355 Exhaust system
Discussion
Hi there folks, looking to pick your collective brains on something.
I'm looking at purchasing an F355 exhaust for my current project and have read about the way in which the exhaust works with the bypass valve above 4000rpm's.
Just a couple of questions :
How is the valve operated, is it electronically from an ECU or does it work off back pressure?
If you were to only use the lower 2 inlets and block off the 3rd upper inlet would the exhaust run in the "below 4,000rpm mode" constantly? This is assuming no other inputs, other than the exhaust gas pressure.
The engine only revs to 7,000rpm so i can't imagine running in the lower rpm mode will hurt the performance too much, or is it very restricted?
Would it be possible to run it permanently in the higher rpm mode if i were to solely use the 3rd upper intake and block off the 2 lower intakes?
Thank you in advance for your help,
Olie
I'm looking at purchasing an F355 exhaust for my current project and have read about the way in which the exhaust works with the bypass valve above 4000rpm's.
Just a couple of questions :
How is the valve operated, is it electronically from an ECU or does it work off back pressure?
If you were to only use the lower 2 inlets and block off the 3rd upper inlet would the exhaust run in the "below 4,000rpm mode" constantly? This is assuming no other inputs, other than the exhaust gas pressure.
The engine only revs to 7,000rpm so i can't imagine running in the lower rpm mode will hurt the performance too much, or is it very restricted?
Would it be possible to run it permanently in the higher rpm mode if i were to solely use the 3rd upper intake and block off the 2 lower intakes?
Thank you in advance for your help,
Olie
Bit of an odd question. Personally, I can't see any reason you'd want to block off exhaust exits....
Anyhow, the valve is operated by a vacuum actuator which in turn is controlled by solenoid.
The engine revs to 8,500. Blocking off the upper outlet shwould not affect lower rpm running running per se, except that restriction in gas flow will strangle the engine and likely cause damage due to heat / gas build up as the revs rise, and you won't get any noise.
As for blocking off the lower outlets, this will cause (at the very least) a Cat ECU error I should think.
Anyhow, the valve is operated by a vacuum actuator which in turn is controlled by solenoid.
The engine revs to 8,500. Blocking off the upper outlet shwould not affect lower rpm running running per se, except that restriction in gas flow will strangle the engine and likely cause damage due to heat / gas build up as the revs rise, and you won't get any noise.
As for blocking off the lower outlets, this will cause (at the very least) a Cat ECU error I should think.
OlberJ said:
Hi there folks, looking to pick your collective brains on something.
I'm looking at purchasing an F355 exhaust for my current project and have read about the way in which the exhaust works with the bypass valve above 4000rpm's.
Just a couple of questions :
How is the valve operated, is it electronically from an ECU or does it work off back pressure?
If you were to only use the lower 2 inlets and block off the 3rd upper inlet would the exhaust run in the "below 4,000rpm mode" constantly? This is assuming no other inputs, other than the exhaust gas pressure.
The engine only revs to 7,000rpm so i can't imagine running in the lower rpm mode will hurt the performance too much, or is it very restricted?
Would it be possible to run it permanently in the higher rpm mode if i were to solely use the 3rd upper intake and block off the 2 lower intakes?
Thank you in advance for your help,
Olie
the valve works by vacuum which is controlled by an electronic soleniod which is ultimately controlled by the main ECU, it opens at 2.5k in all gears except 3rd where it opens at 4.5kI'm looking at purchasing an F355 exhaust for my current project and have read about the way in which the exhaust works with the bypass valve above 4000rpm's.
Just a couple of questions :
How is the valve operated, is it electronically from an ECU or does it work off back pressure?
If you were to only use the lower 2 inlets and block off the 3rd upper inlet would the exhaust run in the "below 4,000rpm mode" constantly? This is assuming no other inputs, other than the exhaust gas pressure.
The engine only revs to 7,000rpm so i can't imagine running in the lower rpm mode will hurt the performance too much, or is it very restricted?
Would it be possible to run it permanently in the higher rpm mode if i were to solely use the 3rd upper intake and block off the 2 lower intakes?
Thank you in advance for your help,
Olie
F355GTS said:
the valve works by vacuum which is controlled by an electronic soleniod which is ultimately controlled by the main ECU, it opens at 2.5k in all gears except 3rd where it opens at 4.5k
MarkAny idea why its 4.5k in third?
Also, did you fit that switch to allow manual opening of the valve?
Thank you very much for the answers.
Indeed it's not for an F355 engine. It is for an Mr2, funnily enough, definitely not a replica though. It's a roadster with a 3.0 V6 and standard bodywork.
What i'm considering is, will the "valve shut" flow for the V8 be enough to let a 3.0 V6 sing it's little heart out or will it choke it at higher rpm too. I guess it's a case of suck it and see. Or rather blow.
