Twin dump, single dump downpipe???
30 November 2001, 11:26 AM
#31
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I recently had a Magnex Twin Dump D/P fitted to my MY99 and now have a straight through Magnex system. As far as I can remember the wastegate pipe goes all the way down to the bottom of the d/p where the bend is b4 rejoining with the exhaust gases.
Not trying to say anything but with what been said above just commenting on the design. I'll be getting it RR'd in Feb so should find out then what its done.........
Not trying to say anything but with what been said above just commenting on the design. I'll be getting it RR'd in Feb so should find out then what its done.........
30 November 2001, 12:32 PM
#32
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thanks pat for that great explanation. I actually managed to stay with you all the way.
Bob appreciate those summing up comments too.
Sounds very interesting, but I am still unconvinced as changing mine to a BPM downpipe on standard ecu at least the car drastically improved.
I suppose with access to ecu mapping now, it might be a laugh to revert to the scoobysport.
Will wait to see how steve gets on first.
Bob appreciate those summing up comments too.
Sounds very interesting, but I am still unconvinced as changing mine to a BPM downpipe on standard ecu at least the car drastically improved.
I suppose with access to ecu mapping now, it might be a laugh to revert to the scoobysport.
Will wait to see how steve gets on first.
30 November 2001, 03:17 PM
#33
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I am now in scanning to other threads seeing people being put off twin dumps just because they believe boost control to be a problem.
I dont know that this is fair as apart from bob no one seems to have made any proper analysis.
Bob has also stated that he saw these effects on his car only.
Mr. Taylor, can you put up something with regard to the benfit of your experience and if mark aigin is out there perhaps you could add something here.
I am seeing people acceptingt his, btu I am not sure I am ready to admit defeat. The BPM downpipe without doubt made my car feel significantly better and caused it to run lean on the standard ecu. When it was mapped I dont recall bob mentioning any boost control problems, but then I do have an uprated actuator, but I dont know if this solves the problem.
Before the masses choose to write off twin dumps perhaps we can get some more feedback from some other mappers?
I dont know that this is fair as apart from bob no one seems to have made any proper analysis.
Bob has also stated that he saw these effects on his car only.
Mr. Taylor, can you put up something with regard to the benfit of your experience and if mark aigin is out there perhaps you could add something here.
I am seeing people acceptingt his, btu I am not sure I am ready to admit defeat. The BPM downpipe without doubt made my car feel significantly better and caused it to run lean on the standard ecu. When it was mapped I dont recall bob mentioning any boost control problems, but then I do have an uprated actuator, but I dont know if this solves the problem.
Before the masses choose to write off twin dumps perhaps we can get some more feedback from some other mappers?
30 November 2001, 04:28 PM
#36
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cullenj - had no probs with magnex on mine - its been on a month and its great, AFAIK 
- but mines a MY99 without PPP. Don't know what boost is like with it though as I don't get a gauge fitted for a couple of weeks yet.....
Edited to say that the magnex twin dump joins again down the bottom of the pipe as I thought and not up by the top, so perhaps this has a different effect......
The sound is great - you can really hear the turbo whistling away like mad!!!!!
[Edited by ScoobyJawa - 11/30/2001 4:30:45 PM]
- but mines a MY99 without PPP. Don't know what boost is like with it though as I don't get a gauge fitted for a couple of weeks yet.....Edited to say that the magnex twin dump joins again down the bottom of the pipe as I thought and not up by the top, so perhaps this has a different effect......
The sound is great - you can really hear the turbo whistling away like mad!!!!!
[Edited by ScoobyJawa - 11/30/2001 4:30:45 PM]
30 November 2001, 04:28 PM
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makes for interesting reading this. I've currently got a standard downpipe on my MY94 WRX Wagon, and I want new one, am currently thinking about either HKS or scoobymania twin dump. Main reasons being that the N1 system I have is 3" and these should mate up nicely to this, plus the twin dump sounds like fun 
30 November 2001, 04:41 PM
#38
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Carl
That must be a wind up......
I think theres a few of us that will be in excess of that territory on standard internals over the next 6 months - of course its torque that counts though!
That must be a wind up......
I think theres a few of us that will be in excess of that territory on standard internals over the next 6 months - of course its torque that counts though!
30 November 2001, 05:26 PM
#39
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cullen, dont be put off. We are talking finite difference here. And people looking for something to blame because their power was not as good as they hoped.
Saying that I am considering a back to back comparison with scoobysport 3 inch.
