I'm planning to put a turbocharger on my A15, what carb should i use to deal with the forced induction of the turbocharger??

Are any Carb that fits the H89 Manifold??
Anyone tryed to do something like me??

Regards
TS

I forgot to tell thats for a blow-through turbo system

i would use 350 holley with the right floats they seem to be the easyest to setup

You can use just about any carburetor for up to 10 psi. The stock carby works good but is small.

Weber 32/36 is a great one for this and will flow enough for a blown A15.

I'd probably go the holley 350 (I'd even consider the 500 - remember the 2 barrels are flowed at a different pressure drop and the 500 only flows around 350cfm when tested at the 4 barrel pressure drop) based on the incredible ease it was on a similar sized motor I did in the past (toyota 3K). TO adapt it to a factory inlet would be harder (here was more 'meat' under the carb base on the 3k inlet, by a small margin) - I'd suggest the following :

get a holley to w/w stromberg (as fitted to holden red 253 v8s) adapter plate, and clamp then weld that on, and open up the inlet manifold carb base section to ensure smooth transition/flow. It _will_ require you build up around the carb base of the original manifold to leave enough meat that you can open it up internally...

I'm about to do the very same thing (well adapter/carb wise, it'll be NA for now) in preparation to putting an a15 in my car.

On setting up the holley - you'll need a nitrophyll float, which can't collapse under boost (commonly availalble). Er, what else, make sure it IS a 350 holley. The 320 holley is basically a re-worked 350 with different booster venturi (and differences in idle/low speed circuit) that was designed (afaik) for economy and emissions purposes, and the fuel circuits likely won't work nearly as well for a blowthrough setup. By the time they were finished, the mods to give better atomisation and signal strength actually cost some flow, hence being called a 320.

Aside from the nitrophyll float, you might experience the power valve blowing out, it won't be 'dangerous' just act as if it was open al the time (using more fuel at part throttle). Not everyone experiences is, I _did_ unfortunately. To get around it I simply ran a power valve block off plug, and had the car had to do a lot of street miles (it was just a thrash machine) I would have reduced the high speed air bleed size, that modification will make it go richer at higher flows (esp under boost) and allow a richer 'boost' mixture without the need for massively sized main jets (which would kill part throttle economy). What else? It seemed to want less acc pump squirt than 'typical' - possibly an idiosynchrasy that 4 cylinders, with less intake overlap (compared to a 6 let alone a v8) produce sharper stronger intake pulses that gets the fuel circuit up and into it quicker, so they need far less acc pump. This was achieved with the 'smallest' cam, but also a small squirter (I think something like 25) compared to the more standard 28.

You can also use the blue teflon (or whatever they are) re-usable gaskets - they seem to seal better under boost, and allow jet changes without an hour of gasket scraping each time.

Lastly - on the carb bonnet issue - first make sure any s/hand holley you get is flat around the air filter base. Having only 2 barrels, half of the air cleaner base doesn't have a carb main body under it to support it, so even mild over tensioning of the air filter nut (more likely on dual fuel setups it would seem) will warp the base. If it does, it'll never seal and be a waste of time. And related to that - make sure the carb bonnet is 'tall' - with the air inlet a good inch above the tip of the fuel bowl vent. If the air entry is too low, air rushing over the tip will cause suction, and depressurise the fuel bowl, and cause fuel to stop flowing. Sometimes it doesn't happen till there's more velocity (like the onset of boost) and it'll get a couple of psi, start to 'launch' then fall down dead, then the velocity drops, fuel flows again and it lurches forward, repeating this 'pig rooting' display continuously. On the 3K a carb had was made using bits of an lpg dual fuel snorkel, and after this issue cropped up (it actually cropped up during initial testing, with the wastegate wired open to prevent boost and get a baseline tune) a couple of extra spacer rings on the stack around the air filter base did the trick. THat thing ended up seeing boost into the mid 20s and that problem never re-appeared.

I've been through the same problem before!

I tried the 32/36 webber, with mixed results. I put the 350 holley and have'nt looked back! as Jmac said previously it is well worth the effort. i bought modified floats to be able to handle boost but i have been told on good aurthority that you can drill a hole in the top and in the bottom of the floats and fill it with foam so it doesn't implode under boost, but that depends on your budget and amount of boost.

In regards to mounting the 350 holley, i bought a 32/36 webber adapter that bolts onto the standard inlet manifold and the aquired a holly adapter plate that bolt to that and then simply welded them together and bobs your uncle!




Theres more than one way to skin a cat!



Let us know how you go

I don't have Holley carbs in Portugal :(
The Weber 32/36 can't handle with the boost? what if i put it in a box like i see people saying in another topics?

Weber DGV (32/36) can handle up to 10 lbs of boost. Just ensure it has the plastic floats and not the brass floats.

This applies to most carbs, they can handle 10 lbs. With the plastic or nitrofill floats.

Of course to avoid detonation you probably want to change the jetting (both air jets and main jets) to be extra rich.

For more than 10 lbs, box the carb.