On the engine it has already a vsv which operates a flap inside the inlet plenum which has a similar effect on low end torque. That comes on song around 4.4K rpm. I guess i could utilise that and plumb the bypass in too, although space is at a premium.
I'm tempted to give it a go on the "valve shut" setting and see how it performs with the bypass inlet covered. I'm a sucker for the way these things sound and i'm constantly trying to make them sound even better, hopefully the F355 exhaust will give me the sound i'm looking for.
Thank you again and i'll post up a video when it's all done.
Indeed it's not for an F355 engine. It is for an Mr2, funnily enough, definitely not a replica though. It's a roadster with a 3.0 V6 and standard bodywork.
What i'm considering is, will the "valve shut" flow for the V8 be enough to let a 3.0 V6 sing it's little heart out or will it choke it at higher rpm too. I guess it's a case of suck it and see. Or rather blow.
On the engine it has already a vsv which operates a flap inside the inlet plenum which has a similar effect on low end torque. That comes on song around 4.4K rpm. I guess i could utilise that and plumb the bypass in too, although space is at a premium.
I'm tempted to give it a go on the "valve shut" setting and see how it performs with the bypass inlet covered. I'm a sucker for the way these things sound and i'm constantly trying to make them sound even better, hopefully the F355 exhaust will give me the sound i'm looking for.
Thank you again and i'll post up a video when it's all done.
Cactussed said:
F355GTS said:
the valve works by vacuum which is controlled by an electronic soleniod which is ultimately controlled by the main ECU, it opens at 2.5k in all gears except 3rd where it opens at 4.5k
MarkAny idea why its 4.5k in third?
Also, did you fit that switch to allow manual opening of the valve?
and yes, switch fitted, works a treat
if you want to fit one, one day, give me a shout 
Edited by F355GTS on Thursday 15th October 17:04
In that case, ditch the 355 exhaust idea. I highly doubt it will sound any good (its quite average on a 355 to be honest).
I'd be tempted to stick in a decent muffler and simply run a branch off before it with a butterlfy valve with vacuum actuation off the TVIS, then plum the exhaust back in after the muffler.
It'll give you the dual sound setup like the Ferrari with a lot more room to play IMHO...
I'd be tempted to stick in a decent muffler and simply run a branch off before it with a butterlfy valve with vacuum actuation off the TVIS, then plum the exhaust back in after the muffler.
It'll give you the dual sound setup like the Ferrari with a lot more room to play IMHO...
OlberJ said:
Thank you very much for the answers.
Indeed it's not for an F355 engine. It is for an Mr2, funnily enough, definitely not a replica though. It's a roadster with a 3.0 V6 and standard bodywork.
What i'm considering is, will the "valve shut" flow for the V8 be enough to let a 3.0 V6 sing it's little heart out or will it choke it at higher rpm too. I guess it's a case of suck it and see. Or rather blow.
On the engine it has already a vsv which operates a flap inside the inlet plenum which has a similar effect on low end torque. That comes on song around 4.4K rpm. I guess i could utilise that and plumb the bypass in too, although space is at a premium.
I'm tempted to give it a go on the "valve shut" setting and see how it performs with the bypass inlet covered. I'm a sucker for the way these things sound and i'm constantly trying to make them sound even better, hopefully the F355 exhaust will give me the sound i'm looking for.
Thank you again and i'll post up a video when it's all done.
Fair play!. That sounds a much more interesting project than all the 355 wanna be MR2's I keep seeing. Hope you get it sorted and it works out well. Indeed it's not for an F355 engine. It is for an Mr2, funnily enough, definitely not a replica though. It's a roadster with a 3.0 V6 and standard bodywork.
What i'm considering is, will the "valve shut" flow for the V8 be enough to let a 3.0 V6 sing it's little heart out or will it choke it at higher rpm too. I guess it's a case of suck it and see. Or rather blow.
On the engine it has already a vsv which operates a flap inside the inlet plenum which has a similar effect on low end torque. That comes on song around 4.4K rpm. I guess i could utilise that and plumb the bypass in too, although space is at a premium.
I'm tempted to give it a go on the "valve shut" setting and see how it performs with the bypass inlet covered. I'm a sucker for the way these things sound and i'm constantly trying to make them sound even better, hopefully the F355 exhaust will give me the sound i'm looking for.
Thank you again and i'll post up a video when it's all done.
Cactussed said:
In that case, ditch the 355 exhaust idea. I highly doubt it will sound any good (its quite average on a 355 to be honest).
I'd be tempted to stick in a decent muffler and simply run a branch off before it with a butterlfy valve with vacuum actuation off the TVIS, then plum the exhaust back in after the muffler.
It'll give you the dual sound setup like the Ferrari with a lot more room to play IMHO...
I see what you're saying, replicate the F355 idea on the Mr2 system.I'd be tempted to stick in a decent muffler and simply run a branch off before it with a butterlfy valve with vacuum actuation off the TVIS, then plum the exhaust back in after the muffler.
