SL55/63/65/R230 AMG: SL65 exhaust: Need advice
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I just read an old post about T/C engines and back pressure. Does anyone know if the car will loose horsepower with straight pipes instead of mufflers? I would think there would be a gain but the issue of back pressure and the physics of it seems to confuse me a bit. Any explanation would be helpful. Thanks.
Without getting extremely technical, you have nothing to worry about. What you read is more theoretical and does apply in certain applications but not in yours. PM me if you want to go into more detail.
FWIW, I have the Eisenmann on my car, and it sounds absolutely fantastic. I think you'd really enjoy them on your car, even if they are a bit pricey.
-m
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Joined: Feb 2006
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From: South Florida
2015 Mercedes-Benz CLS63 AMG S
France,
Without getting extremely technical, you have nothing to worry about. What you read is more theoretical and does apply in certain applications but not in yours. PM me if you want to go into more detail.
FWIW, I have the Eisenmann on my car, and it sounds absolutely fantastic. I think you'd really enjoy them on your car, even if they are a bit pricey.
-m
Without getting extremely technical, you have nothing to worry about. What you read is more theoretical and does apply in certain applications but not in yours. PM me if you want to go into more detail.
FWIW, I have the Eisenmann on my car, and it sounds absolutely fantastic. I think you'd really enjoy them on your car, even if they are a bit pricey.
-m
Your car looks amazing. Thanks for the reply.
I went up to Renntech today and got a detailed explanation from Hartmut (the owner). He told me essentially what you did, that it shouldn't really matter but he did say it is possible to lose a small amount of horsepower (almost un-noticable). Something about resonance, length of tubing, and resistance. He was a real gentleman and spent a lot of time just showing me around.
Renntech is in the process of making a tuned exhaust system for the 55's, 65's, and 600's. It shouldn't be too much longer so I'll just wait for their product. I have a new respect for how detailed they are at Renntech after spending a few hours with them today and I'm sure their exhaust will be very high quality.
It actually may be a mute point for me because I have the bug for a CL65 and may get rid of mine for one.
Last edited by france2112; Sep 19, 2006 at 09:33 PM.
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After having the Eisenmann on my former 600, I will be going with straight pipes on the 65. Even with the Eisenmann the car was only as loud as my current 65 is stock. I really liked the Eisenmann but it's still a bit too quiet. This may be a point of contention with others, but I want my 65 to have (please pardon the language) like IT HAS A PAIR. The truth is I cannot imagine the car getting too loud for my tastes - however if some of you guys want to stay conservative with your cars, then maybe this won't be the route.
Personally, while I like my car being somewhat of a sleeper, at the same time I don't want to fall asleep in it
I will post before and after videos/sound clips for you all. I will be having my MB tuner do the fab work (they installed my old Eisenmann system) so I'm sure it'll look great - although like it's been said we're not talking about anything too complicated.
-m
Personally, while I like my car being somewhat of a sleeper, at the same time I don't want to fall asleep in it
I will post before and after videos/sound clips for you all. I will be having my MB tuner do the fab work (they installed my old Eisenmann system) so I'm sure it'll look great - although like it's been said we're not talking about anything too complicated.
-m
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Your worst nightmare...
After having the Eisenmann on my former 600, I will be going with straight pipes on the 65. Even with the Eisenmann the car was only as loud as my current 65 is stock. I really liked the Eisenmann but it's still a bit too quiet. This may be a point of contention with others, but I want my 65 to have (please pardon the language) like IT HAS A PAIR. The truth is I cannot imagine the car getting too loud for my tastes - however if some of you guys want to stay conservative with your cars, then maybe this won't be the route.
Personally, while I like my car being somewhat of a sleeper, at the same time I don't want to fall asleep in it
I will post before and after videos/sound clips for you all. I will be having my MB tuner do the fab work (they installed my old Eisenmann system) so I'm sure it'll look great - although like it's been said we're not talking about anything too complicated.
-m
Personally, while I like my car being somewhat of a sleeper, at the same time I don't want to fall asleep in it
I will post before and after videos/sound clips for you all. I will be having my MB tuner do the fab work (they installed my old Eisenmann system) so I'm sure it'll look great - although like it's been said we're not talking about anything too complicated.
-m
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From: Houston
2005 CL65
The factory pipes are well designed, but the passenger side pipe flattens out into an oval shape just before the differential to clear the driveshaft. That's gonna be a difficult area to modify. I assume the AMG engineers have shaped that area to minimize restriction, but I agree, there are probably some gains to be made there. Do keep us posted.
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Your worst nightmare...
