s4 turbo, how much power can it make efficiently?
11-28-12, 12:56 PM
#26
there are a few ways to run 10psi on a T2....
i think the #1 thing is an FD fuel pump. if you do the maths, the stock T2 pump will only move 550ccx4 of fuel, its exactly the same size as the injectors, and that is if its in 100% perfect condition. so the best thing to do is upgrade to the FD pump which flows more. its also a great idea to replace both fuel filters, there is one in tank.
second on the list is making sure the car runs right in the first place. i've tried to do this other ways, but on a T2 its just easier to pull the intake and check everything, literally. vacuum leaks are bad, the vacuum hoses need to be hooked to the right place. i find the vacuum diagram isn't good enough, so i actually pull each end of a hose and make sure it is right. etc etc.
third you need some kind of exhaust, the precat should be replaced with a downpipe at least. i like the Rb turbo back system/revII, although in CA we buy two more flanges and put a cat in the middle, it will pass smog like this.
4th, i like the S5 turbo better than the S4, response is better, and boost creep is basically 1-2psi which is fine. i've found the S4 turbo can creep like 6-7psi, and this means you either need to have the car setup for it, or restrict it somehow.
5th, electronics. this is an important step, as you need to get rid of the overboost fuel cut, and then either add more duty cycle OR larger injectors. i have found that if you can increase the injector duty, with an FD fuel pump, there is enough fuel for 12psi with the stock injectors. if you cannot increase injector duty, then larger injectors are needed.
these days the Rtek 2.xx is probably the best way, you get the FCD, you can adjust fuel and timing, and there is no add on boxes, or wiring splices, plus you are tweaking the stock maps, instead of starting from scratch like a haltech
i always ran F-cons, they work great as long as you don't go nuts.
i think the #1 thing is an FD fuel pump. if you do the maths, the stock T2 pump will only move 550ccx4 of fuel, its exactly the same size as the injectors, and that is if its in 100% perfect condition. so the best thing to do is upgrade to the FD pump which flows more. its also a great idea to replace both fuel filters, there is one in tank.
second on the list is making sure the car runs right in the first place. i've tried to do this other ways, but on a T2 its just easier to pull the intake and check everything, literally. vacuum leaks are bad, the vacuum hoses need to be hooked to the right place. i find the vacuum diagram isn't good enough, so i actually pull each end of a hose and make sure it is right. etc etc.
third you need some kind of exhaust, the precat should be replaced with a downpipe at least. i like the Rb turbo back system/revII, although in CA we buy two more flanges and put a cat in the middle, it will pass smog like this.
4th, i like the S5 turbo better than the S4, response is better, and boost creep is basically 1-2psi which is fine. i've found the S4 turbo can creep like 6-7psi, and this means you either need to have the car setup for it, or restrict it somehow.
5th, electronics. this is an important step, as you need to get rid of the overboost fuel cut, and then either add more duty cycle OR larger injectors. i have found that if you can increase the injector duty, with an FD fuel pump, there is enough fuel for 12psi with the stock injectors. if you cannot increase injector duty, then larger injectors are needed.
these days the Rtek 2.xx is probably the best way, you get the FCD, you can adjust fuel and timing, and there is no add on boxes, or wiring splices, plus you are tweaking the stock maps, instead of starting from scratch like a haltech
i always ran F-cons, they work great as long as you don't go nuts.
I may try finding an s5 turbo but I'll already have an s4 but I'll have to get it rebuilt or get one in good working condition, and I know s5 are harder to come by and more pricey.
Car will be running stock boost when I first get her going, but I do want to set it up so it can run higher boost later on without having to remove too much stuff (mainly the turbo: I'll port the waste gate if that will eliminate all my boost creep and allow me to maintain stock boost as well as bring it up without getting boost creep)
rotary>pistons
11-28-12, 12:57 PM
#27
What is needed to stop the boost creep on an s4 turbo? I really can't afford a rtek 2.0 I'll probably be getting a stock ecu or a rtek 1.5 or 1.7
Car will be running stock boost when I first get her going, but I do want to set it up so it can run higher boost later on without having to remove too much stuff (mainly the turbo: I'll port the waste gate if that will eliminate all my boost creep and allow me to maintain stock boost as well as bring it up without getting boost creep)
rotary>pistons
Car will be running stock boost when I first get her going, but I do want to set it up so it can run higher boost later on without having to remove too much stuff (mainly the turbo: I'll port the waste gate if that will eliminate all my boost creep and allow me to maintain stock boost as well as bring it up without getting boost creep)
rotary>pistons
Restricting the intake/exhaust is a good way to prevent boost creep, besides porting the wastegate.
