StephenK

Put the SL600 on a Dyno this afternoon.

473 RWHP.

It was a rather hot day today, and we did it around 5:00pm, the hottest time of the day. He only had one fan at the front of the car, which I don't think helped that much. I will be curious to see the difference on a cooler day and with more fans.

vraa

We already talked about this

I talked with another tuner, they said unimpressive, but then agian, it was in the high 80's and had inadequate air flow. I'd say you're doing pretty well.

Make sure you drive the car as much as you can for the ECU to learn to how you drive.

tiggerfink

Even my SL500 gets hot. I remember last summer my face felt hot air with some anti-freeze smell when I open the door. I experienced than problem several times when I open my door last summer. One time, I thought my face was burning and my vision was blurry. That vision experience was similar to looking down the road in Death Valley in the middle of summer with heat rising up from the road. Dealer could find nothing wrong.

StephenK

As unimpressive as 473 RWHP is, Renntech's best report that they sent me was 515 RWHP. Odds are they had ideal conditions and worked at getting that number more than 2 runs like I had.

Have the other tuner post up some real world data, instead of a UNIMPRESSIVE comment.

vraa

I'll see what I can do, but you know why your numbers aren't as high as even you said before.

tiggerfink

Well from reading Car & Driver and Road & Track, they mention the SL R230s do get hot on the tracks. I think it has an inadequate air flow design or inadequate heat displacement design for driving hard for a period of time. If I drive from Memphis to Nashville nonstop, my SL 500 gets very hot. I never experienced this heat problem on my mom’s Corvette.

vraa

All FI'ed Mercedes' have serious heat issues.

StephenK

With the car sitting still in a shop on a Dyno, I just thought 1 fan couldn't be enough air blowing.

tiggerfink

What is FI'ed?

vraa

Forced Induction.
As I was explaining to StephenK through msn, the E55 forum has priceless information on how they are trying to solve the heat issues. They are actually coming to the conclusion that performance modifications are useless at this point, because after about ten seconds of driving, the amount of heat basically constricts the efficency of the supercharger, therfore slowing the entire car down, rather than speeding it up!

You know what's really amazing about modifiying cars? Once you get over the whole 'it's not OEM' stigma, it's addicting.

StephenK

Renntech called me today about the numbers after the upgrade. Suggested bringing the car to them, since my dyno wasn't completed 100% (No RPMS) and only two runs 473 and 463 rwhp, this seems to be the best plan. Unfortunately my local options are very limited. This to me does show the company actually cares about their customers and what they are selling. I am going to make plans to go this next week if it fits into their schedule.

Sometime next week I will be able to tell everyone what the real deal is with my car and the upgrade.

Being optimistic, look forward to some more impressive numbers.

vraa

RENNtech is a very reputable company to deal with, their guys are one of the smartest in the business. I'm actually kind of jealous that you can actually meet with some of the guys there one on one!

Bilal

Are we talking about heat build-up in the exhaust?

vraa

No, from the engine.

I don't think exhaust would really matter that much, unless you're talking about before the turbos. But IIRC heat doesn't affect a turbocharged car as much as it would because the turbocharger still spools up, it just takes a tad bit longer to spool no?

tiggerfink

I am experiencing around the engine. When I open the door, I can sometimes feel the heat on my face. I can really feel it when I let my arm hang down the door when I mosey down the road.

Bilal

That sounds unusual. I'm no expert on hot weather in Memphis or a mechanic, but with "symptoms" like that, a drive to the dealer looks to be in order.

All Mercedes cars are stringently engineered, I would doubt that heat of the parasitic and regular kind would have been overlooked.

Heat in the engine bay can be difficult to eradicate. Although the SL's engine bay is plenty big, finding vents and other heat dissipation methods can be difficult when the occupier happens to be a 5.5L Twin-Turbo V12.

Vraa, turbo's are capable of spinning much, much higher than superchargers, the speed at which they can spool is dependent upon the size of the engine (more cylinders means more exhaust ) and the size of the turbocharger. Mercedes has used small turbochargers, which have a limit of 580hp, with a specific aim of providing immense low-down torque, smaller turbo's spool quicker.

RennTechV12

I dynoed my SL600 before getting the RennTech Upgrade and it put out 469hp at the rear wheels or 553hp at the flywheel.

After the upgrade it made 522hp at the rear wheels or 635hp at the flywheel.

vraa

Bilal: Doesn't the RENNtech ECU upgrade increase boost though? I wish I had specifics of the upgrade somewhere on my desk... :x

RennTechV12: What were the temperatures @ your dyno?

Bilal

...It does, and many Renntech customers and most notably, Ben Treynor will testify that it has had absolutely no effect on the car whatsoever after repeated drag runs even.

However, not to make bad remarks about tuners, the info that I got about the limit of the turbochargers came from Brabus. Now I'm not one for tuning, and Brabus' upgardes are extortionate, but their most powerful kit for the S600 ECU is up to 570-580hp. Anything more and they have to increase engine displacement and modify turbochargers.

There's this knowledge and then there's Ben Treynor's real-life example... :o


Regardless, it does prove one thing once and for all, mechanically, Mercedes' cars are built with an astounding amount of component redundancy.