2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

twin turbo'd S4 t2 engine

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Old Oct 28, 2010 | 06:38 PM
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twin turbo'd S4 t2 engine

so Im buying a cosmo 13b twin turbo hoping it will fit on a s4 t2 engine
what ecu will i need ? thanks
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Old Oct 28, 2010 | 07:25 PM
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You're buying the cosmo twin turbos?? You'll need a spacer to clear the LIM on the TII engine and some kind of crazy downpipe as the spacer will put the exhaust exit from the turbos about 2" from the frame of the car. You'll also need custom turbo oil lines, custom turbo water lines, custom intercooler piping..

Find out who will be tuning your car and let them recommend an ECU that they're familiar with using...
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Old Oct 28, 2010 | 09:56 PM
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Originally Posted by FrankV702
You're buying the cosmo twin turbos?? You'll need a spacer to clear the LIM on the TII engine and some kind of crazy downpipe as the spacer will put the exhaust exit from the turbos about 2" from the frame of the car. You'll also need custom turbo oil lines, custom turbo water lines, custom intercooler piping..

Find out who will be tuning your car and let them recommend an ECU that they're familiar with using...
not really need a spacer, but you will have to grind away at the lim and then you are going to have to make your own intake piping, and then once that is done, custome downpipe, and then ... a stand alone.
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Old Oct 30, 2010 | 06:46 AM
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anything is possible

make custom manifolds and downpipe. haltech that bitch, tune it then call it a day. im sure its much more complicated than that but ive been waiting to see a 13b turbo 2 TT

edit: wtf is with the twin flux capacitors. ya know FC's still wont be fast enough to go back in time
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Old Oct 30, 2010 | 10:46 AM
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As others have mentioned, they can be made to fit. However unless you run them sequentially, there is no benefit over a properly sized single turbo that will spool faster.

If you wish to run them sequentially, it will take some work and a standalone with enough outputs. TitaniumTT has a fully sequential 13B-RE in his 2nd gen which works quite well. Take a look at some of his posts to see what he had to to do make it work. It's far from bolt on.

The real questions here are: how much power do you want to make, how will you use the car, and how much money are you willing to spend?
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Old Oct 31, 2010 | 01:31 PM
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Originally Posted by SirCygnus
not really need a spacer, but you will have to grind away at the lim and then you are going to have to make your own intake piping, and then once that is done, custome downpipe, and then ... a stand alone.
I tried to grind down the LIM to fit them on and I may have grinded away to much. I got the twins to fit, but the LIM was way to thin. :/ Swapped out the LIM, put a spacer on it and the exhaust exit from the turbos was literally less than 2" away from the frame of the car. I decided at that point to toss a Knightsports hybrid S5 turbo on the car and was pretty happy with that.

Originally Posted by Aaron Cake
If you wish to run them sequentially, it will take some work and a standalone with enough outputs. TitaniumTT has a fully sequential 13B-RE in his 2nd gen which works quite well. Take a look at some of his posts to see what he had to to do make it work. It's far from bolt on.
And a mountain of cash! haha.. I think he's got like a Motec M800. That's a $5k box alone!
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Old Oct 31, 2010 | 01:55 PM
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ugh

just put the money into a real single turbo, it's not like they're getting more expensive.. hell, you can buy a refurbished T04B for $225 or holset for $500 or new master power T70 for $600 or new Garrett GT35R ball bearing for $1050. all will need the same amount to work as a set of twins. all the turbos listed will have as much power and more than the stock twins will.

if you think you can just slap it on and go, think again.

want some real power? suck it up and pin the motor, RX8 stat gears and slap a Garrett T4708 on it, it's good for, oh... 1500 horsepower!
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Old Oct 31, 2010 | 02:54 PM
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^ And 2 runs down the drag strip
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Old Oct 31, 2010 | 03:00 PM
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^Thats better than one run down the drag strip....
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Old Oct 31, 2010 | 03:58 PM
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if the motor could hold together at 1500 to the wheels then it would be worth it!
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Old Oct 31, 2010 | 04:15 PM
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Originally Posted by iani1.1
edit: wtf is with the twin flux capacitors. ya know FC's still wont be fast enough to go back in time
A single flux capacitor sends you back in time... So a twin FC must send you to the future, no?!

