Stage 2 accessport boost and elevation?
 

Hey,
I just got my 04 wrx tuned by s-squared, with a Stage 2 custom map, and was wondering what kind of boost people are getting in Reno (@4500ft)? Right now I am getting between .09-.1MPa, depending on where I am driving. Is this a pretty normal number for a stage 2 map? I know the target boost range is 15.8psi +-.5psi. When he tuned my car, he couldn't get the boost to go up in 3rd gear, so I only saw gains at the very top end of my curve(6000+rpms), which seemed weird. He thought I may have had a pressure leak some where. However, when i was driving back at sea level I was boosting to .11MPa,(almost 16psi) :) in 4th and 5th gear, I think the ecu learned a little. That was a fun drive.
I know that I have an exhaust leak from the turbo to the dp and I can't tighten the bolt anymore w/o breaking it. Do you think that will cause a problem? My engine feels and drives great, so I'm not really worried about it.
Thanks,
Dave

Sounds normal. I was always around .09 Mpa in Reno with my WRX, maybe a little more in winter. But I saw around .12 in 4th gear at thunderhill, which is near sea level.

I had an accessport stage 2 map, and later a custom ECUTek reflash, they both had the same boost.

BTW what numbers did you put down on the dyno? I am interested in what kind of difference the headers made.

Boost is not a learned attribute, it fluctuates with elevation, not time on the throttle. You'll always see more boost at lower elevations, which is why you won't want to tune for more boost up here- you wouldn't be able to drive to California without overboosting.

my numbers were:
Max HP: 208
Max Torque: 185

These numbers seemed kinda low to me. Nate thought my torque should have definitly been higher. I don't think I have a pressure leak because I checked the connections from header to up-pipe, up to turbo, IC hoses, inlet hose. I put all them on my self too with new gaskets. Also, my boost seems normal. It increases as I shift from lower to higher gears. My car definitly feels faster, which is why I question my dyno numbers. I would like to take it back to get it tested one more time on the dyno, see if it puts out higher numbers. Nate also said that some times on 04 wrx's, cobb saw some cars that took a while to adjust to the new engine parameters. This could be the case with me.

One other thing, I saw that you put out higher numbers at cobb tuning than you did at S-squared, and you had the same mods at both places. Just wondering if there was a reason for that?

That is because Cobb's dyno is calibrated to read extremely high (probably a marketing thing so that their stages sound better), while Nate's dyno is calibrated to read low. In reality, the car was probably making more power when it was on Nate's dyno, since cobb's dyno is at 4500' elevation.

Nate might have the lowest-reading AWD dyno on the west coast. He was the only one who read the instructions and calibrated it the way the manufacturer recommends (you know, accurately...) instead of making the graphs look cool on the interweb.

Thanks for the input, that makes me feel better about the numbers I put out on the dyno.

Over 200 whp on a stock turbo wrx on Nate's dyno is impressive.

We need an AWD dyno up here in Reno, so that we can be tuned for our normal elevation, doncha think?

That would be great as long as you never intend to drive the car at sea-level. Remember, lots of boost up here means too much boost down there.

Plus, lots of boost at high altitude means running your turbo outside of its efficiency range. Which can mean blowing the car up even at high altitude due to the high temps.

HAHA Godd stuff I just spat my lunch on my new monitor.

I think a few other Mustang owners would dissagree with that statement mate as if your referring to doing a onsite parasitics test then I know of 3 Mustangs within 100 miles of San Jose who also did that.

I would also say not to worry about your numbers on the SS dyno as it is as stated a low reading load based dyno and you will see the boost change on the boost gauge at elevation.

I would be more concerned about how the car feels after the tune which as stated the car feels great so all sounds good.

Dave, sorry for the lag in getting back to you, my other job has been crazy. As everyone has been saying, it's normal to make slightly lower boost numbers at elevation; we want to make sure you're happy withthe way the car is driving, though, so keep us posted.

Thanks for the backup, guys :D

that's almost impossible.. rediculous numbers man.. also I am really excited to see if s2 dyno really is the lowest.. i guess we'll see at the next dyno day.. whenever that is. haha going to be awesome

mike

Its stock turbo with: UP, DP, Exhaust, headers, IC hoses, Inlet hose, crank pulley, spings and wheels.

what wheels, and what size tires? That can have a significant effect on how much power makes it from the flywheel to the rollers.

18" Rota subzero's, 225/45,
I have a minor exhaust leak from the turbo to DP, that has probably been there since I had it put on. However, It looks like I am getting full boost. Today on my way to work, in 4th gear I hit .1Mpa. Do you think the exhaust leak has any effect on the performance? Since I am reaching full boost, Does that mean I am getting the most HP? Nate said that you could take the DP off and still get full boost. If you took the DP off(no exhaust), How would that effect HP?

I think this is only true for some. If you have a stand-alone boost controller (manual or electronic) or UTEC in closed loop (I think), then your boost builds to whatever the setting is despite the elevation (assuming the turbo can boost that high in that air). Somebody correct me on this if they know for sure, please. I need to drive down to Sac. to see how my UTEC boost varies for myself.

Exhaust leaks *after* the turbo should not affect anything significantly. Taking the downpipe off would require retuning in addition to earplugs and a gas mask.

