190E 2.5-16 help please - PeachParts Mercedes-Benz Forum

NicDale · #1 01-14-2005, 12:04 PM

Hi,

I've got a UK 1991 190E 2.5-16 and its blown a valve on cyclinder 4.

Head is obviously coming off to fix this but while its off what else can be done?

Port and Polish?
New cams? If so which ones and do i need new cam springs or followers?
Tappets? Are mine hydralic or solid? How would i fix the tappet noise?

The head is going to have a good inspection and clean up before going on which should reduce the oil consumption of about half a litre every 1000miles.

What else and in what combinations shall i do?

Also what is the main difference between this engine and the 2.5-16 in the Evo 1 and Evo 2?

Thanks

Nic

MBZ190E16V · #2 01-14-2005, 03:55 PM

u should also try posting on www.190revolution.net

LINDS HANSON · #3 01-15-2005, 12:08 PM

To be honest I wouldnt do any modifications to the cylinder head, the ports and valves where originaly optimised by Cosworth here in the UK for the 2.3 -16 and these specs where carried over by MB to the 2.5-16. The only mods being for either reliability or improved low speed torque. The head is really at its optimum for driveability v performance, any further changes will result in poor low speed drivability etc. The Evo cams can be fitted which again give a power improvment above 4000RPM but actually make the car more lethargic below this point, the Evo 1 had a shorter stroke crank with a larger bore size which allows higher engine speeds and the engine to pickup quicker it uses a different cylinder block. The pistons used by the Evo 1 can combined with your long stoke crank to give 2.6L, this gives a usefull torque increase. The Evo 2 engine tuning became more focused on performance , with only a three main bearing crank, single row timing chain and high lift camshafts this again does nothing for road performance unless driven at high engine speeds. Both Evos run lower final drive ratios to keep the engines up in there higher power band. The main improvments available today would be in throttle body fuel injection and engine management which improve reliability, all round performance and fuel economy. Regards Linds

LINDS HANSON · #4 01-15-2005, 12:16 PM

Sorry I forgot about your burnt valve , basically I have never seen one burn on these engines unless you have a very weak mixture( air leak, bad injector,poor fuel supply, or the valve clearence is too tight[the cam followers are solid with shims to adjust, and must be done accurateley and then redone when the cars as run for about 50 miles]

NicDale · #5 01-16-2005, 11:13 AM

Thanks Linds, so basically theres no real point in trying to get more power out of the std 2.5-16 and i'm just better off getting it running properly?

Nic

mctwin2kman · #6 01-16-2005, 01:07 PM

I would of course fix the valve then port and polish the head. Then get the valves all adjusted properly and put back together. With a Port and Polish it may even run better than you ever remember it. Of course then again I would love to have a 2.5 16V engine in mine!

LINDS HANSON · #7 01-16-2005, 02:47 PM

As I already said theres no more room for improvment on Keith Duckworths head work unless you want to loose power or you are increasing displacement or adding forced induction. The port and chamber design on these heads is far more efficent then the early or late 104 24v engines.Obviously any wear n tear will have to be sorted and spend a few hours getting the clearances spot on.

Racing · #8 06-11-2005, 04:38 PM

Look...
Have had several of them apart.
Own an 85 vintage 2.3-16 myself as a daily beater.

The 2.3-at least the early ones-have VASTLY beefier parts in its innards than the later 2.5;s.
have been into discussions previously as to materials aso.
One thing´s for sure...
The OEM 2,5 parts are NOT to be compared to the 2.3.
Con rods for instance...
The 2,5;s look like a damn joke in comparsion...
Slugs...the 2,5;s are "hypereutectic"(or whatever you wanna call em),and the ones in my 85 are most def forged Mahles..
Crank seems to be forged in both instances tho.
Head...got both laying at the shop.No differences as far as i can tell.2*38mm in asf...
Hedder...yup.The 2,3 is in at a 45mm primary vs a 50 pri for the 2,5.(..and frankly who makes a 2" primary pipe for a 600cc cyl@7 grand?)

None the less..
THe 2,3 makes less power..yup.
AT 500 RPMS LESS!!!
Look at the torq figures between the two,and what rpms they´re achieved.

I´ll put it blunt.
I have no idea why Merc F:ed the cossie idea up.

Racing · #9 06-11-2005, 04:40 PM

To give you an idea.
Old dragracer over here turbocharged one of the 2,3,s back in the late 80;s.
Put it all in a rail chassis and a vega body.
Boosted the living crap out of it and ran a 7,80@330km/h.
What that turns out in power?
You do the math.
Car weighed in at 2200lbs.

