RT Posted July 16, 2007 Share Posted July 16, 2007 just forget using carbs and turbos Quote Link to comment Share on other sites More sharing options...
Unclejake Posted July 17, 2007 Share Posted July 17, 2007 . I think i'm in over my head here... I've got the charger plumbed straight into the top of the carb ( no intercooler at this stage) Mate - I think you are probably right. Superchargers don't create heat like a turbo does so an intercooler is not likely to be of much benefit. It is easy to throw good money toward a bad idea but good on you for having a go. It is the spirit of NZ motoring. Quote Link to comment Share on other sites More sharing options...
fuel Posted July 17, 2007 Share Posted July 17, 2007 id look for a carb off say a mitsi cordia etc Wouldn't be able to use a Cordia carb in a blow through application, as they are a suck-through turbo setup - as I just posted above with pics Quote Link to comment Share on other sites More sharing options...
Mr Revhead Posted July 17, 2007 Share Posted July 17, 2007 well they suck then unless you can mount things real close together such through sucks! Quote Link to comment Share on other sites More sharing options...
Goat Posted July 17, 2007 Share Posted July 17, 2007 I agree with Yowser and WDE_BDY. Putting the carbs in a sealed box and pressurising the box should work. As then the outside and inside pressures of the carb would be the same, so it will do its venturi thing properly. But yea, you would have to make sure your fuel pressure is higher than the boost. Otherwise..... It may be cheaper/easier to find another "boost ready" carb to fit on tho Quote Link to comment Share on other sites More sharing options...
Unclejake Posted July 17, 2007 Share Posted July 17, 2007 I agree with Yowser and WDE_BDY. Putting the carbs in a sealed box and pressurising the box should work. As then the outside and inside pressures of the carb would be the same, so it will do its venturi thing properly. But yea, you would have to make sure your fuel pressure is higher than the boost. Otherwise..... That (to my uneducated brain) sounds bloody dangerous? A sealed box full of fumes etc? Quote Link to comment Share on other sites More sharing options...
kyteler Posted July 17, 2007 Share Posted July 17, 2007 Finding a Skinner's Union carb to fit your application wouldn't be hard, finding a manifold to suit it, probably would be, can't imagine there's a massive amount of SU carb manifolds for your engine. Quote Link to comment Share on other sites More sharing options...
Goat Posted July 17, 2007 Share Posted July 17, 2007 That (to my uneducated brain) sounds bloody dangerous? A sealed box full of fumes etc? In retrospect it does appear to be rather dangerous. But, the box shouldn't fill up with fuel/air mix much Is should be the same as a plenum shouldn't it? Appart from the carbs are inside the plenum. Maby... It has been suggested to me before by a race mechanic. (when he suggested turbocharging the fronte) I can see how it could be very dangerous though Quote Link to comment Share on other sites More sharing options...
Mr Revhead Posted July 17, 2007 Share Posted July 17, 2007 the idea of the box is the carb sits in it, and the turbo feeds into the box that way its equal pressure inside and outside and the fuel ISNT forced out of the carb. therefore no fire. only way fuel can get out is for the pressure inside the carb to excede the pressure outside. as for fuel pressure, raising rate regulator, keeping the fuel pressure higher than the boost pressure so you will need to upgrade he fuel system to cope Quote Link to comment Share on other sites More sharing options...
Goat Posted July 17, 2007 Share Posted July 17, 2007 the idea of the box is the carb sit in it, and the turbo feeds into the boxthat way its equal pressure and the fuel ISNT forced out of the carb therefore no fire. only way fuel can get out is for the pressure inside the carb to excede the pressure outside. Thats what i was thinking. But what about back splashes (dont know what to call them, when the carb puffs fuel/air back out the intake) or wont that happen cos its under boost? Quote Link to comment Share on other sites More sharing options...
Mr Revhead Posted July 17, 2007 Share Posted July 17, 2007 backfire? tune it right! Quote Link to comment Share on other sites More sharing options...
