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actually, it is pretty much impossible - in an underbonnet situation anyway.

the fuel ends up pooling in the intercooler and/or associated piping (think about where fluid will sit - at the lowest possible point) then your engine will run lean and destroy itself.

if you made up a system where the carby was higher than the intercooler, and the intercooler higher than the inlet ports then yes i would say you could make it work.

but i don't think anyone has that kind of room in their engine bay so it would be pretty much a system limited to marine applications.

and to top it off, one carb backfire and your whole front end will explode!

and the fuel does atomise better in a draw thru setup - nothing like a fan spinning at 100,000 rpm to fizz things up a bit!

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I think a stiffer spring or a variable rate spring would take care of this.
As far as running a hose to pressurize the domes, wouldn't the domes get pressure from the same holes that cause the piston to lift? With everything pressurized, wouldn't the flow of air in the venturi still cause a decrease in pressure in the dome and let the piston rise? The air flow won't create a vaccum but if the pressure above the piston is less than the pressure under it, it should rise.
I, too, am typing as I think. And I think I just confused myself.

edit- I thought about this some more. What I'm saying is I think the air flow should create a difference in pressure to lift the piston of a pressurized SU just as airflow draws fuel in a pressurized 32/36.
I don't think you would have to pressurize the piston dome like you would a float bowl, though, because the piston dome is sealed. The pressure acting on the top of the piston, from those holes in the venturi, should be the same and cancel out the pressure acting on the bottom of the piston in the venturi.

Quote: I know what you're saying, but that assumes a linear relationship between boost pressue and the speed of the inlet charge, and hence the vacuum created to lift the piston. In the real world, I think that when you're forcing air into an engine, it won't take long for something in the inlet system to restrict its flow, resulting in a lean-out condition.

SU's a known to work well in the tried and tested draw through setup. It's other benefits are less cost, less components, and less complexity.

this maybe a bit off topic, but the whole thread has sorta wandered from su turbo set ups anyways so i wonder if there would be any use in pre-cooling with an intercooler, before the fuel enters the intercooler, as in having the intercooler, then the carby then the supercharger or turbo, the intercooler can only cool a certain amount so does it matter if it cools before or after the turbo/supercharger ??? is it possible to do as i have said ????

The intercooler is only there to cool the compressed (heated) charge out of the turbo. If you put it before the turbo, the air going though the intercooler fins, will be the same temperature as the air being drawn through the intercooler pipes.

The intercooler would become rice

Good point, the real world is not linear.
But if the air flow was restricted, then wouldn't a leaner condition be needed? The carb wouldn't get the airflow and neither would the engine.

That was what I would have suggested. Seal a heat exchanger core in a box in front of the carb, then depressurize a CO2 bottle through the core freezing the hellm out of the air before it enters the carb. Similar to a water to air intercooler, but using gas instead. Or, chemically cool the charge after the turbo with a fogger nozzle, HEHEHE! Some big arse supercharged big blocks have an intercooler heat exchanger between the blower and the intake ports, howerever this is only really applicable on boats because of the height of the whole arrangment ane the need for a ggod supply of cold water to pass through the exchanger.

My goodness me I got the fastest headache from reading what has been said since I last wrote in here. My My I dunno.... Just keep it simple please lol
How about water/methanol cooling, Its good but I also know the damage it can do to the Compressor wheel if not setup right. Would you have to ensure the finest mist. Could you use an single injector???? I know an E-Boost Gauge has an auxilary output which can be used for water or water/methanol injection....worth a look

Quote:Technically, that is an aftercooler but people started calling them "intercooler" only about 20 years ago. Really an intercooler is one that's between two blowers, you know like on an aeroengine or a big-rig truck.