3SGTE/Turbo: twin charged

[Kevin mr2 1985]

okay so i found a mk2 turbo for really cheap like $50 and i was wondering can u use a mk2 turbo header for the mk1 supercharged?

next question how much does it cost to get a header and full exhaust made for a mr2?

also what kind of crazy tunning has to be done to make this run right?

[Beau Corso]

no, the 3sgte manifold will not directly bolt onto a 4agze.

next, it's not just as easy as bolting it up and tuning it. you have to have the proper bypass valve so that the supercharger can force air in at low speeds and then switch over to the turbo once it's spooled and turn the supercharger off.

its a very complicated setup. you'd be better off with a small-ish turbo that will spool quickly.

[328FTW]

I do know is that it would take a lot of tuning. The turbo and supercharger have to work together so you have to have some way of disengaging the SC when the turbo spools up. It can be done with a stand alone ecu, a good piggyback system might be able to do it but it doesn't have the same flexibility. Not sure I can recommend it unless you are a good mechanic with a truck load of patience.

A full exhaust systems price can vary depending on what brand resonators are used and how complicated the setup is. A header is actually quite complicated to have made but a good shop should be able to do one for 150 based on specs (very rough converting from nz dollars), the rest of the system depends on what brand muffler you use and if it is a dual pipe exhuast. Also remember that the 3sgte turbo is for a 2L so will not be well matched, also being that cheap the turbo seals could be gone and it could have a lot of play, would pay to check it out carefully.

If it doesn't work out can I have your 3sgte? pretty please I want one for my build.

[Kevin mr2 1985]

lol i didnt buy it but i have a really nice header for my mr2 4agze just it doesnt clear the starter so i would either need a different starter or like a spacer made for it to move it out... i might just sell it and get a new header made anyway.

[328FTW]

I had an exhaust that hit the starter. I put it in the vice and just levered it out. It was really redneck but it worked

[div0]

Originally Posted by 328FTW

I do know is that it would take a lot of tuning. The turbo and supercharger have to work together so you have to have some way of disengaging the SC when the turbo spools up. It can be done with a stand alone ecu...

...Also remember that the 3sgte turbo is for a 2L so will not be well matched...

I'm currently working with a local shop on creating a custom twincharger installation on my '88 SC AW11. I'll post a large writeup on a new thread in this section once it is complete, but I'll add a few relevant comments now.

I do expect the supercharger bypass crossover to be rather challenging to smooth out, and I have bugeted extra dyno time for tuning this transition. The ECU has two general purpose I/O lines that will be used to control this transition. The first line controls the supercharger clutch, and the second line controls the Toyota Supra turbo intake air control valve (IACV) that will be used to bypass the supercharger. The lines will be controlled by both engine RPM and throttle position. To provide a smooth transition, the supercharger engagement and bypass valve map will be set up so that the supercharger is spinning while the bypass valve is still open, and then the bypass valve will slowly close. The bypass valve will be open in the low throtle (<50%) and low RPM (<2000) range, closed in the mid range, and then open again in the high RPM range (>~4500) followed by the supercharger disengaging. The optimum throttle and RPM set points will be found during dyno tuning.

I think the 3sgte turbo would actually be on the small side for a twincharger setup. Remember when the supercharger is engaged, the engine equivalent displacement is closer to a 2.8L engine, minus the volumetric efficiency of the SC12 supercharger and post supercharger pressure losses. I also have an oversize pulley that is just making up for these losses so my equivalent displacement comes right at 2.8L. This should get the exhaust gasses flowing sufficiently to spin up the GT3071R turbo in a reasonable RPM range with compound boosting. I'll let you know how it goes in the later thread.

If you do pursue a twincharger setup, I'll be happy to compare notes with you.

[Kevin mr2 1985]

well i first got to get my wireharness and get this 1985 mr2 with a levin gtz motor running... the wire harness is in a whole nouther state so it'll be a while till it gets turned onconsidering i still need to get all vacuum hoses routed

[Jackstand Queen]

Kevin Mr2 1985

If your header interferes with your starter: then your starter is mounted on the wrong side of the engine.

An SC starter is supposed to be on the rearward intake side of the engine.

Good Luck.

[feral4mr2]

i've done a TC and it was a lot easier than people make it out to be.

i never ran a bypass at all , turbo straight through the s/c into the i/c. IMO that is the best way to do a TC yourself with-out the head ache. retained the ecu control of the s/c. and it works well.

[rsfire]

I'm working on twincharging my AE86 with a gze. All I need is a chip in my megasquirt for coil on plugs and tune off of a basemap and it'll run. Hopefully done by tomorrow. But I'm running s/c > turbo > intercooler so it'll spool up a gt35r pretty quick. for a bypass valve i'm using a 2" wastegate. I'll manually tune it unlike div0. I have a pressure switch to turn off the s/c once the turbo reaches 1psi higher than the s/c, then the wastegate will be set for about the same so it'll open right before the s/c shuts off.

Here's what it's starting to look like I can get detailed pics of pretty much anything on it. Oh and div0, i'm curious, are you running s/c > turbo or other way around? Can you send me a pm of what you did for tuning your s/c and bypass on your computer, that sounds like a much better way. thanks

[ebouwman]

Twincharged has to be the coolest setup ever.

