Ultimate Street Sleeper - Mercedes W124 'Superturbodiesel'

[Heaveho]

Is it actually impossible that his particular car can rev to 8k, regardless of whether it's making power or not? That, at least, may provide some clarification as to what is or isn't possible to the laymen among us.

[rassi]

Zombie said:

I think I'm with Max Torque here. basically he's saying that diesel is a slow burning fuel and in order to make the most of it, you need a low reving engine. Which is why he's suggesting 8k rpm is BS.

But, would you, MT, agree that it's possible that the engine could rev that high and be making FA power?

Or are you calling BS on that too?

Seems to me like it's making a stupid amount and they may have calibrated the dyno incorrectly?

+1

Really liked the actual idea of a sleeper W124 with a nicely breathed on derv engine but when the silly figures like 8000 rpm and 560 whp were thrown around, it just lost the appeal, made worse by the insistence that this was true when Max Torque could provide the scientific proof that these figures simply don't stand up to scrutiny.

[maxypriest]

I have read of OM606s with basic mods running 8k,
Fact - IDI diesels rev much higher than DI engines.
My limiter is set at 6200, not that I use it much at all at that end as it's making over 400ft/lbs from 3600 onwards.

[Wills2]

A 680hp 3.0 8k diesel does sound like a fantasy and faintly ridiculous and Max Torque has debunked it, as for dyno charts they can be fudged and the only way to tell is slapping the engine on a bench dyno at a place like MIRA which won't happen.

The other way to tell and what a lot of high end tuners do like 9e is to talk numbers, timed performance numbers as they show the real impact.

I'll go with MT and 400hp which is still great, as has been said if it does produce 680hp then give the Audi Le Mans team a call..

[xjay1337]

Wills2 said:

A 680hp 3.0 8k diesel does sound like a fantasy and faintly ridiculous and Max Torque has debunked it, as for dyno charts they can be fudged and the only way to tell is slapping the engine on a bench dyno at a place like MIRA which won't happen.

How does the sunshine taste out of his ass?


Darkside developments have a 500bhp 2.0 seat arosa tdi also using an s300 turbo. I think 650 bhp from a 3.0 is very reasonable . It usesan elextro mechanical "pd" engine.. the same basic engine you find in a 2.0 golf tdi from the mid 2000s

http://www.darksidedevelopments.co.uk/arosa-mk2-2-...

Suggest you understand the aftermarket tuning scene

Honestly some people on ph..cant just appreciate a good build. Whats to sat mira engine dynamometer is any better than anything that the average poster uses.
If this was a ferrari f40 claiming 800bhp everyone would be licking the OPs japs eye , but because its a crummy Mercedes and a few people are calling BS then it all descendeds into a pissing contense

I believe fully in the op that the car is making 600+ bhp at the flywheel and can run at 8k rpm (albeit not making much power at this speed)

[PhillipM]

In shootout mode, with nitrous.

[Wills2]

xjay1337 said:

Wills2 said:

A 680hp 3.0 8k diesel does sound like a fantasy and faintly ridiculous and Max Torque has debunked it, as for dyno charts they can be fudged and the only way to tell is slapping the engine on a bench dyno at a place like MIRA which won't happen.

How does the sunshine taste out of his ass?


Darkside developments have a 500bhp 2.0 seat arosa tdi also using an s300 turbo. I think 650 bhp from a 3.0 is very reasonable . It usesan elextro mechanical "pd" engine.. the same basic engine you find in a 2.0 golf tdi from the mid 2000s

http://www.darksidedevelopments.co.uk/arosa-mk2-2-...

Suggest you understand the aftermarket tuning scene

Honestly some people on ph..cant just appreciate a good build. Whats to sat mira engine dynamometer is any better than anything that the average poster uses.
If this was a ferrari f40 claiming 800bhp everyone would be licking the OPs japs eye , but because its a crummy Mercedes and a few people are calling BS then it all descendeds into a pissing contense

I believe fully in the op that the car is making 600+ bhp at the flywheel and can run at 8k rpm (albeit not making much power at this speed)

Nothing wrong with the OP's car where did I say there was? But the numbers (680hp) are over the top for me, and stop being rude I know it's late but you sound like a child.

[battered]

Well yes, but the babysitter doesn't mind what he does as long as he's quiet, and his mum and dad will be back soon, then she can collect her 20 notes and go home.

I'm with MT, the laws of physics don't change and if you are claiming something that's off the graph then I'm afraid I don't believe it unless it's checked on a calibrated rig.

400 brake is still bloody good, just not quite as good as Audis £50M Le Mans engine, surprise.

So, custard.

[xjay1337]

Lol this place makes me laugh.
Someone has a dyno print out for a 650bhp diesel sleeper and people are claiming its now 400

There is more proof to say its 650 or whatever it is, than to say its 400

PhillipM said:

In shootout mode, with nitrous.

Shootout mode prooving what? Other than an abilityto read.

[rhinochopig]

For those that are hard of thinking, NO ONE is saying the car or the build is crap - or to use the stupid childish phrase: 'haters'.