The factory pipes are well designed, but the passenger side pipe flattens out into an oval shape just before the differential to clear the driveshaft. That's gonna be a difficult area to modify. I assume the AMG engineers have shaped that area to minimize restriction, but I agree, there are probably some gains to be made there. Do keep us posted.
I know exactly what you are talking about, it is somewhat like a sandwich...I will see what can be made. This is a nice restriction, not to mention the mufflers as well.
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Straight pipe the mufflers
It still won't be too loud, I've heard an SL600 straight piped and I'd say it was on par with an Eisenmann E55 if not a bit more quiet. The turbos really absorb a lot of volume.
It will also cost a fraction of what Eisenmann would, 120bucks vs 3000.
It still won't be too loud, I've heard an SL600 straight piped and I'd say it was on par with an Eisenmann E55 if not a bit more quiet. The turbos really absorb a lot of volume.
It will also cost a fraction of what Eisenmann would, 120bucks vs 3000.
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From: South FL & NYC
Your worst nightmare...
Straight pipe the mufflers
It still won't be too loud, I've heard an SL600 straight piped and I'd say it was on par with an Eisenmann E55 if not a bit more quiet. The turbos really absorb a lot of volume.
It will also cost a fraction of what Eisenmann would, 120bucks vs 3000.
It still won't be too loud, I've heard an SL600 straight piped and I'd say it was on par with an Eisenmann E55 if not a bit more quiet. The turbos really absorb a lot of volume.
It will also cost a fraction of what Eisenmann would, 120bucks vs 3000.
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So wil you just be eliminating mufflers and replacing with pipes? Seems very simple. I am planning on doing this for the 65 but I want to go all the way 3 inch from H pipe to the back. I think some performace gains are to be found in doing this. Please keep me updated with what you find. Thanks!
-m
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I tried straight pipes on my S600 and it was too loud. Sounded great under WOT, but in everyday trafiic, just too much.
I ended up cutting out resonators and leaving stock mufflers alone. Just perfect.
I ended up cutting out resonators and leaving stock mufflers alone. Just perfect.
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sl65
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2003 S600, 1988 RX-7 single turbo vert, 1998 BMW 740IL
kinda scary with all the people that claim that have knowledge of boosted cars, no one has mentioned this.
When you remove mufflers and pre-mufflers you remove the resistance of your exhaust flow which will increase your boost. This raises HP but lowers TQ numbers. Your turbos will no longer have problems breathing and you will get more performance.
Downside. Is boost creep and tuning issues. Now that you have a less restrictive system you should have your car re-tuned. If the stock ecu sees your boost go above preset levels it will compensate by dumping more gas in. This fouls plugs and worse can cause "pings" if its running to lean. Pings are baddddddd.
I am new to these car engines but have destroyed several rotary motors in my rx7 from exactly what I have described above. It also has me wondering at what point these cars would require larger fuel injectors to safely run this type of power levels boosted. I also wonder who will be the first to run a alky injection systems to really cool the intake temps and make pump 93 basically race gas?
When you remove mufflers and pre-mufflers you remove the resistance of your exhaust flow which will increase your boost. This raises HP but lowers TQ numbers. Your turbos will no longer have problems breathing and you will get more performance.
Downside. Is boost creep and tuning issues. Now that you have a less restrictive system you should have your car re-tuned. If the stock ecu sees your boost go above preset levels it will compensate by dumping more gas in. This fouls plugs and worse can cause "pings" if its running to lean. Pings are baddddddd.
I am new to these car engines but have destroyed several rotary motors in my rx7 from exactly what I have described above. It also has me wondering at what point these cars would require larger fuel injectors to safely run this type of power levels boosted. I also wonder who will be the first to run a alky injection systems to really cool the intake temps and make pump 93 basically race gas?
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kinda scary with all the people that claim that have knowledge of boosted cars, no one has mentioned this.
When you remove mufflers and pre-mufflers you remove the resistance of your exhaust flow which will increase your boost. This raises HP but lowers TQ numbers. Your turbos will no longer have problems breathing and you will get more performance.
Downside. Is boost creep and tuning issues. Now that you have a less restrictive system you should have your car re-tuned. If the stock ecu sees your boost go above preset levels it will compensate by dumping more gas in. This fouls plugs and worse can cause "pings" if its running to lean. Pings are baddddddd.
When you remove mufflers and pre-mufflers you remove the resistance of your exhaust flow which will increase your boost. This raises HP but lowers TQ numbers. Your turbos will no longer have problems breathing and you will get more performance.
Downside. Is boost creep and tuning issues. Now that you have a less restrictive system you should have your car re-tuned. If the stock ecu sees your boost go above preset levels it will compensate by dumping more gas in. This fouls plugs and worse can cause "pings" if its running to lean. Pings are baddddddd.