Unclejake Posted July 17, 2007 Share Posted July 17, 2007 I think you mean spitback. But Yuh. I see what you are saying about the ambient pressure. Quote Link to comment Share on other sites More sharing options...
Mr Revhead Posted July 17, 2007 Share Posted July 17, 2007 yeah trick is pressure feeds into a box the carb is in, NOT into a carb that has a box around it Quote Link to comment Share on other sites More sharing options...
Goat Posted July 17, 2007 Share Posted July 17, 2007 But Yuh. I see what you are saying about the ambient pressure. It should, in theory, be just like running the carb with a higher atmospheric pressure. Cos all components will be at the same pressure inside and out. Except that if any spitcack happens, it happens in a small, sealed metal box Which would be rather scary! yeah trick is pressure feeds into a box the carb is in, NOT into a carb that has a box around it Exactly Quote Link to comment Share on other sites More sharing options...
73 'rona Posted July 17, 2007 Author Share Posted July 17, 2007 I'm liking this crazy box idea... I guess i'll need a seal around the throttle actuator? Which will be the first thing to go if it does start spitting explosive mix out. as long as I get it on video making a big mess that would be ok... Pipework would be easier not having to get onto the top of the carb... I'm not sure whether the float will collapse though? I guess i'll just make a box and find out... Quote Link to comment Share on other sites More sharing options...
Burntrubber Posted July 17, 2007 Share Posted July 17, 2007 I used a stock weber a Cortina then one of an Escort it worked fine with removing and sealing up the the choke butterfly's and tapping a thread for the fuel hose tails to screw in as the only mods. I made a hat which sat on top screwed on where the stock air filter screws on. A tiny amount of fuel leaked out of the throttle shafts over time was about a month before I saw any and after several months it was still only a little. The first carb I drilled and tapped threads for dry air seals into the throttle shafts but I had tuning issues with that carb and ended up flagging it. Dry air seals plumb pressure from above the venturi to the shaft so it only leaks clean air not air/fuel mix. The pressure is slightly higher above the venturi so it pushes the fuel back in. I never did it on the second carb cause it was quite an effort and I was to lazy. For sealing the cable on an enclosed carb there a few ways some people have used marine cables or a sealed linkage on the outside connected to original linkage on the inside. Here's a pic of that carb. Quote Link to comment Share on other sites More sharing options...
Ke36 Posted July 17, 2007 Share Posted July 17, 2007 magical box pictures ftmfw yea as everyone else saying need uprgraded fuel pressure etc thats easy tho just get a nice fuel pump which you would need anyway and a rising rate reg for it, would only need to go up to like 15psi (if you ran a max boost of round 10psi, which would be fuckin heaps) anyways id say and run a bigger carb like a weber etc cos it will need extra fuel one off a cortina etc would work mint id say Quote Link to comment Share on other sites More sharing options...
corrupt Posted July 18, 2007 Share Posted July 18, 2007 thats a magical turbo placement Quote Link to comment Share on other sites More sharing options...
Mike-e Posted July 18, 2007 Share Posted July 18, 2007 my old charade turbo motor used a down draught 2 barrel carb - blow through had it set up using a malpassi external FPR to suit carburettor turbo motors, a VL fuel pump and a extra fuel injector fuel injector had its own map sensor and a feed line T on to the fuel line to the carb, with a copper wire pointing down the throat. as soon as it boost reached 15psi the extra injector would dump fuel safe up to 20psi. carb turbo is always going to be a compromise at best Quote Link to comment Share on other sites More sharing options...
SYKOV6 Posted July 18, 2007 Share Posted July 18, 2007 im pretty sure zep had one of those blow thru carb boxs on his gemini at sum stage. mate has toyota blower on a 12a bridgy sucking thru a holley 4 barrel seems to work real well. blower is a bit small for the rotang though tends to run out of grunt at about 7000rpm simply cant flow enough air. makes the 12a bp supa torquey too Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.