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-   -   Should I worry? Over 1 Bar At Full Boost (http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/361553-should-i-worry-over-1-bar-full-boost.html)

BMAN 08-11-2007 06:02 PM

Should I worry? Over 1 Bar At Full Boost
 
I installed a set of headers, Fabspeed exhaust, Fabspeed cold air intake system and waste gate pipe, full tune up, set CO to 3% and once I hit 3K my boost gauge tacks over 1 bar, should I be concerned? I wanted to install a 1 bar spring but now I don't know if I should? I've only have had the car for a few months and it spent most of the time in my garage getting all the upgrades but I don't remember it tacking over 1 bar before all the work.

http://hometown.aol.com/hlrbj/images/930header5.jpg

Miguel Antonett 08-11-2007 06:44 PM

That's a clean looking machine!

The tach gauge is not that acurate, if it was at .8 before the changes it should be OK. Considering you did not change the WG spring.

DDDD 08-11-2007 10:11 PM

Quote:

Originally Posted by Miguel Antonett (Post 3422061)
That's a clean looking machine!

The tach gauge is not that acurate, if it was at .8 before the changes it should be OK. Considering you did not change the WG spring.

I've got to respectfully disagree with that.

When you put new, short headers on a 930 it can overboost quite easily. Some cars overboost or get boost creep which means the wastegate no longer bleeds boost as fast as it builds. This is because the exhaust is sending air to the turbo much quicker than before, yet the pipe going to the wastegate might not be flowing as well, if it is turning back with a couple 90 degree bends.

It all depends on how accurate a boost gauge you have. The factory gauge wasn't great but the aftermarket gauges that replace the clock are usually okay, and if it used to say .8 bar and now says 1 bar, guess what?

I wouldn't worry if it is bleeding off pressure at 1 bar or ever so slightly over, as long as you tune your AFR correctly to compensate for a little more boost.

But if you are creeping to 1.1 bar or more than you may want to reduce the spring in your wastegate to less than .8 bar and run a manual boost controller to make up the difference, the Hallman pro RX with a ceramic ball is the boost controller I just bought. Greddy makes a couple really simple and good electronic boost controllers if you want more control, but the manual ball and springs types are supposed to be good enough.

SCHNELE 08-12-2007 01:01 AM

Get an EBC it will be cheap insurance. And DDDD is right, you may even experience boost creep on cool days when the temps drop and you have a dense air charge.

dewolf 08-12-2007 02:45 AM

Your boost limit cut-out switch should operate at about 1.0bar if it hasn't been grounded. I have a boost controller but still maintain the boost limit switch, just in case.

BMAN 08-12-2007 06:21 AM

Thanks guys... I think I need to start with a new gauge first. Where and which one is the best? The over boost switch has not been grounded.

930LDR 08-12-2007 08:49 AM

The best gauge option typically is the unit that both our host and Performance Products sells. Its manufactured by North Hollywood Speedometer and replaces the clock on your dash. Easily plumbed to the brke booster up ahead of the firewall.

I actually have a brand new (but not for maybe 5 days of use) gauge and plumbing kit that I bought a couple of months ago from Performance Products. My original gauge was being repaired by NHS and I wanted something to use in the interim.

If you are interested pm or email me. Basically if you buy the gauge I'll give you the plumbing kit (which I never even installed) for free.

BMAN 08-17-2007 05:44 PM

I got the mechanical boost gauge hooked up and the good news is, I'm not over boosting. I'm getting 13 Ibs. I wonder if I can run a 1 bar spring with those measurements?

h20cooled7 08-18-2007 05:49 AM

take it for what its worth ,but if your overboost switch has not been grounded you might have a bad over boost switch letting you overboost.

Brent 930 08-18-2007 07:53 AM

Quote:

Originally Posted by BMAN (Post 3422479)
Thanks guys... I think I need to start with a new gauge first. Where and which one is the best? The over boost switch has not been grounded.

Steps for boost control

-Get a known calibrated mechanical boost gauge to replace your clock. I got a dual psi/egt from Westach that worked really well.

-Tap the boost line to the brake boost line (before the throttle plate) for the most accurate readings.

-Get a 46mm TIAL wastegate. Your stock one is most likely leaking through the shaft.

-Get a .6bar boost spring with the TIAL.

-Get a nice electronic boost controller.

You now have an accurate, and sure fire way of controlling your boost. Having a lower bar spring will help control creep, and the extra creep you will get in the winter time. It will also serve you well if you have a lean condition.

Oh, and don't ever ground out (or bypass) the over boost protection switch. Check it and make sure it's working correctly. It should trip at approx. 1.1-1.2 bar so you don't get any false trips near 1bar.

IMO you can't afford not to have superior boost control and protection. Overboost kills motors, and these motors are pricey.

Enjoy

Craig 930 RS 08-18-2007 08:52 AM

First you need to *verify* -

Find a local Porsche shop which has the factory boost test gauge - a HUGE mother, about a foot across. Lay a $20 into owners' palms.
Connect, go for a drive, see what the actual boost is before you do anything else.

Craig 930 RS 08-18-2007 01:14 PM

http://cgi.ebay.com/ebaymotors/Porsche-930-Boost-Vacuume-Gauge-Clock-Replacement_W0QQcmdZViewItemQQcategoryZ38660QQihZ0 09QQitemZ8046788217QQrdZ1QQsspagenameZWD1V


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