Either way, I'm sure a 7 will be able to achieve 88mph.
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Old Oct 31, 2010 | 05:51 PM
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Originally Posted by tuscanidream
Either way, I'm sure a 7 will be able to achieve 88mph.
Unless it's an FB!
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Old Oct 31, 2010 | 07:10 PM
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Originally Posted by FrankV702
And a mountain of cash! haha.. I think he's got like a Motec M800. That's a $5k box alone!
Un-optioned, no harness. But I've never seen or used a better ECU and thier support makes all the other major manufactures look like a ******* joke. Not to mention the software they use is constantly being copied, or at least attempted to be. Let me put it to you this way, go to a proffesional racing, road racing, circuit racing etc event and count how many haltechs, microtechs, megasquirts there are. I would be surprised if you saw one

Originally Posted by Karack
ugh

just put the money into a real single turbo, it's not like they're getting more expensive.. hell, you can buy a refurbished T04B for $225 or holset for $500 or new master power T70 for $600 or new Garrett GT35R ball bearing for $1050. all will need the same amount to work as a set of twins. all the turbos listed will have as much power and more than the stock twins will.

if you think you can just slap it on and go, think again.

want some real power? suck it up and pin the motor, RX8 stat gears and slap a Garrett T4708 on it, it's good for, oh... 1500 horsepower!
You're missing the point of twins. I make positive pressure just off idle, and 12psi by like 2.5k... basically, I make 2x the power of all those turbo's listed at the rpm's that you spend 99% of the time at. I hit the gas, and get instant boost. The benefit of the twins far outweighs some dyno queen making 500rwhp especially when I'm over 400.
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Old Nov 1, 2010 | 09:58 AM
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^ Are you using the Cosmo twins (HT10) or the 13B-REW twins (HT12)?

also, are you controlling them like the FD does stock?

-- one output for turbo control solenoids (Vacuum and pressure), switched ON (+GND) at rpm and TPS breakpoints
-- one output for charge control solenoid, initially ON (+GND) and then switched OFF (+12V) at the same time as turbo control
-- one output for charge relief, controlled using "window switch" logic (+GND)
-- separate PWM outputs for for precontrol and wastegate, each controlled independently

?
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Old Nov 1, 2010 | 04:02 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by TitaniumTT
Let me put it to you this way, go to a professional racing, road racing, circuit racing etc event and count how many haltechs, microtechs, megasquirts there are. I would be surprised if you saw one.
this is a true statement.
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Old Nov 1, 2010 | 04:29 PM
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^ It really is. And then people wonder why their antiquated setups have driveability issues, and software issues, and trigger issues and melting issues and whatever else they have. As far as support... I was sitting on the dyno and we ran into a snag. Called MoTeC, spoke to an engineer instantly and 30 minutes later had the problem solved. Can you say that about any of the other brands? The FD will have a hundred series ECU as well unless there is more info/pricing on thier next gen version, then I may hold out for that. Hell, even the FB that I don't even own yet will be running something MoTeC.....

Originally Posted by arghx
^ Are you using the Cosmo twins (HT10) or the 13B-REW twins (HT12)?
REW HT-12's, bone stock, no porting except to the WG

Originally Posted by arghx
also, are you controlling them like the FD does stock?

-- one output for turbo control solenoids (Vacuum and pressure), switched ON (+GND) at rpm and TPS breakpoints
-- one output for charge control solenoid, initially ON (+GND) and then switched OFF (+12V) at the same time as turbo control
-- one output for charge relief, controlled using "window switch" logic (+GND)
-- separate PWM outputs for for precontrol and wastegate, each controlled independently

?
Yes and no. I was lucky enough to get a set of the Rob Bailey Solenoids days before I was about to bite the bullet and and design a system from scratch. I was not about to use the old stock solenoids, no way.

