes over 140mph on track (not me) im more like 135mph tops and thats Hanger straight..?
Edited by yi8tvr on Wednesday 11th October 16:47
Daftlad said:
yi8tvr said:
trackcar said:
Rumour has it the std T350 exhaust saps about 15bhp .. getting something less restrictive on there is a good move
I was under the impession Julian that less back pressure had an impact on the valve overlap, ie unspent gasses being released through the outlet valves to early at low revs, only to be evened out at high revs due to the valve being at such high speed the gasses are caught in the chamber. Re mapping i cant see curing valve overlap as the sp6 can not have its valve timing changed unless you have a new cam.
Just my thoughts Julian.. ?
What does re mapping do exept change the fuel mixture. ?
Please help as i am not sure.
Mark
I await a response with interest.
I will put this back on the bottom John in case people dont see it
This is a debate i would like to engage in, i may learn something being a mechanical numpty
Edited by yi8tvr on Wednesday 11th October 16:47
Dear all,
Funny how a simple question on a performance exhaust has led to all the other info. I would like to say thanks to everyone, however I am now lost. Talk to me about locks and I can go on for-ever. After all it,s the locks that I fit and the training courses that I run that keep the TVR on the road.
P.S When the exhaust brackets don't fail.
Funny how a simple question on a performance exhaust has led to all the other info. I would like to say thanks to everyone, however I am now lost. Talk to me about locks and I can go on for-ever. After all it,s the locks that I fit and the training courses that I run that keep the TVR on the road.
P.S When the exhaust brackets don't fail.
helo, try checking the nearside engine mounting hasn't disintegrated with the heat from the exhaust. after replacing my knackered mounting the whole exhust had to be re-aligned as the engine was about 20mm higher than before. it seemed to take a bit of pressure off the mounting rubbers aswell...phil
trackcar said:
You might be keeping up now, but if you improve a few areas of your car that make it a better performer you won't just match the other's speed you'll beat it ...
My car needs to be able to finish the day again first. Several track days last year, and it went very very well indeed. Twice this year had head gasket failure. Running beautifully now, so I plan to get back on track asap though (work schedule permitting).
I'm not against making it faster, but I don't want to make it much louder. I do like sports exhausts, but personally don't want to live with one. Can any changes be made to 'loosen things up' in the exhaust system with minimal noise increase?
Well first thing is that altering back pressure *can* be a useful tuning aid, so it isn't always undesirable. If you're running in a race/rally class for example where you have to keep stock gear ratios it might be beneficial to sacrifice some outright top end hp to bias the majority of the hp within a certain rev band ..
however in general back pressure costs performance.
back pressure increases pumping losses, ie that hp required to physically push the remaining exhaust gas out of the chamber.
back pressure will influence what cam timing you can use, because as back pressure builds then scavenging effects from exhaust gas momentum decreases, so you wouldn't want to run a lot of overlap if there was a chance of gas reversal back into the chamber. reducing back pressure will allow you to run more overlap and make it work. This last point is the important one because you can run whatever cam you want of course, but it's effects with be influenced by the exhaust type amongst other things.
back pressure though can tame the effects of a wild cam at lower revs by improving the trapping efficiency of a cam with lots of overlap, but you would want to rduce that back pressure as revs rise and the cam starts to work properly. Some exhausts have variable valves in them for this purpose ( as well as for sound reduction on light throttle)
Momentum effects of the exhaust gas leaving the chamber and exhaust pulse tuning are the two primary ways of scavenging the chamber of all the exhaust gas, if you get it right and then you can use the scavenging effects to pull fresh charge through the chamber, if you have high inlet gas velocity you can use that momentum ram to pressure-charge the chamber. Volumetric efficiencies on some engines exceed 100% by these techniques. In effect you get a super-chargin of the chamber.
Of course on a road car these effects are less acute than on race engines say, but if you have an exhaust which is costing you hp it's likely to make the car slower (discounting our model at the very start of biasing hp to suit certain conditions) . you would need to rolling road the car before and after to make sure you had a gain over a desirable part of the rev range though, ie it's no good gaining 50bhp over the last 200rpm if everywhere else it loses 60bhp .. however if you have a gain over the part of the rev range you want to use then the car will be faster.
generally speaking, exhausts are the one area where you very often get your cake and eat it .. reduced pumping losses and better scavenging benefit hp production and also fuel economy! your exhaust should pay for itself in fuel saved lol! (eventually, and assuming you don't drive it everywhere faster to get the sound of the new exhaust!!)
There will be TVR exhausts that don't cost hp, but they are rare i think. For instance on the cerbera there is nothing to be gained by going up on the size of the intermediate pipes, but the S bend that goes under the diff chassis x-brace is costing 8bhp on a 400bhp car. All you need to do is replace that with larger bore and you have an instant hp increase.
A last word about mapping and hp increases.
