I know this has been posted about, but I just can't seem to find the post. Could it be done, would it work? If someone knows the post please link me to it. And if this is a completely unfeasable and stupid idea, please don't flame, i'm just a little confuse bout it. I mean wouldnt the SC work for the low end and the turbo for high end?

THanks

 

Yikes, compound 'charging! Now that's a messy and complex situation

I've heard about this in automotive fairy tales, anybody have real-life experience?

Cheers, (and good luck!)
Ryan

 

Im in no way an expert, but would an exhaust turbo do anything to help create power. Im not sure how they work. I've seen them before though, but mostly on deisel motors/exhausts though.

Frank

 

Frank,

That's how all turbos are powered - by the exhaust. The exhaust turns a turbine wheel which in turn powers a compressor wheel which, as the name implies, compresses the intake charge and force induces the motor.

It's possible, and being tried by at least one company.

The classic issue with a turbo is the lack of a nice meaty torque curve, because the motor has to produce enough exhaust charge to turn the turbo before you are making power instead of using it to turn the turbine. This is oft called "turbo lag".

I really feel like if we can make good power (260hp or so) without ditching the supercharger, it would be a better way to go.

Now if you want 300, short of pulling the motor and changing it completely, I think a turbo may be the only way to get there. Then it may be a twin charged system, where the supercharger is used to keep the torque at low RPM until the turbo is spooled. The issue with this project becomes one of cost. How much development cost can be incurred on a motor that is already slated for replacement.. We'll see!

 

Randy,
Thanks for the lesson. I didn't know thats how turbos worked. So, all turbos are essentially exhaust turbos, like school busses?

I was also thinking of an exhaust turbo that pulls exhaust out at a faster rate. I don't know if thats possible though.

Cool stuff
Thanks a bunch
Frank

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<A HREF="http://www.shaskan.com/initials.htm" TARGET="_blank">
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I've owned several turbo cars before, and they've all suffered from a certain degree of lag. However, my sister's Jetta 1.8T seems to have an almost lag-free, responsive turbo with an excellent torque curve.
I really must give props to VW for creating an excellent engine with almost zero turbo lag.
Now before y'all come after me with torches and pitchforks, I gotta tell you that I wouldn't trade my MCS for anything in the world! :smile:

_________________
2003 DARK SILVER / WHITE MCS.

 

The 1.8T is actually reverse engineered alien technology - a lot of people don't know that.

It is a masterful work of art, and the turbo is relatively small, which is why there is very little lag. On the monster motors that they are getting over 350hp out of this 1.8, there is substantially more lag because of the larger turbos being used.

There are a couple of ways to reduce the lag. One is the aforementioned &quot;twin charger&quot; system that uses a supercharger at lower RPM to reduce the amount of energy lost to spooling up the turbo. Another way is to use sequential multiple turbos with a small turbo used as a first stage to spool a larger (or the same size) second turbo. There are also just smaller turbos to reduce the exhaust energy needed to spool them - whether they be sinlge, like the 1.8T, or dual non-sequential, like some of the Porsche offerings.

Turbos are just neat because they can make some great power and sound totally cool .

I still like the supercharger on the S though, so I'm going to stick with that development for now.

Randy

 

Randy - I've heard of a new development in turbo-chargers that uses a small electric motor to keep the blades turning while at low RPM's. Have you heard anything about this? It should eliminate the lag problem.

 

&gt;&gt; Now before y'all come after me with torches and pitchforks, I gotta tell you that I wouldn't trade my MCS for anything in the world! :smile:

Good save.

 

It will be interesting to see what sorts of replacement supercharger kits become available. The Eaton M45 is very efficient for a Roots-design, but twin-screw (Lysholm) superchargers offer far better thermal efficiency and can be packaged in the same amount of space. The big weakness of Roots-type blowers is that they don't actually compress the air at all. They simply pass fixed amounts of air from the inlet to the outlet.

Picture an express train that is travelling from a rural town to a busy city. When the passengers get on the train in the rural town, there is plenty of room to stretch out both on the train platform and on the train itself. The passengers have exactly the same amount of stretch-out room all the way to the city, since it is an express train and no passengers get on or off during the journey. It is only when the train doors open in the busy city station do the passengers get squeezed together.

Compressing the intake charge smoothly (as is done in a turbocharger, centrifugal supercharger, or a twin-screw supercharger) results in a far cooler intake charge with more potential energy and less tendency toward detonation.

Turbocharged cars have some unique drawbacks. One is lag. This is the amount of time that it takes to overcome the inertia of the compressor and impeller wheel assembly. In first gear, the boost peak is at a higher rpm than in second gear, since rpm-vs-time is different. The second drawback is shared with a centrifugal supercharger. The amount of boost produced is proportional to the square of compressor speed.

The stock Eaton supercharger on the MCS is able to develop plenty of boost over a very wide rpm range. When spun faster (as with the 15% pulley I have on mine) the supercharger develops a considerable amount more boost, but with a large increase in heat. Removing this heat through improved intercooling will be key to extracting maximum performance from this boost.

