I'd like to see someone experiment with a centrifugal blower on a Mini, a Vortech, Powerdyne or similar. Yes, they are better suited to bigger motors because they don't really alter the normally aspirated engine's torque & power curves, they tend to just give it a parallel shift & the Tritec does really benefit from the boost in bottom - midrange power & torque which the Eaton delivers.
I've seen the characteristics of the various superchargers summarised something like this:
Rootes Type (Eaton) - low efficiency, significant boost to low-midrange power/torque;
Positive displacement (Twin-Screw) - medium efficiency, significant torque/powerboost to mid - higher revs;
Centrifugal - high efficiency, pushes out torque & power at the top end.
It's interesting what the Porsche 928 community are doing with centrifugal blowers :
Admittedly the standard Porsche V8 has big power & torque & it really doesn't need additional torque down low, unlike a Mini. It would still be interesting to see development of a centrifugal blower on a Mini with the appropriate tuning of the brerathing & fueling.
HI Roland,
I still have a fair bit to do regarding all the different combinations ,of different size pulleys ,intake pipes,and throtle body size each can have a major impact on output
also the fuelling requirements for each combination and what the standard car can tolerate .
As a basic conversion
charger,with pulley (maybe a choice ,they are simpler to change than the stock ones)belt,oil lines and adaptor plate,(option for oil cooler)outlet horn(exchange)water pump and hoses,(adaptor for block),intake pipe,dipstick,vent line,brackets
This would form the basic kit , using standard injectors and ecu ,the limitation on power would be the injectors running out so if adding say the jcw ones with the option pulley a second level is available.
beyond that optional pre charger injector(s) can be added in the intake duct (larger)with its own control unit and larger throttle body,plus filter change
beyond that (read expensive) a larger supercharger ,intake pipe,throttle body,stand alone ecu ,charge cooler/intake manifold with laminova cores,traction control system,- this would require engine internal major changes at very high cost , and be far removed from a road car and pretty much undriveable IMHO
What each upgrade produces I have no idea ,but less crank losses and lower boost temps allowing greater boost will have benefits.
So far its all been calculated data used ,and now its time to get actuals , and as you know theory and reality can differ , but so far its been much as expected and close to the calcs
regards Adam
I think the centrifugal compressor has been done (rotrex) top end power is less usefull for a road car ,and changes the charecter of the MINI , The Efficiences of each type of charger varies with boost and rpm and each charger has its benefits the eaton is 90% efficient at low boost for example but drops to 50% at high boost, the screw charger can match the centrifugal but at a narrower rpm band,hence pulley size is important, the centrifugal is next to useless at low rpms --horses for courses
the large v8 engines all run low boost pressures,avoiding compression changes ,and needing huge sizes of charger to supply the large volumes of air.
On balance the twinscrew is a good charger for the car providing the best of each charger type allowing good throttle response and good torque through to the max rpm
if you think the porsche guys are doing alot with it you should read some of the US V8 stuff! some of the guys are pushing massive power out of pretty stock centri superchargers from the likes of vortech and Prchager. the Rotex units are very good and could work well if fited in parrael with the stock supercharger.
Adam & Roland I look forward to seeing how your respective conversions workout.
My only concern with these conversions is the cost. While both will undoubtedly offer major improvements how much are people prepared to spend on a Mini?
In the 944 world Jon Mitchell will build a big-bore 3.2 litre 500 bhp/500 lb/ft Porsche 944 turbo engine for £10.5k for the engine & piggyback set up plus about £1.6k for a Garrett hybrid ballbearing turbo. For this you're getting a replacement block & crank, wet-liners with ceramic bores, balanced assemblies, carillo rods, Mahle pistons (I think), heads, engine management etc all backed by ex-factory Porsche engineers & a few guys in the F1 industry.
I'd expect any engine work on a Mini to come in a lot cheaper than a basically new 500 bhp Porsche crate motor.
Even if you can pick-up secondhand Cooper S's cheaply, I'm sure cost will be the key factor.
DYNO TODAY AT 1320 AUTOS
At last got onto the rollers at Pauls , and I am very pleased with the results despite having the too small 58mm throttle fitted and smaller intake the Opcon made 260bhp and it will make the required 300 bhp with ease
The fuel needs mapping as it is out and this will only improve the numbers
as an indication the max boost was only 15psi ,despite this only 10 degree shift in intake temp from idle to max rpm so a lot more to come
10 psi boost at 2000 rpm !!!! (more than Eaton at max)so very very good low torque will result ,torque held up to over 6500 rpm and will extend further up with correct throttle
I fully expect to get to 325 bhp in my own car .maybe more!!
As a bonus it looks like a 275 option needs less components for a kit and will be cheaper than first reckoned
After so much theorising its nice to see the theory become reality ,I think it will exceed my expectations and perform better than i expected -a true 275 and 300 bhp kit that get 275 +and 300 + on the dyno
every time,hot day ,cold day , any day , and hold torque throughout the rpm range-RESULT!!
Many thanks to Paul and 1320 autos
Before the dyno and numbers become more important than the concept .
It is the on the road performance that is the important thing , how the torque curve is developed , ,throttle response , and a wide power band that pulls to max RPM .
Dynos are great for collating data and getting fuelling correct ,and "seeing" what is happening with the engine
From the first runs carried out I believe whatever mods are carried out using the Eaton it will never equal the Opcon in any aspect of performance
with the power that it is producing at such low boost pressures and more importantly very low temps at the pressures ,it will allow far higher boost with safety -no det- no burnt valves etc
It is still early days and there will be a whole lot of adjustments and combinations to try out ,the s/charger inlets on the Opcon are critical a small variation can add 50 bhp instantly and the inlet I am using is far from adequate (it was a quick temporary fit to get the car running)
A new intake is being fitted and larger TB next week and then we will really see
The pre charger injectors havent been used yet ,this should further increase power
The engine is still on standard injectors and still making good power -there is more to come!!
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some of the guys are pushing massive power out of pretty stock centri superchargers from the likes of vortech and Prchager. the Rotex units are very good and could work well if fited in parrael with the stock supercharger.
