taz069

Morning all. Have a lil 1996 c280 with a blown head gasket. Yeah this sucks only got to put 18 miles on the car since i got it. Got steam out the back and water in the oil. On the bright side, the head is coming off and going to Pilcher's racing machine shop in Enterprise Alabama. While the valve job is being done will have some mods done to the head as well. Might anyone have some suggestions on better exhaust, intake, cams, air intake, computer mods, (roller rocker arms?) Don't know about the last item. Any links are welcome. Don't want to blow out the rear end or tranny. So just a solid 35-60 horse increase is all I'm looking at. With everyday driveability. Thanks all and Happy New Year.

c280drifter

If you want to get more power out of the car put in a 8pin chip and reprogram the ECU,put on a nice Magnaflow muffler and heads the exhaust,K&N cone custom air intake that you will need to make yourself.

durableswedish

have them port and polish everything they can and shove the largest valves that will fit in there. With the extra air flowing through it, you'll need to have it tuned because it'll probably run really rich. Good headwork can easily run $1000-2000 and pick up 20-50hp with a retune. HP=$$ isn't really worth it, but for simplicity's sake it'll be more reliable horsepower then putting together a backyard turbo kit.

vanir

I seem to be having this same conversation a lot with new MB owners here. Straight engineering talk here, having built/raced at local tracks I can tell you the M104.94 already has most everything you'd want to do to a base engine to get it performing well.
You don't bother with lumpier cams because it's got DOHC/24v to start with, it flows plenty. The bonus of this setup is the small, multiple valves means you get high flow rates but good low engine speed velocities (no sacrificing torque for high end flow).
So it's already as good as getting a SOHC/12v like the M103 and putting a big lumpy cam in it, only yours actually returns better torque qualities as a bonus too.

Bottom end is very well balanced and tough as nails. Stock engine speed is around 6500rpm (max power at 5800). The stock head is already ported to flow very well at 4-6000rpm so what more could you possibly need there? Not that there's much more that the best engineers could possibly do for it anyway. It's built to make horsepower as it is. And it does.
You've got 171 cubic inches and over 190 reliable hp as it is, that's more than 1hp/cubic inch and that's a high output build already. Doing more is talking about race tuning, expensive race tuning. You couldn't even bolt a small turbo on it, you'd need a really big one (large island-cfm rating), or the N/A operation would outweigh the turbo addition because it already flows so good.

Stock compression (static) is already 10:1 so you don't want to go any further there. You don't want polishing of the intake, it hurts performance and the porting is already excellent, there's no real gains to be found since the head design is already excellent, it's not like a Ford motor or something where some angling isn't so good and needs boring. Benz engineers spend a lot of effort concentrating on chamber dynamics, using high compressions to squeeze the most out of a given fuel type, they approach it like race engineers at the factory. Normally an engine like this would tolerate about 9.0:1 built by Toyota or Dodge or whoever, Mercedes chamber/porting gets them cooler cylinders for higher comp, it's the best you can do without lowering the dynamic comp with valve timing. When designing the head they carefully studied both cfm and gas velocities per engine speed, the type of equipment and/or experience you'd need to improve on it makes a cost-benefit ratio prohibitive. Unless you're planning on driving it at Le Mans, why?

You want a big power increase, 35-60hp more on an already high performance engine is a huge leap, not a small thing. Don't get taken in by all the aftermarket salesmanship around the place with "bolt in 50hp chips" and whatnot, it's all fiction in the first place, engines put out what they put out, to some extent they maybe detuned for the consumer market and this can be undone by chip remapping and so forth, to some extent, but this just isn't the case with the M104, which uses CIS-E injection and fuel flow is largely mechanical, spark is very simply controlled by a unit responding directly to sensor input. It's not as modifiable as a fully electronic injection system, isn't mapped as such, a lot of it operates mechanically, but word to the wise, it's actually a very good race type injection system used by Porsche and Le Mans engines for years. It can give more than anything you can use fuel wise without modification.
Just make sure your injectors are clean or new, and the fuel distributor is in fantastic condition or get it reconditioned, those are the only two points CIS-E really falls down on, needs to be in excellent condition to deliver and then delivers like crazy.

So let's talk about what you could do.

First up if you want a big power increase, source a 3.2 litre M104 and swap them. Like the relationship between 2.6-3.0 litre M103 everything should bolt right up. Only real difference between engines is one was for the small economic C-class and the other for bigger, more luxurious E/S classes, it's worth about 20hp just for swept capacity.

Following that you're looking at small increases to the anciliary tuning, exhaust and intake piping. Make sure you've always got a new paper filter in the airbox or swap out for a free flowing aftermarket cotton one like a K&N. The piping to the airbox/aircleaner housing you might be able to raise the diameter of and reseal, or cut the entry for a more square intake. The exhaust system itself, Mercedes makes pretty high flow mufflers and cats (among stock factory contemporaries), but they usually choke it a bit ahead of the rear axle for a quiet tailpipe. Your stock system is probably like my M103/W201, twin header running two pipes then a single from the underfloor resonator to a tail muffler. You can cut it behind the cat and ahead of the resonator where it's still two pipes, and either run two pipes back for a twin system (cost more, need 4 mufflers), or a larger bore single system and bigger diameter resonator/muffler in a single (which I did).
Those two things will probably get you 5-8hp at high engine speeds.

