Marcus Frost

I am hoping to get my car in for it's work (finally found the 2.75" bends - you'd think you were looking for gold to find those things!) and now we are just waiting to get the materials in from the supplier.

We will see how close my car mimics Victor's results. My car will be using Kleemann style headers, and 2.75" piping vs. Victor's EvoSport headers and 3" piping - there are a few other minor tricks as well but for the most part it's a very similar setup.

I will post soon.

-m

medici78

Kleemann style headers? Are you eliminating the primary cats on your setup?

Marcus Frost

I bought a set of headers off eBay, had them redone to my liking and so they are a pseudo-custom set, but if you want a visual, look at the Kleemanns. I didn't copy Kleemann, it's just that there are only so many ways to make a set of shorty headers. I prefer the way Kleemann designed theirs, which moves the primary cats away from the block and uses a more straight runner design with a nice collector.

I am eliminating the same set of cats Victor eliminated as well.

Victor - another suggestion - have you measured to see how much boost you are running now?

-m

ScottCLS55

O.k.

AMG rep at the AMG chalenge discussed this idea with me. He stated that the system is tuned to optium levels for stock form. When you take away back pressure in the supercharged engine the boost levels in the combust.. chamber lower. So to have the same boost as with the stock exhaust you will have to actually increase the supercharger output to make it optimum(however you spell that) tune. I am sure when you up the boost you will be able to swap the exhaust back to stock (waste of time) and see the difference with more boost. But "exhaust only" really (according to AMG rep) will really not make you faster, but actually slow you down.
VRUS, its just a case of being ahead of the game. Your exhaust may have came a little early in the game but It will come in handy later with more boost. I dont think more fuel at this point will help either, I think it will take more boost and at same time more fuel to see any difference with the exhaust.

Good Luck, 600 will come soon enough.

E552006

In principal I agree with the idea of this.
Think about the difference between a turbo charged engine and a supercharged engine.
A Supercharger will put the same amount of air through an engine regardless of back pressure in the exhaust system (if the system is already ample for air flow).
A turbo's efficiency is actually increased by the lack of back pressure in the exhaust. The less pressure, the less resistance to spool, therefore increasing turbine effficiency and increasing airflow through the engine.
This is a simplistic explanation but if you think about it what it says is, a turbo charged engine can proform more efficiently with less back pressure in the exhaust.
A supercharged engine's flow will be maximized by back pressure.
It is much more similiar to a NA engine than a turbo charged engine.

Josh

Grumpy666

If you install headers on a S/C car and the boost level goes down, it is not tuned to an optimum level. More boost does not make more horsepower, more airflow does. Increased boost due to an exhaust restriction will actually make less power than less boost w/o the restriction. Removing the restriction allows for more airflow and thus, more power. Also, the higher artificial boost will cause higher intake air temperatures, which will also decrease power.

E552006

Exactly

ScottCLS55

O.K, then why did his hp stay the same? I understand what a "restriction" would do but the factory exhaust is not restricted...

the backpressure in that system is tuned, and until more air needs to go out ie more boost packing more air in the combustion chamber then a larger exhaust is not needed. It will not take away hp but you will lose some low end torque. That is why the amg rep said you will be slower. They have tested and tested that exhaust system to be tuned for stock levels. Looking at his exhaust I see no way it is restrictive.

E552006

Not saying that the stock exhaust is restrictive, only tuned for optimal performance given stock boost levels.
This is also the reason his HP stayed the same IMO.
Josh

vrus

Been busy this past week so I have been a little absent.

Looks like my car does have an issue with the O2 sensors. With my OBDII datalogger, I am getting a "Catalyst Monitoring System" = Incomplete. It used to say "Complete" before.

Also, periodically when I push down on the throttle it feels like the exhaust pipes are clogged up.. It bogs down and won't rev above 4,000RPM. I put my foot to the floor at 4,000RPM and it revs really slow as if the throttle plate isnt even opening.

Someone do this test for me:

- Start your car in your driveway
- push down on the throttle slowly to rev close to 4,000RPM.
- floor the throttle and tell me what happens. Does it bog? Or does it rev right to 6,000RPM ?

There are no trouble codes stored anywhere, and no check engine light, but the O2 sensors have to be contributing to this behaviour. If I remove the battery cable from the ECU the car turns into an animal again but after 2 days goes back to this weird behaviour.

Looks like I will either have to get someone to program out the secondary O2 sensors or put on some O2 simulators.

Does anyone know what SPECIFICALLY has to be done in Star Diagnostics to program out the secondary O2 sensors?

Also, I am 100% positive that I have dropped 1 or 2 lbs of boost (if not more). My MAP sensor readings before & after are not the same.

This is going to require a bit more diagnosing..

I am confident that this system will allow me to get into the upper 600hp range if I get everything dialed in properly. If I made 11hp less and the same torque in this condition, I am hoping that once it is running properly I will see some decent gains here.