I didn't think a DP leak would affect anything, since I am reaching full boost. I know that taking the DP off would result in a annoyingly loud sound and smell. I wasn't planning on taking the DP off, just was interested if it would result in power loss. Since I am reaching full boost, I am guessing I don't have any other leaks to worry about and that I am achieving max power for this elevation(depending on air pressure, density, and Temperature). Thanx

I have a Cu-Seal (copper) DP to turbo gasket I'm not using if you want to buy it. It requires a retorquing after one heat cycle, but should fix your leak.

It is possible to tune a car's boost maps to be elevation specific as WRX's have a barometric sensor that the ECU uses. I get 17 psi all day at any elevation.

I was waiting for someone to say that, very true!!

You have to be careful not to push the turbo out of it's efficiency range though.

True Mike, some would say that I'm pushing too much boost out of the stock turbo, but I trust my tuner and he says 17-17.5 psi is perfectly safe. All I know is my EGT's are never above 1400K degrees Farenheit. I insisted that the longevity of the motor not be sacrificed for performance. As a side note, I don't mind shortening the longevity a stock turbo when they are so readily available used.

When I was running a MBC (back in the UniChip days), every time I went to the bay area I'd overboost like a madman. But up at altitude I was rock solid at 14.5 psi.

The ECU + stock EBC seems to do a pretty good job of reaching target boost at altitude, but I believe it's at the cost of turbo efficiency. The difference between a cool 14.5 psi and a hot 16 psi is probably negligable, or worse, faster at lower boost if the ECU has to pull timing to prevent knock on a hot motor. Remember, the stock WRX intercooler is pretty small. :(

And 17.5 psi on a stock WRX turbo! :eek: That sounds out of the turbo's efficiency range at any altitude! I hope that's tapering to about 13 psi at red line, or you'll probably end up with a motor like mine: on the floor of a shop somewhere! :lol:

How much for the seal? Speaking of boost, 17-17.5psi at 4500ft is probably pretty safe. I know a person who was pushing 19psi with only exhaust. You probably understand that the more boost you pump into your engine, means the more force you are putting on you pistons and seals. So you are defenitly wearing out the engine faster with higher boost, which is why I am satisfied with 14.5 psi at 4500ft.

That is only the case if the turbo actually can push more, given the stock turbo size on a WRX it wont be pushing much more than hot air past 16psi at sea level, at 19psi at altitude you might want a catch can installed on the actual turbo....

It retails for $20 shipped. How about $15 and you pick it up. I live downtown reno.

Wouldn't you say that a better gauge of how much extra wear and tear the motor sees is your max power output? I mean, I never really thought that the stock turbo could put "excessive" wear and tear on the engine as long as you aren't detonating or running lean. Any upgraded turbo will push more CFM than the stocker which I think translates to more pressure on the internals. Correct me if I'm wrong.

I've heard anthing over 15 psi on the stock turbo and your just blowing hot air, but that's just one person's opinion. Blowing hot air just means a less Oxygen...not necessarily more wear on the engine right?

Hmmm. Now I'm really curious how my boost will change at sea level with the UTEC. My turbo's not stock, and it's plenty efficient well above 20psi, so a little overboost would be okay prolly. I've had the car for almost a year now and haven't had it lower than 4000' elevation. I've never noticed a boost change going up as high as 10k'. Hmmm, maybe it's time for a spirited run up Mt.Rose Hwy to see what happens.

The wear would be more on the turbo I would imagine than the engine from the stock unit but the fact that after about 16psi or so it's only blowing hot air is not really someone's opinion it can be proven fairly easily.

The problem w/ running a turbo hot is not that you're putting more pressure on the motor's internals so much as you're asking the car not to detonate on a higher temp intake charge.

The hotter the intake charge, the easier it is for the car to pre-detonate when the pistons compress that A/F mixture. That's why we use intercoolers, water/alcohol injection, etc. Gotta get the intake charge as cool as possible, so we can compress as much oxygen as possible to make as much power as possible. If the air is so hot that the car starts pinging, then the ECU has to pull timing to protect the motor, in which case you may be running a ton of boost, but making less power because of the retarded timing.

For those of you that missed the post, take a look at what Mike Shields had to say about tuning their rally car for the Pike's Peak Hill Climb:

http://www.seccs.org/forums/showthre...ght=pikes+peak

There's some interesting info in there about turbo efficiency and altitude.

That all makes sense, but if you're car is tuned correctly, you should never ping...unless the IC is heat soaked or you get a bad tank of gas.

Not sure how you would be tuned for the excessive charge air temps when pushing the turbo that hard though.

dunno, the car feels strong and shows no sign of detonation. I wish I had a knock indicater, but I don't.

18" Rotas? 225/45R18? Damn, that's a taller, heavier combo than stock, and is actually lowering the amount of power you put to the ground unless Nate specifically altered the dyno software settings to compensate.

A post-turbo exhaust leak only makes noise, it doesn't affect performance much, unless it's a gigantic leak that actually reduces backpressure.

That is correct, however, tuning it not to detonate (or worse, pre-ignite) means less power at higher boost levels. If tuning "correctly" could compensate for pressure ratios outside of a given turbo's efficiency range, there would only be one turbo on the market for every application and we'd all be pushing 45 psi through it and making 500 whp. ;)

So then the question is, am I making les power at 17psi than I would at 15 psi, because my tune has to defend against detonation?