In fact, I think it's fair to say that everyone has been universally positive about someone putting a bloody big engine in a small car.

BUT, Max is correct when he says that if you post stuff on PH that lacks credibility, then expect to be pulled up on it.

PH is different to most car forums in that in its membership it has some of the best engineering and scientific minds in the country, who all share the same passion for cars. Post something that is slightly exaggerated or factually incorrect and you can guarantee that you will be picked up on it by someone who is an expert in that field.

[VeeFource]

xjay1337 said:

Lol this place makes me laugh.
Someone has a dyno print out for a 650bhp diesel sleeper and people are claiming its now 400

There is more proof to say its 650 or whatever it is, than to say its 400

Logic clearly dictates the greater proof is the Automotive Engineer specialising in diesel technology applying his advanced knowledge of physics to the argument than some randomer with a certificate and very probably Adobe Photoshop.

Stepping back from that, an outsider just has to look at the motives by either party. What does the Engineer have to gain by challenging the claim vs what does the randomer gain from making the claim. The risk of upsetting people vs forum glory respectively being the answer.

As Rhinoshopig said though, big engine in a small car is always cool so not a hater here

Edited by VeeFource on Sunday 7th February 07:56

[Luther Blisset]

I didn't think it was possible a few years ago either, but I've seen (and heard) too many engines revving to unbelievable (for me, then) speeds that I don't think they were all optical and aural illusions.
IDI is a different ball game. So what if Le Mans teams don't do it. They use diesel for the fuel economy and to push road tech.
This thing will get single digit mpgs on boost, and smoke like mad.
It's probably not that fast against the clock as the powerband has bugger all under the curve and ideally needs a CVT to harness it.
OP is that using a VGT turbo?

[maxypriest]

https://m.youtube.com/watch?v=U7tywICLsVc

Dunno about 8k but this one is revving high!

[maxypriest]

https://m.youtube.com/watch?v=CJK3z4E6slc

If you have any doubts to just how strong these motors are, black smoke racing used to use ex taxi engines in their w123 with intergalactic mirages on them and use them for drifting. Unopened.

[andyps]

xjay1337 said:

How does the sunshine taste out of his ass?


Darkside developments have a 500bhp 2.0 seat arosa tdi also using an s300 turbo. I think 650 bhp from a 3.0 is very reasonable . It usesan elextro mechanical "pd" engine.. the same basic engine you find in a 2.0 golf tdi from the mid 2000s

http://www.darksidedevelopments.co.uk/arosa-mk2-2-...

Suggest you understand the aftermarket tuning scene

Honestly some people on ph..cant just appreciate a good build. Whats to sat mira engine dynamometer is any better than anything that the average poster uses.
If this was a ferrari f40 claiming 800bhp everyone would be licking the OPs japs eye , but because its a crummy Mercedes and a few people are calling BS then it all descendeds into a pissing contense

I believe fully in the op that the car is making 600+ bhp at the flywheel and can run at 8k rpm (albeit not making much power at this speed)

On the basis the first picture seen on that link is the car throwing out enough smoke to get it removed from road use pretty quickly if seen by VOSA there isn't a great deal of credibility in it for me.

Ask a motor industry (ie manufacturer, credible race team etc) engineer why they use MIRA rather than a cheap rolling road the average poster uses - oh yes, we've already had the answer!

I love the idea of this car and have no doubt it makes a lot more power than standard and is quick within a particular rev range (which the OP has effectively said based on the rev range he uses) so am pleased it exists whatever power it actually produced. I am also really happy to have been educated by Max Torque on some elements of how diesel technology can and can't work.

[abarber]

At 8k with such a long stroke, the piston speed is higher than the V8 F1 screamers. Sorry but for more than a split second, that is not believable.

It's a really cool car though, let's not get too hung up on the extravagant claims.

Sleeper of the year candidate, that's for sure!

[abarber]

davepoth said:

Ah, but that's the thing. This engine is derived from a petrol motor, and very unusually for a diesel motor is oversquare, with a reasonably short stroke of 84mm. Doing the maths tells us that the maximum piston speed at 8000rpm would be 22.4 metres per second. That's a lot, but the highest production numbers for piston speed (Honda S2000 and B7 Audi RS4) are over 25 metres per second.

Sorry yeah, I got some duff figures for the stroke. Doh!

[popeyewhite]

rassi said:

... when Max Torque could provide the scientific proof that these figures simply don't stand up to scrutiny.

MT has provided no 'scientific proof' whatsoever. Neither 'side' in the present discussion has. Until someone posts a verifiable video of a person recognisable as an expert in the field of high performance diesel engines the discussion remains open to criticism from both it can/can't camps.

I do think certain posters have been quite rude to the OP, which is a shame because he doesn't appear to have set out to wind up any prima donnas sensitive souls on here.

[davepoth]

abarber said:

davepoth said:

Ah, but that's the thing. This engine is derived from a petrol motor, and very unusually for a diesel motor is oversquare, with a reasonably short stroke of 84mm. Doing the maths tells us that the maximum piston speed at 8000rpm would be 22.4 metres per second. That's a lot, but the highest production numbers for piston speed (Honda S2000 and B7 Audi RS4) are over 25 metres per second.

