pmrogers

I'm eyeing a Renntech ECU upgrade for my new-to-me 03 SL55, but don't want to do it if I'll be hugely disappointed.

My frame of reference is the NSX I've driven for the past 9 years. While it didn't pull nearly as hard as the 55, its throttle response was instantaneous.

I understand that a boosted V8 will never be able to fully match a normally aspirated V6 for quickness of response, but I'm hoping that an ECU upgrade might get me into the same ballpark.

Currently, I'd describe the SL55 throttle response as 3-stage vs. 1 for the NSX. Slam the pedal and it's: 1) deliver some accelleration, 2) deliver hard accelleration but the boost hasn't kicked in yet, 3) boost. Would an ECU upgrade be able to make this feel more like a 2-stage process?

Thanks for any input,

Paul

donboesch

I have had the stage 2 RennTech upgrade done on my 04 SL 55 and I have been very happy with the results. The throttle response is improved and the car definatley has a more aggressive feel. The ECU seems to addapt to more demanding driving conditions. Are you also getting the pulley kit? I am thinking of going a few steps further. I have been in contact with Kleeman and have been contemplating their stage 3 or 4 upgrades. 635hp. Anyone have an opinion, good or bad?

JSulton

I had the Evosport stage 1 upgrade (ECU and pulley) done to my '04 SL55 and noticed much improved throttle response in addition to the boost in power.

Jeff

SL65amg

don, I believe anything by Kleemann is outstandingly excellent and you can't go wrong ... but ... if you really want power and value for your money I'd recommend picking up a used 2004 SL 600 and throwing in a Renntech ECU upgrade with SL 65 trans upgrade software ..... both together will only total you around somewhere betwen $4,000 to $5,000 and you'll have 650 horsepower with 740 lb/ft of torque, and you'll have the SL 65's steering wheel shift and upgraded and faster transmission shift patterns, increased turbo boost, and acceleration that not even the Kleemann 640 horsepower SL 55 can match. :p :v

What with stock SL 600's capable of high 3's in the Zero to 60 MPH area, if you ECU'd it you should be able to crank off mid 3's all day long and 1/4 miles in the low 11's to high 10's all day long with street legal tires !! With racing slicks .. who knows probably a good bit faster than that in all areas ...... :v

The 600's drop faster in price than the AMG's just because of the insurance companies and the markets' perception of V-12 cars, so you can wait 1 year and pick one up for $80,000 ...... just some food for thought...

I've driven a CLK-55 with Kleemann supercharger and exhaust and brakes and wheels, and the car was absolutely spectacular .... The mechanic who did the car claimied it had over 565 horsepower or such ... the force of acceleration and the seat of the pants feeling was absolutely amazing, crazily instant throttle response and much faster acceleration than even a new model porsche twin turbo 996 coupe I've been in ...... I believe the car was pulling well mid to high 3's in the zero to 60 MPH department .... can't remember for sure though ....

Schiznick

Can someone please help me understand how a software change to the trans will allow it to stand up to far more torque? Isn't the reason that the torque is limited in first and second gears of the SL65 because the trans can not take it? How does upping the torque and changing the shift module solve this problem? Unless internals are changed on the trans I can't see how this problem goes away.

I still don't care how many times that it is debated, just because a car magazine says an SL600 ran under 4 seconds 0 to 60 I won't believe it until I see it with my own two eyes. I have driven both my old SL55 and a SL600 back to back and it was not a second faster 0 to 60. If someone will get a "Stock SL55 and a Stock SL600" I will be happy to pay for the gas to run them at a drag strip. Just name the time and place and let's be done with it.