 

&gt;&gt;&gt;&gt; Now before y'all come after me with torches and pitchforks, I gotta tell you that I wouldn't trade my MCS for anything in the world! :smile:
&gt;&gt;

Hahah! I hear ya! Yeah thats what i was thinking a super and turbo combined system, but thats all i was..turbo's are expensive normally, i dunno what kinda special setup a system like this would need, but im sure it would be expensive. Hmmm but really squeezring out 100 extra HP without any sort of boosting, is it possible? i can see up to 200hp w/ exhaust, intake, etc. hmmmm I dunno

 

&gt;&gt;&gt;&gt;&gt;&gt; Now before y'all come after me with torches and pitchforks, I gotta tell you that I wouldn't trade my MCS for anything in the world! :smile:
&gt;&gt;&gt;&gt;
&gt;&gt;
&gt;&gt;Hahah! I hear ya! Yeah thats what i was thinking a super and turbo combined system, but thats all i was..turbo's are expensive normally, i dunno what kinda special setup a system like this would need, but im sure it would be expensive. Hmmm but really squeezring out 100 extra HP without any sort of boosting, is it possible? i can see up to 200hp w/ exhaust, intake, etc. hmmmm I dunno
&gt;&gt;

The key is keeping the air/fuel ratio and heat within acceptable ranges, and that's got as much to do with the ECU mapping as it does with the physical set up of your engine (intercooler size, turbo size, peak boost,air temp, etc). I think if you want much more than 225 horsepower, you'll need to rebuild your engine and find someone who knows a ton about mapping (and that's providing the ECU has close rpm sequences to accomodate the rapid changes under high boost and can handle the new programinng) and can get you a mass airflow sensor that can accomodate the increased airflow.

Think of your engine as a giant air pump. The more air you add the more heat you'll generate and that has to be removed to avoid detonation, which is what can destroy an engine. Remove the heat and you'll solve the problem. If you can meter your knock-sum and exhaust gas temperature, you can make incremental changes in boost without destroying your engine. More boost at the same heat range equals more hp.

Think of it like this; if guys are pushing 3 liter supras to 900 hp, you can theoretically push your engine to almost 500 hp. It probably won't be smog legal though. They can push upwards of 30 pounds of boost fairly reliably. We were talking about this a few days ago. I brought it up the turbo/ supercharger idea as a hair brained idea thinking a mini with a ton of hp would be amazing. It was mentioned to me by Rob over at RPS clutch. He said there was an oem car in the 30's that had a turbo feeding supercharger. The idea is great, but it is expensive to engineer. If you want to pursue the idea, check out some of the turbo sites on the web like Turbonetics, Turbo engineering Corp (TEC) etc.

See the link under &quot;Increase Horsepower&quot; March 11. And yeah, they flamed me, but I think it got a lot of people thinking... .

 

Fred,

Please do some research on the engine and engine management in the MINI Cooper S (it's obviously that you have both correct and erroneous knowledge gained through working on other cars, but do not have any experience with the MINI). There are some good links out there for technical information.

 

Andy,

Which part is correct and which part is erroneous?

 

Well, for one thing, the MINI Cooper S doesn't use a MAF, it uses a MAP. Also, no way does removing the cat give you 30 hp. I could go on, but you should do some reading about this specific vehicle before spouting more nonsense. :smile:

Unrelated to MINI's, check out this month's Turbo magazine for a wild example of a hybrid forced induction, a big turbo feeding an Eaton blower on a Toyota V6, stuffed into an MR2!

 

Andy,

I've been working on this design, but have decided that the cost of the kit would effectly remove it as a possibilty in the marketplace.

I was using a twin-screw whipple (or lysholm) charger in the design phase, but the cost of the supercharger alone is over $1900. Then the design requires a new manifold to the supercharger from the throttle body, a new manifold to the intercoooler, and a new mounting design (all of which has been designed, just not built). The kit would have been at least $3000 in the end, but would have reduced the heat produced by increasing the boost in the Roots significantly, as well as the added bonus of not requiring as much drag to turn. In this application, the whipple would have done fine with the stock intercooler.

I still have some other designs I'm tinkering with though. I think the cheaper way to go is do a large oil cooooler and bigger intercooler with the reduction pulley on the stock Eaton.

Fred,

As far as pulling the motor apart - why? It already has a relatively low compression ratio, strong rods, and trick Mahle pistons with oil spray cooling. I normally would start with this idea - Carillo rods, some JE pistons, good oil cooling in the motor, knife edging the webbing - but in our MINI's case, most of that has already been addressed by the folks in Munich.

The A/F ratios aren't all that bad - they are a tad rich when you go with the pulley, but not totally outrageous. My plots have the mixture starting at 13.5/1 and dipping to 11.5/1 (11.1/1 right at the redline). You could go a little leaner - 12.5/1 at redline, but until the additional cooling is taken care of, I'm happy to keep it rich for now.

As far as making me think with your last post - I'm always thinking anyway !

Randy

 

Randy, are you reading A/F before or after the cat?

 

After the cat. But those numbers are with the high-flow cat too, so I don't know what variables that introduces.

Randy

 

Here's the results from macncheese' stock '02 MCS on a dyno:



Obviously, the wideband meter used in the above plot couldn't deal with A/F richer than 10:1.

Here is yet another MCS that runs very, very rich:

 

Andy,

Are those plots before the cat?

That is really rich - the pulley actually seems to help somewhat - with the new readings at least staying above 11/1. That is VERY rich; most turbo cars using around 11.5/1 to protect the car at knock detection (along with some backing off timing).

 

I'm pretty sure the above plots are using tailpipe sniffers.