Yowzer Posted July 4, 2007 Share Posted July 4, 2007 So this is what I'm thinking. Drawthrough setup, carb feeds the blower, feeds the engine. Also as the blower has an electronic clutch, Ima have a switch on the dash to turn it on and off, mad max styles, so will also have a bypass valve from the carb straight to the intake manifold for when the charger's off. Heres a very (very) shit diagram of what I'm on about. Don't laugh. Oi, I said dont laugh! Anyway, any ideas, suggestions, recomendations, insults, whatever are welcome. ie. type of carb to use, wtf I could use as a valve etc. Cheers boes Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted July 4, 2007 Share Posted July 4, 2007 run it blow through on a 'modded for boost' DGAV weber form a capri or some shit (38/38 double pump stz). maybe even a 32/36 woudl suffice. the 4m isn't a big revver/ you should only need to enlargen the mounting holes on the carb slightly and it'll go straight on, from what I've read anywho. then mod the linkages possibly. that way you could have mad max steez, although, that would be a tad pointless. switchable on suck through won't work. then, goodbye headgaskets on teh 4m. heh. Quote Link to comment Share on other sites More sharing options...
corrupt Posted July 4, 2007 Share Posted July 4, 2007 this is how i plan to have mine setup, quick explaination: -blow through - modified 32/36 weber -always on setup (have to think it through) - wastegate with how ever much pound spring boost i wanna run in it, probably 5psi, which will be postitioned between charger and carb -wastegate will open when at idle/no throttle as nowhere for the boost to go and will just vent to air/or maybe back before the charger -and some other shit which is all in my head, cbf explaining its what ive planned to do, but havent done it yet, as have to think about it a bit more/research Quote Link to comment Share on other sites More sharing options...
Testament Posted July 4, 2007 Share Posted July 4, 2007 With the drawthrough setup you need to keep the path from the carb to the charger and from the charger to the head as short and straight as possible to avoid problems with low speed and cold running/startup when the fuel might not be totally vapourised. With the bypass idea, I guess it is workable but its up to you whether its worth the effort as opposed to just having it going all the time. - wastegate with how ever much pound spring boost i wanna run in it, probably 5psi, which will be postitioned between charger and carb-wastegate will open when at idle/no throttle as nowhere for the boost to go and will just vent to air/or maybe back before the charger The boost pressure is set by the pulley ratio and blower size, you don't need a "wastegate" as such, its just set as whatever it is unless you change the pulley ratio. You could run a blow off valve, since with the blowthrough setup the supercharger will be pumping against a closed throttle. Quote Link to comment Share on other sites More sharing options...
cubastreet Posted July 4, 2007 Share Posted July 4, 2007 Why would you want a wastegate on a supercharger? Much better to just set up the pulleys right. Quote Link to comment Share on other sites More sharing options...
blakamin Posted July 4, 2007 Share Posted July 4, 2007 and while we on that, why the intercooler? it's not getting heated by exhaust gas like a turbs... Quote Link to comment Share on other sites More sharing options...
corrupt Posted July 4, 2007 Share Posted July 4, 2007 bov's arent made for being held open for long periods of time, wastegates are. the wastegate is acting as a bypass valve when the throttle is closed as in my plans i will have the charger on all the time, which means if theres no where for the charger to blow air, its gonna get extremely hot. so the wastegate with the correct pound spring will solve this. dont argue the idea with me, as ive read a fair bit on aussie sites and, all the aussie guys do it with their commodores. edit: intercooler is becuase my engine isnt made for boost so wanna keep the tempreture down as much as possible and rootes? type superchargers generate a fair amount of heat. also beucase theres space for it where a striaght pipe would go otherwise. / you should be asking toyota why they run them standard on 4agzes Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 4, 2007 Author Share Posted July 4, 2007 Why would you want a wastegate on a supercharger? Much better to just set up the pulleys right. For a blowthrough ya need a wastegate, coz unlike a turbo, the blower keeps spinning with the engine even if ur foots not on the gas. Havin a blower spinnin at 7000 odd rpm into a closed throttlebody/carb means a big big big fat build up of pressure, which will most likley pop something. Or just give you one hell of a surge when ya hit the gas again. Quote Link to comment Share on other sites More sharing options...
corrupt Posted July 4, 2007 Share Posted July 4, 2007 ^^^ exactly boes Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 4, 2007 Author Share Posted July 4, 2007 Haha vent your wastegate into an airhorn! Quote Link to comment Share on other sites More sharing options...
corrupt Posted July 4, 2007 Share Posted July 4, 2007 would be interesting, i should just bite the bullet and slap all my shit on and see how she runs Quote Link to comment Share on other sites More sharing options...