For sure if you want the best from any mod you do, you should have it mapped to suit. however if you're adding say 15hp to a 360bhp car you've incrased the airflow by about 4% and assuming your car is in good order it should be running close to lambda 0.8 under full load, so this would reduce it to lambda 0.84 .. still well within safe limits .. however you may be able to pick up more hp by mapping the car to exactly suit the new exhaust conditions.. you would ideally want to check the car under load to make sure you were perfectly safe though. I think the number of cars now out there running these performance style back boxes suggests there isn't an issue.
however in general back pressure costs performance.
back pressure increases pumping losses, ie that hp required to physically push the remaining exhaust gas out of the chamber.
back pressure will influence what cam timing you can use, because as back pressure builds then scavenging effects from exhaust gas momentum decreases, so you wouldn't want to run a lot of overlap if there was a chance of gas reversal back into the chamber. reducing back pressure will allow you to run more overlap and make it work. This last point is the important one because you can run whatever cam you want of course, but it's effects with be influenced by the exhaust type amongst other things.
back pressure though can tame the effects of a wild cam at lower revs by improving the trapping efficiency of a cam with lots of overlap, but you would want to rduce that back pressure as revs rise and the cam starts to work properly. Some exhausts have variable valves in them for this purpose ( as well as for sound reduction on light throttle)
Momentum effects of the exhaust gas leaving the chamber and exhaust pulse tuning are the two primary ways of scavenging the chamber of all the exhaust gas, if you get it right and then you can use the scavenging effects to pull fresh charge through the chamber, if you have high inlet gas velocity you can use that momentum ram to pressure-charge the chamber. Volumetric efficiencies on some engines exceed 100% by these techniques. In effect you get a super-chargin of the chamber.
Of course on a road car these effects are less acute than on race engines say, but if you have an exhaust which is costing you hp it's likely to make the car slower (discounting our model at the very start of biasing hp to suit certain conditions) . you would need to rolling road the car before and after to make sure you had a gain over a desirable part of the rev range though, ie it's no good gaining 50bhp over the last 200rpm if everywhere else it loses 60bhp .. however if you have a gain over the part of the rev range you want to use then the car will be faster.
generally speaking, exhausts are the one area where you very often get your cake and eat it .. reduced pumping losses and better scavenging benefit hp production and also fuel economy! your exhaust should pay for itself in fuel saved lol! (eventually, and assuming you don't drive it everywhere faster to get the sound of the new exhaust!!)
There will be TVR exhausts that don't cost hp, but they are rare i think. For instance on the cerbera there is nothing to be gained by going up on the size of the intermediate pipes, but the S bend that goes under the diff chassis x-brace is costing 8bhp on a 400bhp car. All you need to do is replace that with larger bore and you have an instant hp increase.
A last word about mapping and hp increases.
For sure if you want the best from any mod you do, you should have it mapped to suit. however if you're adding say 15hp to a 360bhp car you've incrased the airflow by about 4% and assuming your car is in good order it should be running close to lambda 0.8 under full load, so this would reduce it to lambda 0.84 .. still well within safe limits .. however you may be able to pick up more hp by mapping the car to exactly suit the new exhaust conditions.. you would ideally want to check the car under load to make sure you were perfectly safe though. I think the number of cars now out there running these performance style back boxes suggests there isn't an issue.
trackcar said:
Well first thing is that altering back pressure *can* be a useful tuning aid, so it isn't always undesirable. If you're running in a race/rally class for example where you have to keep stock gear ratios it might be beneficial to sacrifice some outright top end hp to bias the majority of the hp within a certain rev band ..
however in general back pressure costs performance.
back pressure increases pumping losses, ie that hp required to physically push the remaining exhaust gas out of the chamber.
back pressure will influence what cam timing you can use, because as back pressure builds then scavenging effects from exhaust gas momentum decreases, so you wouldn't want to run a lot of overlap if there was a chance of gas reversal back into the chamber. reducing back pressure will allow you to run more overlap and make it work. This last point is the important one because you can run whatever cam you want of course, but it's effects with be influenced by the exhaust type amongst other things.
back pressure though can tame the effects of a wild cam at lower revs by improving the trapping efficiency of a cam with lots of overlap, but you would want to rduce that back pressure as revs rise and the cam starts to work properly. Some exhausts have variable valves in them for this purpose ( as well as for sound reduction on light throttle)
Momentum effects of the exhaust gas leaving the chamber and exhaust pulse tuning are the two primary ways of scavenging the chamber of all the exhaust gas, if you get it right and then you can use the scavenging effects to pull fresh charge through the chamber, if you have high inlet gas velocity you can use that momentum ram to pressure-charge the chamber. Volumetric efficiencies on some engines exceed 100% by these techniques. In effect you get a super-chargin of the chamber.