With both, a 3.2 litre changeover and bigger system, free flowing air cleaner, looking at around 225hp is a pretty tough output for the weight of car.

Yes you could do a little more, or go for broke on the 2.8 litre you've got. But what you're talking about is retuning it mechanically, it means you're going to lose some drivability and low-mid range, for a top end gain you'll only ever see when you've got the engine screaming at high rpm.

You can seek aftermarket retuned cam grinds, with a DOHC/24v you want only subtle changes from stock for best returns and probably don't need to worry about duration, just a little more lift. It's tricky though, the timing between cams has to be well conceived and tuned, meaning only reputable engineers experienced with this engine should be used, or you'll lose more than you gain or might just lose power and gain none. Improving on Mercedes engineering take serious expertise, typically it's always best just to go bigger engine capacity, it's what AMG did/do.

Swapping out the valves for bigger diameter will again kill some of the good torque qualities you have, lowering gas velocities at low engine speeds and reducing power in low-mid range driving. I wouldn't advise it because the 24v setup already flows more than enough for 6000rpm and what exactly are you planning, revving its **** off to 8000? You'd probably lose more than you'd gain, but if you ran it at high rpm all the time (ie. this was a track-only car), sure you'd do that for an extra ~15hp along with some bigger rating injectors. Fairly superfluous and expensive for a street car, you'd probably be looking at changing over the whole injection system for an aftermarket fully electronic one you can map and remap trying to get it right.

From what I can figure, you could swap the inlet manifolding for the 3.0 litre sports M104.98 one (300E-24 and S-24 models), it flows a little more up top but kills some torque to do it. Stock injection bolts right on. But here is what I was talking about, car would actually be a little more sluggish in normal driving for a hp increase on paper, that most of the time you never see. That's the thing about chasing power figures, performance isn't about that it's about tuning and parts matching. The engine with this manifolding had variable valve timing and cylinder cooling jets to compensate, but Mercedes replaced it with the 3.2 litre M104 for the same effect and better torque. Still it could get you something like 7hp on the 2.8 if you wanted to squeeze that engine.

What it comes down to is if you're chasing 250+hp you're really looking at a professional, experienced turbo kit installation, from someone like Mosselman. It's big dollars but would get you something like 300hp.
Otherwise, respect the fact you've already got a 171cid engine that pumps out well over 190hp and that's big power as a performance engine in its class, look past the fact it acts so sedately. Your aims for reasonable increase should be much more subtle, 3-7hp here and there for some anciliary improvements, put in some quality plugs and make sure maintenance and tuning is in tip top shape. You could aim for something like 210hp with the 2.8 or 230hp with a 3.2 litre engine swap, if you do exhausting and just replace anything aged/worn with the best.

Headwork? There's really nothing to do there. At most, polish the exhaust port a little, that's it, don't touch inlet. Keep the valve sizes you've got, and don't let someone go cutting up its excellent factory porting, or shave it. Or ask a Mercedes engineer to have them tell you the same thing. Hell I got told this even for my M103, and it wasn't in their interests since they could've gone ahead and charged me a packet for superfluous work. Mine's SOHC so I'm doing a major cam upgrade, they told me specifically the stock head is already flow-benched for a lot more than my aftermarket cam can deliver, it's a waste of money and probably hurt performance messing with it.
And that's the engine series prior to yours, it doesn't have 4v/cyl like yours, and it doesn't flow as well as yours...signified by your higher static compression for the same power band. The higher compression on same fuel means lower operational cylinder temperatures, meaning better excavation, meaning better porting, chambering and flow. If you took the head off a '96 Ford 4.0 litre and took it to a machine shop they could find things to improve, on your M104 engine they're just going to say, hey it's already done...or worse, charge you a fortune for work that actually reduces performance and didn't need doing.


Conclusion: swap it for a 3.2 litre. Get an aftermarket exhaust from the cat back. Get it in tip top condition and tuning. There's your reliable power increase without costing a house.
Alternatives are superfluous and/or extremely expensive if you want any more than just a couple of hp here or there. It already puts out heaps of power in its class, as engineered from factory. Re-engineering is a ground up prospect, being the starting point is really good already.
Otherwise: specialist turbo kit installation, Mosselman or the like. Big bucks.

Most people are pretty happy with just an aftermarket exhaust on these sort of Mercs. With a universal aftermarket cat and big bore system, not really as much of a power increase as idealists propose, but the sound and sensation is very sporty which is the part about their Mercedes that they really wanted to improve in the first place. Just a driver enjoyment thing. You should be finding stock power isn't bad at all, become clear about what you really want from it, you'll probably find it's just a more sporty feel from a snarl in the pipe.