M271 supercharger type, screw or roots

[Bellow]

Ok back on topic, superchargers and boost plus heat management, I can come back to heat management later, it is important with a roots type blower, in post 9 if modifications are made in the right order, reducing restrictions on both intake tract and exhaust, boost lowers, would it not be ok to fit the larger charger off the -/+ 200 HP 230?

This may achieve the same result as a pulley chane with the original charger to bring boost back to original level, but with the benefit of not pushing the charger out of efficiency and just generating heat, you can over speed a charger, , another topic,

If you ended up having to reduce the speed of a larger blower you may well end up running it at reduced volumetric efficiency (more time for air leakage back past the rotors). If the smaller blower can handle more rpm without any other efficiency loss - I'd work with it.

Supercharging (mechanical or turbo) brings another variable that isn't well acknowledged, namely, a gain in engine volumetric efficiency by lowering the compression ratio. Not immediately obvious as to why, but if you are chasing power above all else (as opposed to a more (fuel) efficient road motor) - worth considering.

 

[Stocious]

Thank you, I had ideas how to get round the compression ratio issue, looking a what can be done with SIM4lke atm, I’ll leave the intercooling alone as what you say is correct and I can’t phrase what I’m getting at correctly, fuel economy would not be the issue, I understand how compression effects it at different loads, , thinking now, the best starting point is buying the higher rated engine and improve on that as the combustion chamber seems to be of very high standards and blending and cc’ing will not provide any noticeable drop, can I pick your brain? Am I right in thinking the higher rated horsepower engines has a clutch on its charger?? Thanks

 

[Bellow]

Thank you, I had ideas how to get round the compression ratio issue, looking a what can be done with SIM4lke atm, I’ll leave the intercooling alone as what you say is correct and I can’t phrase what I’m getting at correctly, fuel economy would not be the issue, I understand how compression effects it at different loads, , thinking now, the best starting point is buying the higher rated engine and improve on that as the combustion chamber seems to be of very high standards and blending and cc’ing will not provide any noticeable drop, can I pick your brain? Am I right in thinking the higher rated horsepower engines has a clutch on its charger?? Thanks

If I can help at all - I'm happy to.
The 55s(?) have clutches - there's often threads on this forum about them 'chirping' on engagement. I thought the four cylinder motors had them too? That and a by-pass for part throttle cruise fuel efficiency?

 

[Stocious]

Mine just has basic pulley, looking around the better engine seems to have electric clutch, idk, not up on the models , yes it has a bypass, , look at the size of the intake valve, it seems they were overbuilt, and under rated

 

[Stocious]

Looking at a very good performance orientated N/A engine the valve sizes are on par,

 

[Bellow]

Looking at a very good performance orientated N/A engine the valve sizes are on par,

When the first of the (205hp) Sierra Cosworths appeared everyone was blown away by the headline power figure. What they missed was that the head without turbocharging would have been good enough for 150hp. Prior to its launch, 4 valve/cyl motors were pretty rare and many looked at the Cosworth's power as being roughly double that of the 100hp Pinto. Wrong comparison. A comparison with a good flowing 16 valve head would have shown the turbo only added circa 55hp. A gain of around 35%.
Getting the basic breathing right is as important with a blown motor as a NA one. What used to confuse the issue though was cam choice - often in the early days of turbos to get around lag issues. VVT takes care of that nowadays.

I'm less enamoured with blown motors than I once was. The need to over-fuel to keep temps and detonation in check isn't as things should be in my opinion and if emissions tests tested at real load - I wonder if forced induction would be so prevalent.
Something I've picked up on on a USA forum that I've not encountered on a British one is fuel enrichment for keeping cat temps low. The theory is the enrichment excludes any possibility of oxygen being present in the cat which would (chemically) overheat it. Maybe a consequence of lower octane fuel in the States with lower CRs leaving more heat in the exhaust stream. Maybe the more modern motors are less dependent on this than the large bore, 2 valve/cyl motors we're running but they will heavily enrich after 60 seconds of running at 60% of WOT or more.

