Feral you are a life saver. I just did the math
(teacher was right I did need it some day)
and running a 1:1 pulley (already made)
it would be making 16.7 pounds of boost !
I better get a smaller pulley ,which will be better anyway, because the slower you spin em the cooler the charge, cooler charge is denser , denser charge =MORE POWER
But you probably new that already.

Blown1400 I know your blower is 4agze
what ratio are you running and do you know
what litres per rev it makes?

keep on charging dudes

Bart

Hey lads, couple of good points that you have brought up there a14force. Several things about the inlet manifold. I had an aluminium welder whip it up out of several different size tubings and it basically looks like a plenum chamber.
It must be understood that it is not so much a plenum chamber as a pressure chamber- once that the s/c begins to make boost (just off idle) it pressurises that chamber and then when the valves open- that 5-10psi of charged mixture is forced into each cylinder.
The difference between cylinders 1 and 4 as opposed to 2 and 3 is negligible as the pressure is reasonably uniform throughout the chamber. i actually took pressure readings from the end of the chamber and from the middle and the gauge that I had read the same for each.
As far as pulleys and stuff go it was all trial and error and I can't give you the litres/hour rates or the ratios. I was more concerned with poundage of boost and haven't really done the sizings.
Just one other thing of interest, when the motor was idling, I was seeing temps of around 50 degreesC on the inlet side (25 degrees above ambient). This stressed me out and I immediately started looking at intercoolers etc. BUT once that the car was on the road and the s/c started to really suck and the airflow started pumping through the inlet manifold it fell down to about 40 degreesC...no more stress.
I still put a water injection system on which only comes on when I have full throttle. This just cools the charge a little bit more and is a natural knock resistor (not that it has every knocked or detonated). Works a treat and if I feel like I am going to have a bit of a play, I throw half a bottle of methylated spirits in with the water and this really keeps it cool...

How did you do your water injection? Ive been told the easyest way is with a wndow washer bottle and a switch to trigger it under the gas pedal. Im really looking forward to seeing some photos of it

Like everything else, I went through a load of info about water injection before even considering it. I always thought that prevention was better than cure, and if you needed water injection to solve a problem, then you should try and go to the heart of the problem and fix that instead.
That was a load of garbage- water injection rocks. It is cheap, reliable and easy to install. The results are quite remarkable and you can really dial in some timing once that you hook it up.
I basically plumbed in a line after the SU carby and before the s/c. Several reasons: i figured that this would cool the charge before it got to the s/c (and once that it is compressed, that's when it gains most heat). The other reason was that the s/c would ensure that the water was adequately dispersed through the charge- like a big mixer.
I used a small pump (around 35psi i think) and a small atomising nozzle which had an external thread and threaded it straight into the hole that i drilled.
it is all hooked up to an actuator switch at the back of the accelerator, that only comes on when my foot is flat. Quite simple, works well and keeps the little bugger cool and not detonating...
Washer bottle is fine, but I am looking for something a little more asthetic- maybe polished aluminum - don't know yet - any ideas???

Will have photos soon...promise...!

Someone correct me if im wrong but apart from pistons you could lower the compression by using the a15 stock and getting a low comp head which are the open chambered ones found in early pulsar a14 front wheel drive. I heard these heads produce a slow burn which would suit forced unduction best. The other way could be to get some high silicon content pistons I forget their name dyourelectic whatever which are cheaper than forgies but can handle high temps and road abuse or use cast ones and get them high temp and friction jet coated. Forgies can crack if not taken to the right operating temp consistantly which is common with everyday road use.

Hey Errol ,, you mentioned the stroke differance of 5mm from a A15 to A14 .. But the piston only sits 2.5mm lower on the deck due to radius of crank being 2.5mm differance ..just wondering if you worked the Comp Ratio on 5mm or 2.5mm.. Its Awhile since i worked this out as i was going to build a engine .. Any way thinking back now you may be correct on you comp ratio being that low on a STD engine specs .. I was going to use 78mm Mazda B6 turbo pistons with a a14 crank .. I got it all machining done but didnt go any further .. Actually i was wanting to use the B6 turbo rods as well but the are the same Lenght as the A15/14 series and Same Conrod bearing Dia ,, the problem was they where narrower on width the bigend .So i couldnt go any further with using the rods ...Unless some has got some ideas to fix this problem ..A mate of mine used a 1.5mm copper head gasket from ridgecrest as well as the std head gasket to lower the Comp Ratio on his A15 Supercharged engine .. it worked ok but the std pistons ringlands cracked most likey from to much timming .. he was running water injection as well Cheers Cam

Cameron,
I'll fess up. I stuffed it up and calculated on a 5mm below deck clearance volume.

Actual comp ratio with 2.5 mm below deck clearance would be 7.22:1. Apologies to any who were misled.

is the 7.22:1 for an a15 block with a14 crank? would this be a good idea instead of using a shim?

A15 block with a14 crank. It gives 2.5mm extra clearance volume .

A shim would be easier and probably cheaper unless you were doing a full engine rebuild.

Bart,
Where abouts in Chch are you?
I'd love to have a look at your setup and may be able to help you abit having been there and had one myself.
To answer some of the questions raised there are 3 issues that you MUST address when going down the forced induction route;
1) Do not underfuel
2) Do not overspark
3) Do not overboost
The standard pistons are safe and reliable to 12 lbs IF everything else is okay.
My strong recomendation would be to o ring the block ( especially if its apart ) and use chrome moly top compression rings.
The SU carb is great ( and very cheap ) for your intended use.
I'll dig out some pics of the best sort of inlet manifold to fabricate for you.
Cheers.