Schiznick

draggingcents2

Please read my post of the SL600 VS E55! We race heads up 3-4 times if you read I lost first race but the next 3 I was faster 0-120mph. I own the E55 but will soon get a used SL600 because of the above post.

draggingcents2

am thinking about buying a SL600 and trading in my 04 E55 so I have been talking to the dealers here. I have a friend who is a sales man at --- --- MBZ in California and his sales manager let him take the new SL600 to my home for a test drive. When the car arrived I was grinning ear to ear. We first went out to toll road did a 60MPH role on-all the way to shut down 155mph the SL600 pulls so hard from 60-155 it is great. I also got to launch it 4-5 times 0-120ish. Car has hard time getting of the line. Turbo lag is offset with a high stall TQ but it still has it. After I drove the SL600 my brother did. I called his cell phone when he was out. I told I was pulling my E55 shizil out and to set up a run. We did a 0-100 run first but I let him have the move. Big mistake the SL handed me some *** 0-100 put 2 cars on me. We raceed again 0-120 about 3 more times after that. The SL600 never got in front of the E55 after the first run. The SL600 is fast 0-155 but 0-120 I got its number all day in fact each race I was able to launch a little better each time and by last run was able to get out at least 1 car by top of first. The SL600 was coming hard on each run. I think it was my BFG's Drag Radials that helped. The SL600 had 5200 miles on it dealer demo car and the E55 has 11,400 miles on it.

IngenereAMG

Paul:

I had my ECU upgraded by Oliver at Speedtuninng USA. It was the best money I've spent on the car. The throttle response is improved. I note that you say, "Slam the pedal"....I have always found that if I SQEEZE the pedal I get better accelleration. Anyway.....the throttle response is better....there is more HP/torque and the speed limiter is removed. Overall, a great choice to do.

pmrogers

Thanks, Don, Jeff, Dino

I'm going to start with just the ECU. Right now I don't feel like the car needs more power or torque, just more responsive delivery.

Regards,

Paul

Wolfman

I second that, it's tiresome to read some of these posts that claim low 3's or "possibly even high 2's" with some simple Renntech upgrades.
My experience with SL600's (2 different cars) is that they have about as fast as the SL55. At least I certainly haven't felt a noticable speed difference. Even your SL65 I believe is spec'd at 4.2 sec to 60mph.

While Americans seem to be more obsessed with 0-60 or 1/4 mile times, Germans are not and focus on acceleration at higher speeds, which is what actually matters on the highway (starting at 100mph+)

You can definitely make these cars faster, but unless the car looses some weight or gets four wheel drive,you can't get that power onto the road. In short, most hp increases (even 150hp) will only give you small second increments.

Just my 2 cents...

Wolfman

Schiznick

Thanks Wolfman, I totally agree.

In my new SL65, hp is by far not the problem traction and weight is. Trying to move the two tons quickly is quite the task!

Schiznick

SL65amg

You will greatly and hugely improve your ability to launch your SL 65 by taking it to Atlanta Classic Cars and having them put a fender widening upgrade on it so that you may put much larger tires on it. Then you can put 345/30 ZR-20 Michelin Pilot Sports on the back .... then you will blow away all competition especially if you get the Renntech ECU & TCU upgrades. :v

This can all seriously be done it's not that difficult for those guys at all.


Not to mention the car will look even a lot more bad *** and mean ... like a real street warrior predator ready to eat all cars who dare try to overtake it. :v :v :v

IngenereAMG

So much of this is academic. Maybe I am just being old but I can remember when performance cars had around 200hp!! and they were challenging to drive!

With the SL55 and 65 we have two cars that have HUGE hp, fantastic accelleration and top speed capabilities...and thanks to the world of computers (and tire technology), great handing.

Straight line speed is one thing, but a sports car is something that works with you on a give and take road (or track). Given the proper training and experience my SL55 (which is essentially stock...save 19" AMG wheels w/Pilot Sport tires, and ECU mods) will outperform most cars on the market and ones that are 2-3X the price.

Probably the best investment (from a performance standpoint) would be a driver's school and some track time. THAT will pay the most return. Given the performance capabilities of so many cars on sale today I think that the manufacturers should throw in a driver's school so that we can enjoy what these machines are capable of....as well as not kill ourselves!!!

Have fun...

pmrogers

Thanks for the detailed info, Dino! Since SL55 is my daily driver I'm a little concerned that the ECU upgrade will make it twitchy and difficult to drive in a relaxed luxo cruiser mode. Given your stable I guess you may not drive your SL very much in normal use, but if so, have you felt that the ECU reprogramming has degraded the daily driving qualities?

Thanks again

Paul

IngenereAMG

I drive the SL all the time. I have noticed only better throttle response, and more punch.....and most importantly....no speed limiter!!