 

[Stocious]

I stick to the 100hp/liter baseline when comparing things, my last car was an Audi S2, 280hp from 2.2 liters, dated but a fantastic car to boot, the new 07k 5 cyl flows more stock than a perfectly ported if such a thing, 3B head, That engine needed a rebuild, I believe it was detuned before sale as it had substantial invoices from DIALYNX, I’m keen to get the most out of the M271, including most miles, dosnt the USA have very stringent emissions laws, oxygen bonds with something in the exhaust I think creating a unwanted gas, not sure on that so if I’m wrong tell me, but it’d be no good if cars weren’t legal in all states, now I want three things , a tyre machine, engine stand , exhaust gas anylizer,
As it stands I’d like to watch boost from a dig to redline and measure exhaust back pressure also, call it logging

 

[Bellow]

Isn't there an app you can use via the OBD port to log some of what interests you? Back pressure I've tried to monitor via a pressure gauge on a small 2-stroke but the violence of the pulses make it difficult. Maybe easier with a 4 cylinder 4 stroke - and/or use an electric/electronic sensor (that can withstand the heat - or mount remotely) and monitor it's voltage output. I'd be interested to know what your back pressures are.

I have a bit of 'logging' to do. I'm running LPG and the software allows real time data to be read on a lap top. Lambda data is what I need. I have to take a USB lead from the engine bay to the cabin first though.

Not really sure what the thing is with the Yanks and their overheating cats but it does bother them. Melted cats are pretty common it seems if they get things wrong. Apparently, the EML light will flash if the cat temps get too high. Don't know how and where it's monitored but I've never heard of this outside of the USA.

 

[Stocious]

Back pressure method, drill a hole before cat, steel brake pipe size, hammer in a bit of brake pipe, and you a carb synchronizer to read pressure, that’s also what you needed with the 2 stroke, but you need a valve inline which you keep pinching shut till the needle stops bouncing, when your finished mig the hole, works to rule out a blocked cat also, I’ve maintenance work yet to do, and have to before I start messing, I have auto data I’ll see does that read boost, have no idea why I didn’t think of that all ready

 

[Stocious]

Autocom I meant, have autodata too can check both, a documented value and live data, worries me, scan tools and Mercs, youl always find a few codes, there so gizmo dependent

 

[Stocious]

Boost boot to floor to rev limit : 8.8 psi
from a dig as far as I can tell you almost get full boost instantly
The graph goes literally straight up and raises slowly to max, ever so slightly,
I went through three gears result all nearly identical each gear

82 degree coolant
IAT. 38 degrees

The spike in boost is when the bypass valve closes, part load or cruise it produces very little boost

 

[Stocious]

For comparison after a quick search

VAG 1.8t 9psi. 150 hp crank
My car is running same boost with a 13hp advantage not to forget loss through turning blower

 

[Stocious]

Will test boost again once I have cold air intake pipe bought and fitted, it was torn, 9 psi seems to be the norm on a cold day

 

[markjay]

Can't help with any of the tech info, but just to say that as far as I know the difference in output between the 1.8L M271 on the C180K (143/156bhp), the C200K (163bhp), and the C230K (201bhp) is down to reduced compression ration in the combustion chamber and increase in supercharger boost pressure.

But I don't know for fact if the higher boost pressure was achieved by using a different supercharger, or just a different pooley (or both).

Increasing power (safely) on the M271 engine isn't straightforward because in addition to increasing the boost you need to also skim the cylinder head (and remap the ECU).

 

[Stocious]

Can't help with any of the tech info, but just to say that as far as I know the difference in output between the 1.8L M271 on the C180K (143/156bhp), the C200K (163bhp), and the C230K (201bhp) is down to reduced compression ration in the combustion chamber and increase in supercharger boost pressure.

But I don't know for fact if the higher boost pressure was achieved by using a different supercharger, or just a different pooley (or both).

Increasing power (safely) on the M271 engine isn't straightforward because in addition to increasing the boost you need to also skim the cylinder head (and remap the ECU).

