Decatting the E36 M3 EVO
Discussion
I have done some of the available power upgrades (apart from carbon box and cams) and suspension (coilovers, polybushes, x-brace, stiffer arb's) and brake upgrades (4pot ap bbk) and am now looking for a de-cat to compliment the eisenmann sport backbox.
I have heard that on the e30 m3 deleting the stock x-pipe midsection looses 15 bhp so in theory adding one to an e36 m3 will gain a bit of power and loose a bit of weight?
I am looking at supersprints offerings:
The car is a currently a road car (not stripped) and has done 4 trackdays so far this year (and many more to come hopefully)
I notice that the slightly cheaper black one buldges out a bit, does this mean it is resonated and less raspy for road use compared to the all metal racing version? Which one would you recommend?
I have heard that on the e30 m3 deleting the stock x-pipe midsection looses 15 bhp so in theory adding one to an e36 m3 will gain a bit of power and loose a bit of weight?
I am looking at supersprints offerings:
The car is a currently a road car (not stripped) and has done 4 trackdays so far this year (and many more to come hopefully)
I notice that the slightly cheaper black one buldges out a bit, does this mean it is resonated and less raspy for road use compared to the all metal racing version? Which one would you recommend?
Don't know about the sound as mine still hasn't arrived, but my understanding is that fitting the decat can create a bit of a flat spot that'll need to be mapped out.
Look at the performance increase from the weight loss rather than an outright power gain.
And yes, my expectation is that it'll sound nice and raspy.
Look at the performance increase from the weight loss rather than an outright power gain.
And yes, my expectation is that it'll sound nice and raspy.
What sort of weight saving are you talking about, 10kg? You won't notice that.
I am also thinking about one of these for the future, but don't want to lose the deep grunt from my Blueflame exhaust, not a fan of the raspy noise.
Think I'll speak to Miltek about their sports cats or get a custome set made up.
I am also thinking about one of these for the future, but don't want to lose the deep grunt from my Blueflame exhaust, not a fan of the raspy noise.
Think I'll speak to Miltek about their sports cats or get a custome set made up.
I have had a supersprint de-cat pipe and supersprint full system. The decat pipe will give you a flat spot in the middle of the rev if I recall 2250-3750 rpm. I now run 100cell cats (supplied by Prospeed) and the car is much smoother. Also worth noting when I swapped to the full Prospeed setup i.e. system and cats I got a little more power as well. Sounds awesome as well!!
I have cams and airbox etc and also found with the decat I got the most horrendous fumes from the back of the car!! Had to polish my bumper very frequently to get the fume staining off!! May not be so bad with a more standard engine but better to be aware.
Good luck!!
I have cams and airbox etc and also found with the decat I got the most horrendous fumes from the back of the car!! Had to polish my bumper very frequently to get the fume staining off!! May not be so bad with a more standard engine but better to be aware.
Good luck!!
zmrjason said:
I have had a supersprint de-cat pipe and supersprint full system. The decat pipe will give you a flat spot in the middle of the rev if I recall 2250-3750 rpm. I now run 100cell cats (supplied by Prospeed) and the car is much smoother. Also worth noting when I swapped to the full Prospeed setup i.e. system and cats I got a little more power as well. Sounds awesome as well!!
I have cams and airbox etc and also found with the decat I got the most horrendous fumes from the back of the car!! Had to polish my bumper very frequently to get the fume staining off!! May not be so bad with a more standard engine but better to be aware.
Good luck!!
Do you mind me asking how much you paid for the prospped cats? Are they custom made on your car or an off the shelf kit? Again, any idea on weight saving figures?I have cams and airbox etc and also found with the decat I got the most horrendous fumes from the back of the car!! Had to polish my bumper very frequently to get the fume staining off!! May not be so bad with a more standard engine but better to be aware.
Good luck!!
scz4, I paid £850 is for full system and 100cell cats made to suit and fitted piece by piece over the course of a full day. They look similar to oem but bigger 83mm tailpipes. They sound very good as well!
With regards weight I have no idea but they are obviously lighter. Sadly I cant comment about the x pipe, but we spent a lot of time trying to alter the mapping to loose the flat spot and could not. It was completely down to the decat pipe and it went straight away with sport cats. No brainer IMO, also road legal and dont stink of fumes!
EDIT: With reference to the 2 linked Supersprint options, I had the first of the 2 Supersprint decat options. I now have a system with 2 seperate pipes running to each back box, no balancer/X pipe.
With regards weight I have no idea but they are obviously lighter. Sadly I cant comment about the x pipe, but we spent a lot of time trying to alter the mapping to loose the flat spot and could not. It was completely down to the decat pipe and it went straight away with sport cats. No brainer IMO, also road legal and dont stink of fumes!
EDIT: With reference to the 2 linked Supersprint options, I had the first of the 2 Supersprint decat options. I now have a system with 2 seperate pipes running to each back box, no balancer/X pipe.
Edited by zmrjason on Monday 22 June 22:08
The reason for an X pipe is to transfer the pulses in a tuned system.
After each bang, there is a brief lull which if timed correctly, can be used to help suck the gasses out of a neighbouring cylinder.
If you hold a lighter to a tailpipe at idle, you'll see the flame doesn't get blown back, or swap between standing, and blown back, but actually flicks into and out of the exhaust.
It's that low pressure pulse you are trying to utilise.