Only thing the dude swapped was the slugs,and cut the cam sprockets to be able to dial LCA in.

Cosworth Benz · #10 06-08-2007, 12:46 AM

Old thread but interesting all the same. Just to chip in my two cents: Cosworth has codes for the 2.3-16 (WAA), the 2.5-16 (WAB) and EVO -short-stroke- (WAC). Which seems to suggest that Cosworth's involvement lasted longer than just the period when it manufactured the original heads.

I have a AUTOCAR magazine article dated 7 August which an interview with Mike Hall of Cosworth who was the cheif designer of the 16 valve. He said "It was a fairly straight forward job.... For a start, that 2.3 block was very strong already. The bottom end was entirely standard." The article goes on to say that apart from extra sump baffles, crank, con-rods/caps, bearings in the 2.3-16 were all standard.

Interestingly the 2.3-16 was Cosworth's first one piece head with integral camshaft beds journals machined into the head. This resulted in shifting the camshaft bearings to in-between each cylinders camlobes, as opposed to in-between each cylinder, which Mike Hall saw as beneficial interms of camshaft flex. He went on to describe how he need to access cylinder head bolts determined the distance between camshaft centers, and this in turn determined the 45 degree included angle of the valves. Previous Cosworth designs being around 40 degrees.

From the article, "That particular angle also left me able to choose a combustion chamber volume that allowed me to use flat-topped pistons to get the 10.5-to-1 nominal compression ratio to ensure good efficiency. In fact the final configuration is extremely efficient."

It goes on that the original brief from Mercedes-Benz was for an output of 320bhp, hence the biggest valves that could be practicably fitted were fitted to the combustion chamber. Cosworth were then instructed to detune the engine to 185bhp for street use. 'Hall went back to the drawing board, but revisions required to bring the Cosworth head down to the required 185bhp were limited to reducing the inlet and exhaust port sizes and adjusting the camshaft profiles to milder settings. Gone was the necessity for the dry sump configuration, special conrods and the specialised Kugelfischer fuel injection gave way to the more everyday electronically-controlled mechanical Bosch K-Jetronic injection.'

Hall also talks about the fact that although the order was for 5000 (this is 1987) were being manufactured at Cosworth, "Mercedes does machine and assemble some of the heads itself because at the moment we are not able to cope with the demand."

No talk of engine blocks being shipped to England, however. Rather Hall says "The (exhaust) manifold is a Mercedes Benz product but otherwise Cosworth delivers to Stuttgart production heads ready to bolt into place."

Much has been posted about increasing the power of over the stock level, and I think I've read most of it. And my summary of it all is that almost any power increase will result in loss of flexibility. This was the certainly the case with the 320-380bhp race engines! However reading a recent road test of a stock EVO II in Mercedes Enthusiast, they comment in how much like a standard car it felt like until revved right out, when it gave extra power very close to redline. So the increased power had much to do with the extra revs afforded by the short stroke motor. But going short stroke isn't really an option.

The head flows extremely well and apart from minor cleaning up and port matching forget heavy modification if you want to street the car. Really there seem to be few areas that can be worked: induction/injection and cams.

Cams are and interesting proposition, as the aim would be to fatten the upper-mid range of the torque curve rather than shift it too much higher. From my motorcycling days one way of achieving this was almost grinding a 'cheater' cam profile. Essentially duration and overlap were left pretty much unchanged but the valves were accelerated open and closed more quickly to increase the duration at or near maximum lift. This type of modification can be hard on the valve train and valve springs may have to be uprated and great care be taken in the design of the ramp section of the profile (this eases the valve off and on to its seat).

Other posts have decribed great success in modifying the induction side of the engine with the most radical fitting ITBs and programmable EFI such as Megasquirt. A friends track car has higher compression (racing fuel) modified cams and still uses the stock bosch CIS-E system with the slots in the fuel distributor remachined to match the timing changes. The car makes about 240-245bhp, after all the stock EVO II uses CIS-E. Although to go further custom ITBs and plenum with EFI is required.

t walgamuth · #11 06-08-2007, 05:52 AM

if you have a broken valve you will probably have some damage to the piston as a minimum,

good luck

tom w

pentoman · #12 06-09-2007, 05:59 AM

Good info people

Quote:

Originally Posted by Cosworth Benz

It goes on that the original brief from Mercedes-Benz was for an output of 320bhp, hence the biggest valves that could be practicably fitted were fitted to the combustion chamber. Cosworth were then instructed to detune the engine to 185bhp for street use. 'Hall went back to the drawing board, but revisions required to bring the Cosworth head down to the required 185bhp were limited to reducing the inlet and exhaust port sizes and adjusting the camshaft profiles to milder settings. Gone was the necessity for the dry sump configuration, special conrods and the specialised Kugelfischer fuel injection gave way to the more everyday electronically-controlled mechanical Bosch K-Jetronic injection.'