I was under the impression that the pistons were different determining compression, the heads should be the same across the board, if I’m wrong it’s a new thing I need to look into,
Basically if I can get my way it’ll be a rebuilt highest output engine with all the intake and exhaust side improved, that includes cylinder head porting, gasket matching and a three angle valve job, any specialist work I can get done in the local engine centers, I have loads of time and I’m keen, Ive previously been on another forum where the ecu was reverse engineered and I know anything is possible even a quick search shows that it’s been done, the boost figure, hp ratings, induction type, leads me to believe there’s a bit to free up yet, there a good engine

 

[Bellow]

Boost boot to floor to rev limit : 8.8 psi
from a dig as far as I can tell you almost get full boost instantly
The graph goes literally straight up and raises slowly to max, ever so slightly,
I went through three gears result all nearly identical each gear

82 degree coolant
IAT. 38 degrees

The spike in boost is when the bypass valve closes, part load or cruise it produces very little boost

For comparison after a quick search

VAG 1.8t 9psi. 150 hp crank
My car is running same boost with a 13hp advantage not to forget loss through turning blower

Lower boost figures than I might have expected.
My 700cc smart runs 0.8 bar (12psi) boost for 60hp, the 75hp version uses 1.0 bar- the whole 14.7psi.

 

[markjay]

I was under the impression that the pistons were different determining compression, the heads should be the same across the board, if I’m wrong it’s a new thing I need to look into,
Basically if I can get my way it’ll be a rebuilt highest output engine with all the intake and exhaust side improved, that includes cylinder head porting, gasket matching and a three angle valve job, any specialist work I can get done in the local engine centers, I have loads of time and I’m keen, Ive previously been on another forum where the ecu was reverse engineered and I know anything is possible even a quick search shows that it’s been done, the boost figure, hp ratings, induction type, leads me to believe there’s a bit to free up yet, there a good engine

I wasn't suggesting that the lower compression ratio was achieved via using a different head - it may have been the pistons, I don't know (there's more than one way to achieve it).

What I meant to say is that if increasing the boost pressure as a mod, then the compression ratio will need to be reduced, and the easiest way of doing it is by skimming the head. Replacing the pistons on the C180K engine gets you to a point where you should be asking yourself if it's worth it, i.e. why not just buy a C230K engine and be done with it - they are very common across Europe and can be easily imported from beakers.

On a general note, modern engines tend to be highly-stressed in order to maximise efficiency and reduce emissions and fuel consumption (and, a smaller engine doesn't just consume less fuel, but it also weighs less, further aiding emissions/economy), so getting more BHP out of them isn't as easy as it used to be... the M271 is fitted to mundane run-of-the-mill C180K cars, but I am old enough to remember the time when 'DOHC 16' was rare and exotic and had the 'wow' effect on petrolheads

 

[Stocious]

Lower boost figures than I might have expected.
My 700cc smart runs 0.8 bar (12psi) boost for 60hp, the 75hp version uses 1.0 bar- the whole 14.7psi.

I’d like to know how much horsepower the charger consumes to sum things up

An alternator is somewhere in the region of 5hp charging,

Exhaust back pressure next I think as we’re both interested in that

 

[Stocious]

I wasn't suggesting that the lower compression ratio was achieved via using a different head - it may have been the pistons, I don't know (there's more than one way to achieve it).

What I meant to say is that if increasing the boost pressure as a mod, then the compression ratio will need to be reduced, and the easiest way of doing it is by skimming the head. Replacing the pistons on the C180K engine gets you to a point where you should be asking yourself if it's worth it, i.e. why not just buy a C230K engine and be done with it - they are very common across Europe and can be easily imported from beakers.

On a general note, modern engines tend to be highly-stressed in order to maximise efficiency and reduce emissions and fuel consumption (and, a smaller engine doesn't just consume less fuel, but it also weighs less, further aiding emissions/economy), so getting more BHP out of them isn't as easy as it used to be... the M271 is fitted to mundane run-of-the-mill C180K cars, but I am old enough to remember the time when 'DOHC 16' was rare and exotic and had the 'wow' effect on petrolheads

I wasn’t trying to wrong you, thanks for your input, I can always look back at this thread for info

I think I will buy a c230 engine but I know nothing about them at present, still supercharged?? Are they not the evo engine?? I just want the best start to bolt to an engine stand and go from there, it needs to work with an E class w211 auto, the box is more than capable

 

[Stocious]

Here’s a question you don’t hear often but may indicate if head was used in F3 application, or even just a similar design,
What diameter are the hydraulic followers??