Shorrocks supercharger bulkhead clearance.

[L7MAD]

Just starting to mock-up my Shorrocks supercharger install on my 1966 Austin Cooper before I start it's restoration. My question is does anyone know if I have to make any bulkhead modifications because on first look the supercharger outlet manifold appears to clash - I know I have to move the hydrolastic pipe as this is mentioned in the fitting instructions but there is no mention of the need for bulkhead modifications for clearance? I am going to use the Shorrocks alloy inlet manifold (CNM 0015) but maybe the cast iron inlet manifold from an 850 might give more clearance? Any first hand experience would be helpful.

Regards Paul.

[59fan]

I can't comment on the CNM 0015 as I've never tried fitting a blower with one but in theory you shouldn't need bulkhead mods. My first Shorrock car i bought pre-done, and that did have a bit taken out, but when I installed the engine and blower into another mini it did fit without mods, but was pretty close. I have 4 engine steadys, the two underneath, the standard one top O/S and a home made one top N/S just to make sure.

Ian

[mk1]

Using the alloy Shorrock inlet you will not need to make any B/H mods. Its cl;ose but not TOO close. Using the cast iron standard manifold gives a little more bulkhead clearance but the blower WILL touch the bonnet.

Fitting a Shorrock blower to a mini is a juggle, if I'm being honest there isn't really enough room to do it, but with a good faff about it will go in.

I found it helpful to make an adjustable engine steady that allowed me to crank the engine forward slightly to get more clearance.

I have fitted 3 of these now so if you have any questions, please feel free to ask, I'm not saying i will be able to find a solution every time, but I'll certainly try.

[59fan]

Good point about the bonnet, both of mine needed bonnet mods.

Ian

[L7MAD]

Thanks Ian and Mark for your helpful replies. I've done quite a bit of juggling since my initial post and the fit is alot nearer, although there is still a clash at the moment (still using the cast alloy inlet manifold) but I'll keep juggling .

I found it helpful to make an adjustable engine steady that allowed me to crank the engine forward slightly to get more clearance.

I've seen one of these but was wondering if they would work with a Cooper gearbox with it's remote change as it would be pushing against this .

On another detail what would you suggest in the way of a suitable blower pulley diameter as I have been offered an 85mm dia one and all I have read seems to point to an 82mm dia one for a 998 engine with an 89mm dia crank pulley - my thoughts on engine speck so far are balanced 998 Cooper engine with a Speedwell alloy Clubman head, 1.5 ratio forged rockers, maybe a Swiftune SW5 cam (someone elses suggestion but I'm open to others) and a medium bore LCB exhaust manifold (again if I can get it to fit ) - what would you think would be a comfortable redline for such a setup , I'm not after building a screamer of an engine as its for fun on the road including touring events. The guy has offered to turn the pulley down to 82mm dia so do you think this would be better

Sorry for all the questions and I'm sure there will be alot more as although I've built a Caterham this is completely different.

Regards Paul.

[mk1]

I've seen one of these but was wondering if they would work with a Cooper gearbox with it's remote change as it would be pushing against this.

Good [point, I used a magic wand gearbox in all my creations, so it wasn't an issue, I still suspect that you would get some adjustment, but not as much as I did.

On another detail what would you suggest in the way of a suitable blower pulley diameter as I have been offered an 85mm dia one and all I have read seems to point to an 82mm dia one for a 998 engine with an 89mm dia crank pulley

You don't mention the id of the other end, so it's impossible to say. Personally I would be looking at a blower ratio of around 1.2 : 1, ie, the blower would be rotating 1.2 times for any given engine revs. this gives more boost than the original set up, but usually only compensates for a worn blower, as most of them are nowadays. This will give you a safe max engine rpm of 5,500, with 6,600 at the blower. For normal use I'd keep this down to 5,000 at the engine for reliability. For this you want a compression ratio of no more than 9:1 with 8.75 probably being better.

- my thoughts on engine speck so far are balanced 998 Cooper engine with a Speedwell alloy Clubman head, 1.5 ratio forged rockers, maybe a Swiftune SW5 cam (someone elses suggestion but I'm open to others) and a medium bore LCB exhaust manifold (again if I can get it to fit ) - what would you think would be a comfortable redline for such a setup?

That looks fine bearing in mind the observations about CR & rev limits above. Personally speaking I think the 1.5 rockers are a bit OTT. I would stick with 1.3's myself.

I'm not after building a screamer of an engine as its for fun on the road including touring events. The guy has offered to turn the pulley down to 82mm dia so do you think this would be better

As a matter of interest where did you get your blower? Please feel free to e-mail me direct if needs be.

[L7MAD]

Thanks again Mark - very helpful.

I got the supercharger off ebay last summer - a friend who knows Shorrocks units has looked at it and reckoned it's OK as is so I'll give it a go - although someone else suggested it would be a good idea to strip it to clean out all the oil ways.

I'm going to get the pulley turned down to 82mm and the crank pulley is 89mm so the ratio is a lot lower than 1.2:1 but I'll see how it goes - I can always get the pulley turned down more later on for more blow if required.

I will fit an adjustable tie bar just to gain a little bit extra clearance and probably adapt an ultimate engine tie bar to fit at the thermostat end as well.

With the CR I'm hoping to reduce it via machining of the pistons rather than opening out the Speedwell head chambers so as not to render it only any good for blown engines.

Regards Paul.

[mk1]

I used a 1 :1 ratio on my 850 & only just made 6lbs boost, so you will be lucky to make 3.5 - 4 using the same ratio on a 998. Still, at least it's not to hard pulling the blower pulley off & chopping it down in the future.

There aren't really any oil ways as such in the shorrock blower, so it is highly unlikely that they will be bunged up. Do check to make sure that the oil restrictor pin is in good condition & a very good fit, I used to get my own ground with just 1/4 of a thou clearance, without this these units will do an excellent impression of the Red Arrows in full song.