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compound charging/twin charging


d.p.n.s

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any updates on this?

surprised there be no mention of where the throttle is positioned. will make a big difference to how it operates. throttle before the sc is safe option. and does not necessarily require a bypass valve due to sc operating in a vacuum. the ABV you see on toyota sc12/sc14 are there to create an on/off boost transition when the charger is switched and gives better efficiency when transitioning off boost (but charger on). using these factory fitted abv in a setup that has throttle after sc may be too restrictive of air flow and could allow the s/c to create boost when throttle is shut. So it should be pointed out that in any setup with throttle after a positive displacement charger (roots), the setup MUST use a recirculating valve big enough to reduce pressure back close to atmospheric if you want any sort of reliability and economy when not boosting. not to mention extra noise created from the pulses being pushes through a restriction. not using one could be catastrophic due to bent/broken throttle shaft. roots + restriction = pressure. if you're lucky you'll pop a hose off. Funny how people without one complain of belt slipping or black dust around the drive belt. put throttle before roots and its not an issue.

A traction control butterfly could be an option for a bypass valve (throttle after sc) as they're often stepper motor controlled so long as you have the electronics to drive one. need to check it's air tight when closed.

The intake vacuum valve on a diesel could be an option. these are often operated via a diaphragm or stepper motor. not all types are air tight though.

A poppet valve ie 'external wastegate' are suitable so long as the diaphragm is large. The diaphragm has to overcome the spring pressure that's holding the valve shut. these are probably the most common valve used like in the HKS 4agze twincharge kit.

a BOV are not suitable due to their sudden release of air. (uncontrollable).

don't know about you guys, but i'd get pretty annoyed driving that orange twincharged volvo powered Kadett. The amount of charger noise that thing makes is horrible. Looks like he's running a parallel system blowing into a flapper valve with throttle after chargers. one of the very few! (never saw the logic in this compared to a series setup). and yes roots chargers make noise. factory setups don't usually use gilmours! The factory toyota setups are not too noticeable in noise due to them having the throttle before the charger. this effectively muffles the pulses eminating from the charger at partial throttle position and reduces how much air is actually being pumped when throttle is shut (running in a vacuum).. so reduces the medium for noise to travel. BUT swap the charger in front of the throttle and you have a direct noise path back up the intake. have any restriction after that charger and noise is more of an issue. The noise is most likely to come out of the recirculation system after the charger. The twin lobe roots chargers are pretty much the worst for creating inlet pulses. Toyota used an expansion chamber on the 2tzfze sc14 to reduce noise. search youtube for the sc 5k ke70 or ke35. borrrrrrrrrrr

There is an artical in think on autospeed.com about supercharging a prius for the author's missus. They tried various ways to baffle,muffle, suppress noise. The outcome was it was eventually canned due to noise. maybe not a consideration as a sprint/gymkhana car but i'd get pretty annoyed if it were a daily driver. (i'd compare it to open wastegates or fart cannons on auto vtaks). [insert puke face here]

one of the best sources of twincharge info imo is the eng-tips.com forum. see comments by 'warpspeed'. one insane car to come out of this is Donald's black evo5 twincharger in scotland or up that ways. user 'madmac666' or 'evomadmac' on youtube. his build thread is http://www.lancerregister.com/showthread.php?t=315815. impressive to say the least.

Interesting to note that in his compound charged system, heat was an issue. this was rectified by balancing the system and better efficiency from the charger.

ok nuff said. me like this subject. one day this will be done and i'll have my own experience on the subject... http://toycrazy.net/mark/KE25engine.htm[/quote

thanks for the info mate another very good read.

yes im still going ahead with it the turbo is all mounted now and ive had to swap the alt and supercharger

over as there was more room on the driver side for piping.

im just waiting for some cash to pickup another sc14 with the factory cluch setup still in place

as mine doesnt and i would prefer to have the option there if i decide i want to turn it off or run it all the time.

cheers

dan

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  • 5 weeks later...

Hi, any developments with this?

I am also doing a Twincharge project for my last year and continuing it with this years final uni project,

it was good to read this as how the ideas have evolved in this thread is exactly how my project develped this time

last year to the point now where i am at the same stage as this thread.....small world :D .

My project is based on a 4AGZE (AE101), in a RWD setup in a 83 KE70.

I too am taking the parallel approach, Im trying to keep the system as self regulating and simple as possible.

Compounding is good if exceptionally efficient inter and after cooling is going to be used to restore the air density,

but engine bay space is always an issue.

Tractor Pullers use compounding for a reason, but then again they have to ratchet strap the heads and blowers on :lol:

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  • 1 year later...

what about a big reed block/box after the sc, then the sc can be left on or turned off. when turned off the turbo can draw though the reeds without any need for fancy mechanical valves

or am i dreaming?

Instead of reed block would Exhaust Check Valve work to keep things simple

to stop charge from trubo exiting through supercharger in a parallel system

Have most parts, just stuck on the values on a parallel system

Any place in NZ to buy from, or any suitable butterfly valve.

http://www.marinepartssource.com/partdetails.asp?pnumber=MMD903030&cat=4&catname=Exhaust Systems&sub1=9&sub2=0&sub3=0&subcategory=Exhaust Inline Check Valves&mfgno=MMD-9030-30

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