spyderx

iTrader: (17)

I have a question regarding this. On dynoject we put down 340whp/342lbs on my IX with Hallman MBC set to and peak boosting to 24lbs. Yet at topend it tapers to 16lbs or so. Is this tapering more due to my hiflo cat?

I'll probably switch over to EBC, soon.

shbomb8188

iTrader: (23)

i would like to know also. i too have a hallman mbc tuned to spike 23psi, but taper to around 17 up top. other mods are intake, tbe w/ hfc and fp. i will be installing a tp soon, but i would still like to know.

20psiMR

iTrader: (6)

Nope. Has nothing to with the cat. It tapers because its flowing a ton of air and cant really keep up at high RPM's. Its going to taper, thats just the way it is. Usually they dont taper that much though, usually fall down to about 18. Check for leaks, but that sounds about normal to me.

boomn29

iTrader: (47)

+1 - it's normal to taper to redline with the stock turbo.

Running a spike of 24psi isn't as normal though, make sure it's safe!

spyderx

iTrader: (17)

I wonder if EBC would help to compensate the taper at top.

A local IX stated that w/ AEM Tru Boost ebc, he holds steady at 19lbs.

anyone else?

spyderx

iTrader: (17)

have you dynoed yet?

20psiMR

iTrader: (6)

19 maybe. But hes not spiking all the way up to 24psi either. Usually like I said, the head flows so well the turbo cant keep up, so it tapers down to 17-18 psi at redline. Doesnt really much matter what you do boost controller wise.

Dr Evo

Something is not right. Maybe you set it up wrong, I only drop about 2 lbs to redline, if that much. I spike at 22 and drop to 21 maybe 20.5. I have a Forge MBC and have been told that's the best one to get.
All I have is TBE and a drop in filter.

Dr Evo

Oh I also have the Jestr flash, which eliminates the boost taper. So maybe you are set up right but need a tune as well.

Evo05lution

iTrader: (27)

hmm...what are you running your vacumm lines off of? WG and Turbo pipe? or WG and BoV Line? Cause with my hallman mbc i have it set at 22 psi and i hole all the way through redline...and thats without a flash...if you havent...run your vacum lines off the wastegate actuator and tap the bov line...you should be golden...if you have this done already then def look for boost looks....good luck

Dr Evo

Yup, just did a test run, 21.5 spike, 21 to redline.

20psiMR

iTrader: (6)

Hes talking about with IX's though guys. You can hold easy on 8's, but the Mivec head flows ALOT more. Thats why they had to make the turbo bigger, and it still tapers some.

Dr Evo

I have a IX.

Warrtalon

iTrader: (6)

Actually, you're mistaken, and this is exactly why people like SpyderX end up making threads like this. You do not sustain that much boost to redline. You just think you do, because you look at your gauge. What you fail to realize is that it does not truly stay flat and hold 20psi at 7k rpm. You can't use a gauge to determine this - you must log it with a MAP sensor to verify. If you do this, you will surely see your IX taper down well below 20 - that's a fact.

Also, there is no way your Jestr flash reduces taper if you have an MBC, because the ECU is not connected to the boost system. Another misconception by many newbies...

Warrtalon

iTrader: (6)

Chu, like so many other IX owners, you have fallen prey to "boost taper syndrome." People get so worried about their "boost taper," because they see other noobs claiming "OMG, I hold 21psi to redline!1!1!1!1!1!1!. Then, at the same time, they ignore their amazingly powerful dyno and track numbers. Look at your numbers - those are awesome, yet you're worried about boost taper even though you don't see it affecting your power. Worry less about phantom issues and more about results.