Ive come to my senses and realized that a all out NA setup is labour intensive (I'd be doing all the work) and very costly considering the power you would be making in the end.

So...I've had a squiz at some turbo setups and it seems the stock A series is capable of a decent amount of boost in stock trim with a good tune.

My situation is that I will not be using an intercooler but I will make a water/alch. Injection setup so the argument that you can intercool a draw through here is nill.

My concerns are that...

1. In blow through (BT) carb requirement are less than draw through (DT) as the air is pushed through where as in DT the carb just sees more flow (ie bigger engine basically) so you need more CFM/bigger carbs in DT right?

2. BT is harder to tune because the carb is in a box or jammed between a turbo and manifold and makes removal harder, where in DT basically you undo the hose clamp from the carb/turbo connection and the carbs off ready for tuning. So DT is easier to tune.

3. BT needs a better fuel pump, return line and a rising rate fuel pressure regulator (RRFPR), where in draw through all thats needed is the stock fuel line and pump. DT is cheaper.

4. BT benefits from fancy flowing manifolds where in DT a rough old "log" manifold will work better to keep F/A in suspension from turbulence meaning a DT manifold is easier to make.

5. In DT you cant vent your BOV to atmosphere, it has to recirculate. Unlike in BT where they can recirculate or go to atmo.

6. Using a stock enigne + stock carb needs no re-jetting for a BT setup

7. MY MAIN CONCERN - Throttle Response. Can any one with real life personal experience here tell me how a blow through setup and draw through setup compare in response? Did the suck through setup use a carb with accel. pump? Do you think an accel. pump would help? If you blip the throttle from idle does the engine feel like the tail pipe is no bigger than a Mc Donalds straw (ie revs take ages to build/drop)?

Ive got heaps more on my mind but I'll leave that for later.

So does anyone have any draw/blow through experience? Whats throttle response compare between them?

I have no experience personally, but I can say that you shouldn't need a BOV with DT. So the looping the BOV back into the air cleaner wont matter. Think about your vacuum cleaner. When you put your hand over the pipe, the motor speeds up. This is because with no air passing through, there is no load on the compressor wheel. So when you shut the throttle the compressor wheel will have no load on it, and should keep spinning all by itself. If it can't get any air, it cant make any boost.

driven/owned blow through twin turb with different carb configurations
driven/owned blow through with injection

driven suck through single turbo

all had awesome response and lack of lag

my opinion, suck through is easy and gives good power gains

blow through requires injection to be anywhere near safe/reliable, but gives better gains too

After watching these vids...

http://www.youtube.com/watch?v=Wj2iOlwPGGg&feature=related

http://www.youtube.com/watch?v=OYV4yxXhj-4&NR=1

It obvious that if the carb has an accelerator pump, lag is no issue (good response on them vids even with huge carbs!)

Draw through seems the logical thing to do as theres no need for a return line, no need for a BOV (good point on not needing one A14Force, this reminds me of some F1 tricks - see below), tuning is easier, you dont need high pressure fuel pumps.

And with blow through I get the feeling that your trying to make something that its not (if that makes sense) since your basically turing the carb into a variable flow injector that responds to boost and engine vacuum where as in draw through the carb just sees more flow.

In Formula 1's turbo years the teams had the throttle body infront of the turbo, so when the throttle shut the turbo kept spinning in its vacuum, which is kind of like draw through (throttle plate before turbo).

So with a good design of manifold (keep fuel in suspension) and using short inlet/turbo/carb tube lengths and having it a bit up hill of the inlet, a draw through setup will perform great for the difficulty it takes - a blow through setup will take say 40% more effort to get together but will only gain 15% (if that) more than the draw through.

If anyone was wondering - my idea was to run a turbo setup (suck through) with a big ass 48mm Mikuni HSR flat slide and H20/Meth injection after the turbo. Boost wise I would plan on running no less than 1 bar. Ignition would be mechanical with the vacuum advance hooked to boost to act as boost retard - if that doesn't work I will lock the dissy and if the locked dissy runs poorly I'll run the Jaycar programmable ignition.

definately give this a read: a12 draw through
It sounds like a very ideal setup, cheap and easy, with good power returns.

I dont think you cant run water inj after the turbo on draw through.
It has to be just after the carb before entering the turbo as the
pressure will be too great.

Nah my homemade injection will be more complex than the ol' washer bottle jobs.

It will have a 70PSI pump and a few pressure switches (plus a controller than when you run out of water it will have boost cut to prevent pinging). Firstly, the pre-stage at around 5psi will turn the pump on and then at around 8 psi the solenoid will open allowing the anti-detonant to flow through a circuit with a rising rate fuel pressure regulator, needle valve and a injector nozzle.

The idea is that the preliminary pressure will be greater than boost (enough to properly mist the mixture) then as boost pressure increases so will the pressure to the nozzle via the RRFPR and then I can control the flow with the needle valve.

This is working on the fact that as boost pressure increases so does the charge air temp and thus the likely hood to knock. So by setting the needle valve to have sufficient flow at the beginning to prevent knock, the RRFPR will increase this flow in accordance to boost (I'm pretty sure its a linear relationship, if not; Ill put in a bit too much anti detonant at the start and then will end up with enough when on boost).

what injection nozzle you using and will be be angled and facing a flat zone part of the
inlet manifold opposite the supercharger outlet for even distribution?

Due to the complexity of your water inj setup sounds like you might as well go EFI.

Yeah it sounds complex but all there is, is a handful of parts. There wont even be any semiconductors, I can get buy with 2 or 3 relays.

I just dont like efi - to much "crap"; MAP, IAT, O2 sensors, ECU's, injectors, IAC valve, surge tank, fuel pump and the list goes on.

Then theres the fun of tuning it.

In my draw through setup there will be a single 50mm flat slide motorbike carb which tuning would be a dream (I personally find tuning motorbike carbs just easy) - in one afternoon I could get it running 90% then connect my wide band O2 to check the a/f and see if there's any room for improvement.

My injection nozzle will be on the turbo output side facing down the piping - the log style manifold and the bend or 2 needed to pipe the turbo to the engine will allow plenty of time for good mixing. I'm trying not to inject before the turbo as the water droplets will erode the turbine.