I have a 2015 E550 Cabriolet, Dyno tuned by RennTech of Stuart FL. Orig numbers 402HP/430TQ. After tuning only, now 560HP/713TQ. Considering new sport mufflers, downtubes, and Diverter valve. I’m told by RennTech Tech that the mufflers and downtube swap should add 30HP and the diverter valve should allow for an increase in boost. Don’t know what HP increase can be added with higher boost.

Is there a known HP level beyond which I would need new head bolts, etc, etc. I would not like to venture into internal mods.

Any and all info greatly appreciated.

 

with all that torque did you upgrade your wheels and tires?

 

Not yet. Tires will need to be replaced soon, that will be upgrade time. Upgrade for brakes will happen then also. Have not started thinking about that yet. Busy time.

 

Every road racer knows that before you start upping the power you upgrade the brakes, tires and suspension. Once you do that and actually learn how to drive, you will actually be able to safely use the power it came from the factory with. And quickly figure out you dont need more power

Amateurs......

 

WRC-LVR: I disagree 100%. I've never had a vehicle that had enough power. Every single one has left me wanting, and usually all I can think of when I floor them is a Moped. Anyone remember those? You always give them full throttle or you're braking, there really isn't an inbetween. When you give it gas from a stop you just sit there in complete boredom waiting for the max 35-40mph to approach. In a typical car I think the same thing, I floor it and look at my watch, check my email, do my taxes while I wait for it to build speed. My truck (Chevota) has enough power in 1st gear, more or less, since it'll break the tires free if I floor it any time in 1st, which ended in 2nd at 60mph. It was a 4x4 so in 4wd it would hook in 1st, so from that perspective I very much wished it had a ton more power. My current E 350 is severely lacking in power, and while I search for an acceptable E 550, which will be much better, I know it too will be lacking so I'm already planning the ecu programming to push it to the limit.
I guess enough power for me would me I can't get it to the ground, as in flooring it at 100mph it'll be burning rubber, but then I'd just want a 4-matic to make use of it and the quest would continue. My guess is it would take well over 1000hp to make me happy, probably closer to 2k, so basically I'll never have "enough". I'll settle for a car that accelerates quick enough that it keeps me entertained so I don't have time to be bored, but I've yet to drive such a thing.
Sure I'd like better brakes/suspension on my C207, more specifically I'd want wider and substantially stickier tires, but the suspension and brakes are not lacking as severely as power, they aren't even in the same failure ballpark. So increased power is easily, without question, the #1 drawback of virtually all cars and therefore #1 on the list of things to improve. In fact it's # 1 thru 6 on a list of of 10. I think the new Tesla that does 8sec 1/4z is the one exception. If I can get an E 550 in the mid 11's I'll at least be happy enough that I may look at the suspension etc, but probably not... Actually I'd want to fix those anti-lock brakes first. Who the F thought those were a good idea? I've come very close to hitting things, cars and people because of that stupid system. Sure it may help an old lady do an emergency stop in the rain, but for me it's far more dangerous than any drawbacks with the suspension.

Coobat2: I wish I could say but my guess is you'll just have to push it until something gives. Hopefully you only pop a head gasket but I worry it'll be a rod. That is a lot of tq for such a small motor... Makes me wonder if you'd be better off tuning out a bit of lower end tq and maybe trimming a bit off the peak rpm to be safe. Like my 400 Chevy could easily make more power if I revved it higher, but I set the rev limiter to 7800 because I felt like I was already pushing my luck despite really really wanting to see the tach hit 8. Maybe you'll be fine, I don't really know and turbos aren't my thing, it just makes me nervous since I've lost motors and I've seen a lot friends lose them, and I can't imagine how much a 550 motor costs... Meanwhile, your power numbers give me hope of having a car I'll be much happier with

 

There's plenty of people who have done turbo upgrades to these cars that have gone into the 7-800 HP territory, and the cars have worked perfectly. The m278 is a stout engine, no worries there, so add your DPs and mufflers, you'll be fine!