There is some discussion on MINI2 that the new engine wont be able to handle more than 250 HP (or so) being aluminum. Head made of plastic? It might be offset by being lighter but anyone care to comment?

 

yea I think someone told me the same thing on here somewhere... I think it was Brian from Webb Motorsports... He said something about having to do something with iron I believe if u wan't to go over that... heat/strength issue I think he told me...

correct me if I am wrong!

Mikey

 

don't know if its true but my guess would be:
PLASTIC HEAD = GARBAGE.

 

No, Your RIGHT. Aluminum crankcase vice cast iron. Plastic head??? I think that is exactly the issue.

 

Is it possible to have a plastic head?

 

how much HP are people pushing with engine alone on the current Coops?

 

Read that on Motoringfile.com's writeup on the new engine.

 

not coopers, but on MCS, people are pushing close to 300whp, so that's pretty close to 340bhp.

 

There is no such thing as a plastic 'head'. The valvetrain cover can be made of plastic (as in our current engine) as well as the intake manifold (in the MC only, MCS is aluminum), but a plastic head would melt.

Old timers to the MINI will remember how the early days of probing the performance limits of our little 1.6 was accompanied by predictions that much over 200 was not possible, and people are still pushing this engine to new limits. It still has a lot of potential.

An iron block, while not very elegant in today's terms is still the most able to handle large amounts of stress and remain reliable. This is not to say an aluminum block cant (most race engines, including 5000+ HP Top Fuel dragster engines are made of aluminum), but the strength must be engineered into the block to begin with, just as it is with an iron block.

I've looked over the specs and construction details of the new engine and I believe the bottom end will hold up pretty well. The aluminum engine will have a ladder-style unitized main bearing sdalle like the curent engine has, along with a deep skirt design, forged crank and sufficient crankpin and main journal size to hold up to some decent HP levels. Hopefully the engine will have enough beef in the bottom end to hold up to higher HP levels reliably.

 

^^ i can't wait the new motor

 

Thank you for clarifing. Thats why I asked.

Oh, and it said "cylinder head cover made of a special plastic material" whatever that means.

 

hehe, thats I guess what I meant but is that with the super charger or without? Because if it means engine alone can push 250, does that mean, then a turbo can add another lets say 50HP OR total 250hp.

 

I think they're talking about how much the bottom end can handle. They were saying that the bottom end can handle 250hp similar to how a skyline and supra bottom end can handle 1000hp.

 

ahhh ic ic. Seems that 250hp might not be a whole lot wouldnt you think for just an engine? Alot more then I got going right now, 115

 

If an MCS engine is putting out 300+hp at the wheels then the engine's putting way more than that at the flywheel. Drivetrain loss is around 10% to 15% and don't forget that supercharger requires bunches of HP to drive.

At that output level the supercharger alone can eat maybe 20 to 30 (or more) HP, so at the crank, the engine could be pushing out 360hp if one could measure the HP without the supercharger's needs being already subtracted. (One can calculate the amount of HP the supercharger consumes...)

The turbocharger version will not have the parasitic load from a supercharger so the engine will not have to be stressed as much to deliver the same (or even more) usable HP. Mileage should go up a noticable amount with the engine delivering the same perceived performance.

Sincerely,

RockC.

 

RockC wrote:
>The turbocharger version will not have the parasitic load from a
> supercharger so the engine will not have to be stressed as much
>to deliver the same (or even more) usable HP. Mileage should go
>up a noticable amount with the engine delivering the same perceived >performance.

Well, I had to disagree with ya, there Rock. Turbochargers do indeed
have parasitic load. It takes energy to compress air, no matter whether
it's from power taken directly from the crankshaft, or by using exhaust
gas to force air through a restriction in the exhaust system. Think of
it this way: what makes more power - a motor with a tuned header
and open exhaust, or a motor with a restricted stock exhaust system
and catalytic converter? Turbos work by placing a restriction in the
exhaust system. Even with waste gate, they still are more restrictive
than nothing at all.

On the issue of fuel mileage, again, you're forgetting the main reason
the current Cooper S gets crappy mileage. It's the low compression
ratio. Any supercharged engine, be it mechanical or turbo supercharger,
needs to have a low compression ratio, else when you go to positive
manifold pressure, or "boost", the effective cylinder pressure will go
far beyond the fuel's ability to resist detonation. In short, it would
ping itself to death.

Low compression ratio means less mechanical efficiency. So turbo
or supercharger, fuel mileage will be significantly less than a naturally
aspirated motor with high compression ratio. If you want to debate
whether there is any gains to be had in mileage between a turbo
and a supercharger, my guess is we're talking 1mpg, give or take.
<shrug>

The one advantage that a turbo brings to the picture, is that under
light cruise load, they do indeed present less parasitic load than a
mechanical supercharger. Since our stock Cooper S does not really
have that much boost capacity, it's hard to say just how much
more parasitic load it presents than an turbo equipped one. I would
suspect not much. Increasing the drive ratio (smaller supercharger
pulley) indeed will correspond with more parasitic load, and would
lower the average fuel economy.

