I am going to replace my secondary catalytic converters and resonators on my E55 daily driver with an x-pipe for more sound. I love the way my beast sounds and would like to share it with the world. Right now the powertrain is stock, but I do plan on adding either more pressure (boost!) or chemical power (NO2 or water/meth). I am trying to decide if I should replace the primary cats now with high flow cats or keep the stock primary cats. I am torn between spending $100-$200 now for more sound or saving up $400-$600 for better exhaust flow later.

The beast is a 2006 with just over 71,000 miles on the clock. I have heard of catalytic converters failing, which might necessitate a replacement anyways. I live in Colorado, which does test emissions every 2 years, but haven't had to check the beast since I purchased it in December. We are not nearly as strict as CA, but I don't want to run cat-less for over 2 years in Denver.

I am planning on drag racing the car at the local strip starting in April, so (traction willing) I can use every HP/TQ available. Even at a mile high, the traction control is stepping in when taking off in first gear on a relatively heat soaked engine (160+ F).

Assuming I am in state this year, I do plan on registering for the Colorado Mile and the Central City Hill Climb. Both of which will benefit from splitting the cooling system, but are only 2 of 20+ racing events this year. My fiance and I attend 18+ "test 'n tune" drag racing nights at the local strip. On the flip side, how many times to do get to take your beast over 140mph in a controlled race setting?

The current decision is thus:

1. Efficiency: The car is over a decade old anyways and will probably fail emissions in the next 5-10 years. I might as well spend the extra few hundred dollars now to replace the cats with some good, high flowing cats. I should pass emissions and can accommodate future power mods.

2. Cooling: The beast hasn't failed an emission inspection yet, so I might as well spend the money to split the cooling system now and worry about emissions later. I might be wasting some power with a somewhat clogged cat, but the cooler IATs make up for the difference. When/if the cats do fail emissions I will replace them then at that time.

3. Traction: F*** it all and save up for some drag radials to walk corvettes in the 1/4 mile. Who knows, I might even surprise a Lambo or a Tesla? We aren't racing for "pink slips", but a 11 year old car walking a brand new hyper car is just awesome/funny.

What do you think? Efficiency for a daily driver, cooling for the weekend warrior, or traction for the strip? If I were made of money, I would have all three, but as it stands, I can only afford one.




P.S. I just replaced the pads and rotors, so breaking is not an issue. Once My Conti DWSs are worn down I will replace them, so everyday traction is not a concern. Also, I have the Blue Driver dongle and app, so if anyone would like any logs of my car, please let me know. At a minimum, I monitor my coolant temp, IATs, and cylinder 1 spark advance. I do live in Denver, so the air is a little thin up here if you would like to compare your beast.

 

I vote A or B
A) Split cooling ($50 in parts) and replace Cats ($300 plus welding).

You will gain about 20+/- bhp by getting some vband clamps welded on to some straight test pipes to run at the track (eliminating primary cats). Then you can put in your cats once you are home for some docile road fun.

B)
I have heard good things about a stock tuned car with split cooling so perhaps that could be another $400-450 route
I think thats about 30-40bhp fwiw

 

OP- you are very fortunate to be so close to Kleemann, in Colorado Springs. You should take advantage of that and have Cory tune your car.

 

I agree with this. Splitting the cooling without adding volume to the cooling circuit isn't going to help many cases when monitored your AITs rise. To be honest when it comes to the exhaust or the power of this platform the exhaust manifolds are total crap when it comes to flow. If you have to run no headers then have to stock manifolds gutted and change the pipes to the converters and you will pick up 25 plus. Shortys mids or longtubes are worth the money.
You won't pick up a lot of sound untill you got rid of or gut the stock mufflers.
Good luck

 

If you go to 18+ drag events a year, it's a hands-down-no-brainer get the drag radials first!!!! Hoosiers on CLK wheels FTW!

 

Thanks for everyone's' responses!

BoostedAero,
I am thinking about either splitting my cooling OR installing new primary cats. If I had the tools and time I would do both in a heartbeat! Your vband clamp cats is an interesting idea, but I would be worried about exhaust leaks.

DVC,
Ironically, I just took my car down to Kleemann a couple weeks ago to have them install new pads and rotors. In addition to them specializing in AMGs, their labor rates are great! I have also toyed with the idea of having the car tuned. I would like to install some physical mods first before tuning the ECU. I prefer to give the beast more potential power and then optimize the ECU for that power.

LS1toAMG,
First off, nice handle. Second, sorry if I didn't explain it properly, but when I split the cooling system, the supercharger part will have a separate reservoir. That way I will be increasing the total volume of the cooling system and separating the supercharger cooling system from the engine cooling system. This is mostly a first step towards keeping the beast cool and at max power. Also, right now headers aren't in the budget. I would love to get some long tubes for the beast, but am going to do some cheaper mods and maintenance first.

JoeJErnst,
I have been contemplating either Hoosiers or Nittos for when I get some drag radials. How have your Hoosiers treated you? Knowing that the two things that hold the beast back are cooling and traction, any personal experience with racing tires is appreciated. Also, why did you choose CLK wheels and what year/model CLK? Why not get some OZ Supperleggeras or Einke RPF1s?

 

I went with the Hoosier/CLK combo after doing tons of research on this forum; it seems to be the Gold Standard for traction on our cars. The wheels are from a '98-'02 CLK, and they are forged factory units which makes them incredibly light and strong. The Hoosiers are also lighter than a comparable Mickey Thompson tire, or so I've read. I love this setup and I doubt any other single mod will lower your ET by as much.

They're easy to toss in the trunk:


And they let you do this:



As for cooling, specifically at the track, I mounted a pair of 6" Spal fans to the front of my PLM Heat Exchanger so I can get some airflow over the coils while sitting in the staging lanes. Any other cooling mods (except a Killer Chiller or Meth) will be "neutered" so to speak if you don't get some air flowing over the H/X, so keep that in mind if you spend a lot of time in the staging lanes like I do.

It's especially important if you do any bracket racing:

 

Joe, what was your short time on that wheel/tire combo?

D-

 

I think my best ever 60' was a 1.69, but it's usually 1.75-ish.

 

Are you launching in 1st or 2nd?

 

1st. Those numbers were all before I installed my Wavetrac. I don't have any timeslips yet since I did that.

 

Edit: I looked through my timeslips tonight and found a 1.60! Maybe the Wavetrac will get me into the 1.5's

 

Nice!

Honestly, it really should. Nice setup!

D-

 

JoeJErnst,

I can only hope for the day of a 1.60 60'. Awesome!

Foregoing NOs and water/meth for now, can you provide any more details about installing your 6" Spal fans on your H/X? For my purposes, that seems to be the most cost effective upgrade for drag racing considering that we might be in the staging lanes for 30+ minutes once things get busy.

Did you install them yourself or have a shop fab everything up? Do you have a fused switch connected to a battery to turn them on or do you have them wired for different conditions? How do you keep coolant flowing while in the staging lanes? Was there enough room around the H/X to install the fans or did you need to fabricate brackets? Do you know the part # of the fans?

Any information you can give will be appreciated. I would like to think that I can install some H/X fans, but knowing the complexity of these cars I don't want to get out of my depth half way through a project. Just finding out about the low-viscosity DOT4 brake fluid needed for the car has given me hesitation to do any modification without thorough research.

 

It was a very easy job to do myself. Here's a thread where I gave a few more details. I'll try to get some pictures soon to show the details of the setup.

https://mbworld.org/forums/w211-amg/624097-good-day-track.html