The solenoids operate like stock. I have them setup slightly different though. I had them all setup based off of TPS first, under a certain TP, they would run NS, BUT it was jerky, so I set them back to sequential and I'm still doing some datalogging, or was until the car came off the rd, to find an acceptable break point. Under X value, NS, over X value sequential then the solenoids would revert to whatever load or RPM I was at to function as they should. Idea was fuel mileage, stay in vac as long as possible... Draw back is response which is what these are all about so I'll probably just end up leaving them sequential full time.

I have a trim switch on the dash that allows me to go from WG to 15psi by turning a ****.... lets see your megasquirt do that

I have the WG and Pre-spool valves setup with a PWM. The PSV acts like THE WG under transition. Then the WG becomes active.

The turbo control valve is basically a switch.

The charge relief and charge control are also PWM controlled. Although they ramp up over the course of only a few hundred RPM's. One more benefit of the MoTeC software, I can set RPM increments down to whatever I want.

All in all, I LOVE the setup, the car pulls close to 4.0s 0-60 times.... and yes it's been video'ed and datalogged. 6-spd trans and 4.3 gears made a big difference.... the 6-spd made the biggest. Top of 2nd is 60, not 80
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Old Nov 1, 2010 | 04:43 PM
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From: cold
Originally Posted by TitaniumTT
The solenoids operate like stock. I have them setup slightly different though. I had them all setup based off of TPS first, under a certain TP, they would run NS, BUT it was jerky, so I set them back to sequential and I'm still doing some datalogging, or was until the car came off the rd, to find an acceptable break point. Under X value, NS, over X value sequential then the solenoids would revert to whatever load or RPM I was at to function as they should. Idea was fuel mileage, stay in vac as long as possible... Draw back is response which is what these are all about so I'll probably just end up leaving them sequential full time.
I've dissected the way the Power FC does it and compared it to all the FD service manuals and it seems to be very similar. There are TPS % breakpoints, and at each TPS % there is a transition point to both turbos coming online ("High" value) and a hysteresis point where the engine returns to sequential operation on deceleration ("low" value).



I have a trim switch on the dash that allows me to go from WG to 15psi by turning a ****.... lets see your megasquirt do that
Does it send a CAN command to the control unit or is it some kind of variable resistor to send a 0-5v signal? Or is it just a hi/low boost switch?

I have the WG and Pre-spool valves setup with a PWM. The PSV acts like THE WG under transition. Then the WG becomes active.
That's how Mazda did it.

The turbo control valve is basically a switch.
That's how Mazda did it.

The charge relief and charge control are also PWM controlled. Although they ramp up over the course of only a few hundred RPM's. One more benefit of the MoTeC software, I can set RPM increments down to whatever I want.
That's how Mazda should have done it IMO. Maybe on the 16 bit ECU for the series 7 & 8 they did.
Attached Thumbnails twin turbo'd S4 t2 engine-transition.jpg  
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Old Nov 1, 2010 | 09:05 PM
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Originally Posted by arghx
I've dissected the way the Power FC does it and compared it to all the FD service manuals and it seems to be very similar. There are TPS % breakpoints, and at each TPS % there is a transition point to both turbos coming online ("High" value) and a hysteresis point where the engine returns to sequential operation on deceleration ("low" value).

Is the TPS a linear 0-5V? Meaning .996V is basically 20%? Because if it is, there's really no need for a transition @ 20% trottle.


Originally Posted by arghx
Does it send a CAN command to the control unit or is it some kind of variable resistor to send a 0-5v signal? Or is it just a hi/low boost switch?
0-5V signal. You can go into boost trim, there are a few different ways to trim it, boost vs gear is usefull too, but you basically trim the WG duty cylce from a 0-100% multiplier. Works really REALLY well.

Originally Posted by arghx
That's how Mazda did it.
That's really the only way to do it.

Originally Posted by arghx
That's how Mazda did it.
Again, yeah I agree, really the only way to do it.

Originally Posted by arghx
That's how Mazda should have done it IMO. Maybe on the 16 bit ECU for the series 7 & 8 they did.
Not sure they did but I think it's smoother, and a little less strain on the turbo's IMO.
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