11-28-12, 01:00 PM
#28
How do you go about doing that? I always thought reducing the restriction is what brings up the boost pressure so it'd be hard to reduce the restriction while still having some restriction on it. I thought all you needed was to port the wastegate
rotary>pistons
rotary>pistons
11-28-12, 01:47 PM
#30
Port the wastegate out to >1", weld a valve as the new 'flapper'. Plain washers will deteriorate and will end up looking like a snowflake.
It's easier to identify a component turbo/intercooler/injectors that you don't want to replace and do everthing needed to support that component. You can't do the bare minimum but be ready for more later.
I appreciate that you are doing things on a budget, but cutting the wrong corners is how rotaries get such a bad reputation outside this forum. And in the v8 section.
It's easier to identify a component turbo/intercooler/injectors that you don't want to replace and do everthing needed to support that component. You can't do the bare minimum but be ready for more later.
I appreciate that you are doing things on a budget, but cutting the wrong corners is how rotaries get such a bad reputation outside this forum. And in the v8 section.
11-28-12, 03:06 PM
#32
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What is needed to stop the boost creep on an s4 turbo? I really can't afford a rtek 2.0 I'll probably be getting a stock ecu or a rtek 1.5 or 1.7
I may try finding an s5 turbo but I'll already have an s4 but I'll have to get it rebuilt or get one in good working condition, and I know s5 are harder to come by and more pricey.
Car will be running stock boost when I first get her going, but I do want to set it up so it can run higher boost later on without having to remove too much stuff (mainly the turbo: I'll port the waste gate if that will eliminate all my boost creep and allow me to maintain stock boost as well as bring it up without getting boost creep)
rotary>pistons
I may try finding an s5 turbo but I'll already have an s4 but I'll have to get it rebuilt or get one in good working condition, and I know s5 are harder to come by and more pricey.
Car will be running stock boost when I first get her going, but I do want to set it up so it can run higher boost later on without having to remove too much stuff (mainly the turbo: I'll port the waste gate if that will eliminate all my boost creep and allow me to maintain stock boost as well as bring it up without getting boost creep)
rotary>pistons
second on my car i had enough fuel so that boost spikes were fine, so i never did anything. everyone else tries to run the stock ecu/fuel system and port the wastegate so they can run less boost.
the S5 turbo controls boost way better
so you have choices
11-28-12, 03:14 PM
#33
Well maybe I'll try to get an s5 turbo if its a direct bolt on, I just figured I'd use s4 since I already have one, I'll have to check the cars exhaust to see if its stock...I'd just rather use the s4 because it'll cost me less money.
From what I'm hearing there's really no reason to keep the s4 turbo if you have the oppurtunity to upgrade it (which I will since I'm rebuilding the engine)
rotary>pistons
From what I'm hearing there's really no reason to keep the s4 turbo if you have the oppurtunity to upgrade it (which I will since I'm rebuilding the engine)
rotary>pistons
11-28-12, 03:27 PM
#35
tru but in all honesty i would personally run what u have and make sure that u keep the boost at a stock level until you have the resources to run what u want to run. i built my s4 conservative so that i can have fun but also have it as my daily driver. now if you already have a daily driver i would take the time to build it right so that way u can do what u want to do to it. just my 2 cents. my fc was a budget build some wheelin and dealin with the guys here on the forum. im pushin 14psi on rtek 2.1 550cc prim 820cc sec 3 inch exhaust stainless steel tubular mani. apexi avc-r boost cont garett t67. we guesstimate anywhere from 300 to 350ish also forgot aeromotive 340lph pump and a few other things.
Last edited by demon721; 11-28-12 at 03:31 PM.
11-28-12, 03:34 PM
#36
Yea I want to keep it close to stock, I'm very paranoid so I always make sure about everything before I do it.