Like everything in the big biz corporate world, I suspect the driving
force that is behind a switch to a turbocharger is economics. It's
probably cheaper to make a turbocharged engine than a supercharged
one. But that's just my opinion....

cheers!
ratbike john

 

Considering most high performance cars use aluminum blocks now, I don't think it will be an issue. They might be using iron sleeves in the aluminum block if there are concerns about longevity, which is what I think Subaru does with the WRX.

I think the fuel mileage will increase significantly in the 1.6L turbo model over the old unit as it will weigh somewhere around 100 lbs less, will have DOHC and have variable valve timing. I would hope it will boost the MCS to around 30 mpg in the city..

 

I couldn't agree with you more. There is a reason that the E46 M3 block is made from iron.


Yes, but at what cost? And at what driveability penalty?

 

100 lbs isn't a great deal.......to achieve 30 mpg you're looking for a 20% increase in fuel efficiency for the MCS, which I think is unrealistic. I bet the mpg will increase marginally, not significantly.

 

The efficiency of turbos is much better than a roots blower, so that's an advantange for the turbos.

A good turbo can be operated with a thermal efficiency of ~85%. The roots we have is lucky to get 70%. That comes out to quite an advantage.

There a post about a combo SC/Turbo being done in Europe by VW. SC for down low, and the turbo for up high (not like the sequential twincharging done now on the Mini) that gets pretty good performance, and much better overall efficiencies at all RPMs.

Matt

 

Just curious, aside from speculating about future turbos, are there any that currently are both good performers and fuel efficient? The only ones I know are WRXs and S4s and they have horrible mpg.

One thing I know I don't want is that silly blow-off sound - the SO used to have a WRX that sounded so blatently goofy with that sound, sounded like it was dyspeptic

 

the new GTI has a turbo that combines good performance with decent consumption levels - better than the MCS I believe, and it's a much heavier car.

 

turbo engine has 10.5:1 compression ratio, fully variable intake timing and 177 ft lbs torque from 1400 rpm to 4000 rpm The engine is impressive and vastly superior to the current design. I would not doubt a 20% increase in real world economy. No need to rev it out to accelerate hard, and lots of economy measures built in.

Oh well. Probably a lot more to go wrong with it too, and much more expense to fix it too.

win some, lose some.

 

and others that use the low pressure turbos (5-7 lbs boost maximum).

Matt

 

Turbo-chargers do not present a parasitic load because there is no direct drive of the turbo-charger by the engine.

The energy used to drive the turbo's compressor is energy that would have been wasted. While the turbo-charger does present a bit more restriction in the exhaust gas flow, it is not very much and the gain from the heat energy that would have simply gone out of the exhaust pipe is considerable. It more than makes up for the slight increase in exhaust gas restriction. (I suspect a slight change in valve overlap will allow some intake air to help evacuate the combustion chamber and render moot any increase in back pressure presented by the turbo...)

The reason the MCS gets poorer gas mileage is not from the lower compression ratio but from the fact the compressor stuffs more air into the cylinders than a naturally aspirated engine of the same size would normally get, and this air requires more fuel in order to maintain the ideal air/fuel ratio and this results in the engine burning more fuel than its size alone suggests it should burn.

Add in the HP required to drive the compressor and the engine's slightly heavier fuel consumption is understandable. It really should be compared against an engine of larger displacement. I forget what the ratio is but it is not insignificant.

The engine starts out with a low compression, but if you monitor the manifold pressure you'd see the engine's getting lots of air. (My turbo-charged turbo-diesel engine's manifold pressure would under some conditions reach 60 (or higher) inches of mercury. At idle, with essentially no boost, it would read around 29.0 inches of mercury (which is atmospheric pressure but being a diesel with no throttle valve this is as expected.) From the manifold pressure one I believe can derive the effective compression ratio.

BTW, low(er than optimum) compression means lower thermal efficiency. Running an engine right at the onset of knock or detonation is where the engine is most efficient.

The switch to a turbo-charged engine will deliver considerable increase in gas mileage at no decrease in HP. Quite the opposite, I suspect.

MINI must think this too, know it to be true, otherwise why would it go to the trouble to make the changeover?

A turbo-charger is more expensive than a supercharger but the fact that MINI sells all it can make of this car tell it that price is not that big of a deal and it can pass on the increase to the customer. The turbine must be able to withstand the heat of the exhaust which can get quite high, especially for a gasoline engine. Additionally, a boost limiter is needed to prevent overboosting at higher engine speeds, unless the turbo is sized to deliver maximum boost at maximum engine speed (which kills driveabilty which MINI is not wont to do).

A turbo requires fancier routing of the intake and exhaust too.

No a supercharger is a cheaper way, easier way to go, even factoring in the drive hardware.

But increased fuel economy, as good as and probably better performance than the comparable supercharged engine, reduced noise, make the changeover to a turbo-charger a win win.

Sincerely,

RockC.