If you could vary boost by gear..., ...what would be your boost profile?

Title of the thread pretty much sums it up--if you had the ability to set a different boost level for each gear, what would your boost profile look like? Would you start off with low boost for 1st and 2nd gear (as a means to help maintain some level of traction) and then hit your target boost in gears 3-6?

I do not see the use of a variable boost by gear... use the gas pedal.


THe closer thing to your idea is the traction control

you can do that and lots of people do.

Modulating the gas pedal until you have full traction is more time consuming then simply lowering the boost in 1st and 2nd.

I know there are S2000 owners who have two different "boost maps" (one for daily driving and one for the track), but I haven't heard of any S2000 owners setting boost by each gear. Can an AEM EMS even do that?

In a word: Yes

Actually, you can set up the EMS to very boost based on a couple of conditions. You just have to have the EMS control your boost solenoid.

You can do this and it makes sense. It works and it's been proven effective on numerous other platforms including the RX7 and EVO.

Traction control is more intrusive but there are some aftermarket systems for high performance sports cars that are supposed to be great.

In a word: Yes

Actually, you can set up the EMS to very boost based on a couple of conditions. You just have to have the EMS control your boost solenoid.

That's cool.

So, back to my original question: what would your boost profile look like?

Say your target psi is 10; would your profile look something like:

4-6-10-10-10-8

I'd just run 10 across the board. 10psi on the S2000 with good tires will only spin first if launched hard. A NA S2000 will do the same. Remember it's the torque that causes the wheels to spin, and there isn't much of that in the S2000.

Before I got the turbo installed on my car i was seriously looking into doing different boost levels for different gears, but after getting the car back and driving it, I felt that doing that just wouldn't feel right. Like someone else already pointed out, your foot is the best boost controller. And that's what I love about turbo setups... you control the boost at any point on your own. You just have to get used to the car and learn how to limit the boost and power in different situations, not rely on some other means...

Keep in mind that if you plan on driving your car on curvy roads the variable boost can be very confusing if youre in the heat of driving hard... you might forget that youre in 3rd gear and not 2nd gear and give it more throttle than necessary for the extra boost in third thinking that youre still in a lower gear... which could end in disaster.

Now if you are planning on doing only straight line runs from a standstill, then lower boost levels for lower gears might be alright... but again IMO, your right foot along with very conservative amount of traction control setup through the AEM EMS should be perfect.

Just a question though, in your hypothetical boost level per gear setup, why do you drop the boost to 8 psi in 6th gear?

Ok...here is my current boost profile:

1st: 6
2nd: 8
3rd: 9.8
4th: 9.4
5th: 9.0
6th: 8.5

Because the MY06 S2000 has a returnless fuel system, I am currently limited to just under 10 psi. Within the next few months I will have the system converted to a return-type so that the boost can be increased. Anyways, I have RT-615s (225/255) and in first gear the tires will light up if I mash the gas (even though I am only boosting 6 psi). Second gear isn't much better as the tires will pretty much spin to the rev limiter as well.

1st - 7psi
2nd - 10psi
3rd - 10psi
4th - 10psi
5th - 11psi
6th 12psi

You have to fight drag some how

Driver more than boost makes the difference on coming out of the hole. Below is a prime example.

The car on the left is a completely stock S2000 with the exception of an Exhaust. On the right a 9 psi Turbo S2000. Both cars have street tires “NO DRAG RADIALS”. This is a perfect example of the “DRIVER MOD”. This car was at 9-10psi from start to finish. And as you can tell by the 60ft there was no problems hooking up. I included a video for comparison.

Stock S2000 – 2.6 60ft < a stock s2000 should pull at least 2.0 60ft w/ a decent driver
Turbo S2000 – 1.8 60ft < Turbo S2000’s all depend on power levels and Tires.

Unless you plan on running close to 20psi. I wouldn’t worry about variable boost controllers.
Click here to see Video

Thanks for your inputs--I really appreciate them!

When my S2000 was tuned a short while ago the tuner thought that the boost should be slightly lower in 6th gear. I don't have a good answer as to why he did it that way.

That makes more sense... as you get faster, there is more air resistence (drag) and the Cd is already pretty bad on our cars. You need extra oomph up top to have it keep going, not pull power away at that point...

glad I could help...

As far as the car loosing boost... as long as your wastegate can handle it and your boost controller is functioning properly, you shouldn't lose boost. You might want to check with him to see why exactly it was losing boost at that point...

Thanks for that input!

I know that I have a lot to work on as a driver, especially since I now have a turbo S2K. I only drag raced my S2000 two times prior to going to boost and my best 60' was 2.1. This was on RT-615s, which from what I hear are horrible for drag racing. Regardless, I know that I need to work on my driving skills.

I don't believe the car is actually loosing boost--the tuner specifically set the boost limit to 8.5 in 6th gear.

The boost profile I provided above is based on "hard-keyed" boost limits in the EMS.

Boost per gear is often used by high horsepower cars.

its very difficult to gain traction w/ big boosted cars on lower gears.

its much more effective to run different amounts of boost depending upon the gear. and your goal is to run as much boost possible without breaking traction loose.

so for you lower boost guys, you wont benefit like a high horsepower, big boost car.

I don't know if this helps, but I was running 20lbs of boost, and never had to run this on my car.
If I was to set it up, 1st would be 40% less and 2nd 25% less, by 3rd it would be full boost.

If you're worrying about traction off the line under drag conditions, why not leave the boost levels and program a dual stage rev limiter? Your right leg can do the rest then

My EMS has a launch limiter; is that the same thing that you are talking about? This launch limiter only allows me to input one setting, and it is currently at 4500.

I have thought about this one a bunch. I was figuring on doing something like this.


1st-8
2nd-12
3rd-20
4th-32
5th-32
6th-32

-Chris

32 psi? Holy fawk!

I wouldn't use the launch limiter on the EMS. I have seen a few burnt rings from it.