Been slow but on the way....
organising pulleys this week then checking to see what mods I have to do to the lid to make sure it fits!

Will post dwgs if all parts fabbed- pretty easy thus far
Go to
http://www.postimage.org/image.php?v=PqMHu90 
http://www.postimage.org/image.php?v=aVLbgqS 

looks good Nick
look forward to hearing it

very nice but don't forget the blow of valve or you will be picking bits of your blowers vanes all over the state
also get the dizzy right or you will be tearing your hair out wondering why it won't rev

That was the plan Greedy, looking for a pop off/pressure relief valve. Any recommendations?
The way I see normal blow off valves work is they are vacuum driven off the vaccum found upstrem side of the Sc inlet in a draw through application.
So when you close the throttle the blow off valve is sucked by the vacuum driving the blow off valve to open and allowing a positive pressure on the down stream side ( from over spoooling) to be vented.... I think

Nice looking install!

However, roots style blowers don't require, or normally use a blow-off valve.

Ideally you work out the boost you want to generate (above atmospheric pressure) for your engine capacity and rpms. You look at what your blower
produces and calculate the pulley sizes you need to generate the required amount of boost....

You don't get overspooling with a SC because the drive
is directly related to engine rpm (unlike a turbo). You are better off doing the calcs rather than trying to control 'unknown' boost levels with a BOV on an SC....

regards

RobK

Rob BOVs in this situation are installed as blow back protection - not to vent boost

even the original Judsons and shorrocks have the same thing
if the engine spits back thro the carb its gonna try and spin the blower backwards and as its belt driven that aint gonna happen so as Steve said there will bits of blower lobes everywhere

Nick, i just run a garden variety Greddy style with no vac hooked up bolted to the blower manifold and as i pointed out in my thread its saved the blower a couple of times

just set the spring tension right so it wont leak boost but will open on a spit back
ive had mine upto 10psi with no dramas

Ah .... sorry I saw the comment relating to vacuum and overspooling and thought it was going to be used to try and control boost level.

Obviously good insurance and well worth doing although some would argue the serpentine style ribbed belt will slip and it's the Gilmer (tooth) style drive setup that causes a SC to pop....but why test that?

regards

RobK

should just put a 911 rear end with a stock motor in it and be done with it.

why? did ur mates, uncles, freind do that back in the day?

I was goin to use one of these:
http://www.greddy.com/products/display/pop.php?my_img=560.jpg 

How expensive is the greddy?

What about a 'traditional' pop off plate?

http://www.jegs.com/i/Weiand/925/7155/10002/-1 

you can buy em on US ebay from dale wilch and land
em for about US$65 (not that hard to make one in this
style either.....)

regards

RobK

i foiund a wrx on ebay cost $45 works well as my little unit was playing rough for a while, and back fireing like mad with no damage
and as for putting in a porsche rear end in $$$$$$ my blown motor cost all up $500.00 and $350 was for the blower to get a 80-83 bhp my first job that i built with no money i made a blow of out of a 1 inch pipe with a screw on top a valve spring and some drilled holes at and a tap washer now thats doing it the hard way but it worked. and as for roots type blowers they had a blow back plate that blew when it back fired if you watch the drag cars you may see the plate blow and sometimes it just blows the entire blower
good luck

yes this is the great fatso BOV for the budget conscious




that one would be fine nick

i just went the plumb back style cos one of these days i was gonna plumb it outta the engine bay just for safteys sake

HI guys throwing around ideas on the belt drive
Up for comment, thinking of doing something like this:

http://www.postimage.org/image.php?v=Pq1mp51i 

Why? To be different to the great work that others Like Joel on this forum have done, and secondly have a set up that can be introduced without engine removal.

In short its a set up like a serpentine belt, the difference being the tensioner is a double pulley with the second pulley driving the supercharger itself.

This allows the engine to be removed from the car without the additional obstruction that results from having an additional pulley sticking out 2" past the crank. (my speedsetr replica has even less space than a stock beetle!)

This also allows the changing of boost by changing the tensioner pulley without removal of the engine to gain access to the main crankbolt.

You can use the standard generator washers to establish tension on the generator side allowing the "tensioner" to have a single plane of adjustment for the superchager side (may not need that additional tensioner on the SC belt).

Hope I described it ok.. Joel & Greedy any comments?
PS Greedy I see your set up is great and works but I do not want to cut the shroud in 1/2 yet...

Comments will be appreciated.

Hi Nick
thats actually very well thought out
theres a bit of extra engineering involved in setting it up i cant see why there would be a problem if you could get good tension on both belts without to much strain on the idler pulley it should work well

i toyed with the idea of running a scat serpentine belt kit running the blower as well but couldnt get it to all line up right

im still thinking of going the rib belt for the alternator on my car after witnessing first hand the difference it made on kims bug

Joel, do you think I will have the generator side contating the belt enought to actuately drive the SC without slipping?
I was planning on keeping the std V belt on the Gennie side of things

well for my 2 bob worth. i think that running both on the middel pulley will give you a headache when doing the tighten up as you will need to adjust the genny pully from the genny's aju8stable system because if its loose the engine will over heat with a slow fan and because these blowers will generate head by just being a blower and heating up the air
so try an keep things as simple and if you do a blower belt it will still run well with a standard system without the blower it's all a juggeling act but when you get it right it feels really gooood

Nick are you keeping the 5pk belt on the blower?

cos your gonna have to create a hybrid Vbelt/rib belt mule pulley if your staying Vbelt on the genny

No you have it all wrong

the SC stands for Sexy Car

so where did it all go wrong with 911sc then??

well its litterly 9 11s which is double sexy LOL

sc isn't that single cab

ok an update is due

Thanks to a buddy at work I have had parts machined up.
First off a press fit, dowelled and pinned bit of Aluminium onto the original SC drive allowed the offsetting ofthe belt closer to the crank
While a removable lower pulley hanging off the main wheel (Held in with Aerospace Fasteners Hiloks) which allows boost to be modified by changing the pulley without remoival of the main crank bolt!!
http://www.postimage.org/image.php?v=gx1NR7Wr 
http://www.postimage.org/image.php?v=gx1NR2X9 
Next BOV and then ignition... Stay tuned

looking good guys

Looking good, I like the inlet manifold design.
Be interesting to see how it performs.

Looks good, I personally after having experience with blowers and pulleys would of run a toothed belt rather than a serpentine style. I found my old blown engine to slip at big revs and ended up snapping the bolt off in the snout of the blower.. These were brand new pulleys and belts so I changed it over to a gilmer style and could run a slack belt and never slip. It is worrying how much tension and load must be on the crank and bearings with the belt pulled so tight to one side. If you could, this is what I would do. Good luck T54

HI guys just an update, Tensioner sorted and belt is on:



Here are the picts, still waiting on over pressure valve to arrive from US.
Still have not figured ou here to route accellerator cable,
After that is sorting out the remaping of the dizzy.

Here tis:

Nick i just ran a longer one with its own spring type conduit from a bike shop
fits inside the standard vw tube
let me know if u need details

This is very similar to what I did some time ago...

john have you got any pics of that one finished?
pretty much identical layout to mine