Turbo V supercharger V twin charged

[Stott69]

So as some know Im looking at changing turbo setup on the Aristo and I've come across the idea of using a supercharger either on its own or for low revs boost. Is there any advantage or disadvantage of this?

[iOnic]

In this day and age I don't think there is actually any need for a setup like this. Turbo technology has come a long way and you don't need to sacrifice low end response to get good top end out of a lot of modern turbos.

IMO don't bother - choose a turbo (or turbos) wisely and it'll perform just as well if not better than a twin charged system.

[matt dunn]

So as some know Im looking at changing turbo setup on the Aristo and I've come across the idea of using a supercharger either on its own or for low revs boost. Is there any advantage or disadvantage of this?

Yes,

we ran a car with a SC and a Turbo,
it was a 1GGZE/GTE combo.

With both the SC and Turbo it was um, fun to drive.
30psi boost at 1200rpm,
But it had so much power down low all it did was spin the wheels and higher in the revs it had no HP as the SC could not flow enough and was too inefficient.

We ran the car at an event where the car had previously been top 4 when it was turbo'd only and were struggling to make top 30 in the field twincharged,
took the SC off and replaced it with a bent piece of pipe and went back next day to be one of the quickest again.

IMO for a street car good fun but hard on tyres,
but for a race car the toyota type SC's are too inefficient.

[Mr Revhead]

I think the successful systems don't run them in series though.
They have a valve that switches between s/c and turbo when the boost crosses over.

Lot of stuffing around though. So if you wanted to do it "because you can" go for it. But if you are after bang for buck and don"t have a huge budget for it, go one or the other.

[Stott69]

Being Auto at the moment means I spend alot of my time in the 1-3g rev range hence the idea of a charger appeals to me a bit. As Rev said would run in parallel so once turbo has the puff the charger would shut down n switch over to the turbo, could possibly run the switch off the factory sequential feed?

[hsmidy]

with the system your talking about,

say the s/c runs 10psi, the valve blocking the turbos impeller outlet wouldnt open untill 10psi correct?
other wise you would be lossing boost back out towards your turbo.

so when the turbo is building pressure against the valve/butterfly and its got no where to go....surely this cant be healthy - simillar to running no BOV?

just a thought i had....might be way off

[Stott69]

Im thinking more of a non return valve on the outlets of the turbo and SC and the use the sequential to switch the electric clutch on a sc14?

[AE82 FXGT]

Bottom line would be too much hassle and weight for the benefit.

[matt dunn]

trouble is findng a non return valve that flows enough air to make it worthwhile.

[stolic]

trouble is findng a non return valve that flows enough air to make it worthwhile.

What about the flapper/butterfly combo that the 2jzgte uses? It seems like a simple setup that could be reproduced on a larger scale to flow more air. At least that's what I've been looking into.

[Lith]

What are you actually trying to achieve? Do you have a power figure/power delivery in mind? Don't just go hunting ways to go when if you don't know what your intended destination is.

[Mr Ree]

Its sounds overly complex for a street driven car.

As Lith said, what is your goal? That will help with you path getting there.

[sergei]

If doing twin-charging the only reliable way to switch over between chargers is using re-purposed flyby-wire throttle body controlled by ECU.
Failing that you can use waste gate actuator to open the bypass throttle on the supercharged when pressure from the turbo reaches certain point.

This is how VW does it:




And this is how nissan did it 30years ago:

[matt dunn]

What about the flapper/butterfly combo that the 2jzgte uses? It seems like a simple setup that could be reproduced on a larger scale to flow more air. At least that's what I've been looking into.

yeah we looked at them,

the std one wont flow enough to make good hp,
and was going to be a mission to make a bigger one relaible
and not take 1/2 the engine bay and weight of the car.

Let me know if you find a good design for one.

[Lith]

A mate of mine has a turbo/supercharged setup in the build at the moment for a MIVEC Mirage - should be done in a few months at this rate I suspect, will be interesting to see how that goes.

If I were going to explore twin charging then I'd probably look into doing a regulated two-stage type setup, probably be tricky but I'd like to think it could make made to drive more "natural" and generally make more sense in practice - I'd say giving the impression that it is still turbocharged, but instead of trying to make instant boost and holding it.... more like having a turbo capable of 1000hp spooling like a turbo capable of 350hp, or something along those lines. Something like that might have made Matt's car more predictable/controllable to drive....

[stolic]

Let me know if you find a good design for one.

