Anyone ever tune for less boost?

4388 Views 19 Replies 8 Participants Last post by NotAnAlien, Oct 27, 2016

moarboost!

Discussion Starter · Oct 21, 2016

This might seem rather counter intuitive to what the norm is for owners when modifying their WRX's however, I was just brain storming while bored as work and thought why not get some opinions from here. I am speaking mainly to the MY15+ crowd.

My thoughts here come from wanting to modify my wrx but I am not terribly interested in gaining the max amount of power from the modifications as the factory power is fine for my car as its a daily driver but to make it more efficient and perhaps increase long term reliability.

Would it be silly to do intake and jpipe modifications with a protune but have the tuner use less boost so that while I would still make a little more power and have a much better tune than factory while also having the engine effectively not working as hard to create the power?

I also posted this in NASIOC.

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Steemax

· #2 · Oct 21, 2016

Strong username to content ratio....

Anywho, sure you can.... they can use other parameters to make power other than boost, either way from what I've seen the amount of boost added from stock to lets say "stage 2" is next to nothing. In most cases I've seen stock cars boosting 20+ psi lol.

MainFrame

· #3 · Oct 21, 2016

Sure.. nothing wrong with a conservative tune. Make it a little on the rich side, with moderate boost and moderate timing and it should be pretty reliable. You could even lower the redline a tad if you wanted.. power falls off in the top end anyways.

moarboost!

Discussion Starter · #4 · Oct 21, 2016

My thought was that instead of making the mixture more rich to keep the power down, having a healthy air fuel mixture that would otherwise provide decent power numbers but intern turning the boost down a couple PSI. For instance (purely hypothetical) someone went stage 2+ with their wrx and a pro tune was able to achieve 300 Wheel HP. However, the owner only really wants 280WHP. Could the boost specifically be dialed back to achieve this number. I see this as making the turbo working less hard and putting less strain on the engine to get the 280WHP. Am i way overthinking this?

Steemax

· #5 · Oct 21, 2016

moarboost! said:
My thought was that instead of making the mixture more rich to keep the power down, having a healthy air fuel mixture that would otherwise provide decent power numbers but intern turning the boost down a couple PSI. For instance (purely hypothetical) someone went stage 2+ with their wrx and a pro tune was able to achieve 300 Wheel HP. However, the owner only really wants 280WHP. Could the boost specifically be dialed back to achieve this number. I see this as making the turbo working less hard and putting less strain on the engine to get the 280WHP. Am i way overthinking this?

Well i want to say it's a tad more complicated than that.... from what I understand it's more of a juggling act trying to balance fuel/air/boost. Changing just one parameter would throw off the other in a sense. I.e lowering boost will require less fuel which could introduce knock which in that case you would need to pull back some timing advance.

moarboost!

Discussion Starter · #6 · Oct 21, 2016

Ok, understood. So it is possible to tune for a lower boost level, it would just require additional adjustments in fuel and air. Would it even be worth it to go this route? Do you think it would really help put that much less strain on the engine. I just see it as being much less restrictive so it doesnt have to work as hard to make the same power.

MainFrame

· #7 · Oct 21, 2016

moarboost! said:
My thought was that instead of making the mixture more rich to keep the power down, having a healthy air fuel mixture that would otherwise provide decent power numbers but intern turning the boost down a couple PSI. For instance (purely hypothetical) someone went stage 2+ with their wrx and a pro tune was able to achieve 300 Wheel HP. However, the owner only really wants 280WHP. Could the boost specifically be dialed back to achieve this number. I see this as making the turbo working less hard and putting less strain on the engine to get the 280WHP. Am i way overthinking this?

You can run as little boost as you want (down to spring pressure, which is like 5psi), and in general, less boost will provide less strain on everything.

A conservative tune will still usually be on the rich side to increase the knock threshold. That doesn't mean it's not a healthy mixture.. rich runs cooler, and won't be as prone to predetonation. When I say on the rich side, I don't mean like stock tune rich, I mean like 10.9-11:1 under boost, not like 11.4-11.6:1 that you would target for maximum power. Most people will usually want the tune to target a slightly rich AFR in case you get some bad gas or something.

moarboost!

Discussion Starter · #8 · Oct 21, 2016

Thanks for that. Im starting to get this more now. I was talking to another member on nasioc and he did something like this, (sits around 12lbs, peaking at 13-14 at redline) and was able to move the torque curve back to help the rods and was able to get better top end as well. It also sounds like there would also be a gas mileage benefit to this as well.

MainFrame

· #9 · Oct 21, 2016

moarboost! said:
Thanks for that. Im starting to get this more now. I was talking to another member on nasioc and he did something like this, (sits around 12lbs, peaking at 13-14 at redline) and was able to move the torque curve back to help the rods and was able to get better top end as well. It also sounds like there would also be a gas mileage benefit to this as well.

Torque is usually what breaks things, so that's not a bad idea.. and the powerband will probably feel nice ramping up a little as the revs increase. As far as any gas mileage benefit, that will depend on how heavy your right foot is. It wouldn't make any difference in my fuel efficiency because I can drive all day without ever going into boost if I want.

moarboost!