E55AMG99

In neutral? The rev limit is lower in neutral.

vrus

Well, there is 2 behaviours.. It was bogging on me while driving on the street.. When I would hit 4,000 RPM and mash the throttle, it felt like the exhaust pipes were clogged and wouldnt rev anymore.

Then, I parked the car in the driveway and tried to rev above 4,000RPM and it would barely rev above it. (Car was in Park position).

Grumpy666

What is the status of your secondary sensors? Are they installed after the cat?

Grumpy666

It sounds like the ECU is putting the car in some sort of safe mode. Possibly due to the cat incomplete issue. Disconnecting the battery from the ECU would clear the memory registers where this parameter is temporarily stored, allowing the car to react normally again - for a while.

vrus

Yes. The location of the primary and secondary O2 sensors remain the same as stock.

Primary O2 sensor, then catalytic converter, then secondary O2 sensor.

No check engine light. No stored DTC codes. But, the datalogger is saying the Catalyst monitoring system is incomplete which means it thinks something is wrong with the cat.

I have a feeling the secondary O2 are doing more than just checking if the catalytic converter is working. They must be affecting the A/F ratio or something else in the ECU because the car runs very weird.

Grumpy666

Re: Catalyst Monitoring System = Incomplete

Here's an excerpt from a Google search (http://www.babcox.com/editorial/us/us20212.htm):

Something else today’s technicians need to be familiar with are OBD II’s "readiness flags" that indicate each monitor is doing its thing. As we said earlier, the misfire detection, fuel system and continuous system monitors are active and ready all the time, but the non-continuous monitors require a certain series of operating conditions before they will set - and you can’t do a complete OBD II test unless all of the monitors are ready.

To set the converter monitor, for example, the vehicle may have to be driven a certain distance at a variety of different speeds. The requirements for the monitors can vary considerably from one vehicle manufacturer to another, so there is no "universal" drive cycle that will guarantee all the monitors will be set and ready.

As a general rule, doing some stop-and-go driving around town at speeds up to about 30 mph followed by five to seven minutes of 55 mph plus highway speed driving will usually set most or all of the monitors (the converter and EVAP system readiness monitors are the hardest ones to set). So if you’re checking the OBD II system and find a particular monitor is not ready, it may be necessary to test drive the vehicle to set all the monitors.


Another thought: Is it possible for you to get the waveforms from the secondary O2 sensor? If everything's working correctly, the output from this sensor should be a fairly constant voltage. If the cat is not performing adequately (eg, not enough cells), the output from the secondary sensor will be switching back and forth similar to the primary sensor.

vrus

I datalogged for almost 1.5hrs and the ready state was not set. In all my other datalogs it always said COMPLETE so I know it is malfunctioning now.

Not sure how I would get the waveforms.. I was hoping someone could tell me how to disable the secondaries in Star Diagnostics so I could verify that wa the problem. Either that or I have to order some O2 sims.. I didnt want to do that yet because it would require splicing the wires and I didn't want to mess up the factory wiring.

medici78

Can you splice the sims in using the O2 sensor connector, thereby bypassing the factory wiring?

eclou

Vrus,

Did you ever check your plugs?

vrus

Well, the O2 sims come with 2 bare wires. They dont have a connector on them.

Hmm.. Maybe I could try to purchase the MB connector from the parts department and fit them that way. Hopefully they sell the connector.

I bought new plugs with the intention of pulling them and swapping but they are still sitting waiting for me to pick them up from the parts dept.

I've been so busy that I didnt have a chance to do that yet.

WayneE

Sims I've used on other cars always had the factory weatherpack connectors installed. What's the connector for the rear O2s on the Benz? If you can't get sims with the correct connector, can you hack up a set of rear O2s and use the connectors?

Also, where did you get the cats? I use RTs on my C5 and would love to find a cheaper source Here is a pic of the cats in my exhaust.

Good luck!

WayneE

I've purchased OEM connectors from Casper Electronics. Google 'em for their website.

vrus

The O2 sims I bought for my vette had the weather pack connectors on them. But these generic ones I found have only bare wires and you are to splice them yourself.

I was wondering if I could get away with using the C5 versions of the sims on the E55 but I dont know if the voltages the ECU is expecting is the same.

I thought they were standardized but I guess not.

I sourced the cats through a friend of mine in the business.. They were only $100 cheaper than what you would pay if you bought an RT labelled cat.

Thericker

Maybe I'm not qualified enough to make a sugestion here but....Since you said your car returns to it's beastly self after disconnecting the battery, why not get it dynoed right after doing this to see if indeed there are any gains to be had from this new exhaust system?

Marcus Frost

Victor,

We need Cory to chime in here. Kleemann's exhaust system eliminates 1 set of cats here and according to them it's a non-issue. I'm sure he could shed some light on this subject.

-m