It'll give you the dual sound setup like the Ferrari with a lot more room to play IMHO...
That's an idea but i'm flowing 3.0 worth of air through the system rather than the original 1.8 the standard systems are designed for.
Having the 2 downpipes run right out to the box and not have to "y-merge" would be beneficial to the sound i think.
I'm not trying to replicate the dual sound, purely to have that raw, almost tinny howl that you seem to get from certain Ferrari exhaust notes. I know it's 2 cylinders and quite a few revs short but they can sound good.
The closest we've got to it so far, IMHO is this :
http://www.youtube.com/watch?v=pAVYM7Fwx5Y
It's a Skytune exhaust system, sepcifically for the Mk2. Unfortunately these don't really fit the Mk3 without major modification so if i'm in for a penny...
Ah, OK.
I used to own an MR2 turbo so have some recollection of the layout (having done 2 turbo and exhaust swaps etc). The problem you're likely to run into (I think) with the 355 system is that the muffler is flat but tall and designed to fit into the space where the MR2 boot resides. I would therefore think that unless you sacrifice the boot (or part of it), you're going to run into space issues just fitting it in there.
Secondly, the lower pipes on the 355 muffler are only designed for low speed running and choke the car at high rpm unless the bypass valve opes, allowing flow into the upper chambers so I expect that even with V6 (which is only 500cc short of the 355) you're going to run into flow restrictions using only the lower entry pipes.
Just a thought, but have you had a look at an E46 M3 muffler, as I imagine from memory they are nearly the ideal shape to fit under the MR2 exhaust bay and have twin entry (avoids merging the pipes) and 4 exit layout. Loads for sale on Ebay...
Just a thought.
I used to own an MR2 turbo so have some recollection of the layout (having done 2 turbo and exhaust swaps etc). The problem you're likely to run into (I think) with the 355 system is that the muffler is flat but tall and designed to fit into the space where the MR2 boot resides. I would therefore think that unless you sacrifice the boot (or part of it), you're going to run into space issues just fitting it in there.
Secondly, the lower pipes on the 355 muffler are only designed for low speed running and choke the car at high rpm unless the bypass valve opes, allowing flow into the upper chambers so I expect that even with V6 (which is only 500cc short of the 355) you're going to run into flow restrictions using only the lower entry pipes.
Just a thought, but have you had a look at an E46 M3 muffler, as I imagine from memory they are nearly the ideal shape to fit under the MR2 exhaust bay and have twin entry (avoids merging the pipes) and 4 exit layout. Loads for sale on Ebay...
Just a thought.
Cactussed said:
Ah, OK.
I used to own an MR2 turbo so have some recollection of the layout (having done 2 turbo and exhaust swaps etc). The problem you're likely to run into (I think) with the 355 system is that the muffler is flat but tall and designed to fit into the space where the MR2 boot resides. I would therefore think that unless you sacrifice the boot (or part of it), you're going to run into space issues just fitting it in there.
Secondly, the lower pipes on the 355 muffler are only designed for low speed running and choke the car at high rpm unless the bypass valve opes, allowing flow into the upper chambers so I expect that even with V6 (which is only 500cc short of the 355) you're going to run into flow restrictions using only the lower entry pipes.
Just a thought, but have you had a look at an E46 M3 muffler, as I imagine from memory they are nearly the ideal shape to fit under the MR2 exhaust bay and have twin entry (avoids merging the pipes) and 4 exit layout. Loads for sale on Ebay...
Just a thought.
It's an Mr2 roadster, or Mk3 rather so the exhaust sits like :I used to own an MR2 turbo so have some recollection of the layout (having done 2 turbo and exhaust swaps etc). The problem you're likely to run into (I think) with the 355 system is that the muffler is flat but tall and designed to fit into the space where the MR2 boot resides. I would therefore think that unless you sacrifice the boot (or part of it), you're going to run into space issues just fitting it in there.
Secondly, the lower pipes on the 355 muffler are only designed for low speed running and choke the car at high rpm unless the bypass valve opes, allowing flow into the upper chambers so I expect that even with V6 (which is only 500cc short of the 355) you're going to run into flow restrictions using only the lower entry pipes.
Just a thought, but have you had a look at an E46 M3 muffler, as I imagine from memory they are nearly the ideal shape to fit under the MR2 exhaust bay and have twin entry (avoids merging the pipes) and 4 exit layout. Loads for sale on Ebay...
Just a thought.
Hence why i was looking at the 355 exhaust.
After looking at it last night though the issue may be that the inlets for the 355 exhaust are in line with the subframe, which would mean i would have to Y-merge the 2 downpipes and have them feed into the top "high rev" bypass inlet. This i guess isn't ideal.
I'll keep searching and see if i can find another suitable back box, unless anyone has any good suggestions for me to try out?
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