VTC_CiViC

Not sure if you're all aware of this or not (you may very well be), but I made a MAJOR improvement to my turbo yesterday, just wanted to share it with. This is especially beneficial if your turbo is getting up in the years/milleage like mine and has a weaker wastegate spring.

The Greddy instructions tell you to attatch the little blue vacuum hose to the wastegate directly from a small vacuum port on the compressor of the turbo itself. This gives the wastegate a very quick reading on how much boost the turbo is creating, it also presents a problem though. The turbo spools up and immediatley the wastegate (attatched per GReddy instructions) wil read it's pre-set max of 5.5psi causing the wastegate to open right away so as to keep the boost regulated at its 5.5psi. The problem is, by the time the boost created at the compressor, snakes it's way though the charge piping, intercooler and up into the manifold, it's lost alot of it's pressure, commonly known as 'pressure drop'. This is why for the longest time, when I'd turn my AVC-R (EBC) off and run soley off the wastegate, my boost would normaly shoot up to .37bar (about 5.5psi), and immedatley drop off and hold around .22-.26bar (~3psi). Why? The compressor was making a full 5.5psi, and the wastegate (attatched to the compressor directly) was seeing 5.5psi and regulating there, but of course I was only seeing an actual 3psi in the manifold after the drop in psi. This also explains why my AVC-R had such an incredibly difficult time managing my boost. It took the AVC-R some time to get .45bar (6.5psi) to hold *somewhat* steady (.56bar spikes were common), and .70bar (10psi) was always a total nightmare with what I like to call 'boost flux', that is, boost would constantly jump from as much as 12.5psi to as little as 8psi and do this over and over and over, while I could feel the car surging back and forth. I put up with this for nearly a year, tinkering with every single setting the AVC-R has, finally ending up in my nearly selling the AVC-R for another boost controller.

Well yesteday, I finally got off my lazy *** and decided to give the new vacuum agrangment a try. I capped off the vacuum port on the compressor, and ran a line from the manifold to the wastegate, so it would now regulate boost based on what I was actually getting as opposed to what the compressor made. I arranged it so that the BOV and wastegate were T'd in to my FPR line, and my AVC-R boost sensor and GReddy boost gauge T'd into my cruise control line. Jump in the car, turn the AVC-R to "off" and take a spin. Punch the throttle and anxiously look at the AVC-R readout... instantly the boost hits .35bar (5psi)..... and HOLDS!!!!! Well, actually it hung around .32-.36bar, but hey, .04bar is ALOT better than over .1 bar that was flux'ing before!

Now I try the higher levels. .45bar (6.5psi) which normally takes multiple pulls in 3rd gear to set, was done in just 1 pull! Actually, I had to keep dropping the duty settings on the AVC-R (from 53% to 40%) because I was getting much more boost much sooner now. After the adjustment, it'll jump to about .48bar initially, and hold around .44-.45bar to the redline! I tried .70bar (10psi) but only for a moment since it gets the Civic moving too fast. But in just a little tweaking at abround 64% duty, I was making .75bar and holding between .66-.72bar. Seems the higher boost levels are harder for the wastegate to hold reliably, probably because this turbo has over 80k miles and I'm sure the spring is old and tired, but none the less, I haven't had a single .80+bar spike (as high as .90+bar in a few cases!) which was the norm b4 the vacuum change!

So the lesson learned.. don't be lazy! I would've saved myself ALOT of aggrivation and headaches if only I'da listened to myself and done this sooner. And if you havent' already, change your vacuum post settings asap (for those of you with similar setups), it's WAAAAAAAAAAAAAAAY worth it!

X2BOARD

Bad boost readings ownz j00 !!!

Glad to hear it's pretty much fixed.... found that vaccum leak ?

98civicEX

dave, you gotta pic of which one you capped? good job fixing the "flux"

VTC_CiViC

Nah no pics, but you know which one it is, it's the little vacuum port right on the turbo itself. Just capped it off and ran the line that was going there to the manifold instead

ladysman

What did you cap the turbo off with? I just put in my AVCR boost controller and noticed this same problem. Can't wait to fix it now!! Thanks a lot for sharing.

RoaringTurtle

good to hear you fixed the problem

CovertFI

i tried that mod and i noticed my car was quick becuse of faster spool. if anyone has a turbonetics wg any boost spikes are normal. that is why they suck monkey nuts

ion_four

I did this mod the very first day my car was turboed, because it wasn't reaching full boost till around 4500 or higher with a small T3...however! I connected the wastegate vac line to the very end of the charge pipe, right before the TB...would connecting it to the other side of the TB, in the manifold, have any negative effects, since when your TB is closed, your wastegate will be closed as well as your BOV being open? Actually...that might cause the BOV to function even better and allow it to stay spooled up even more efficiently, now that I think about it!

xci_ed6

I would suggest moving it from the manifold to just before the TB. I think that in the manifold will cause it to correct for boost at part throttle (so that 90% is the same as 100%). Try it. If I'm wrong change it back, If I'm right mail me a cookie, contact krustindumm@yahoo.com for shipping info.

-Dustin

niedejb

Isnt this a mute point with a ebc? My profec senses boost in the manifold, but the compressor nipple is to the in of the solenoid.

TurBoXBirD16

would it still be beneficial to do this even i don't have a boost controller??

also, how do you CAP that hole...???

VTC_CiViC

It would be especially good to do if you don't have a boost controller to ensure you get full boost and keep it. Even if you have a BC I'd do it because this way the controller won't have to keep fighting itself when it get's one reading from the pressure sensor, and yet the boost is comming on erraticly. I know it's made boosting low tremendously easier, the only problem I'm still having (albeit not nearly as bad as before) is getting high boost to hold steady at .70bar which may just be a case of the wastegate being overworked since it's an old 5psi spring. I reset my AVC-R last night and was messing with the duty setting back and forth, seems like it's getting full boost on alot less duty %, but it's still fluxing somewhat on high boost from .62-.72bar. Alot better than before when it'd hit .90+bar on occasion!

To cap it, I just used a short length of rubber vacuum line, stuck a screw in there to seal it and tied it tight with a tie-wrap.


[Modified by VTC_slow_CiViC, 10:14 AM 8/28/2002]

TurbothisLS

very interesting!
thanks for sharing!
i love to read about theory

ladysman

Thanks for the info!!

CivicEJ1

I'm going to bring this thread back to life.....

Any input guys?

ATS*Mark

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RoaringTurtle &raquo;</TD></TR><TR><TD CLASS="quote">good to hear you fixed the problem
&lt;IMG NAME="icon" SRC="http://images.zeroforum.com/smile/emthup.gif" BORDER="0"&gt; </TD></TR></TABLE>

what the hell are you doing in here you all motor ***!!!!!!!!!

VTC_CiViC

Wow.. 2 year old posts haunt me!

To date this is still the only way I hook up wastegates/controller, kicks ***

boostincoupe

This post helped alleviate my boost flux problem too

EKhothatch

Cool, nice info. I'll have to try it.

snoochtodanooch

good info, thanks for the post