Engine Specialist to this thread!
 

Alright so i've looking around at ways to mod my c350 and yes I already know the main stuff, exhaust,intake,ecu. But after doing some research, how is it that porsche can get 450hp out of a 3.8l flat 6 engine? I know it has a lil more displacement on our cars but the 3.5 c350vs the 3.0 c300 is what? only 40hp and thats .5l bigger? I know our cars are no where in the same category as the gt3 rs. But any information on how to mod our cars and any information on how porsche gets 450hp out of a 3.8l flat 6 would be great.


In short: How to get more power out of our 3.5l v6 and how does porsche get 450hp out of a 3.8l flat 6 without turbo/supercharger?

Learning cap is on! :zoom:

im just going to take a shot in the dark on this, there are a number of things that could be done differently one of the biggest is Head work, porting, polishing gasket matching identicle cfm runners, piston material, crank grind, cam degree, intake and exhaust valve jobs....in short there are a number of things that can be done internally to make 2 "same" size engines , very much different., im probably way off, but it was just a thought.

^^^ basically what he said.
MB designed the engine for family sports car category, and then the AMG unit for flagship c class category.
if u done what was said above itll probably be another engine already, sacrificing some reliability and some mpg probably, or u could always slap on some twin turbo setup to get top hp per dollar spent
but whats the point, if u want fast, get AMG
oh and besides flat 6 and v6 behaves differently too so for same cc flat 6 will probably be more powerful

Alot of the performance gains relate to compression, cam size/shape, valve size, intake/exhaust size and how the fuel and timing maps are set up. The powerplant engineers make a decision that has to balance power, reliability, and emissions. So for instance the C350 is 3.5L, 11.3:1 compression and makes 268 HP... The stock 911 is 3.6L, 12.5:1 and makes 345HP. The carerra S is 3.8L, 12.5:1 and makes 385HP and finally the GT3 is 3.8L, 12.0:1 and makes 435HP.

When mercedes settles on the design for the C350 engine, they are specifically looking for an engine that will last the warranty period without any issues, have very low emissions, and provide a decent amount of performance for the driver ( i would say that C class owners tend to be performance minded). The C350 meets all these requirements and does it at a price point that is pretty darn reasonable. When you start to get into the porsche vehicles, you have and engine that is only a little bit bigger but it makes 75 HP more. They do this by (1) increasing displacement a little (2) increasing compression (3) increasing intake and exhaust valves (4) increasing the size of the intake and exhaust systems (5) mapping for lower emissions (still within the legal limit of course) (6) mapping for higher power with lower reliability (7) using lighter parts inside the engine. The Gt3 takes this further by incorporting a variable valve lift system called variocam which allows more fuel to be pumped in at peak periods while scaling it back otherwise (normally increasing valve lift duration has some pretty negative effects at low rpm/power levels like rough idle and terrible emissions).

Of course all of these improvements come at a cost, both in materials and in reliability... The porsche engine simply will not last as long as the mercedes engine. It is still a reliable engine but there is an inherent decrease in operating life that comes with increased output. Parts will cost more on the porsche engine; they will use stronger materials and be machined to tighter tolerances to achieve the better performance.

If you want to increase performance of a W204, it starts a simple as having the ECU reflashed with new maps. Often just a reflash will give 10-50 HP depending on the engine and how conservative the OEM was with the original maps. tuners are listing gains of 30-40HP for the C350 which is a nice gain for not physically changing anything... Just remember that these sorts of tunes *will* decrease you engine life and/or reliability...

rob,

Excellent explanation - thanks for the detailed information !

Would love to hear more about 30 - 40 hp gains for the C350

( of course I understand these are just "claims" )

Any particular tuners you recommend or have any experience with ?

Thanks,

Nick

I had the powerchip ECU tune on my C300 and it does run stronger. For $650 it was well worth it. I believe it added about 30hp and a fair amount of torque.

Great responses from everyone! Especially rob.

The reason I'd like to mod the 350 is for good mileage and at 19 with a bad record a 63 would cost me soooo much lol. But like any car enthusiast I want to learn with hands on experience on how to mod my car and gain more knowledge on car modding. As well as going to school for mechanical engineering.

