Ok so I have been trying to drop my spool up on my turbo through tuning. I have heard a couple different theories on tuning down low. Some say lean it out and give it advance so that it has more throttle response and torque at the sacrifice of some spool. Some say to retard the timing for higher EGT's to aid spool. Some say retard the timing and lean it out for max EGT's. Any theories or advice?
make it rich, more fuel=more spool. But...none of that is going to make a huge difference. IIRC the 07 STi uses the smallest orifice for boost control. Get one of those, then jack your wastegate duty way up. Be careful not to overdo it and over boost. You will need to tweak your fuel and timing maps as well. Make sure to be data logging and have a wideband. I'd say use the AVCS...but, you dont have it.
Fuel does not = spool. You are only going to be able to make a small change(200-300rpms), spool has more to do with the turbo than anything. You could dump fuel in and pull lots of timing, which will raise youre egts, but youre throttle response will suffer. What turbo is on youre car that you are unhappy with spool? Matt
It's just a stock turbo with a minor port job. I have been playing around with it to see how I can best get it too spool. There are some guys that CLAIM that they are able to hit 16-17 psi by like 2700 rpm by tuning. I have not been able to do that yet. What I have found that changed it so far was adding advance and leaning the mixture some prior to making boost seems to work. This is all road tuning so it is hard to tell. Sure, I can make it by 2800 in 5th, but not in 3rd or 4th.
GM BCS will help retard a little timing create a little more exhaust flow in sacrifice for torque Port your exhaust
Hey....if you wanted a well designed properly working turbo car then you should have bought something else. These things are P.O.S. LOL Matt
If early spool is so important then do what the factories do... stick a small ass little turbo on it and keep the boost low. It'd be cool to track down one of those VVT turbo's though to try out.
At this point I am not concerned with changing out the mechanicals of anything...this question is from a tuning aspect and I was curious what others are doing and how they are going about making the car spool faster from a tuning point of view. Hence why this question is in the "ECU Tuning" category. Hopefully someone will have something a little more helpful to say than buy a different car...
It wasn't meant to be harsh. There are lots of problems with subarus design which is why the spool is so slow even on a stock turbo. From a tuning stand point there isn't much you can do to get it to spool faster. I personally prefer to run as much timing as possible in that area of the curve because it makes the throttle response nice and crisp. It honestly depends on youre driving style though. Matt
Found this on NASIOC from the tuner at TurboXS: You asked a very good question that I am happy to answer. I guess this is sort of the short version of “the wrx tuning guide” so have fun. Think of your air fuel curve as the inverse of your torque curve and you'll have a good start. Run leaner at areas where you make less torque (low RPM and high rpm as well) and you'll want to run richest at peak torque. With that out of the way let's talk about boost and spool-up issues. I like to break this down into 4 stages. 1. Pre-spool up (enough exhaust gas energy to produce low boost pressures, but not enough to cause the boost pressure to rapidly rise) 2. Spool up (enough exhaust gas energy that boost is quickly build towards peak boost) 3. Peak boost (max boost level achieved and waste-gate open). 4. Declining boost (waste-gate closed). During stage 1 I typically run a car at around 14.5-7:1. Turbines like heat and by leaning out this area of the map you can usually make the transition to spool up quite a bit quicker. One of the best tools for tuning this area is your EGT gauge. You want to get a rapid rise of EGTs in the pre-spool up stage. I typically shoot for about 600-700c in this area. Hot exhaust gas will do wonders for getting the turbocharger to produce more boost at pre-spool up and will quicken the transition to spool up by a substantial amount. In stage 2 I start to bring the fuel back into the mixture. My goal is transition smoothly from mid 14:1 AFR to the 10.8:1 AFR I run at peak torque during stage 3. Your EGTs should continue to rise, but not as rapidly as before. During stage 2 you’ll usually gain another 100c or so of EGT. Your primary responsibility here is to dump fuel and pull back timing to keep the rapid rise of cylinder pressures from inducing knock. We pull back timing during this area for another reason. The denser a mixture is in the cylinder the faster it burns. There is no need for huge timing numbers in these areas as your VE (volumetric efficiency) is rapidly increasing. It’s important to note that this holds true across the board. The more air you shove in your cylinder the less ignition timing you will have to run (assuming AFR is kept constant) at the same RPM. Stage 3 will see peak torque. It should also see at or near the lowest ignition timing numbers and AFR numbers you’ll run on your map right at peak torque. EGT’s should be stable at about 800-820c at this point. As I’ve said before I try to hit 10.8:1 as a general rule of thumb for 93-octane. I will maintain this 10.8:1 AFR as long as the torque stays relatively the same. During this stage you’ll get some additional VE benefits from having your waste-gate fully open, but you’ll need to start adding ignition timing back into the mixture as RPMs rise. As RPMs rise the pistons are moving faster which gives your combustion charge less time to complete its burn. Therefore as RPMs raise you must add timing to the mix to ensure a complete burn. If you have rapidly rising EGTs in this area while your AFR stays constant, it’s likely because you are not adding enough ignition timing back into the mix which causes the exhaust valves to open while your cylinder charge is still burning. During stage 4 torque starts to rapidly decrease. In a WRX you can usually see this torque downturn around 6000rpms. Peak power may still happen in this stage because of the mathematical benefits of producing torque above 5252rpm, but your VE is rapidly falling. It is in this area that we start to do all the little tricks to keep the car producing power. You’ll need to add timing back into the map at a more rapid rate here simply to combat the loss of VE; as the mixture gets less dense it burns slower thus requiring more ignition advance. In addition the RPMs are still rapidly rising so you’ll need to double your efforts to stay on top of things to keep EGTs from going out of control. The further boost drops off the more ignition timing you need to add in. The old stage 1 map had 26 degrees of ignition timing at redline. The new stage 1 maps have more like 23. The difference is that we are not counting as much on boost taper in the new maps and we decided to remove a little of the extra advance at redline to make the map a little more low octane friendly. You may be able to bump that up a little bit. We also start leaning out the AFR as torque drops. By redline you should be looking to run around 11:1 for 93-octane. This will help keep the torque up and make up for some of the slow down in the combustion process, but it’s common for peak EGTs to be experienced in this area. I usually try for about 830c-850c in this area, although I know several people that tune for 900c and have had their cars run for quite some time. 900c seems a little excessive to me and I’ve seen USDM WRX heads with small cracks near the spark plugs after long-term 900c usage. Keep it a little cooler and your motor will thank you. Ok… that should be enough to get you started. -Nathan
Timing and AFR's have little effect on trying to spool a turbo on a subaru since the turbo itself sits so far from the actual exhaust port. AVCS tuning will make the largest difference..... that and some Nitrous.
Yup, saw your post on the nitrous suby that you are running...what kit were you using or was it a custom design?