Does this mean that increasing the inlet and exhaust port sizes again will bring power back up? Can that be done easily?

I took the head off my car just yesterday (see Head coming off - tuning?) and while I am there am continually having thoughts of tuning work etc.!

Quote:

Originally Posted by Cosworth Benz

Cams are and interesting proposition, as the aim would be to fatten the upper-mid range of the torque curve rather than shift it too much higher. From my motorcycling days one way of achieving this was almost grinding a 'cheater' cam profile. Essentially duration and overlap were left pretty much unchanged but the valves were accelerated open and closed more quickly to increase the duration at or near maximum lift. This type of modification can be hard on the valve train and valve springs may have to be uprated and great care be taken in the design of the ramp section of the profile (this eases the valve off and on to its seat).

I could get cams made by a friend of my dad's who used to do them for Cosworth back in the day... but I don't know if I would get much improvement? Does it require lots of calculations and stuff to come up with what you want? Because I don't know anything about that!

by the way I have this article too linked if anyone wants to read it here

Racing · #13 06-08-2007, 03:49 PM

Being one of the few around that actualy is hands on as far as tuning these engines..
I´d say that within limits CB in on the money.

However..
I´ve taken quite a few apart by now and that the innards of the 16V would have all that much common with for instance its 8V counterpart is false.
They differ.A lot.

Stretching the envelope-power wise-of course also leads to the occasional failure.
In the case of the 16V and my behalf though these have been extremely few all things considered.
To tune the engine though..the following should be kept in mind;

1/Above 8 grand OR 400hp in SCd form the OEM conrods HAS to go as these will break.This pertains to the "late" style ones found in late 2,3s and 2.5s alike.

2/Valves are really to soft to rev to the sky.A lot can be found in the OEM manuals about how to quiet the engine down as the customer complains about racket and noises.Therefore..soft material valves et al is a biproduct of the streetworth of the engine i guess.
Anyways..above 8 grand-again-the valves NEEDS to be replaced by heavy duty ones.
The ones i´ve chosen to use is Ferreas,and then from the motorcycle listings.

3/For engines of high rev acceleration the OEM timing chain is also way to soft.This is easy to remedy for a high performance car though as the split of the gears are an industry standard 3/8".
I´ve personaly settled for a hardened chain from the japanese maker Tsubaki.

4/As is stated in the cossie article these engines have to be considered extremely sturdy.
I have never seen a block that from a tech standpoint needed deck cutting for instance.That we opt to do this anyway,and then by average 3/100mm to get it completely straight and true,is mainly to let the headgasket get a fresh surface to bite into
Likewise i´ve never opened one of these engine that needed attention in the main web area.

5/One design "flaw" or whatever you want to call it is the idea of putting the pressure relief valve for the oilpump out of stainless steel into a cast aluminium housing.THis is accessable from the outside,but none the less these DO gall over time,rendering a situation where the valve might get stuch leaving you with conrod bearings that go awol in a flash.
Therefore..ALWAYS take the front cover and give it a go over on overhaul.Better safe than sorry.

6/The KE-jetronic system.
Toss it the F out of the car and be done with it already for ANYTHING but a stock car.
I don´t CARE who is capable of what with it...
It is a dayum hazzle,and if nothing else delicate as well as extremely time consuming to work on.
I´ll take a shoot out on that standing any day of the week-and am currently converting KE cars by loads.

Racing · #14 06-09-2007, 11:40 AM

Pento.
Again.
Numbers don´t lie.
A more or less stock 2.5 head on its 28mm ports will flow inxs of 350CFM.
Do the homework.350CFM is way beyond what you´ll ever encounter a need for with anything close to a streetable motor,so...again..port it...and chances are that you´ll toss driveability down the toilet.

320hp?
I seriously doubt that as the "klasse1" engines develop around that mark,and they´re not to be considered streetworthy in any way if you ask me..
Those are race engines.
It IS a fact that these engines can be had to pull to approx 12 grand these days with state of the art stuff,but be aware that we´re talking a thorough race horse in such a scenario.

pentoman · #15 06-10-2007, 06:00 AM

Sorry I forgot to upload the article I linked to.. it's there now

http://www.knapplane.plus.com/190e/16v/mag/

called "Flying flag"

From autocar magazine when the 2.3-16 was launched