I was just blown away at the fact that porsche can get 450hp out of the 3.8l 6 and was wondering how on earth they could do that without turbos or s/c.

One other question is, with installing lighter parts ( pistons/rods/rebalancing crank) would that allow for easier/higher revs?

@joearch, who/where did you get the ECU tuned at, and i am assuming it was a case of pulling the ECU out and shipping it?, what was the down time?

I did my ECU with Carlsson, and besides doing an excellent job at it, they made sure I was not left with a voided warranty unlike most other ECU flashers. The Carlsson warranty is honored by any Mercedes dealership without any hassle.

Yes... any lightening of moving/rotating parts will have the added benefit of increasing the engine response as it decreases the inertia that needs to be overcome. This is especially helpful with things like the piston and connecting rods which are reversing direction. Any decrease in mass of the piston in turn decreases the stress on the material (although to be fair by lightening the pistons they may also have lower overall material strength so there is alway a tradeoff).

The porsche engine is a pretty remarkable achievement: at 450/3.8L thats 118HP/L which is pretty much the highest power/displacement ration you can find on a NA production car. (the elise/exige comes in second at 190HP/1.8L or 105 HP/L). Both engines do this using a variable valve technology although the porsche variocam system is more advanced as it has greater variability. The variable valve technology is really the future of performance and efficiency improvements in all engines with the big gains coming from the move to camless engines (electronic valve technology). It is thought that the moving to electronic valve systems can put engines in the 130-140HP/L area although the real gains will be designing very small FI engines that have extremely low emissions with great performance (think 1.0 L turbo engine that makes 180 HP and gets 75 mpg when you drive "nice")

Interestingly enough the W204 c class was supposed to be the first production car that used a camless engine with electronic valves. it was called W204 KDI EVT (kompressor direct injection electronic valve train) and it was supposed to be out back in 2007. Obviously that didnt happen;they are still working out the reliability issues with the technology butthey are coming... now supposedly next year...

From what i know is available for the w204 an ecu tune is the best bang for your buck.. it will give your c350 about 35 hp(not to the wheels)..i had an ecu upgrade on my c300 and i noticed a small difference(was told only 15hp).. main thing i noticed was the way the car shifts and it was less hesitant/more responsive. What i learned to accept is that our cars are just not fast!! There are plenty of cars out there that you could have purchased for the same $$ that would blow our cars away,and the amount of work you would need to do to the motor to make it "fast" would cost a rediculous amount oif $$. Id say just be happy with what you have.. its still a beautifull mercedes!

NEVER!!! :rolf: :rolf:

My friend owns a c350 and has the renntech ecu/header pkg. He got it done at knauz and was able to keep his warranty. Aside from the renntech he also has a remus exhaust w/x-pipe and it sounds perfect! not annoying or "hey look at me" type of noise. and I think he has BMC or green airfilters, don't remember.. but overall I've driven stock and then renntech and its a night and day difference! Don't expect to be c63 fast but expect to change your thoughts about this car not being fast. But where this car shines is the highway it rockets to 155 like nothing. fter this set-up its either forced induction or get a faster car from factory. theres nothing much more you can squeze out of this car with out heavily modding it and risking the inveitable. sure you can make this car have 600+ if you strap a turbo. but what about the rear end, trans, internals of the motor...etc that porsche motor was designed from ground up to handle 400+hp and everything in and around the car is designed to handle the power. your comparing apples to oranges. one is luxury brand aside from AMG, and the other is race breed. mercedes wants their cars to be reliable, safe, and then comes performance. AMG is driven by power. Porsche is in a different league. They are made to go fast and not only in a straight line.

LMAO with the guy above me...true gear head

Great information again rob!

My plan for this car is to get 350hp and around 3000lbs although the wieght will be hard.
I got some major plans in the works just waiting on the cash to flow in. But i could care less about blowing money, I'm learning and having fun 1 project at a time.

I went to Powerchip in costa Mesa. They took out the ecu and did the work while I waited. Took a couple of hours