I am new to these car engines but have destroyed several rotary motors in my rx7 from exactly what I have described above. It also has me wondering at what point these cars would require larger fuel injectors to safely run this type of power levels boosted. I also wonder who will be the first to run a alky injection systems to really cool the intake temps and make pump 93 basically race gas?
For what it's worth - my car, without mufflers, ran a 11.5 @ 121mph on 20" wheels, stock.
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2003 S600, 1988 RX-7 single turbo vert, 1998 BMW 740IL
comments were not pointed at anyone, they were general.
I do would however like to know how mercedes solved the ageold boost creep problem going up through the gears that every boosted vehicle in the world experiences. Does the stock ecu have a boost cut feature after the ecu sees x amount of boost? because there is only 2 ways to deal with it. 1 dump fuel in, which causes u to run rich, fouls plugs and you actually loose HP/TQ or holds the wastegate wide open until factory levels are back to normal which makes the car feel like it fell flat on its face.
What do these ecu's run for AFR's? What duty cycle are the injectors running at under full boost? these are all questions that I personally would like to know the answer to. I bet alot of other people who are risking there $30k engine would like to know as well.
I do would however like to know how mercedes solved the ageold boost creep problem going up through the gears that every boosted vehicle in the world experiences. Does the stock ecu have a boost cut feature after the ecu sees x amount of boost? because there is only 2 ways to deal with it. 1 dump fuel in, which causes u to run rich, fouls plugs and you actually loose HP/TQ or holds the wastegate wide open until factory levels are back to normal which makes the car feel like it fell flat on its face.
What do these ecu's run for AFR's? What duty cycle are the injectors running at under full boost? these are all questions that I personally would like to know the answer to. I bet alot of other people who are risking there $30k engine would like to know as well.
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2003 S600, 1988 RX-7 single turbo vert, 1998 BMW 740IL
"Our ECUs do not let our cars run lean from the factory, and are far more sophisticated than the ones you may be used to." My rx7 has a fully programable haltech e6x. Does'nt get a whole lot more complicated than that.
Marcus when it comes to tunning the rotary engine, our tuners have to build the most complex fuel injection maps there are. That's why there are so few in the world. Not compairing the 2 engines just merely stating that FI tuning principles are universal and when ever you are already above stock boost levels (ecu flash) and you remove resistance from the exhaust system which will make your boost levels higher you should have your AFR's checked on a dyno.
Marcus when it comes to tunning the rotary engine, our tuners have to build the most complex fuel injection maps there are. That's why there are so few in the world. Not compairing the 2 engines just merely stating that FI tuning principles are universal and when ever you are already above stock boost levels (ecu flash) and you remove resistance from the exhaust system which will make your boost levels higher you should have your AFR's checked on a dyno.
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V12-Biturbo
"Our ECUs do not let our cars run lean from the factory, and are far more sophisticated than the ones you may be used to." My rx7 has a fully programable haltech e6x. Does'nt get a whole lot more complicated than that.
Marcus when it comes to tunning the rotary engine, our tuners have to build the most complex fuel injection maps there are. That's why there are so few in the world. Not compairing the 2 engines just merely stating that FI tuning principles are universal and when ever you are already above stock boost levels (ecu flash) and you remove resistance from the exhaust system which will make your boost levels higher you should have your AFR's checked on a dyno.
Marcus when it comes to tunning the rotary engine, our tuners have to build the most complex fuel injection maps there are. That's why there are so few in the world. Not compairing the 2 engines just merely stating that FI tuning principles are universal and when ever you are already above stock boost levels (ecu flash) and you remove resistance from the exhaust system which will make your boost levels higher you should have your AFR's checked on a dyno.
Removing back pressure on these MB's equates into boost drop, not increase
Average SL600/65 AFR sits stock @ 12.2-12.5
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V12-Biturbo
& cutting off mufflers has ZERO effect on their future health. you really need to better inform yourself before posting this drivel...
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Marcus when it comes to tunning the rotary engine, our tuners have to build the most complex fuel injection maps there are. That's why there are so few in the world. Not compairing the 2 engines just merely stating that FI tuning principles are universal and when ever you are already above stock boost levels (ecu flash) and you remove resistance from the exhaust system which will make your boost levels higher you should have your AFR's checked on a dyno.
I suggest you do a bit more reading on here and about the community before you assume we are doing mods to our cars with no comprehension for the basic fundamentals of thermodynamics and forced induction. I can assure you, we have some very intelligent and experienced people on this forum who put a lot of effort into the development for the aftermarket and performance of these platforms.
-m