Markus if you are in the market for a 3 inch downpipe, I may have my BPM up for grabs. Do not buy the HKS as I have said before, its blanking of the wastegate removed most of the benefit of changing.
Remember that the BPM is mild steel and as such is significantly quietre than stainless steel equivalents.
Saying that I am considering a back to back comparison with scoobysport 3 inch.
Markus if you are in the market for a 3 inch downpipe, I may have my BPM up for grabs. Do not buy the HKS as I have said before, its blanking of the wastegate removed most of the benefit of changing.
Remember that the BPM is mild steel and as such is significantly quietre than stainless steel equivalents.
30 November 2001, 07:02 PM
#40
Gents, put whatever takes your fancy onto your car, it is your car after all.
Adam whilst all my testing has been done using my car (well it would wouldn't it) I can safely say I have come across a large number of different combinations of down pipe and exhaust. Some seem good, some seem not so good, I can spot the ones that are not so good these days.
No one should start getting paranoid about which downpipe they have fitted, if you have a twin dump and you are happy then whats the problem, and vice versa.
I pass on the benefits (I hope) of my experience when asked thats all. If anyone else has done the sort of testing I have then I look forward to hearing about the results, if they found to the contrary then the reasons why etc are of great interest. If, however, a claim is based on theory then that's not so good I'm sure everyone would agree.
The performance of a car is not totally controled by its exhaust.
Regarding comparisons then David T is a good point of reference having just switched over,Steve has a 2 1/2 inch system from the bottom of the downpipe back currently, once he changes (assuming his clutch is fixed first) and the maps are adjusted then he will be another good comparison. And Steve will tell you if he's unhappy. The best comparison for any individual is that individuals view though.
As you say, mild steel has a different resonance to stainless but its not "quieter" in the sense that some might think, the full 3" open neck pipe is similar in note.
Adam whilst all my testing has been done using my car (well it would wouldn't it) I can safely say I have come across a large number of different combinations of down pipe and exhaust. Some seem good, some seem not so good, I can spot the ones that are not so good these days.
No one should start getting paranoid about which downpipe they have fitted, if you have a twin dump and you are happy then whats the problem, and vice versa.
I pass on the benefits (I hope) of my experience when asked thats all. If anyone else has done the sort of testing I have then I look forward to hearing about the results, if they found to the contrary then the reasons why etc are of great interest. If, however, a claim is based on theory then that's not so good I'm sure everyone would agree.
The performance of a car is not totally controled by its exhaust.
Regarding comparisons then David T is a good point of reference having just switched over,Steve has a 2 1/2 inch system from the bottom of the downpipe back currently, once he changes (assuming his clutch is fixed first) and the maps are adjusted then he will be another good comparison. And Steve will tell you if he's unhappy. The best comparison for any individual is that individuals view though.
As you say, mild steel has a different resonance to stainless but its not "quieter" in the sense that some might think, the full 3" open neck pipe is similar in note.
30 November 2001, 08:33 PM
#41
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Originally posted by steve McCulloch:
Where's the wind up? I'm willing to bet that over the next six months there are more people on here with less than 350bhp than there are with 350bhp or more. I reckon someone with a PPP considering a Magnex twin-dump downpipe probably isn't interested in chasing 350bhp at this time
That must be a wind up......
I think theres a few of us that will be in excess of that territory on standard internals over the next 6 months - of course its torque that counts though!
I think theres a few of us that will be in excess of that territory on standard internals over the next 6 months - of course its torque that counts though!
01 December 2001, 08:00 AM
#43
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Well this is an interesting thread!
My comments from changing my downpipe recently is as below.
I had a BPM twin-dump on the car which was good, no question, also with an HKS Hiper and gasflowed headers it seemed to be the optimium way forward.
An input from another source nagged at my mind that maybe there was something in the Scoobysport story.
So I have now fitted a 3in S/S special which gives me a straight through (ish) 3in system.
Does it work - well yes, but it ain't perfect.
Good things
Masses more torque, not in peak, but in 'under the graph' car comes on boost very early, which is great on the road and on track as proven yesterday
Power is good, my highest ever R/R figure of 346bhp (BTW Pete, Bob's officially recorded best at PE was 'only' 343bhp according to Dynomite)
So it is a good thing
Bad Things
Much noisier - up 5db - with an literally an edge - I reckon it is the shape of the collector with a very significant lip on it
Less boost - car reluctant to control boost over 1.4bar - this is interesting as it is counter to experience reported above - maybe I need to relearn this, but the BPM enabled me to control boost up over 1.4bar on the occasions this was necessary
Overall, I want the sound level of the BPM, torque of the S/S and the boost control back to where I was
Not asking for much.
