I have an aftermarket EBC and my stock boost controller is not only disconnected but completely removed. Yet, 1st gear always has been and still is limited to about 10PSI and 2nd gear at 12PSI on a good day. What enforces these limits when my EBC is set to 15.5PSI?

jason

 

Mine the same way. I have my mbc set for 15 psi in 4th (4eat)
But in first gear, it doesnt have time to reach 15 and second gear just hits it for a sec then tapers off. It Normal

 

Nope, that's not it, I am sure. There is actual limiting going on. A rotation of the turbine is a rotation of the turbine. For the same RPMs you should have the sme CFMs. And, in turn, for the same rotations you should hit the same boost... provide the wastegate hasn't opened.

My first guess is that boost is dumped at a more controlled rate but in a similar fashion as how an overboost CEL occurance results in a dump of boost... and how does that happen? Its always sounded like the BOV to me, but I'm not sure.

jason

 

"For the same RPMs you should have the sme CFMs." that's not necessarily true. boost is dependent on a bunch of things... engine load, rpm, ignition timing, egt... that's one of the reason you don't build boost in 1st and 2nd like you do in say 4th or 5th, the engine is under less load due to the gearing. under stock boost control, the ecu limits it to like 8 or 9 psi. i think the reason you're still not building your 15.5psi is engine load.

 

Yeah, I realize that somethining is limiting boost... but WHAT? You say the ECU, that's fine, but what is the mechanical part that does the limiting? AFAIK once you remove the factory boost controller nothing else touchets the wastegate actuator. So what is the physical mechanism that controls boost when the factory boost controller is gone? That's what no one is really answering. Its way to consistent to be just a lack of load... and yes I agree with the load theory, but like you say something else is limiting it... what is the ECU using?

jason

 

There is the significant possibility that your combination of components is incapable of producing more boost in lower gears.

 

Inertia/time. 1st/2nd gears go by so fast you don't even have time to spool completely.

Put 4 fat friends in the car, and head uphill, I bet you'll make full boost.

 

LMAO!!!! :banana:

 

hey jason, its me ryan. we met at hollywood video.
i think you are right about the bov. follow the vaccum line to see if it has something controlling it.

 

I get full boost in all 5 gears in my stock '03. There was a discussion long ago that touched on this. It seemed some folks were getting ~ 10PSI in 1st & 2nd gear while others were ahchieving max in all 5. What we finally noticed was that only folks with '02's were experiencing the lower boost levels in the first two gears. Everyone in the thread with the new (at that time) '03's had no problem getting 13+. I know this doesn't answer the question, but I thought I'd throw it out there.

- Kean

 

So after I left Ryan and friends last night and we talked about my BOV theory I did some tests. Barring any other data, like it was a cool night, etc, I can't recall 1st gear that well, but I do recall that I nabbed a peak-hold of 101kPa (with a limit of 107), so for you imperial types, that's 14.6psi. So, I hit higher than stock. I don't recall this happening before, but honestly I did't do controlled tests where I let off after 2nd gear so as not to obliterate the 2nd gear peak hold in 3rd.

Now in 3rd and 4th I could easily hit my peak 107kPa (15.5psi). And here comes the the real reason for the original issue... I can't control boost set levels with my Blitz Spec-R on a per-gear basis. To keep from blowing by the limit I base the set level upon the load of higher gears, causing the lower ones to suffer. Lately, to keep from timing being pulled, I've lowered my set level and I've notice the power loss more significant which made me wonder and write the original post.

So, mystery solved... the solution to the problem, though, is a better EBC or a reflash, etc. I'd like to hit that 15.5 in 2nd gear

jason

 

my ball and spring gets me there! any gear you want...

EBCs are inherenly laggier than their purely mechanical couterparts. i think they always will be.

hth
ken