Questions About Turbo Performance

[plush]

Ive noticed that when I request bad ass power from my MS3, sometimes my turbo kicks in a bit harder than others. I dont think that there is a problem with my engine or ECU, but rather, it might be a function of what RPMs Im driving at when I start to accelerate, how fast Im already going, what gear Im in etc. Sometimes when the turbo kicks in Im like holy **** and sometimes Im just like thats pretty good. I havent experienced any engine hesitation or weirdness, so I really think that it might be the way that Im driving the car. I usually do the power tests rolling @ about 30 40km/h in 3rd gear starting at approx 2800rpm as that seems to be the money gear for raw acceleration, and Ive tried different styles of acceleration like 100% throttle right away or 80% throttle up to about 3300rpm then 100% throttle. I know that maximum power is at the 5000-5500rpm mark, but it seems like maximum acceleration is in 3rd gear.

Really, Im just wondering what is the best way to get the most out of the turbo on the MS3 and are there any driving techniques that will maximize the engine performance. Also, I havent tried doing hard accelerations with the DSC off. Will doing this increase power output or have adverse effects on my engine/drive train? Another thing is that Im probably getting used to having 260bhp in a car, and the power doesnt seem as awesome any more. But I swear that I can tell a difference from one hard acceleration to the next.

FYI, this MS3 is completely stock.

Any feedback or suggestions would be greatly welcomed!

 

[AllLostThings]

I'm just starting to feel mine out also. Sometimes I shift perfect and get jammed back in the seat right away and sometimes it's an ok shift. It's all in where the RPMs fall and we probaly just have to learn where that is.

 

[2URBO6]

Why is there two of these posts?? Anywho here is my same response:

From what I have heard is that 1st and 2nd gear are limited to 5 psi. This is to control the torque steer. I am not sure of this fact but have heard it from a friend of a friend who used to date a friend whose dad had a friend that works at Mazda.

 

[AllLostThings]

Yes it is very true that power is limited in 1st and 2nd gears. I don't know how it's limited though.

 

[aaronc7]

I've read some threads where users that have boost gauges have reported that sometimes it's not always giving us full boost. If i remember right...someone said if they were just crusing in 3rd gear lets say at 3.5k rpm and floor it, they would get 1 or 2 psi short of full. Whereas if they ripped through first, second and then onto 3rd then that time they would get full boost in 3rd. Sometimes I feel like I may not be getting full boost and its definitely faster when i plow through all the gears, but then again I dont have a gauge so I could just be imagining thing. There seemed to be no real definitely conclusions or consistency though.

boost is limited in the first 2 gears. more so in first than second. Best shifting point seems to be around 6k for me. I shifted at 5500-6000 before i got the CAI

 

[justa4banger]

Search around and you'll find there are alot of variales that tell the computer how much boost/power to give you in the first 3 gears, steering angle, speed, air temp, knock etc................
i agree that there are times where it seems the car has more punch than other times. any way you cut it though the car is FWD and FWD sucks (avatar check)

get a CAI and unleash more ooomph. I got a MS CAI and i love it. the car is great minus the gas mileage, mainly due to a heavy right foot.

 

[fourthmeal]

This is a phenomenon that occurs with turbocharged cars. There is a scientific reason why, and I'll try to explain that without going overboard on the the technical side of things...

Turbos work off of load, not just RPM. There is this thing about turbos that makes them non-linear at times, and it has to do with exactly what amount of air is flowing in the intake, and what amount of gases are flowing in the exhaust. Since the turbocharger uses the heat-energy of the exhaust to drive the compressor of the intake side, the overall output of horsepower in the engine varies greatly depending on how much exhaust is flowing out of the engine. That all sounds remedial to some, but to others it may be enlightening.

A few examples:

When you open the throttle plate to WOT, (or the computer does it for you in our case), air from the intake piping is under suction for a brief moment while an air charge (with fuel) is deposited in the cylinder. Of course, the mixture is exploded on a power stroke, and expelled on the upstroke, right out to the turbo's turbine. This pulse of exhaust gas then drives the compressor wheel, now pressurizing what was just a vacuum. This level of pressurization depends on just how much spinning the exhaust gas has created on the "hot" side of the turbo. So, high load, low to mid RPM, large internal explosions in the cylinder...those are the things you need to make lots of boost, thus power.

I think you'll find that short of load-braking the turbo with your foot on the throttle, and your other foot on the brake, that the most power you'll wrench out of the turbo will be when you floor it just as the turbo's efficiency range starts up. That should be around 2400-2500 in 3rd gear. From there, you want to ride that wave of power up till about 5800 or so, and try to keep the throttle plate at least partially open while you switch gears, enabling the hot exhaust to keep spinning the compressor on the other side, which will continue the boost. Shift fast, try not to let off the throttle, and the next gear should be another ride up till 5800. Repeat until you run out of gears, road, or balls.



Clif-notes version...its all about load. Load the turbo up and boost will hit like a ton of bricks.

 

[clos561]

Why is there two of these posts?? Anywho here is my same response:

From what I have heard is that 1st and 2nd gear are limited to 5 psi. This is to control the torque steer. I am not sure of this fact but have heard it from a friend of a friend who used to date a friend whose dad had a friend that works at Mazda.

i thought it was 1st - 8psi , 2nd - 10psi, 3rd - 6th 15.5 psi.....thats y you can assume 3rd gear is the "money" gear since the car is running full boost. I do most of the roll racing from 3rd but its all in throttle play with turbo cars so the turbo stays spooled before u give it 100% throttle if you decide to race or something like that.

 

[mazdaspeed32007]

sounds like your getting some heat soak as well. if you beat your car up three of four times in a row your inter-cooler gets hot. thats why people ice their IC's in between dyno runs to prevent the heat soak and loss of power.

just watch out for how hard you run your car and how fast your going. if you run it hard through 3-4 gears then stop and run it hard again from launch....that heat soak is going to hit you noticeably. if you run it hard and are still rolling at lets say 10 mph then the heat soak may not be as bad because you have some air running through it. or just get a bigger FMIC or TMIC.

 

[mazdaspeed32007]

Also, I haven’t tried doing hard accelerations with the DSC off. Will doing this increase power output or have adverse effects on my engine/drive train? Any feedback or suggestions would be greatly welcomed!

if your running it hard off launch with the dsc on you can tell especially if you have wheel spin. youll loose power for sometimes 2-3 seconds depending on how good you launch. i launch with dsc off to maximize the power output of the car for best accel. you just need to learn how to do so without wheel spin so you dont lose a lot of time burning rubber instead of taking off. practice makes perfect my friend. just dont launch 250 times in a row. youlll experience that heat soak. plus your motor mount can only take so much abuse.