Actually have looked into a couple of solutions.
Currently I'm expolring using the cheapy china wastegate/bov with a custom soft spring rate as one idea for a bypass.. or one or two GZE ABV's perhaps, just to deal with any pressure spikes from the turbo anyway.
The main switchover between s/c and turbo would be handled by a 70mm T/b set out like the VW image above. To control the switchover I'd use a two-way actuator (have drawings on napkins) that would hold the t/b open on idle/vacuum/cruise, then close it on low vacuum as the supercharger is engaged, then open again once the turbo starts coming on boost and the s/c is turned off. I plan to use vac/pressure to control the actuator directly via pressure realys coupled with valves in the vac lines. I feel this will give a smoother transfer compared to using stepper motors by using a vac chamber to even out spikes in pressure. The pressure relays I'm thinking of have an adjustable switching range, allowing for fine tuning of the system. Finally, I plan to have an in-cabin switch that would cut the s/c relay and activate a locking solenoid to lock the t/b open (actuator set to fail to open state anyway.. ) incase something goes wrong, or to help with inital tuning, or if i run out of rubber
Will it work? maybe. I'll let ya know when I actually have more than just an idea on paper. Obviously there are a few finer points about how the vac system all works etc etc.. but I'm finished "work" for the day and it's time to hit the gym

[Stott69]

Quick edit of the VW one in to the way I was thinking of running it. So would cut in a non return valve then a y in between the turbo n inter-cooler. non return valve would be to stop back spooling of the turbo. In my theory they would work independently to create boost

[Dell'Orto]

Why not run a pair of small turbos, with one spooling early then the other one taking over in the high revs? Oh wait....

[AE25]

Is the aristo not boosting up early enough?
can you not upgrade the larger turbo for an even bigger one?

you might notice that the nissan march twincharger was under 1ltr and the VW is a 1.4ltr. both small capacity. you have the cubes to run normal sized turbo for low end.

but anywho..
one of the most successful twinchargers i know of is the following evo5.
http://www.madmacmotorsport.com/the-car.html

his project thread.
http://www.lancerregister.com/showthread.php?t=315815

evomadmac on youtube

His system does not bypass the sc when on boost. it's TURBO - I/C - SC - I/C - throttle - ENGINE.
ie, series mounted and compounding chargers.
but the sc does have a diaphragm operated bypass butterfly valve for when throttle closes. The charger needs to be large enough to flow your max power.. but only running 8psi or so due to the compounding affect.
Forget using an sc14 on a 3ltr. prepare to be spending thousands on a decent twinscrew setup.

this is a good read for twincharging theory. user 'warpspeed' is a wealth of info.
http://www.eng-tips.com/viewthread.cfm?qid=267889

Not many successful parallel twincharge sytems around using one-way valves or flapper valves. A turbo blowing into a shut valve doesn't give the results of a sequential or compounding setup. try finding a successful system! I only know of one.
http://www.hilmersson-racing.com/manta-bildarkiv/
can see one of his flapper valves in front of turbo
http://www.hilmersson-racing.com/wp-con ... 60x195.jpg

external wastegates with a large diaphragm or throttle bodies seem to work the best for a bypass valve though. so long as they have a good seal. not all throttle bodies do. 4agze uses poppet valve as does the hks 4agze twincharger kit, but the 2tz-fze sc estima and nissan ma09ert super-turbo used a butterfly bypass.

I've research this heaps. If you want to know particular info i could probably find a link to it. hoping to one day complete a 20v twincharger myself. I don't see the point on a 3ltr twincharged though?!?
ie this 86 was 2jz TC, but he went back to turbo only.
http://www.hachiroku.com.au/2009/10/cra ... -2jz-ae86/

most suitable toyota valve for a bypass i've come across is the 3c-te efi diesel turbo estima. still needs the holes riveted though.
http://www.toycrazy.net/mark/pics/ke25/ ... evalve.jpg
http://toycrazy.net/tech/pics/tc/3c-te_valve.jpg

I have my own TC dreams blogged. check "the build plan". its the most publicly up to date with exception of teh club-k build thread.
http://toycrazy.net/mark/KE25engine.htm

[2jayzgte]

Wow seen this whole thread sounds like a whole lot of work for not alot of gain .I gotta think you gotta simplyfy go with it while this sounds like a decent idea the twin charged idea and it would make the Aristo unique for the cost vs the gains and the time to do it yeah I'm not sold.