This topic has been discussed before, but in my searches, it was not to the scope I would have liked. A lot of people post boost gauge results or butt dyno results, but I want real dyno results.

I've had a modded VIII in the past. Now, I have an IX with only a turbo-back exhaust (stock O2 housing), MBC, and a flash. On the two cars, in addition to a 30R, I've had three different 16G turbos: Stock 2003, a TME, and now my stock 2006.

Here's my problem: I'd like to get a little more power up top, and am willing to sacrifice some in the middle.

Every car we have come into the shop that uses a manual boost controller deals with the same thing: You have to run ballistic boost in the middle and you have lots of cylinder pressure to retain any amount of sane boost up top- I HATE this. My car at 23psi in the middle on my Forge UNOS pukes-n-dies to 17psi at the rev limiter.

Well, you know what happened- I made 300 on a Dyno Dynamics in around March, it got hot outside, and my tune was getting 6-10 counts in the middle, killing power up top. At the time of the tune, the tune was perfect and without knock. But heat, humidity, little changes in boost, different motor octane from different gas stations (I always try to run Shell 93 when I can), yada yada yada will cause a tune to fall off.

In the past, I had an MBC on my VIII with the stock turbo: Same problem- Run big boost in the middle and it tapered like crazy up top. Over the course of time, I switched to a Vishnu XEDE in my VIII. I liked this a lot better, because I had RPM dependent boost control and much more precise. I didn't run anywhere near as much boost in the middle, but could wick the duty cycles way up as the RPM climbed, and retain a ton of power up top like that. With this method, I could make 20whp more up top, no knock. Why don't I have an XEDE on the IX? There's no harness, simple as that.

So, I guess I'm asking if any of you are using EBCs or the GM solenoid with good success on the stock IX turbo?

Here's what I've tried so far in the past that has not worked:
(1) ECUflash boost control with stock BCS- Does not work for me in the midwest. Set it in the summer at 22psi, atmospheric conditions change and its making 27psi in the winter and knocking like crazy.
(2) Forge UNOS Manual boost control: Very repeatable boost curve shape, but really falls off up top due to it being crude. It would work great on a bigger turbo that wasn't running out of efficiency up top, but not ideal on the 16G.

Here's what I want:
I want the car to set in at about 21psi and hold as much boost as possible until the rev limiter. If it could hold even 19psi at the limiter, I would be elated. I don't need super midrange boost because of Mivec. I'd rather be gentle with it throughout and not provoke knock by running pressures I'm not comfortable with.

So this leaves me with the options of the GM boost solenoid or an EBC.

I want real dyno results, please, because everything I've seen from just reading a mechanical gauge is not nearly as accurate.

Thanks in advance for any help.

 

you want dyno results? or data logs from a car with an EBC? cause i promise you a apexi AVC-R will hold 20-21 psi all the way till redline. i know cause i did a car last night. i can post up plots later this evening if you want to see for yourself. it was for a 91oct car, peaked at 21, and held that all the way with fluctuations of about 1psi max.

 

Logs are great too, of course!
I'm wondering if my car just falls off worse than others, but I've seen a lot of MBCs that do the same thing my car has.

 

what altitude are you at?
because that plays a big part in you holding boost!

i know the HKS EVC 6 is also pretty good holding the boost, i have yet to play with mine

 

480' altitude.

 

have you tried a forge waste gate actuator with a red spring 24-25psi in it with the propper amount of preload you can hold 21 psi i hold 23 -24 psi at 8k

 

IMO, if you want boost up top, you need to minimize your pressure drops accross your entire inlet system.

i am talking about airbox, inlet tube too turbo, compressor discharge pipe, licp, fmic, throttle body.

all the oem pieces posses some amount of pressure drop.

i have a bull$hit tme & I can manage 21 psi @ 7,500 rpm in 90f heat, while making ~360 dj whp, via my aem logged map sensor. btw, my manual boost gauge verifies what i see in logged data too.

if i were to rank the largest culprits for pressure drop:
1. oem airbox
HUGE restriction / check this out https://www.evolutionm.net/forums/sh...d.php?t=248120

i dont know what was worse, the airbox, inlet tube or maf, but it all adds up.

if you put a grain of sugar on the table, it doest amount too much, but when you look @ a full sugar jar, theres a lot there.

2. licp & discharge tube....evo 9 tubes are a lot better than oem 8's
3. inlet tube-from maf
4. fmic
5. throttle body

 

Then you most likely had your closed loop load targets with offset set wrong or your pill size or lack or pill wrong. Did the 100% stock BCS system overboost with the 100% bone stock ecu map?

We have been getting great results from ecu-controlled boost here in California. 20+ evos tuned with it and more using it every week. I have seen large gains from it being able to hold more boost up top (with the properly sized turbo side pill)

The most important thing for this system to work well is to have all the maps tuned correctly. If they are not, you will have unstable/weird boost.

The really cool other advantage to RPM base ecu-controlled boost is that you have 16 points of RPM boost control. So you can make the boost curve look however you want. Some cars like more boost in the midrange, and less up top, etc etc, here are some various boost logs for you to check out, all from different evos with different mods, but all with ecu-controlled boost, either stock BCS or GMBCS:

 

I'd recommend doing a search on here for TURBODAWG from NC. He sells a manual with specific settings for RPM-controlled boost - used with an HKS EVC 6, and has videos showing his car holding like 23psi straight past 8500rpm on a stock turbo... Also, he has quoted dyno gains of like 20-30 top-end whp over a traditional mbc....

This is what I will do one day when I can afford that EBC...

 

With a tiny turbo pushing it beyond its efficency may yeild additional boost levels, however in most cases the increase in back pressure and additional heat in the charge air will negate any gains

Also, in the higher rpm range in many cases stock fmic is starting to get very warm after a long pull and thus the intake temps begin to rise dramatically with a turbo pushed too far

Careful road testing is needed to assure stability under normal operating conditions

This is particularly the case with a IX which will pick up knock very quickly

 

All of your replies have been very helpful, and I appreciate it a ton!

The first thing I tested was the stock airbox with K&N, stock airbox with side cut, and Buschur filter to replace the stock airbox.

None of the three offered any difference in power post tuning on the dyno, nor in amount of boost drop, nor in detonation tendencies. That said, I put the stock airbox back in last night. I was making 110whp more with the stock airbox with the 30R in my VIII, so I don't see it nearly as much of a restriction as others have in my testing.

This is not to say the Buschur filter isn't a great part, but at my low power level in this IX, its unnecessary at this time.

I'm going to take a shot at ECU controlled boost here the next time I can get down to the shop with the GM 3 port solenoid. I like the fact that it has 16 points of boost control, but most of all that it is integrated in ECUflash and not a separate entity like an EBC/MBC.

Razorlab- It didn't overboost stock, but I need to do more testing with my friend who has done a lot more cars successfully with ECUflash. I've always used interceptors in the past, so this reflash gig is a bit of a learning curve for me. Thanks so much for supplying all those graphs. ECU controlled boost, here I come.

 

You may want use the Perrin boost solenoid instead of the GM unit. Apex'i AVC-R can control what ever boost you want in what ever gear. Worse case scenerio, convert your turbo to external wg and no more crazy boost problem.

 

There is a thread in the ECU flash forum concerning installing and configuring the GM BCS.

 

But then you would just be using a shiny item of the same thing.

 

That costs alot more to boot..

SQ