8 replies to this topic

[Brucey]

Hi all,

I am seriously considering going for the supercharger forced induction route on my A+ 1275 weber 45. Before going any further, I have looked into turbocharging and although many prefer it, it's not for me. I have no wish to alter my bulkhead and would not like to lose the sight of my weber 45 in a plenum.

I am going for the suck through route, so carb into charger into head. I plan on enlarging combustion chambers and using dished pistons, preferably the cast 1275 omega 6.5cc dished option.

I know there are kits available, however I'd like to make this my own project and do my own inlet manifold design.

I do have a couple of questions. The m45 eaton charger seems to be the popular choice. However, could I use the smaller and newer eaton unit from the 1.4 TSI Fabia VRS? I understand that on the skoda, its used in conjunction with a turbo and is only responsible for providing boost till 3500 rpm, after which the turbo takes over.

Would this be an issue if I solely use the charger to provide boost into the higher rpms on the mini? I feel the smaller unit is far better matched displacement wise compared to the BINI m45. It is also a much newer supercharger, and by the look of the flanges seems far nicer to attach a carb and inlet to.

My second question, is what is to be done with the belts, can I run a single belt? My engine is originally a 93 rover spi, thats now converted to carb. Do I need to make a new billet pulley for the supercharger in order to do this? I would like to retain the factory water pump, alternator etc.

My last question is, I am going to go for mappable ignition. I am looking at the DAT kit from MED, as opposed to megajolt as it seems to be tidier. Any thoughts on this? Would I run into any issues with attaching the trigger wheel while using the supercharger?

Thank you in advance for taking the time to read this, and I would appreciate any feedback!

[nicklouse]

some reading http://www.theminifo...rced-induction/

[mini13]

The Eaton on the VWs is the m24, might be a bit small fora 1275, unless your looking for a small boost, probably good for 6-8 psi

[Brucey]

Thank you for the replies so far. If a mod wants to move this over to the forced induction sections, please feel free to do so!

I dont plan on running very high boost. Doesn't the m45 drop off a cliff after 10 psi anyway? 8-9 psi sounds ideal, so if I can get away with that on the m24 that sounds perfect!

I'm after the magic 100bhp to the wheels, if possible. So if I can get that, I am happy. Would I need to move to 1293, or can I stick with 1275? I'm not sure how expensive the boreing out process is.

Do the m24s have the teflon coating like the m45s? I've heard that the coating is not inherently bad for the engine if it was to come off.... Thoughts?

Edited by Brucey, 27 January 2019 - 01:46 PM.

[DeadSquare]

I have 55 years experience of swapping the same 2nd hand suck through Shorrock supercharger from 948 to 848 to 997 to 1098 to 998 and even a 1071 and 1340 somewhere in the mix, with all sorts of carbs and pulley combinations.

 

As an ignorant  youth, I 'fixed' a second pulley to the water pump pulley and drove my blower from that, mounted on top of the rocker cover in the convenient bulge in a Morris Minor bonnet, so all my other blowings used the same sort of modified water pump pulley, albeit, with the crank, water pump, dynamo  pulleys sometimes up graded to a B section belt.

 

Never use a chain !!   A backfire caused my first Shorrock rebuild.

 

I think that it would be fair to say that for much of the time, I hadn't got a clue what I was doing, but I enjoyed about 25% more power and much nicer torque with not much higher fuel consumption.

 

On the race prepared 1071, I think I might have seen nearer 50% as I was dicing with 1500 Cortinas, but the Mini's frontal area is much smaller.

 

The Eaton is a considerably newer / more efficient blower, so a 1275 (without the cost of rebore and pistons) should easily give you your 100bhp and by asking "Turbo Phil" nicely about cams and things, you might to get a super wide torque band; always remember that it is torque that gives you acceleration which is what is desirable in a road car.

 

I would always go for a blower that is on the large size, lifting your foot to reduce the power costs nothing.

 

While on the subject, I always hankered after a combination Roots and Centrifugal set up, so that Roots gave low RPM torque and the other fed in as the revs picked up, but somehow the years passed and I never got around to it.

Edited by DeadSquare, 27 January 2019 - 07:45 PM.

[HUBBA.HUBBA]

Why don't you do a blow through set up with a merc eaton supercharger with a re-circulation valve built in

Edited by HUBBA.HUBBA, 27 January 2019 - 06:32 PM.

[Brucey]

I'm not familiar with this. Could you go into some more detail?

Wouldn't I need to pressurise the fuel bowl and seal the carb if I do a blow through?

[Gr4h4m]

I have run a charger for about 10 years. I took some time to get 100 at the wheels. It would be much easier to use a correct size turbo. Fusion fab will have some manifolds, and turbo Phil will sort you a head.

[HUBBA.HUBBA]

I'm not familiar with this. Could you go into some more detail?

Wouldn't I need to pressurise the fuel bowl and seal the carb if I do a blow through?

Just need a turbo hif44 carb or convert an NA hif44 to pressurised.

You could have an intercooler and easily plumb in water injection too then.

one of the main issues for me with my blow through was the re-circulation system not being up to it. I used a Bini re-circulating valve and the bellows blew also the butterfly passed charged air when closed, losing precious boost.

Don't get me wrong, its not a simple process but at least its a bit different.