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4agze Twincharger Conversions


AE25

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had a nissan march Super Turbo come into pickapart. (cheers luke for the heads up) interestingly they use a bypass butterfly operated by a diaphragm and a stopper solenoid which I'm assuming to keep the bypass open 1/4 way between gear changes. (imo much better system than the hks popper valve).

 

engine bay had already been pulled to bits.. but i'd be assuming it was setup as follows...

the two air lines on the diaphragm fit before and after the bypass butterfly. the gear change solenoid stops the bybass completely closing so that airflow thru the intercooler and inlet piping does not suddenly halt or change direction (rather it exits via a BOV before the throttle(s) for gear changes. who knows?

 

this highlights a good point when setting up a bypass to have it partially open between gearchanges. an easy way to set this up would be to add a second diaphragm that holds the valve at 1/4 open or so, and connected to inlet plenum with a restrictor needle valve and one way valve in parallel so it takes a few seconds of vacuum to engage (but returns immediately) to return bypass valve to fully closed position (for idle and supercharger on modes). a separate recirculating valve is used on the SC for idle and part throttle.

or even use another diaphragm on the bypass for recirculating duties? air direction would be reversed so could cause unknown issues?

also found a uk forum with quite a bit of info on the nissan Super Turbo (ST)

http://www.micra.org.uk/forumdisplay.php?f=79

 

superturbovalve1sml.jpg superturbovalve2sml.jpg superturbovalve3sml.jpg

Edited by AE25
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  • 1 month later...

Looking at the VW design, wouldn't it be a little more space efficient (thinking of the cramped space on these things) and energy efficient to have your intake, then a Y pipe split off to go through the turbo and superchargers serperately and then back together instead of having one before the other? That way you could go with only the one intercooler behind the 2nd Y pipe instead of having to go with two and wouldn't have to worry about the turbo pushing past the super or the super having to suck through the turbo.

 

I'm an engineer but fairly new to working with cars, so feel free to tell me if there's some other consideration I'm not thinking of :D

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  • 2 months later...

this is usually the first system thought of when building one. and yes have seen it done.. but will only work if you have some sort of flapper plate after the chargers to shut off the other one otherwise the air will try blow back out the second charger. i have read of differing results.. it works for some but not for others. that system i believe is a poor design from the start. reason is the turbo will be pushing against a closed flap as it's spooling up so i would think this will increase turbo lag. once both chargers are flowing air then the flap will sit at the right spot so both are pushing air into the engine.

 

heres an unfinished 3sgte twincharger in a te71 GT sedan many years ago at NZ 4 n rotor nats. notice the two air filters.

more pics at bottom of this gallery http://www.toycrazy.net/gallery/nats/2001/index.htm

 

nats90.jpg

 

Looking at the VW design, wouldn't it be a little more space efficient (thinking of the cramped space on these things) and energy efficient to have your intake, then a Y pipe split off to go through the turbo and superchargers serperately and then back together instead of having one before the other? That way you could go with only the one intercooler behind the 2nd Y pipe instead of having to go with two and wouldn't have to worry about the turbo pushing past the super or the super having to suck through the turbo.

 

I'm an engineer but fairly new to working with cars, so feel free to tell me if there's some other consideration I'm not thinking of :)

Edited by AE25
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