Speed - Source - Design. Fabricate. Produce. Install. Maintain. sells a turbo exhaust kit for the MK1

RSFire, that setup sounds pretty impressive

[rsfire]

thanks. ya, i meant to say bout the headers too. I had some for an 86 which wern't even close to fitting so my buddy basically cut them into many pieces and completely rebuilt them to make the turbo top-mount. that was a really long process. the car has been in a shop for about 4 months too.

[div0]

Originally Posted by rsfire

Oh and div0, i'm curious, are you running s/c > turbo or other way around? Can you send me a pm of what you did for tuning your s/c and bypass on your computer, that sounds like a much better way. thanks

I'm running turbo > A2W intercooler > S/C > A2W intercooler > throttle body. The IACV bypasses the first A2W intercooler > S/C and dumps directly to the second A2W intercooler. When fully bypassed, it is running as a pure turbo setup. The primary purpose of the SC is to compound the initial boost and rapidly spool the turbo to the boost controller limit, and then switch out after the tubo is fully spooled.

The build is still in progress, so I don't have any tuning data to present yet. I expect the project to be finished in April. The numbers I presented above will be the starting point, but we will move the RPM and throttle setpoints and bypass close speed as needed to obtain a smooth transition during dyno tuning. The computer allows setting the GPIO outputs for the SC clutch and bypass valve vacuum line switch based off of throttle position and RPM.

This build is a little unique in that the throttle body is positioned after the positive displacement SC12 supercharger, along with a blowoff valve. Twincharging is the final stage of this project. The previous stage build had already moved the throttle body post-supercharger, with the supercharger engaging at 60% throttle and RPM > 2000. I actually find this rather unpleasant, as past 60% throttle the SC comes on hard and there is very little difference between 60% and 100% throttle at that point. So if the SC is engaged, you might as well punch it to the floor. I'm have high expectations that the slow bypass valve transition surrounding the SC engagement will significantly smooth the transition.

I'll let you know the final setpoints, along with the final dyno chart, once we have completed it.

[rsfire]

I'll need to look into the GPIO for the clutch, and for a bypass i've got a big wastegate so i dont know if i can make that smooth though.

I'll be running the s/c through the turbo so my guess is that would be the fastest way to spool since it's spinning the turbine too. Though my s/c will always be on until the turbo is spooled so in theory i should be making boost at idle, that will either hurt me or be awesome. lol I should be able to fire it for the first time and start tuning so i'll let ya know how it goes if ya want.

[rsfire]

I'll need to look into the GPIO for the clutch, and for a bypass i've got a big wastegate so i dont know if i can make that smooth though.

I'll be running the s/c through the turbo so my guess is that would be the fastest way to spool since it's spinning the turbine too. Though my s/c will always be on until the turbo is spooled so in theory i should be making boost at idle, that will either hurt me or be awesome. lol I should be able to fire it for the first time and start tuning so i'll let ya know how it goes if ya want.

[feral4mr2]

dont run s/c to turbo. you can blow the seals out, plus it wont really help the spool of the turbo that much to be worth it, the s/c takes care of the lower rpm's anyways, if you want the turbo to spool ealier match the turbo size to when you want it to come in. a 0.63 exhaust a/r works well on the 4age twincharge, mines a 0.84 a/r and i feel is a little large. plus it is a large 6 cylinder diesel turbo.

there are quite a few running TC's and are running the turbo through s/c, most with no bypass. it's been proven to work and be relieble.


here is some reading that might be of use. read warspeeds posts closely.
Engine & fuel engineering - twincharging estimated results

[rsfire]

i'll go ahead and read that. but it's a little to late. my project's just about done. i'm going to try firing it today.

[Kevin mr2 1985]

wow so i could theoretically run a turbo into the IC then to the supercharger with a bleed off valve set for the psi i want? with nothin else to do other than that?

[feral4mr2]

Originally Posted by rsfire

i'll go ahead and read that. but it's a little to late. my project's just about done. i'm going to try firing it today.

maybe you should of done more research before you started...

wow so i could theoretically run a turbo into the IC then to the supercharger with a bleed off valve set for the psi i want? with nothin else to do other than that?

well yes and no. yes the TC is a lot simpler than people make it out to be, that probably because they try to stuff around with s/c bypass valves and working out ways to turn the s/c off at a given rpm or amount of turbo boost. the simplest effective way is to leave the s/c ecu controled with no complicated bypass set-ups. but no you dont just slap it on and go..
air filter - afm (if you have one) - turbo - throttle body - s/c - i/c - inlet manifold.
i'm running stock 4agze with stock 4agze ecu etc. have put some 440cc 7mgte injectors in just in case. but it ran ok with the 365cc. never got the air/fuel mix checked though..
using an external wasegate which get's it's signal from the inlet manifold not the turbo outlet. as mentioned in one of the post on that link i posted up above.

[Kevin mr2 1985]

well it was just an idea i had and it is less difficult than i originially was told but im sticking with a super charger till it blows out or till i go just to turbo or tc.