I'd bring it up 1 psi at a time, slowly bringing it up. I'm in no hurry but I do want to eventually get it close to 10 psi but that's a long term goal, short term would be 6.5-7.5 psi
rotary>pistons
I'd bring it up 1 psi at a time, slowly bringing it up. I'm in no hurry but I do want to eventually get it close to 10 psi but that's a long term goal, short term would be 6.5-7.5 psi
rotary>pistons
11-28-12, 03:43 PM
#37
its very possible to do that but from experience ur gonna want to boost her. they love it. also i run water injection aswell which i think helps alot with knock and so forth. u seem to have ur head on right and kno what u want. luckily this forum helps out a lot with questions anyone has.
11-28-12, 08:28 PM
#40
Its really easy to port the wastegate on an s4 I did it inside an hour after I got the turbo apart.
One of the better ways to restrict boost creep I've found is to keep the stock airbox and intake piping. It won't eliminate it totally if you have a free flowing exhaust but it really helps.
You will need an FCD. I think I have one for an S4 somewhere.
One of the better ways to restrict boost creep I've found is to keep the stock airbox and intake piping. It won't eliminate it totally if you have a free flowing exhaust but it really helps.
You will need an FCD. I think I have one for an S4 somewhere.
11-28-12, 10:15 PM
#43
Okay, so I'll still be able to run the stock 5.5 psi though without it , and anything up to 12 psi with it ? I guess I'll just have to figure this all out when I get everything put together, I just want to be able to run stock until I do want to run more later, I do plan on porting the wastegate so it'll prevent it from overboosting, that's definitely not something i want to happen, one person said you can boost spike 6psi over, which scares me.
03-02-13, 05:03 PM
#48
do you have a wideband a/f gauge? get that and a boost gauge as your first mods, then you will know whats going on in the engine
if the exhaust and or intake is not completely stock, then you will get boost creep, you definitely want to port the waste gate as big as u can, and if your exhaust is really free flowing you still may run into some creep.
I don't really see any point buying the rtek 1.5 if your going to run it at stock boost levels keep the stock ecu, that way if your boost does creep youll hit fuel cut and know to stop instead of keep going and risk running lean and blowing up. ( it can be argued hitting fuel cut in it self is pretty bad, but I think its a hey stop what your doing warning, vs wrapping it out on a cold day in 4th gear and blowing it up)
if you want to go over stock boost on a stock ported motor, and stock turbocharger at all id at least just get the 1.7, walbro, and the 720 injectors. it adds more headroom for if your boost does go somewhat higher than u planned.
also get all of your injectors cleaned/flow tested, and change your fuel filter.
if the exhaust and or intake is not completely stock, then you will get boost creep, you definitely want to port the waste gate as big as u can, and if your exhaust is really free flowing you still may run into some creep.
I don't really see any point buying the rtek 1.5 if your going to run it at stock boost levels keep the stock ecu, that way if your boost does creep youll hit fuel cut and know to stop instead of keep going and risk running lean and blowing up. ( it can be argued hitting fuel cut in it self is pretty bad, but I think its a hey stop what your doing warning, vs wrapping it out on a cold day in 4th gear and blowing it up)
if you want to go over stock boost on a stock ported motor, and stock turbocharger at all id at least just get the 1.7, walbro, and the 720 injectors. it adds more headroom for if your boost does go somewhat higher than u planned.
also get all of your injectors cleaned/flow tested, and change your fuel filter.
03-02-13, 05:41 PM
#50
The car doesn't have an s4 Turbo I'm upgrading to s5, car does have a full exhaust, stock intake/airbox, stock tmic, blitz bov, and I do have a fuel cut defender.
I will run stock 550cc primaries and 680cc 1st gen gsl-se secondaries (flow same as 720cc on 2nd gens from increased fuel pressure), fuel pump and ecu will be stock until I can afford to upgrade.
I do plan on porting the wastegate, do I have to take apart the turbo to do it?
I plan on getting a boost gauge for when I first get it running and possibly a manual boost controller (if peak boost is really low like 6 psi), I'll later get a wideband.
Rotary >Pistons
I will run stock 550cc primaries and 680cc 1st gen gsl-se secondaries (flow same as 720cc on 2nd gens from increased fuel pressure), fuel pump and ecu will be stock until I can afford to upgrade.
I do plan on porting the wastegate, do I have to take apart the turbo to do it?
I plan on getting a boost gauge for when I first get it running and possibly a manual boost controller (if peak boost is really low like 6 psi), I'll later get a wideband.
Rotary >Pistons
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