Of course on a road car these effects are less acute than on race engines say, but if you have an exhaust which is costing you hp it's likely to make the car slower (discounting our model at the very start of biasing hp to suit certain conditions) . you would need to rolling road the car before and after to make sure you had a gain over a desirable part of the rev range though, ie it's no good gaining 50bhp over the last 200rpm if everywhere else it loses 60bhp .. however if you have a gain over the part of the rev range you want to use then the car will be faster.
generally speaking, exhausts are the one area where you very often get your cake and eat it .. reduced pumping losses and better scavenging benefit hp production and also fuel economy! your exhaust should pay for itself in fuel saved lol! (eventually, and assuming you don't drive it everywhere faster to get the sound of the new exhaust!!)
There will be TVR exhausts that don't cost hp, but they are rare i think. For instance on the cerbera there is nothing to be gained by going up on the size of the intermediate pipes, but the S bend that goes under the diff chassis x-brace is costing 8bhp on a 400bhp car. All you need to do is replace that with larger bore and you have an instant hp increase.
A last word about mapping and hp increases.
For sure if you want the best from any mod you do, you should have it mapped to suit. however if you're adding say 15hp to a 360bhp car you've incrased the airflow by about 4% and assuming your car is in good order it should be running close to lambda 0.8 under full load, so this would reduce it to lambda 0.84 .. still well within safe limits .. however you may be able to pick up more hp by mapping the car to exactly suit the new exhaust conditions.. you would ideally want to check the car under load to make sure you were perfectly safe though. I think the number of cars now out there running these performance style back boxes suggests there isn't an issue.
however in general back pressure costs performance.
back pressure increases pumping losses, ie that hp required to physically push the remaining exhaust gas out of the chamber.
back pressure will influence what cam timing you can use, because as back pressure builds then scavenging effects from exhaust gas momentum decreases, so you wouldn't want to run a lot of overlap if there was a chance of gas reversal back into the chamber. reducing back pressure will allow you to run more overlap and make it work. This last point is the important one because you can run whatever cam you want of course, but it's effects with be influenced by the exhaust type amongst other things.
back pressure though can tame the effects of a wild cam at lower revs by improving the trapping efficiency of a cam with lots of overlap, but you would want to rduce that back pressure as revs rise and the cam starts to work properly. Some exhausts have variable valves in them for this purpose ( as well as for sound reduction on light throttle)
Momentum effects of the exhaust gas leaving the chamber and exhaust pulse tuning are the two primary ways of scavenging the chamber of all the exhaust gas, if you get it right and then you can use the scavenging effects to pull fresh charge through the chamber, if you have high inlet gas velocity you can use that momentum ram to pressure-charge the chamber. Volumetric efficiencies on some engines exceed 100% by these techniques. In effect you get a super-chargin of the chamber.
Of course on a road car these effects are less acute than on race engines say, but if you have an exhaust which is costing you hp it's likely to make the car slower (discounting our model at the very start of biasing hp to suit certain conditions) . you would need to rolling road the car before and after to make sure you had a gain over a desirable part of the rev range though, ie it's no good gaining 50bhp over the last 200rpm if everywhere else it loses 60bhp .. however if you have a gain over the part of the rev range you want to use then the car will be faster.
generally speaking, exhausts are the one area where you very often get your cake and eat it .. reduced pumping losses and better scavenging benefit hp production and also fuel economy! your exhaust should pay for itself in fuel saved lol! (eventually, and assuming you don't drive it everywhere faster to get the sound of the new exhaust!!)
There will be TVR exhausts that don't cost hp, but they are rare i think. For instance on the cerbera there is nothing to be gained by going up on the size of the intermediate pipes, but the S bend that goes under the diff chassis x-brace is costing 8bhp on a 400bhp car. All you need to do is replace that with larger bore and you have an instant hp increase.
A last word about mapping and hp increases.
For sure if you want the best from any mod you do, you should have it mapped to suit. however if you're adding say 15hp to a 360bhp car you've incrased the airflow by about 4% and assuming your car is in good order it should be running close to lambda 0.8 under full load, so this would reduce it to lambda 0.84 .. still well within safe limits .. however you may be able to pick up more hp by mapping the car to exactly suit the new exhaust conditions.. you would ideally want to check the car under load to make sure you were perfectly safe though. I think the number of cars now out there running these performance style back boxes suggests there isn't an issue.
OK Julian i will be back in a few days im just of to the library.
yi8tvr said:
Right ok Julian i'm back...
So you agree with me that opening up the exhaust costs HP (penultimate paragraph}.
How much of your very interesting reading ( i mean that) is applicable to the sp6.
Can mapping only change fuel leaness or richness.
Cheers
Mark..
So you agree with me that opening up the exhaust costs HP (penultimate paragraph}.
How much of your very interesting reading ( i mean that) is applicable to the sp6.
Can mapping only change fuel leaness or richness.
Cheers
Mark..
nope i dont agree that openig up the exhaust costs hp .. going overbore can cost you if momentum effects are reduced where they had previously beeb beneficial thogh, but unless you did back to back tests you wouldn't know.
I don't know how much of that is beneficial to SP6, I've just been told be a reliable source that geting a good system on the T350 is worth 15hp.
mapping can changea lot of things .. fuel / ignition are the basic ones but there's al sorts of paramteres you can change
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