Got a Shiv tune for 92oct at FAME and since I didn't have any race gas, he loaded a base 100 map in bank 1.
Today I went to get some race gas, my light had been on for 20 miles, so I prolly had ~1 gallon of 92 left.
They started pumping the 100 in and ran out at about 4 gallons. So I'm probably about 98.4 octane. Anyway I switched maps, drove conservatively for about 8 miles and then got on it.
It really doesn't seem any faster. It's ~15 degrees warmer today than yesterday, maybe 65. I expected maybe 15-30hp gain from the racegas, was that unrealistic?
I tried to listen for any knocking, etc. and it doesn't sound much different. Doesn't hestitate or anything, just doesn't seem much stronger. Maybe a little more blatty in the exhaust note.
Is there a color difference on the Xede lights between bank 0 and bank 1? It flashed orange for a second, then stayed on green I think.

Thanks for any input.

 

How much boost were you running?

 

In Xede, or according to my boost gauge?

Dunno about the Xede (am at work now), but the stock boost gauge gets a fuzz past 1.5kg/cm^2 and stays there. Actually, I don't remember watching it closely on this last drive, was on my lunch hour.

What should I look for- over or under boost?

Thanks!

 

On race gas, you should be hitting ~1.8 kg/cm^2. Since your gauge doesn't go any higher then that, you don't know if you're hitting it. Some cars need a pressure bleeder installed in order to reach higher boost levels. Your car may need one, but you don't know since your gauge doesn't read above 1.5.

 

On the gauge, it does go a bit above 1.5 on my 92 map, even. I'll watch the gauge closer on the ride home.

Even if it is not generating much in the way of additional boost, does it seem like it should have a noticeable bit more power through more timing advance? While I don't remember the actual figures, there was definitely less negative numbers in the race map timing table.

 

On pump gas, you'll see a spike up to 1.6kg/cm^2 at around 3000rpm.

Without turning up the boost, you would have to have a very sensitive butt dyno to notice much of a difference. If you're ever in my area, stop by and I can hook up my calibrated boost gauge to it. I also have an extra pressure bleeder if you need more boost.

 

I'll check the boost table for my 100 map tonight. Maybe I'll post it here and have you see if it looks like too little of a increase vs. my 92 map.

So you make it sound like a little bit more timing won't be noticable. That confuses me- isn't the whole point of the YEeeeeeahaaaa!!! thread that the Xede will dynamically tune timing ONLY, and that it made Dustin's car way faster?? Or am I missing part of it, as usual

Thanks!

 

The dynamic tuning will give a little extra power, but its main advantages are the ease of tuning and driveability. Improved on/off boost response, reduced spool up, slightly more power, etc.

Remember, you are using a off-the-self 100 oct race gas map. You'll probably only see a 30hp improvement when running 26psi.

 

Jeremy,
How does that bleeder valve work and where does it go? I've heard it mentioned before and have wondered since I removed the little pill when I put in my XEDE. I did put the stock vacuum hose back in when I did my last round of mods because someone (maybe it was you) said that the ID made a difference in the boost and I was using an off the shelf hose for a while. I just replaced the stock one so I didn't have to pull the pill out....guess I'm lazy. Then again, how lazy am I to have done all those mods myself then skimp out on pulling that little pill out?

Damn, rambling here, time to leave work and go home. Back to the question, bleeder valve...

Sam

 

The Evo uses air pressure from the turbo to regulate the boost pressure. The more pressure that the turbo develops the sooner the wastegate will open.

The basic layout of the boost pressure system is like this:

Line from the turbo to a "T" a line from the wastegate to the "T" the last port of the "T" goes to the boost solenoid.

There are two "restrictors" in the system. One is in the line from the turbo to the "T" and the other is after the "T" and before the boost solenoid. Basically, these "restrictors" are actually nozzles. The one near the turbo bleeds pressure off by accelerating the air through it. This keeps the pressure in the system lower so the wastegate can stay closed. If this restrictor was removed then you would only have 12 psi of boost due to the pressure of the turbo.

The second restrictor (located near the boost solenoid) works the other way. It causes more pressure in the system which opens the wastegate earlier, and lowers boost pressure in the manifold. That is the reason we remove it for the XEDE. WORKS uses a special restrictor in that line that moves more air in order to maintain the 19 psi to redline.

Now that you understand how the system works, I can explain the pressure bleeder. The pressure bleeder is just a small plastic housing w/ 2 hose barb ends w/ a small hole in it. The hole bleeds out some pressure which gives you a few more psi. If you still aren't getting enough boost then it can be drilled out until your desired boost level is acheived.

Hope this explains it.

 

It sounds like a MBC installed in that line. That's basically what an MBC is isn't it? An orifice/valve that can be increased and decreased with a knob? Why would some people need it and others not? Is it something I should opt to install just to get that extra bit of boost or should I just put some extra preload on my waste gate actuator rod?

Thanks,
Sam

 

It works the same as a MBC in theory, but there is only a hole that regulates pressure instead of a knob. You won't put a MBC in this place either.

Some cars just don't produce the same boost as others. I am sure its due to manufacturing differences. If you can't hit 26psi on race gas then you should get a bleeder. You can also adjust the preload on the wastegate, but I have never done this and I don't know how much adjustment there it.

 

I'm not sure about a stock turbo but my TME arrived with no pre-load on the waste gate actuator rod which meant only 12 sluggish psi until I figured out the problem. One new radiator and some pre-load later, the car boosted like a champ. They say about 2mm of distance between the eye of the rod and the part it slips onto which means a little bit of force is required to get it on, but I imagine that increasing that gap will aid in boost numbers. On the TME and the stock turbo the shaft is threaded to allow for adjustment, you just can't really get to it with the heat shields in the way.

Sam

 

That is not necessarily true. My old stage 3 A4 had 30 more whp on 104 octane programming than pump gas and it ran the exact same amount of boost regardless of the octane mode it was in. It ran a TON more ignition timing and leaner on 104, obviously.

 

Okay so I looked at the gauge and it is stopping around 1.7/1.8kg/cm^2. So am not sure if it is just not boosting much or if my gauge is simply maxed out. I think it is the gauge. How much more boost does the bleeder valve give?

So I ran out of 100 and switched back to 92 and I could then feel it was a little bit slower. Not so much when under WOT, but seemed slower at partial throttle/off/low boost. Not a bunch slower, but a little.

I still have to post my 92 and 100 maps later, hoping you can look and comment.

Do you think that my having maybe 1 gallon 92 with only 4 gallons 100 caused the ecu to pull timing, thus making it not seem so fast? What does pulled timing feel like? A big flat spot? It did not do that. Am just comparing the signifcant additional pull when I installed the TB exhaust vs. the 100 map- there wasn't a comparable gain with 100.

Thanks!