Discussion Starter · #10 · Oct 21, 2016

Thanks for the info!

STI Version6

· #11 · Oct 22, 2016 (Edited)

Just do all your supporting mods. Crank it up a little. And enjoy your regular dose of fun. For a long time.

RayfieldsWRX

· #12 · Oct 22, 2016

MainFrame said:
As far as any gas mileage benefit, that will depend on how heavy your right foot is. It wouldn't make any difference in my fuel efficiency because I can drive all day without ever going into boost if I want.

This is what I was thinking, as I read this. I was able to get some pretty good mpg numbers (relatively speaking) even out of my hybrid build WRX, simply because I was gentle with it, staying out of boost, stoplight to stoplight. I'd put the hammer down when a great occasion for it happened, but there's no point pushing 19psi in traffic.
If it were me, I'd simply work on driving technique. I completely believe in "Safe" tunes, that's what I asked for from my builder, in the sense of preventing detonation, but I enjoyed my WRX's character too much to "short leash" it.

moarboost!

Discussion Starter · #13 · Oct 22, 2016

I really don't get on my wrx very often. It sees mostly highway mileage an i have no complaints with my current fuel mileage. My main reason would be for efficency. If mpgs increased due to that then great.

MainFrame

· #14 · Oct 22, 2016

I would expect fuel efficiency to improve a little bit with just the tune. AFR won't be quite as rich, and with the timing adjustments and everything it will make more power off boost so you won't have to press the throttle as much to accelerate the same as before.

RayfieldsWRX

· #15 · Oct 22, 2016

You're saying "efficiency", but I think it's really a focus on the "long term reliability" that you mentioned in the original post, right? I can relate, I used to really be in that camp, and babied my cars accordingly. Something happened, over the last 10 years (probably has something to do with middle age, watching parents die, etc.), and now I don't spend time worrying about that, anymore. If I bust up the engine in the BRZ, I'll go have someone build a stouter one. :tongue:

Over a long enough timeline, all of our cars will be junk. Then the sun goes nova, more heavy elements are created, and more cars can be built by a future race. All good.

SD_GR

· #16 · Oct 22, 2016

I know Ford has done this in the past, and I think Volvo also. They've both sold map-specific versions of their cars. Owners usually like the less aggressive map.

EJ257

· #17 · Oct 22, 2016 (Edited)

You're going to a professional to calibrate the ECU. When discussing what you want out of the car, mention that you are looking for a safe/reliable tune (you aren't looking for a kill map). Don't go in saying "I want XX PSI" or something of the sort, just let them do their job; you're going to them because of their expertise, anyway.

You're talking about simple modifications / basic calibration here. Nothing in that calibration should cause mechanical issues (that wouldn't have happened on the stock calibration), unless they don't know what they're doing. This isn't a 400whp build that you're worried about the engine/transmission crapping out, such that you dial it back to "delay the inevitable" while you get yourself setup with the funds to repair what breaks.

If you don't need the full power from the map they've put on the car, then use your right foot to modulate it accordingly.

There are times where power can actually get you out of trouble, too, where you want as much as possible. Say, for example, you go to merge on a relatively blind intersection, and as you start to pull out, you notice a vehicle come around the bend / over the hill at a high rate of speed. You do not have enough time to brake, reverse out of the way, but instead, you need to peg the throttle to avoid being on the receiving end of automotive buttsex. This is an instance where you may not have wanted the ECU calibration to limit your last 20-30whp (vs your right foot). I use this example as it hits close to home; there's a section of US highway right by my house that I've needed to peg the throttle to avoid being struck by someone coming over a blind "hill" who is traveling 20+ MPH over the speed limit. There are major injury / fatal accidents (plus those that aren't as severe) here at least once/year.

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moarboost!

Discussion Starter · #18 · Oct 24, 2016

Hey Rayfield, yes, I am certainly interested in long term reliability so in a sense, you are correct. I also understand where you are coming from, i see myself in those shoes more and more as the years go on. If it blows up down the road so be it. I just posted this as more of a hypothetical to see what the thoughts were on this.

EJ257, when the time comes and I go for a protune it sounds like I will just have to ask for a very conservative tune as it would be the best way to go. I am not the kind of person anymore that is a 24/7 lead foot so I would be able to control that pretty easily.

I appreciate the info here.

RayfieldsWRX

· #19 · Oct 24, 2016

moarboost! said:
Hey Rayfield, yes, I am certainly interested in long term reliability so in a sense, you are correct. I also understand where you are coming from, i see myself in those shoes more and more as the years go on. If it blows up down the road so be it. I just posted this as more of a hypothetical to see what the thoughts were on this.

Fair enough!

NotAnAlien

· #20 · Oct 27, 2016

Remember the wrx come stock with a very high compression ratio of 10.6:1 Compared to other 2.0t cars focus st/2014 sonata turbo 9.3:1/9.5.1

focus st 252hp and 270 torque at stock max boost 18psi
14 sonata 274hp and 269 torque at stock max boost 17.4psi

So lower boost might not be a bad thing

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