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Discussion Starter · #1 ·
Received it yesterday, one insight with instructions was make sure the battery is fully charged before install, so did early today. Tomorrow I hope to do install, test drive Monday. This is on my '15, we have emissions tests here in Colorado so wanted to be able to switch it back to stock easily, and the RENNtech has nothing under the hood, just plug to OBD port, plug in again and change back to stock if you want to, any time you want. The only other performance mod I have is AMS high flow air filter and that is a good piece, obvious advantages over paper. So we will see, they got me on a labor day sale of 10% off, I've never seen them discount anything. Shipped super fast, so my install ease (fingers crossed) and seat of pants are what I will be commenting on.

My car stock is rated at 355 HP/332 Lb ft. RENNtech as all others do, dyno their improvements (Rear wheel) and extrapolate back to Crank numbers used by manufacturer, using 18% loss for drivetrain in case of AWD. They state 428hp and 417 lb, and I have the high flow filter, but I'm thinking 425/415. And that should be very evident when I drive it. So we shall see.

I see people asking them what their improvements will be with newer version, say 2018, but they don't seem to understand, the stock mapping of fuel, air, (not even any boost) that are lightly tweaked in newer version don't mean a thing to the tune as it overwrites from my understanding. Simple example, if say my car gets 4.1 of fuel and air, and the '18 gets 4.2 of both, but RENNtech tune delivers 4.5 and more boost, the absolute HP/TQ dyno number would be the same for both cars.
 

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Your input will be interesting on how it performs. I am sure it will be fun and a blast to drive! I am enjoying my current plug-in piggyback, but I am looking forward to when I get my tune, not sure which one to go with yet (Weistec, RENNtech, or other). Do you plan to dyno it and get your own numbers? Curious to know what your reason for going with them and not Weistec or someone else? I like that ability to flash back to stock; comes in handy in your state since you have inspections. Which other tunes did you consider?
 

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Discussion Starter · #3 · (Edited)
I thought about an under the hood flash for half the cost. Never wanted to pull my ECU and send it somewhere. In the end, in summer, the heat under the hood, I just was concerned the cheaper stuff would not last, plus the extra wiring. If you can afford the RENNtech, that was so easy. RENNtech is the most known name, been tuning MB since 1989. They are in Florida but they are also linked to Germany site for tech. I trust them over any others.

So just briefly since I have only driven it a couple times, not meant to really check out performance, some thoughts. The install perfectly smooth....slow charge your batt if you don't drive much like I do, the instructions if followed delivered my tune in just over 1 minute. I had a "4matic unavailable" code after install, but instructions tell you to turn key back off, then back to the two clicks (no engine on), then back off and repeat again, and it was cleared. Started up and drives exactly like stock. However, I immediately noticed that some throttle brought the motor to life very noticeably stronger than where I was. Give it more gas and it's a serious smile on your face, the car still drives the same, but the power is way more noticeable, so the torque curves and what not are likely pretty much the same, but the power is undeniably there.

Tomorrow I plan a more spirited drive where I can focus on the performance. Between 1/4-/1/2 tank of gas in car, just will really focus on punch when I get on it. No race start, but I can already assure you this is no 25 hp improvement, it's very significant, and likely every bit what the stated increase says. Not sure on dyno ing of my car, will see after tomorrow. I know what this should feel like when I get on it, if around 425HP. A dyno will give me WHP, likely 18% less which is how RENNtech claims their figures in the first place.
 

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Discussion Starter · #4 ·
So today I was able to get it out on more open roads. I'm even more impressed, here's why:

  • I'm not sure it has changed initial turbo lag, perhaps a little better.
  • Power doesn't just come rushing in, it stays smooth, but you can definitely feel a large difference.
  • The car is so smooth, it now just keeps pulling as you get up in RPM for each gear, which now goes to about 61-6200RPM before shifting (in S mode). I think mine used to get to about 5900-6k. I used to want it to pull harder all the way to RPM.
  • The way they tuned this, it's smoother than stock, but you still completely feel all the extra power, and especially torque.
Did I mention it is smooth? (y) :D RENNtech did a wonderful job with this tune. My temp gauges for coolent, oil, gear have not changed (no sign it's getting extra hot).
 
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If it's anything like the maps I've had, you can figure around 340+ HP at the wheels on a 4-wheel dyno.

I also had a thermostat failure where it was stuck on partial open. During that time, the engine couldn't maintain "white state". Our cooling system really is very very good. It's getting held back in a major way by the thermostat. There's massive overhead in our capacity.
 

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Discussion Starter · #7 ·
If it's anything like the maps I've had, you can figure around 340+ HP at the wheels on a 4-wheel dyno.

I also had a thermostat failure where it was stuck on partial open. During that time, the engine couldn't maintain "white state". Our cooling system really is very very good. It's getting held back in a major way by the thermostat. There's massive overhead in our capacity.
yep, RENNtech dyno has it at 351HP, how they get to their crank number.
 

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Discussion Starter · #9 · (Edited)
I'm just curious now about experiences with other tunes. I can't get over how smooth this is, and yet I don't want anyone to think that when they push the gas they won't "feel it" like crazy. It simply is smooth and pulls and pulls. Oh, I've also reset the mpg over distance calculator to see what difference I see. I don't do hardly any highway miles, and I only drive the car now about 2400 miles annually, mild town driving with roads averaging speed limits of 30-50mph generally. Stock I would get 24mpg over time, if I watched my right pedal play I could avg. 25.

Does anyone know of a fairly inexpensive 0-60 timer that would start on launch, or show a 3-2-1 launch to mimmick being at a track, which would make your reaction count for/against you? I'm wanting to try the race mode for the first time, and I have the ability to also put my tune back to stock and do the same. Hmm, I just remembered the timer has to know when I reach 60 so would have to be plugged into my car somehow.

Edit: also appreciate you guys chiming in about excess capability built in with cooling and what not based on my comments. I know I'm not going "stage 2" with larger turbo, more tune, exhaust, blah blah but I am seriously focused on reliability of the car just with what I have.
 

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Does anyone know of a fairly inexpensive 0-60 timer that would start on launch, or show a 3-2-1 launch to mimmick being at a track, which would make your reaction count for/against you? I'm wanting to try the race mode for the first time, and I have the ability to also put my tune back to stock and do the same. Hmm, I just remembered the timer has to know when I reach 60 so would have to be plugged into my car somehow.
Dragy is probably your best bet. It uses GPS to track speed so no OBD2 interface with the car. Plus you can upload your times to see how you run against other 45’s around the world.

Dragy Website


Amazon Prime Ordering Link
 

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Discussion Starter · #11 ·

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Is there a product out there that does those niche level logging and polling rates that we got with the Dashhawk ?

they used to trade depending on screen burn, hard to believe something that couldn't function in a 64 bit environment has no modern equivalent.
 
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