Superchargeing a Carby motor, 4k, blow thorugh setup

**Sherlock** · 22-10-2008, 12:59 PM

i think maybe i would need one of those spring loaded pressure releif valves for boost control and also for somewhere for the air to go when the throttle is not fully open.

and as for air flow when the supercharger is off or disengaged, as far as i can tell there would not be any?
so the switch that disengages the clutch on the supercharger should also open the a large valve like an ABV or similar which can allow filtered air in to run N/A. and when the clutch is engaged this should then close and allow the pressure releif to get rid of excess pressure and control boost.

ppls thoughts on that? poke some holes in it?

would be used so that when starting the car would have the clutch disengaged and have a valve open to let air run freely so would strat as an NA, then at idle flick the switch to close the valve, then when the throttle is not on boost will build up quickly but this will be handled by the pressure releif valve.

**oldcorollas** · 22-10-2008, 01:03 PM

draw diagrams for each state of running

and which direction the air volume and pressure will go... easiest way to get it sorted.

**Sherlock** · 22-10-2008, 02:49 PM

is ther a sort of gate that can be switched and let a large amount of air in, to use to make the car NA when charger is disengaged,
it doesnt have to be heaps resposive or anything, just not to restrictive so the car can start and run properly before the charger takes over, if you know what i mean

**TERRA Operative** · 22-10-2008, 06:46 PM

You realise your power will be dismal when running NA, unless you keep stockish compression?

**Sherlock** · 22-10-2008, 10:19 PM

yeah well aware of that,
would only be off boost when starting the car,
not sure how much i will decomp either yet

how much boost do people think a stock 4k could reliably take without decompression, i think they are about 9.4:1 stock, a fair bit, so i will probly get a decomp gasket

**oldcorollas** · 23-10-2008, 12:16 AM

9:1 stock.
but that will be the least of your problems

change to ACL pistons while you can

**Sherlock** · 23-10-2008, 12:31 PM

mmmm, dunno,
not planning on spending a huge amount on the rebuild,
i have a 3k, so i will use the 3k pistons if they are alright as i heard 3k pistons are stringer than 4k ones for some reason, ther toyota genuine and 4k has repco ones?

**oldcorollas** · 23-10-2008, 02:18 PM

something liek that.. the 4K ones i have seen have been fragile, and they have all been branded "repco-トヨタ"
the 3K don't have the repco name on them....

but.. if you don't make sure fuel and especially spark are spot on, then any piston will break....

**wa5** · 23-10-2008, 05:00 PM

if this is to be a budget power upgrade, I wouldnt fool around with switching the Blower on and off. just lock it up.... to work all the time.

Any carb on a forced induction engine is a compromise, I have seen a couple of suck through setups and one blow through set up .. Having the carb on the low pressure side of the super/ turbo charger did seem to make for (a little) easier tuning....

**Sherlock** · 23-10-2008, 08:57 PM

ive decided on the clutch just haveing a manual switch, it wil be on most of the time,
if i can get my hands on a k motor efi setup i might go down that path,
i got myself a rebuilt/resealed 32/36 weber today,

what sort of timeing changes should be done when running boost?
also if anyone has pictures of SC setups on k motors could you please post em up, or post a link to them, keen to see ways ppl have mounted them.

this project is ongoing, and doesnt necassarily have a low budget, it just means i will have to save for longer before its done lol