[jdk81]

Just a questing im contemplating re carb sierra

If you had postive air pressure entering the sierraintake manifold, would this then screw up the vacuum controlled timing advance and other things on the sierra system?

Anyone who has supercharged/turbocharged a carbie sierra able to comment?

[want33s]

Positive pressure on a carby is fine if the carby is totally enclosed... Vaccuum advance is useless though and you'll need to go to purely mechanical advance.

[unique_seek]

mate you can boost the carbie g13a,BUT you can only run low boost on the internals(around 5-7psi)with the carbie,the only way to boost through the STD carbie would be to box the entire carbie,to keep te preasure equal,if you dont do this the preassure will push fuel through all the seals.You can get carbies bult to handle boost,but thhey cost big $$$

Your best bet will be a sc12 supercharger(off a 4agze) and run a drawthrough system,so you will have the carbie feeding into the charger,and the charger straight into the intake manifold.You can do the same with a drawthrough turbo,BUT you need a special turbo with mechanical seals to handle the fuel running through the turbo.

Or you can just do a G13B Turbo conversion

Best of luck mate!

[unique_seek]

Ah yeah about the dizzy,you need to modify it to handle boost..the stock dizzy do not have any form of retard mechanism for boost conditions. If you retard the timing enough to prevent pinging it will be too retarded off boost and feel very sluggish.

The answer is to get ahold of the distributor from the 12A Turbo EFI engine. These have a boost retard setup in the vacuum advance diaphrams , and can be recognised by prutruding 8mm nuts on the diaphrams themselves.So you basically run the 12A system on the g13a,or something that runs a dizzy and is turbo

[unique_seek]

http://www.redlinegti.com/forum/vth.299 ... +turbo.htm

Join redline,they are very helpful on there!bud just do a search on there

[jdk81]

Thanks for the input.

I was just curious as i am currently finishing a snorkel/ram air setup. Before you guys laugh, I was making a snorkel anyway, just decided if I could get some extra benefit out of it.

Calculations are indicating positive pressure into air box, and carby @ 100km/h (approx 400Pa or 0.06 psi boost). I think im going to need to add a boost guage, blow off valve yo control this powerful beast. Make up some wings for downforce and I might finally break the 2 minute quarter mile.

I highly doubt there will be positive pressure into the intake manifold, but was curious.

Once I finish painting and fit it, I will borrow a pitot static tube and do some testing.