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Discussion Starter #1
Anyone knows the function of Performance Exhaust to the engine or any other effect to the mechanical? I really don't care about the sound. I like more quiet engine because I hear the noisy in the lab everyday.
 

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Anyone knows the function of Performance Exhaust to the engine or any other effect to the mechanical? I really don't care about the sound. I like more quiet engine because I hear the noisy in the lab everyday.
A performance exhaust is always going to be louder because the only way to really increase hp though the exhaust is to decrease unnecessary back pressure which, therefore, inherently increases noise. I don't think MB is advertising any performance/hp gains from the upgrade. I believe the major difference is aural. If you don't want a louder car then don't opt for the upgraded exhaust.

-Eric
 

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Thank you Eric. You are right. For the engine like M133, decrease the back pressure of turbine will increase the compression ratio which means the pressure in the cylinder will be also increased. This may be dangerous. I don't think MB will do this. I have another question that how this engine works in high temperature condition like the temp in California? Any experiment about it?
 

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My guess is that the change in back pressure isn't that great and that the AMG engineers are comfortable with its effects. Remember, MB isn't a bunch of 16 y.o. kids with too much money, too much time and not enough skill to start playing with an engine. I don't think they want to start replacing engines any more than we want them replaced. They have a vested interest in making sure the cars are reliable when they reach the streets.

Also, just like every modern car the CLA went through countless hours of extreme hot and cold weather testing. I wouldn't be too concerned about the effects of CA heat on the engine, turbo, etc. It's certainly possible that there's an undiscovered long term problem just like with any new engine but my guess is that if something does come to light it won't be linked to external temperatures.

-Eric
 

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My guess is that the change in back pressure isn't that great and that the AMG engineers are comfortable with its effects. Remember, MB isn't a bunch of 16 y.o. kids with too much money, too much time and not enough skill to start playing with an engine. I don't think they want to start replacing engines any more than we want them replaced. They have a vested interest in making sure the cars are reliable when they reach the streets.

Also, just like every modern car the CLA went through countless hours of extreme hot and cold weather testing. I wouldn't be too concerned about the effects of CA heat on the engine, turbo, etc. It's certainly possible that there's an undiscovered long term problem just like with any new engine but my guess is that if something does come to light it won't be linked to external temperatures.

-Eric
Of course, MB is professional, I know that. I don't need to concerned about the reliable or even the undiscovered long term problem. These won't be the problems of mordern tech, especially for the MB. What am I thinking is how much hp left in 100F and the compression efficiency of the compresser in 100F. I work with the jet engine and I konw the temp will be a big problem for jet thrust, but I am not sure with the interal combustion engine. My friend had tested some auto engine with turbo, the temp seems to be a problem also. MB gives us the hp of the engine, but they doesn't show the engine gives the power in what condition.
 

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Turbos don't like heat. My guess is that the CLA's engine is going to feel materially different in 100F versus 70F weather regardless of the exhaust upgrade. A car in Denver is going to be noticeably quicker than the same car in Phoenix in the Summer. Anyone looking to abate the symptoms of heat soak will want to look into a water injection system. I'm not aware of any car company who discloses hp variances based on climate conditions. Hp/tq are determined at optimal operating temperatures.

-Eric
 

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Zhchmx are you seeking to find hp and compression loss in 100f temps in normal daily driving or are you looking at it from a tracking standpoint? I don't believe it (heat soak) would be so noticeable in normal daily driving in those temps, unless you were driving aggressive (doing back to back pulls). If you were tracking it, heat soak would come into play at some point. Idk, but I would think any car would, could suffer heat soak in 100+ temps combined with how hard it is being driven and for that I don't see how this engine would be more susceptible than any other engine.
 

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There is a noticeable difference driving my Volvo in 100F heat versus on a nice 70F afternoon. It just doesn't have the same power on the hotter days that it does on the cooler ones. It's not a performance chasm like stepping out of a Ferrari and into a Trabant but you can feel it without driving aggressively (e.g., entering a highway). The issue usually creeps up slowly as temperatures increase incrementally but during crazy Summers like we've had this year with 100F+ heat one week and 70F degree weather the next you can really feel it.

-Eric
 

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In driving my B8S4 I don't find that to be the case unless I'm getting on the car for a period of time on high temp days of which I usually avoid doing. Obviously it being supercharged the colder months it benefits from that. But I can't say that driving onto entrance ramps in summer that I've ever reflected back and said I feel a power loss.
 

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Your B8S4 is supercharged. I'm not expert but I don't believe superchargers create the same kind of heat as turbos. Heat kills power. I don't think superchargers are immune from heat soak but I do believe the problem is different for a turbo. All I can tell you is that it is absolutely noticeable in my Volvo and my friends who have added water injection systems have found new life from their engines after doing so.

-Eric
 

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Don't most, if not all, modern turbocharged engines have intercoolers? My Volvo certainly does but people still install large FMICs to help dissipate heat. It's not for a placebo effect or just because people think they look cool (regardless of whether that might fuel part of their mod frenzy). Hot air kills performance in any car so anything you can do to cool the air before it goes into the intake will help control detonation and improve the operation of the engine. If you're not cooling the air before the intake or your car doesn't have the capacity to cool it enough (or enough of it) you're car is losing power incrementally and the hotter it is outside, the more performance you're going to lose. All I can tell you is that in my car when it is 100F outside, my car has lost enough power that I can tell and I'm not racing my car.

-Eric
 

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you do realize this engine has an air to water intercooler right?
Two inter coolers actually one up front behind the grill and one in the front wheel well.

Audi TT's have air to air intercoolers but I would think air to water is more efficient but more expensive.
 

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Air to water intercooler is more expensive to produce however in the CLA45's engine this intercooler will allow for much shorter charge piping, which will give more engine response and much less boost lag. Also the coefficient of heat transfer from the water is much higher than a air to air.
 

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Discussion Starter #17
Hi, guys! Thank you for your information. I think I need to explain why I so care about this engine hp in high temp. The most important reason is it has a big compressor. The compression ratio is 1.8bar. For jet it is nothing, but for auto engine, it is really big. The higher compression ratio, the higher loss of intake in when high temp. The high hp of this engine are all from the high cylinder pressure and high cylinder pressure is from high intake pressure. For this reason, I doubt this engine will lose more hp than other turbo engine in high temp. It may be more sensitive to the temp. Other engines may be different at 70 VS 100, this one may be different at 70 VS 90.

For the intercooler, I don't find any information about it from MB. I am not sure if this engine has it like the GTR has it. The only inforamtion from MB I had read is M133 has a more efficient (20% more) cooling systerm. I don't know this systerm is for the cylinder cooling or intake cooling. My guess is this engine doesn't have intercooler, because it has only a single-stage compressor, it is meaningless to put a intercooler after the compressor. The only way is cooling the air before it goes into the compressor. Anyone knows if there is a cooling systerm before the compressor in the inlet?
 

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For the intercooler, I don't find any information about it from MB. I am not sure if this engine has it like the GTR has it. The only inforamtion from MB I had read is M133 has a more efficient (20% more) cooling systerm. I don't know this systerm is for the cylinder cooling or intake cooling. My guess is this engine doesn't have intercooler, because it has only a single-stage compressor, it is meaningless to put a intercooler after the compressor. The only way is cooling the air before it goes into the compressor. Anyone knows if there is a cooling systerm before the compressor in the inlet?
??????

What do you mean it is meaning less?
When you compress a gas you put work into it. This work is turned into heat.

EDIT: also you guess is this engine doesn't have a intercooler??? Please stop. You are jumping to conclusions without any facts at all....
 
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