Ok i have an idea fora sequential turbo set up on my sr20 or any 4 cylinder.
up front on a top mount manifold. run a gt35 or equivalent. externally waste gated but the external gate will be circulated back in. then run a 2nd turbo t25 or t28 externally wastegated with like a 40mm waste gate maybe larger and 10psi spring at the axle. where the muffler would normally go. then have the air intake on the rear turbo compressor and have its out let follow the exhaust back up and dump into the intake of the lager turbo. the larger turbo would then dump into the intercooler and up to the intake like a normal turbo does on an sr. put the BOV right next to the throttle plate so you can relieve pressure quickly with out loosing all pressure and spool.
the smaller turbo would be completely controlled by the spring in the waste gate. while the larger turbos wastegate would be controlled by my apexi avcr boost controller
the reason for the larger waste gate at the back would be for by passing the smaller turbo after the larger one has kicked in.
the only problems i can see is if the larger turbo once it gets going will be sucking so hard that the smaller turbo will be thinking it is in vaccum as soon as its waste gate opens up. and try to make boost to catch up with the vaccum. it will need its boost source for the wastegate to come from the the intercooler piping coming out of the larger turbo.
i think this setup will be easier for me to do then a twin scroll set up. and sense i am going fora narly power curve this will deliver the torque
sequential turbo set up on sr20
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idahotuner
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v6z24e
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Re: sequential turbo set up on sr20 (idahotuner)
dude, sick idea. My first car was a 6cyl Z24 and there were a few people that have done homemade rmt setups that all worked very well.
As far as you're idea....could you possibly let each turbo use it's own intake, and use an electric exhaust dump on the intake to switch between the two turbo's? I doubt it would seal 100%, but it wouldn't need too. use another one in the exhaust and have it bypass the rear turbo. they can be both controlled by a rpm activated switch. Get what I'm saying...? You wouldn't have to worrie about the rear turbo causing trouble then, use a push through MAF for sure, so both turbo's feed it. the tough part is timing the switch right as the big turbo starts hitting positive pressure. That may be just as much trouble to set up though...the only benefits are you could use the internal on the small turbo as is, and there would be no worrie of damage to the smaller one.
idk, I get ideas in my head that make sense, but may not work well in real life sometimes. Perhaps like you said would be better, have you though of an exhaust cut out though? For once the big turbo takes over to prevent it from feeding/overspooling the smaller one
As far as you're idea....could you possibly let each turbo use it's own intake, and use an electric exhaust dump on the intake to switch between the two turbo's? I doubt it would seal 100%, but it wouldn't need too. use another one in the exhaust and have it bypass the rear turbo. they can be both controlled by a rpm activated switch. Get what I'm saying...? You wouldn't have to worrie about the rear turbo causing trouble then, use a push through MAF for sure, so both turbo's feed it. the tough part is timing the switch right as the big turbo starts hitting positive pressure. That may be just as much trouble to set up though...the only benefits are you could use the internal on the small turbo as is, and there would be no worrie of damage to the smaller one.
idk, I get ideas in my head that make sense, but may not work well in real life sometimes. Perhaps like you said would be better, have you though of an exhaust cut out though? For once the big turbo takes over to prevent it from feeding/overspooling the smaller one
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v6z24e
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Re: sequential turbo set up on sr20 (idahotuner)
after I posted that I reread you're description and saw the part about the wastegate to stay open on the small turbo to bypass it. Would the wastegate be big enough to let out all the exhaust that the big one would make? I'm not good in mspaint, but i tried this...
That is better than what i said before because the big turbo will have all solid connections after it. the small one 'may' loose a small amount of boost though the cutout. but there will be no chance of damage to the small one as well as no restriction to the big one on the intake or exhaust side. Use the same idea of an electronic controller to open the cutouts, either by RPM or boost lvl....still have the BOV on the clod pipe of course
What do you think?
That is better than what i said before because the big turbo will have all solid connections after it. the small one 'may' loose a small amount of boost though the cutout. but there will be no chance of damage to the small one as well as no restriction to the big one on the intake or exhaust side. Use the same idea of an electronic controller to open the cutouts, either by RPM or boost lvl....still have the BOV on the clod pipe of course
What do you think?
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idahotuner
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Re: sequential turbo set up on sr20 (v6z24e)
yes i thought about using two intakes. now the ideal thing would be to use a MAP set up of absolute pressure in the intake manifold instead of MAF. MAFs done hold up long under pressure.
i also thought about using a dual intlet intercooler.
but with my current idea. i think that ones the big turbo kicks in it will take the load completely off the little turbo. and if it is sucking so hard that it makes the turbo think it is in vacuum that will hold the wastegate open and the exhaust gases would not be flowing throw the turbine housing of the little turbo at all. now on the other side of that i think the exhuast gases might flow quite a bit more then the little turbo can handle but it wont be bale to push more air then the big turbo is pulling in. keeping the wastgate completely open the whole time. so have the air will be flowing through the little turbo and half through the waste gate.
i have a slightly differnt idea for the little turbo to be mounted right below the bigger one to reduce distance from for possible air leaks.