The e30 M3 is a 4cyl compared to the 6cyl e36 m3, and the e36 was designed with 2 separate tubes all the way to the backbox. There is tuning done with the fancy manifolds, so anything else is likely to upset the balance, or need some very clever maths to it.
There is every chance the addition of an X pipe will cause a tuning effect at certain revs, and increase BHP, but at another point, create this flatspot that has been felt.
The fact that people always look at peak BHP figures (which in most cases are at about the redline, and rarely utilised) means that at lot of tuners need to go for a headline figure of, say, +10bhp at peak, when +5bhp over the complete rev range would be of more use, as the +10bhp exhaust will sell, and the +5 one won't.
If in the above case, there wasn't an x-pipe, but there was a loss of mid torque after adding a de-cat, it won't be due to backpressure. Backpressure is always a hinderance, but what people often mistake as a backpressure problem is due to messing up the tuning.
This could suggest that the cats themselves act as a part of the tuned resonance, and it that is the case, a gutted cat might avoid the problem.
After each bang, there is a brief lull which if timed correctly, can be used to help suck the gasses out of a neighbouring cylinder.
If you hold a lighter to a tailpipe at idle, you'll see the flame doesn't get blown back, or swap between standing, and blown back, but actually flicks into and out of the exhaust.
It's that low pressure pulse you are trying to utilise.
The e30 M3 is a 4cyl compared to the 6cyl e36 m3, and the e36 was designed with 2 separate tubes all the way to the backbox. There is tuning done with the fancy manifolds, so anything else is likely to upset the balance, or need some very clever maths to it.
There is every chance the addition of an X pipe will cause a tuning effect at certain revs, and increase BHP, but at another point, create this flatspot that has been felt.
The fact that people always look at peak BHP figures (which in most cases are at about the redline, and rarely utilised) means that at lot of tuners need to go for a headline figure of, say, +10bhp at peak, when +5bhp over the complete rev range would be of more use, as the +10bhp exhaust will sell, and the +5 one won't.
If in the above case, there wasn't an x-pipe, but there was a loss of mid torque after adding a de-cat, it won't be due to backpressure. Backpressure is always a hinderance, but what people often mistake as a backpressure problem is due to messing up the tuning.
This could suggest that the cats themselves act as a part of the tuned resonance, and it that is the case, a gutted cat might avoid the problem.
TheEnd said:
The reason for an X pipe is to transfer the pulses in a tuned system.
After each bang, there is a brief lull which if timed correctly, can be used to help suck the gasses out of a neighbouring cylinder.
If you hold a lighter to a tailpipe at idle, you'll see the flame doesn't get blown back, or swap between standing, and blown back, but actually flicks into and out of the exhaust.
It's that low pressure pulse you are trying to utilise.
The e30 M3 is a 4cyl compared to the 6cyl e36 m3, and the e36 was designed with 2 separate tubes all the way to the backbox. There is tuning done with the fancy manifolds, so anything else is likely to upset the balance, or need some very clever maths to it.
There is every chance the addition of an X pipe will cause a tuning effect at certain revs, and increase BHP, but at another point, create this flatspot that has been felt.
The fact that people always look at peak BHP figures (which in most cases are at about the redline, and rarely utilised) means that at lot of tuners need to go for a headline figure of, say, +10bhp at peak, when +5bhp over the complete rev range would be of more use, as the +10bhp exhaust will sell, and the +5 one won't.
If in the above case, there wasn't an x-pipe, but there was a loss of mid torque after adding a de-cat, it won't be due to backpressure. Backpressure is always a hinderance, but what people often mistake as a backpressure problem is due to messing up the tuning.
This could suggest that the cats themselves act as a part of the tuned resonance, and it that is the case, a gutted cat might avoid the problem.
I will be saving my money for a lightweight flywheel instead, thanks.After each bang, there is a brief lull which if timed correctly, can be used to help suck the gasses out of a neighbouring cylinder.
If you hold a lighter to a tailpipe at idle, you'll see the flame doesn't get blown back, or swap between standing, and blown back, but actually flicks into and out of the exhaust.
It's that low pressure pulse you are trying to utilise.
The e30 M3 is a 4cyl compared to the 6cyl e36 m3, and the e36 was designed with 2 separate tubes all the way to the backbox. There is tuning done with the fancy manifolds, so anything else is likely to upset the balance, or need some very clever maths to it.
There is every chance the addition of an X pipe will cause a tuning effect at certain revs, and increase BHP, but at another point, create this flatspot that has been felt.
The fact that people always look at peak BHP figures (which in most cases are at about the redline, and rarely utilised) means that at lot of tuners need to go for a headline figure of, say, +10bhp at peak, when +5bhp over the complete rev range would be of more use, as the +10bhp exhaust will sell, and the +5 one won't.
If in the above case, there wasn't an x-pipe, but there was a loss of mid torque after adding a de-cat, it won't be due to backpressure. Backpressure is always a hinderance, but what people often mistake as a backpressure problem is due to messing up the tuning.
This could suggest that the cats themselves act as a part of the tuned resonance, and it that is the case, a gutted cat might avoid the problem.
TheEnd said:
Lots of useful info
Great post, thanks for that.Speaking personally, I'm not too worried about low-end torque. I'll be doing other mods to the car that will affect that anyway (lumpy cams, de-vanos), but the weight saving of the decat pipe along with a race-spec backbox will help, and as much as anything I just want a bit more noise from it
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