Jay GTi Posted July 4, 2007 Share Posted July 4, 2007 and while we on that, why the intercooler? it's not getting heated by exhaust gas like a turbs... You're compressing air, so the supercharger will still generate heat. Boyles law I think... (been about 10 years since I studied it). Plus the mechanical heat as Corrupt already mentioned. You don't need one for low boost set-ups though. Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 4, 2007 Author Share Posted July 4, 2007 Blowthru needs a bit of extra crap like fuel pressure regulators, better fuel pumps n whatnot, which is why I was thinkin of going with the drawthru setup. However I sorta want an intercooler as I'm thinkin of runnin around 8-9psi, but intercoolers dont work on drawthru as the fuel just ends up condensing in them. So I'm still a bit undesided on the matter Quote Link to comment Share on other sites More sharing options...
corrupt Posted July 4, 2007 Share Posted July 4, 2007 Blowthru needs a bit of extra crap like fuel pressure regulators, better fuel pumps n whatnot, which is why I was thinkin of going with the drawthru setup.However I sorta want an intercooler as I'm thinkin of runnin around 8-9psi, but intercoolers dont work on drawthru as the fuel just ends up condensing in them. So I'm still a bit undesided on the matter yeh and if your crash they go boom beucase of the pressurised fuel/air that runs through them. with my pulley ratio it should be pumping 7psi Quote Link to comment Share on other sites More sharing options...
Yowzer Posted July 4, 2007 Author Share Posted July 4, 2007 ...that way you could have mad max steez, although, that would be a tad pointless. switchable on suck through won't work.then, goodbye headgaskets on teh 4m. heh. Haha yeah I know its pointless, especially as I'll prob have it goin most of the time anyway, but I just wanna be able to do it. Also wouldnt havin the blower switchable on a drawthru work better? coz ya dont need to worry about fuel pressure and all that? And who needs head gaskets? Quote Link to comment Share on other sites More sharing options...
blakamin Posted July 4, 2007 Share Posted July 4, 2007 You're compressing air, so the supercharger will still generate heat. Boyles law I think... (been about 10 years since I studied it). Plus the mechanical heat as Corrupt already mentioned. You don't need one for low boost set-ups though. I can see your point but I'd personally run the blower with the shortest possible route to combustion anyway... meh... used to V8 setups... these fours, jap/euro sixes and rotes get me all fucked up on most things.. the merc is my first OHC engine that I have actually considerin doin something to besides driving it... (had a 4-pot corty when I first come over from Oz but when I found you couldn't just bolt a 250 crossflow in, I sold it) Quote Link to comment Share on other sites More sharing options...
cubastreet Posted July 4, 2007 Share Posted July 4, 2007 the wastegate is acting as a bypass valve when the throttle is closed makes sense. had visions of the sc working overtime and the wastegate letting half of it out. Quote Link to comment Share on other sites More sharing options...
Flippy Posted July 4, 2007 Share Posted July 4, 2007 Haha vent your wastegate into an airhorn! Ive always wanted to do that. Quote Link to comment Share on other sites More sharing options...
Spencer Posted July 5, 2007 Share Posted July 5, 2007 Hmmm yea intercooler is still desirable as compressing air generates heat tis basic thermodynamics. Crazy v8 setups still run intercoolers usually water/something colder sits under the super charger. I think an sc14 is a pretty asthmatic charger its runs out of puff pretty quick on a 1ggze. Also yea throttle after the blower = just run a couple of bov's to vent the pressure, seen a few 4agze's setup like this its stops the lag of the engine sucking up the air in the cooler piping when you throttle off. But gives you crazy throttle response with that boost waiting there basically pushing the butterfly open!! Quote Link to comment Share on other sites More sharing options...
sentra Posted July 5, 2007 Share Posted July 5, 2007 offset cheap carburation setup heat problem with expensive electronic water injection in seriosuness have you looked at what other people have acheived via draw thru, short inlet tract + simple pressurised bottle of water into low pressure side of carb? 1 Quote Link to comment Share on other sites More sharing options...
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