Any performance experts on the forum?

[312 Sprinter]

There was a guy on here from the States who turbocharged a 3.0 litre W210 with a head spacer. I think Koolvin ran his turbo kit with a slightly thicker head gasket. The problem with running custom pistons is firstly they have to be made up and second there is no guarantee that the head will cope with the tolerances. There is another guy in Australia who has turbo'd a 230K engine who ran custom pistons. The guys who made them said that it would be better with the OEM piston set up.

I dont think the tolerances are that close not to cope with a 1.5-1.9 mm head gasket. I'm not running a ton of boost either it will only be about 0.5-0.6bar and even that will be set up on a rolling road.

If it works out cheaper just to use a 230K head or block then I'll start looking for one.

If you're only going to use 0.5 bar of boost is it really necessary to lower the compression ratio? I've never turboed a Mercedes engine, but I've done more than a few Volvo engines. At that sort of boost providing the fuelling is correct I reckon you'd get away with the NA compression ratio.

If you're going to use tight squish you need to get the crown of the piston to within 40 thou (imperial) of the head.

I too wouldn't bother with a 5th injector, use a correctly sized set of injectors and a rising rate fuel pressure regulator. If you try to address under fuelling with a single additional injector you're almost bound to end up with the pots furthest away from it running lean or the nearest one running rich.

 

[yellerduke]

i think mercedes fitted shorter con rods so all the gaskets are std fit, on the cars they modded.

 

[NW_Merc]

why do u need a 5th injecter why not just up rate the other 4 my sierra cosworth has 500 bhp and 500 lb ft of torque and still has 4 injecters! are you going to up rate the managment to an after market ecu so it can be mapped and set up right?

The stock injectors are controlled by the stock ECU, upgrading the injectors still wouldnt solve the problem of extra fuelling unless I map the stock ECU

IMO a fifth injector is a bit of a bodge. There is no way of ensuring that the fuel air mix is getting evenly distributed between the cylinders meaning that you may be washing one cylinder and risking serious pre-ignition on another, one will shorten the life of the engine the other may destroy it or at best the knock sensor will force the ecu to retard the ignition to a point where any power improvement is lost anyway. (Both will kill your cat) Without the ability to analyse the flow to put the injector in the right place (I'm assuming you don't have access to a super-computer to model the airflow) there is no way of knowing if it is in the right place. After market (or re-mapped original) ECU is the only, reliable, way to go. Do it right or not at all.

As andy says above with the right mapping / injector choice you shouldn't need an extra injector. (Having said that I vaguely remember RS500s had the facility for an extra 4!)

We're talking about a mercedes M111 engine not an RS500 which is much more tuneable, mainly because there are many ford tuners. The 5th injector will be controlled by an injector driver which in turn will be run by a piggyback ECU. This ECU will control the 5th injector by way of a MAP sensor which will run independently of the stock ECU

If you're only going to use 0.5 bar of boost is it really necessary to lower the compression ratio? I've never turboed a Mercedes engine, but I've done more than a few Volvo engines. At that sort of boost providing the fuelling is correct I reckon you'd get away with the NA compression ratio.

If you're going to use tight squish you need to get the crown of the piston to within 40 thou (imperial) of the head.

I too wouldn't bother with a 5th injector, use a correctly sized set of injectors and a rising rate fuel pressure regulator. If you try to address under fuelling with a single additional injector you're almost bound to end up with the pots furthest away from it running lean or the nearest one running rich.

It would be much simpler only using a FPR. However when Koolvin's car was set up Mark300SL came to the conclusion that the car was running lean and hence needed more fuelling. This why the extra injector was used.

Please can you give examples of where a mercedes engine was turbo'd and therefore I can make an educated guess as to what to do to upgrade the fuelling and set up the turbo correctly.

 

[Ian B Walker]

For your 5th injector, use a Split Second. Mappable and very easy to fit. Janner has one fitted to his car and I fitted one to another.

 

[NW_Merc]

For your 5th injector, use a Split Second. Mappable and very easy to fit. Janner has one fitted to his car and I fitted one to another.

I'll come talk to you about other things I'll need very soon mate

 

[nick.ged]

when ford commissioned the cosworth, the finished prototypes had 350 bhp.

At the time ford were un-willing to put a warranty on a road car with such an high output, so they were 'turned down' to 200ish.

this is one reason why they are so easy to tune to 350-400 bhp.

i had a scooby type RA that had a fifth injector, which was fitted as std. when the turbo was uprated the engine didnt last long, and it had been mapped, was probably just poor distribution.

if the extra injector was fitted ust after the throttle, as in the 103 tt setup, it may negate that problem, and also cause cooling effect on the intake charge.

with 0.5 bar, maybe the std injectors and a rising rate fuel pressure gauge would suffice?

 

[NW_Merc]

with 0.5 bar, maybe the std injectors and a rising rate fuel pressure gauge would suffice?

Any examples of brands mate?