Trout (aka David T/Rannoch)
My comments from changing my downpipe recently is as below.
I had a BPM twin-dump on the car which was good, no question, also with an HKS Hiper and gasflowed headers it seemed to be the optimium way forward.
An input from another source nagged at my mind that maybe there was something in the Scoobysport story.
So I have now fitted a 3in S/S special which gives me a straight through (ish) 3in system.
Does it work - well yes, but it ain't perfect.
Good things
Masses more torque, not in peak, but in 'under the graph' car comes on boost very early, which is great on the road and on track as proven yesterday
Power is good, my highest ever R/R figure of 346bhp (BTW Pete, Bob's officially recorded best at PE was 'only' 343bhp according to Dynomite
)So it is a good thing
Bad Things
Much noisier - up 5db - with an literally an edge - I reckon it is the shape of the collector with a very significant lip on it
Less boost - car reluctant to control boost over 1.4bar - this is interesting as it is counter to experience reported above - maybe I need to relearn this, but the BPM enabled me to control boost up over 1.4bar on the occasions this was necessary
Overall, I want the sound level of the BPM, torque of the S/S and the boost control back to where I was
Not asking for much.
Trout (aka David T/Rannoch)
03 December 2001, 08:05 AM
#44
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Over here in Australia some guys are getting excellent results with custom modified HiTech dump pipes. I can't comment from experience yet (I will be getting mine done shortly) but guys who have it are getting better bottom end response and more top end. Even better than the more expensive offerings.
If you are keen perhaps you should investigate.
If you are keen perhaps you should investigate.
03 December 2001, 02:04 PM
#45
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This is a very heavy thread....
I have read it all, I can summarise:.....
Basicaly, the mangex single dump is the best downpipe in the world.....ever!
I just so happens that I have one up for grabs in the Private section....
Seriously, this weekend, a couple of very resourceful and helpful chappies fitted a BPM twin dump DP to my MY95 WRX. I was previously running a single dump (blanked wastegate) Magnex DP.
I have not yet had a chance to give the car a good spanking (had the missus with me on every run since the install), however, I have noticed a change in boost.....
On the way back from having the DP fitted, on the motorway, about 100 or so, foot down, boosted to 18psi then dropped to 14 and started to build up? I have never seen this before? The ECU then cut the boost and almost shoved me through the windscreen!
During the couple of small runs I have had since, the car does not appear to be producing as much boost as it did with the Magnex in place....? With the Magnex, it was boosting to 16/17psi the holding at 14. Now with the BPM it is boosting to 15/16 psi and holding at about 13.... the car does not feel any slower....
Anyone had an experience like this?
I am sure the DP is not leaking at the turbo (arnt we David !)
Cheers
Paul (Actualy I think I will start a new thread with this too
)
I have read it all, I can summarise:.....
Basicaly, the mangex single dump is the best downpipe in the world.....ever!
I just so happens that I have one up for grabs in the Private section....
Seriously, this weekend, a couple of very resourceful and helpful chappies fitted a BPM twin dump DP to my MY95 WRX. I was previously running a single dump (blanked wastegate) Magnex DP.
I have not yet had a chance to give the car a good spanking (had the missus with me on every run since the install), however, I have noticed a change in boost.....
On the way back from having the DP fitted, on the motorway, about 100 or so, foot down, boosted to 18psi then dropped to 14 and started to build up? I have never seen this before? The ECU then cut the boost and almost shoved me through the windscreen!
During the couple of small runs I have had since, the car does not appear to be producing as much boost as it did with the Magnex in place....? With the Magnex, it was boosting to 16/17psi the holding at 14. Now with the BPM it is boosting to 15/16 psi and holding at about 13.... the car does not feel any slower....
Anyone had an experience like this?
I am sure the DP is not leaking at the turbo (arnt we David
!)Cheers
Paul (Actualy I think I will start a new thread with this too
)
03 December 2001, 08:22 PM
#46
Paul, the BPM caught your ecu out, its characteristics squeeze the gas flow and the wastegate does get restricted somewhat as it opens. the ecu has reacted to that, if you do an ecu reset and then progressively build boost again it may end up as before ... possibly. Get your fueling checked though as it may be sending things leaner wrt the Magnex.
David ... still waiting to get on the rollers now I don't have my standard intercooler anymore ...
David ... still waiting to get on the rollers now I don't have my standard intercooler anymore ...
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