but i have a way to air pressure test my entire system up to 30 psi. and the less connections i have between the little turbo and the big one the better, so it could probably be two complete pieces using only three couplers. on at the little turbo, one in the middle and one going into the large turbo. and the main pressure will be the normal places on the intercooler set up.
and i will only probably run about 20 psi max. because this should give enough low end torque to do the job i wan. and 20 psi on a gt35 or so should make 450 to the wheels if not 500. at a low enough pressure rating to not require 100 octane fuel
i also thought about using a dual intlet intercooler.
but with my current idea. i think that ones the big turbo kicks in it will take the load completely off the little turbo. and if it is sucking so hard that it makes the turbo think it is in vacuum that will hold the wastegate open and the exhaust gases would not be flowing throw the turbine housing of the little turbo at all. now on the other side of that i think the exhuast gases might flow quite a bit more then the little turbo can handle but it wont be bale to push more air then the big turbo is pulling in. keeping the wastgate completely open the whole time. so have the air will be flowing through the little turbo and half through the waste gate.
i have a slightly differnt idea for the little turbo to be mounted right below the bigger one to reduce distance from for possible air leaks.
but i have a way to air pressure test my entire system up to 30 psi. and the less connections i have between the little turbo and the big one the better, so it could probably be two complete pieces using only three couplers. on at the little turbo, one in the middle and one going into the large turbo. and the main pressure will be the normal places on the intercooler set up.
and i will only probably run about 20 psi max. because this should give enough low end torque to do the job i wan. and 20 psi on a gt35 or so should make 450 to the wheels if not 500. at a low enough pressure rating to not require 100 octane fuel
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idahotuner
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Re: sequential turbo set up on sr20 (idahotuner)
the thing i would change with this, is to put the MAF in between the small turbo and big one so when that valve closed it would be in a vacuum, and only be underboost when the smaller turbo is spooling. and they do make butterfly valves that seal one hundred percent, i saw them when i was at sema last year and talked to the guys that designed them. They are made for exhaust blocks for like v8s when they want to run straight pipes sometimes so they flip a swtichv6z24e wrote:
What do you think?
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v6z24e
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Re: sequential turbo set up on sr20 (idahotuner)
I had thought about saying you should keep them both under the hood for oil pluming ease, but idk how space would be, mine is bottom mount and I'd like to keep it that way. Using a MAP would definitely be easier, you are on a full standalone I presume? I'm still a bit confused on why you think the small turbo will see vacuum and try and spool up, use a MBC between the cold pipe and the wastgate, should run just like my car does now, once the big guy takes over it will read way more boost than it's set for and hold the wastegate open to try and bleed it off. No? This is my first turbo car, and I've only had it ~1yr, I could be wrong on how that part works.
My concern would still be trying to pull though the amount of air that you want without the small turbo acting as a restriction. You are are prolly right about the exhaust, a big enough wastegate, or using an external and the internal will divert enough air to keep the small one from over spooling.
What else uses a system like this we could bounce ideas off of? I know the VR4 and Stealth R/T guys are the same size. Don't stock mkIV Supra's use two diff sizes turbo's? How to they switch between them?
In all honestly, this is a cool idea I'd love to see/experience, but is it worth the trouble just to get response? I mean, it's more of a bragging right. You could hook up a small 35/50 shot of nitrous on a WOT and window switch to kick in at 2/2.5k and shut down at 4/4.5k once you are in full boost on the turbo. Or even just do a dry kit that sprays into the header right at the exhaust wheel, set up same way, WOT switch and a 2k-4k widow switch.
Just for the sake of posting, here is one of the first guys to do a rmt on a Z24. He started with a stock 2.8, boosted it, then engine swap to a 3400, followed by a bigger turbo. Has done two high 11's passes with stock internals on 215 d/r's. He does address how to run a oil system back there.
http://khturbo.net/rmtz24/RMTZ24.html
My concern would still be trying to pull though the amount of air that you want without the small turbo acting as a restriction. You are are prolly right about the exhaust, a big enough wastegate, or using an external and the internal will divert enough air to keep the small one from over spooling.
What else uses a system like this we could bounce ideas off of? I know the VR4 and Stealth R/T guys are the same size. Don't stock mkIV Supra's use two diff sizes turbo's? How to they switch between them?
In all honestly, this is a cool idea I'd love to see/experience, but is it worth the trouble just to get response? I mean, it's more of a bragging right. You could hook up a small 35/50 shot of nitrous on a WOT and window switch to kick in at 2/2.5k and shut down at 4/4.5k once you are in full boost on the turbo. Or even just do a dry kit that sprays into the header right at the exhaust wheel, set up same way, WOT switch and a 2k-4k widow switch.
Just for the sake of posting, here is one of the first guys to do a rmt on a Z24. He started with a stock 2.8, boosted it, then engine swap to a 3400, followed by a bigger turbo. Has done two high 11's passes with stock internals on 215 d/r's. He does address how to run a oil system back there.
http://khturbo.net/rmtz24/RMTZ24.html