Sorry yeah, I got some duff figures for the stroke. Doh!

And I just got some duff figures for the speed! the maximum piston speed is 38.3 metres per second, much higher. But that's still lower than either an F1 engine or for that matter a NASCAR engine.

http://www.epi-eng.com/piston_engine_technology/co...

I think it's at least feasible, although unlikely. MB did build things extremely strong in that period, and with the block based on a petrol engine the geometry is correct for sustained running at higher RPMS. If they built the rods strong enough it would probably work for long enough to do a dyno pull at least.

[anonymous-user]

Zombie said:

But, would you, MT, agree that it's possible that the engine could rev that high and be making FA power?

Firstly, the OP has addmitted that this engine has never actually been to 8krpm. He (eventually) said that it was just the fuel pump has been tested to 8k (of course, he means the fuel pump has been tested to 4krpm, as being a 4 stroke, the pump is geared 2:1 to the crank. i.e. the crank would have to be doing 16krpm to drive the pump at 8k.....) .


Lets look at all the other evidence:

1) i've never seen a single "pure" diesel engine (ie no extra fuel from propane or whatever) make peak power above 5500rpm. If you take the theoretical maximum flame speed, calculate the burn rate for an optimum chamber (with optimum turbulence) then funnily enough, you get peak power at a max of 5500rpm.

2) Being DI or IDI doesn't matter. You have to create peak cylinder pressure at the optimum reciprocating geometry, which depends on crank stroke and rod length, but usually is say around 12degCA ATDC. As you can't instantaneously burn the fuel charge (even in a gasoline engine, which relies on moving the point of spark ignition to optimise the Pmax crank angle) you have to start burning the charge early. And the more charge you have to burn per firing event, the earlier you have to start. With an IDI you could start to inject the fuel very early indeed, but it doesn't actually help for two reasons:
a) it won't actually ignite till sufficient enthalpy exists, which only happens as the rising piston compresses the charge and heats it sufficiently. (so inject early, and that fuel sits around in a wet puddle, doesn't even burn when finally it gets hot enough, as just comes out the exhaust as black smoke. (look familiar anyone??)
b) If you burn the fuel early, your cylinder pressure is increasing on the compression stroke (because the mean heat release (10-90MBF (Mass Burn Fraction)) has been moved forwards (in terms of crank angle). Increasing pressure on the compression stroke reduces torque.

Those two factors are the fundamental reason diesels are effectively self limiting in terms of the engine speed at which peak power is generated. It's also why engines designed to make the most power possible have a large cylinder count (for a low swept volume per cylinder) burning their fuel in lots of small short bangs and not a few long big ones.


Now lets look at BMEP (Brake Mean Effective Pressure)

The highest power std OM606 according to Wiki( don't shoot me if this is wrong) makes 130 kW @4400rpm and 330 Nm @1600 rpm.

Peak Power = 12 bar
Peak Torque = 13.8 bar

These are reasonable, if slightly average figures for an IDI engine designed in the early 1990's


Lets look at the current most power full production diesel, BMW's 3.0 M550d, which makes 280kW @4000rpm and 740Nm @2000rpm.

Peak Power = 28 bar
Peak Torque= 32.5 bar

These are very very good figures and the amount of mechanical design (to get the necessary strength to support those pressures and thermal loads) and combustion optmisation to burn that amount of fuel cleanly is world class (hence not every manufacturer has a diesel engine that powerful!!)


Lets compare then, those two benchmarks to the OPs claims of 562 or 680bhp. For the moment, lets assume the chassis rolls power graph he posted is accurate, reproduced below:




The engine is shown to make a very narrow band of peak power, with what i'd suggest is peak torque of 586lbft (794Nm) at 5000rpm, and peak power 562bhp(419kW) at approx 5100rpm. He also claims these figures are wheel figures and that the flywheel figure is 680bhp (506kW) (obviously no details of the method of estimating flyhweel power are given)

Peak Torque, 794Nm @ 5000rpm = 33.3 bar
Peak Power, 562bhp @ 5100rpm = 32.8 bar
Peak Power, 680bhp @ 5100rpm = 39.9 bar


So dear readers, i'll leave it up to you to decide what you think about those figures, but here are some questions to ask yourself:

1) On std internals, would an engine designed for 12/13.8 bar BMEP support 33.3/39.9 bar?
2) Is it likely that the combustion system on a 30 y/o engine is capable of making more BMEP at peak power (5krpm) than the current best ever production diesel engine can make at peak torque (2000rpm)?


An extra interesting analysis that can be performed is to calculate the Brake Specific Air Consumption (BSAC) figures that would be necessary to support the claimed performance of the OP's engine (all the data is there in the graph to allow you to estimate it fairly well). I'll leave it to the interested reader to do that, but by my calc's, the in order to make 680bhp, the OP's (mostly standard, 30year old) engine is slightly more efficient than the current crop of Hybrid F1 engines...........




Now, i'm all for people tuning and modifying their cars, but lets keep it real eh, and unfortunately, physics doesn't lie....... ;-)