legacycentral bbs

Hi there,

I've heard of instances where Legacy turbo owners have uped there boost levels to ~13 pounds without an intercooler, running 91 octane fuel and had no problems with detonation. Anyone here done this? If I do intercool my car though, is the little hood scoop enough to provide any sort of adequit airflow to the intercooler?

Thanks,
Mark

I have done it and I am sure others have also but while the stock Legacy turbo can do this the charge temperature is getting pretty hot at this pressure and there is a little risk. I have a Liberty air to water intercooler and run 15lbs and 20lbs for short periods. The legacy hood scoop is designed so that it forces air over the turbo itself and on shutdown the hot air is supposed to reverse and exhaust through the scoop and cool the turbo down.
AL(CO)

FWIW, I spiked to fuel cut (13-14psi) a bunch when first installing my AVC-r, pre-intercooler, and I didn't detonate at all. But consistantly running at those levels is a different story.

[sidenote]: Al, the more you talk about runinng 15-20psi, the more I'm gonna have to get one of those torque chips you've got. 13psi is stock as far as i'm concerned

-mike

What torque chip?

This torque chip www.torquechip.com

Keep in mind that the amount of boost you can run varies GREATLY with the density of the air in your area. I know mile hi is up there and prolly has pretty thin air . . . read: less O2 density, requiring more boost to acheive the same effect. I'm not sure about Ottawa (could be the same), but I really wouldn't recommend those levels of boost closer to sea level (at least w/o an intercooler).

Jason

I don't know about that, there has been a lot printed , discussed, talked about ect. In one book I have on this subject it says that boost is boost whatever altitude you are at and if you do have a container (we have) 13 lbs of pressure is the same absolute pressure no matter where you go until you get to what is called critical altitude and then the turbo just will not make any boost.
One thing I do know is that the turbo up here has to work harder (spin) to make the 13lbs and therefore the charge will be hotter than one developed at sea level and will be a bit more prone to detonate. But I guess it is what chance you want to take as losing on a chance can get expensive. A lot will depend on fuel octane, supply and mixture.
Some time ago an outfit made a simple boost controller and a FCD and a lot of people were running 14lbs with it.

Al mentioned a key word, Absolute pressure.

If you take a barametric air pressure reading in Denver, vs. Houston. they are going to be different. I have not a clue what actual values would be.

But the air molecules a mile up will be less then at sea level. If you take a 1 cubic foot box and put air in it from Houston & from Denver you are going to have different absolute pressures. If you compress the air to a certain psi it will have the same pressure. However the temperature will be different.

With more air molecules you don't have to compress the air as much to get that specified pressure. With less air molecules you will need to compress the air more. Hence more work is being done on the air, which in turn means more heat is added to the air.

Air density is more of a factor, rather then pressure.

Turbomachinary is rather complicated......I'd like to learn more about it. I didn't bother taking that class in college because it would've prob takin up moucho amounts of time.

What Josh said

I swear, that's what I meant

Ottawa's elevation is ~400' ASL. So no, were not that high up.

Mark,

We are being shorted a few pounds up here I have charts on this and a lot of conversion charts, turbo info, ect if someone is really interested. The chart I have here lists sea level at 14.696 psi and 5000 ft altitude at 12.23 psi. Some time ago we ran a '93 Impreza at Bandimere speedway with an ej22t with Garrett turbo, fmic, chip, exhaust, and 26lbs of boost and that was good for a 318hp at the wheels 13.35 1/4 mile and that would be about 12.35 at sea level. We didn't know at the time but the fuel pump was the weak link if we had known this we possibly could have done better. We built a'97 Impreza running 30lbs with a high efficiancy atwic the owner hasn't run it at the strip but it dynoed at 340hp at the wheels.

Some nutbar I know around Peterborough is running 1.3 Bar (around 20psi) constantly in his BONE STOCK 91 Legacy turbo, no problems as of yet, but we'll see how long his motor lasts. So far it's been around 4 months at 1.0 Bar, and around 2 at 1.3. Only other mods to his car is 2.5" turbo back exhaust.

Is it by any chance a red Sport Sedan with really weird chrome rums ? Cause I've heard of a guy over there running 20 pounds but he has a a truck fmic. Just curious how long his RHB5 turbo lasted or is gonna last, hehe.

Mark,

I'm running about 10 PSi. I made a bleed type MBC ( IggBleed(tm) ), so boost varries with temperature. I usually adjust it so I'm around .06-.065 MPa. I get the occasional sound of a single kernel of popcorn popping in the exhaust from unburnt fuel. But I also get this momentary rumble/hesitation like the engine missed a beat or 2. I'm worried it's knock/ping/detonation, but it's too quiet. I can feel it in the hesitation more than hear it. I hope this isn't ping cause I don't like that whole "engine dying" thing that usually accompanies it. is there such a thing getting knocking wihtout the audiable "rocks in a tin can" sound?

I was wondering what that sound was. I have heard that sound on my car. I thought it was a loose bolt or something. It only happens when i go over 8psi.