Wolfman

Have seen the Renntech info as well and it is tempting. But our 2017 is already faster than our old one (more hp and 9speed). Also running the PSS

Love to see how tires and ECU make a difference

DATURK

WOW....Renntech must have double standards....as soon as I found about the update I contact them, I've been told by my sales rep that I have to pay one half of the original pricing which is $2600 one half is $1300.00 that's what I have to pay, find my post on this forum "RENNtech's new ECU tune for M278...." clearly I opt out not to pay.... that was my experience with RENNtech, put in search it I'll pop out. I'll contact them again to see what they have to say...

ericnaustin

Daturk,
I was working with Legor Ratunda and three days after being told the upgrade was free, received the email below. Renntech still honored the free upgrade with no issue. I just assumed he wanted processed ASAP. I sent it out the following week with no issues and quick turn around. Big performance gain! Haven't yet had the time to test with timer, but significantly more power.

Hi Eric,
I need to inform you that the cost for new tune for 550 engines will be 1370$ ( 50% of the original price) for those who have our tunes already and they were done within previous 3 years.

As I have informed you previously , ( before the new pricing policy was applied) I will honor the free upgrade for you if you will process that asap. I will not be able to honor that proposition later.

BR,

ericnaustin

*initial email below. Nice guy to work with. Seems to really know their performance products.

Hi Eric!
That is good to hear,
You have free updates for 3 years of the initial purchase – so let me know if you would like to send us your ECU!
The only thing you will need to cover is shipping.

Best regards,
Iegor Ratunda
Product Specialist

DATURK

WOW...as soon as I mention your experience to my sales person, they have given me the same deal, my sales rep dropped me an email and informing me that as long as I cover the shipping they will do it, I just emailed him back asking him when I can sent in my ECU for the new tune...

Thnx for your post and thanx for sharing your exprince, if I had not seen your post, I was out of a deal...

Thnx Eric...

ericnaustin

So glad to have helped!

Eric

ericnaustin

2013 SL550 with 30,000 miles
Renntech ECU flash - 540 HP 705 TQ
Renntech mufflers
high-flow air filter
Michelin Pilot Super Sport tires

Factory Stock
0 - 60: 4.27 / 4.28

Post above modifications
0 - 60: 4.01 / 4.07 / 4.10 (consistent 4.1)

All testing occurred at the same location as before.

Overall impression
The newest flash from Renntech for the M278 is a huge improvement over the previous version. The car now makes big power and pulls considerably harder both from a standing start or from any speed. Even more wheel spin from a hard standing start and between 1st and 2nd, but enough power to more than make up for it as shown by consistently quicker 0 - 60 times.

I was getting the quickest times by turning off the traction control and just smashing the gas. Car gets a little sideways off the line and lots of wheel spin between 1st and 2nd, but consistently getting the quickest times. I suspect times could be improved through better feathering of the throttle to limit wheel spin, but the few times I tried that technique my times were actually much slower. With a little more practice I suspect I could improve my times using this technique.

The car is definitely more fun to drive post flash and I would recommend the flash to any M278 owner.

ericnaustin

DATURK

Received & install my re-flashed "New Tune" last Friday, I dont have the SOLO to test but I can definitely tell that there is a huge improvement, car pulls very hard, I can almost say as hard or harder than my S63 (with RennTech Tune) incredible it spins on first & second, I don't know if it was a fluke but I tried of the hard accel. at red light, I didn't get spin on first but did get little spin on second this happen only once and tail whip as well..., I couldn't replicate this, almost all hard accel. 1st & 2nd get a spin....no complains here, its like a new car now...lol

Box5232

Had my eyes on the RennTech tune for a couple of years, and the only reason that I held off was that I would've had to send in the ECM. Then RennTech came out with the hand held tune, I waited and then finally purchased it. Not disappointed in the least. Out in the open country a couple of years ago, before the tune, I got my SL up to 140 mph, the car was noisy and the engine was loud relatively. Last week, with the RennTech tune, I got it up to 150 mph easily, and there was still plenty of peddle left and it was truly low altitude flying with none of the issues experienced previously. I've never been a big zero to sixty fan, drag racing is too one dimensional for me. With the RennTech the car is much quicker off the line and fast, a true sports car. Be careful though, because the traction control features are modified in favor of performance, don't turn a coroner and accelerate to quickly, or you'll end up like a vette driver and spin out. Also, the upper speed limit is modified as well so be careful. The other SL ride performance features inherent in the vehicle compliment the tune. Money well spent as far as I am concerned. The RennTech tune truly unleashes the car's performance, and I've always enjoyed pushing my vehicles to the outer edge of their performance envelopes. No, I am not a paid spokesperson for RennTech.

alpine788

Bought a 2014 sl550. Thinking of adding the Renntech tune. IS IT WORTH IT? Looks like mixed reviews on this thread. Car still above 4 seconds? Hard to believe its not faster.......

Wolfman

Traction is the culprit. The SL63 official 0-60 time was 4.1sec. as well. You can always get a tune (like Eurocharged, etc.) for the fun factor. Just don't expect any significant gains from a stop. Different story from a roll...

griza

When the time comes for my tune, I am leaning towards Pressertech. Equal performance for about half the price. Anyone use Pressertech?

mercshepherd

The SL550 acceleration from a stand still is traction limited because of its RWD and high torque and hp
I had a 2015 SL550 that consistently ran 4.1 second 0 to 60 times STOCK. (measured with high quality G Tech performance meter)

I believe the reason was that it had a good set of Continental All Season Tires on it. Specifically Continental ExtremeContact DWS06 Plus Ultra High Performance all season.
They may not be as sticky as Ultra High Performance summer tires on a hot day, but I believe the All seasons stay softer and provide better traction in colder temperatures and are better all around. They also last longer.
Never the less, I was getting 4.1 second 0 to 60 times with the Continental DWS 06 Plus All Seasons

I missed my SL550 so much that I recently bought another 2015. And Im considering getting a Renntech tune for it
Any new thoughts or impressions on the Renntech tune would be appreciated!

alpine788

Renntech is fantastic. I got a 20% bump in torque and hp (guesstimate)... only downside is in Cali, if you want the top notch package, you must add racing fuel to blend the 92 to 93 or above... no biggie for me.. around 7 miles away from racing fuel retailer.. but for some it may be. They have a lower hp/tq for those living in Cali and not near or wanting to mix racing fuel /pump gas. I say, why bother if not the whole schebang. Is easily brought back to stock tune as well.. with the handheld. Very good deal for the amount of performance gained. IMHO

Apifane

Eric, I may have missed this in the thread so excuse me if you already answered this, but did you go for the ECU+ Upgrade or the standard ECU upgrade? Doesn't sound like you were using the hand-held tuner, but please clarify. I have a SL63 that I am interested in modifying. More interested in performance in the 60MPH+ range the 0-60. Pilot SS are great by the way.
Cheers

JD101b

how wide are your rear tires? Stock is 285. I’m thinking about a similar upgrade for mine (tune + tires but I’m trying to figure out if I can go as wide as 315)