930 drivers question

JoeF · 05-23-2007, 01:47 PM

I dont have alot of driving expierence with a 930. Is a working turbo boost guage a necessity for safe operation?
JoeF

equality72521 · 05-23-2007, 02:05 PM

I would say yes. If you don't what your boost is how will you know when you over boost? Possible blown engine, that's how.

David · David's Garage

I would say no for normal driving in a relatively stock car. If the car's smoking the tires through first gear you might be over boosting

. For extended runs, it's very nice to know.

Miguel Antonett · 05-23-2007, 03:48 PM

I'd say no, unless you have made significant changes to the system.

You should know by "feeling" when you are on boost and when over boost.

equality72521 · 05-23-2007, 05:03 PM

Quote:

Originally posted by Miguel Antonett
I'd say no, unless you have made significant changes to the system.

You should know by "feeling" when you are on boost and when over boost.

He says he doesn't have much experience with a 930 so where is he getting this "feel"? I say without thoroughly "knowing" this car he "needs" a working boost gauge.

dentist90 · dentist90's Garage

Forgive the newbie question, but do stock 930's have adjustable blow-off valves or pressure limiting valves? I thought boost pressure was factory limited.
On my Talon Tsi I can keep my foot in it until I have to shift, as pressure is limited to ~12psi.

I'll tell you, when I'm in GO-mode I'm not watching the boost guage. I'm watching the road and listening to the revs for the next shift.

equality72521 · 05-23-2007, 05:13 PM

Quote:

Originally posted by dentist90
Forgive the newbie question, but do stock 930's have adjustable blow-off valves or pressure limiting valves? I thought boost pressure was factory limited.
On my Talon Tsi I can keep my foot in it until I have to shift, as pressure is limited to ~12psi.

Yes, it is factory limited but an old stock faulty wastegate can still cause a problem. It's best to see what you actually have.

9dreizig · 05-23-2007, 05:57 PM

I respectively disagree,, the stock boost gauge is so unreliable that it wouldn't ever save your engine....

equality72521 · 05-23-2007, 06:02 PM

Quote:

Originally posted by 9dreizig
I respectively disagree,, the stock boost gauge is so unreliable that it wouldn't ever save your engine....

He never said stock, he said working. Now I would agree that the inference is the stock but we don't know that. However, a stock one is still better than none.

DRV2FST · DRV2FST's Garage

Quote:

If the car's smoking the tires through first gear you might be over boosting

What if it is still smoking them half way through second as well?

David Goodman · 05-23-2007, 07:18 PM

I would disagree also Mark. There are more discernible signs ones engine is overboosting, like the overboost switch cutting the ignition.
Dave

equality72521 · 05-23-2007, 07:24 PM

Quote:

Originally posted by David Goodman
I would disagree also Mark. There are more discernible signs ones engine is overboosting, like the overboost switch cutting the ignition.
Dave

So all of the people posting about boost gauges are wrong?

David Goodman · 05-23-2007, 08:36 PM

A properly operating boost guage is a nice tool to have but as I understand the question, it is not necessary for the safe operation of the motor.

Here's my point. If the car hasn't been messed with, there is a failsafe that prevents overboost. The result of an overboost is as subtle as getting poked in the eye.

While it's nice to know what your boost pressure is at any given time, for it to provide that level of safe operation you would have to watch it constantly.

The same is true for an oil pressure guage. That's why people install those huge warning lights and in some cases low pressure cutoff switchs. Because you can't always monitor/trust a guage.

Facey · Facey's Garage

no 930 experience here. but i have wired my oil and fuel pressure wanring systems into my car alarm, and eventually ignition shut off, when driving at the point that those failure could occur you simply are not looking at the guages.

that being said, i have fuel and oil pressure guages as well. And if i ever build a turbo engine, it will 100% forsure have a functional boost guages that read at least 30% my planned max boost.

rlh930 · 05-24-2007, 12:35 AM

Quote:

[i]If the car hasn't been messed with, there is a failsafe that prevents overboost. [/B]

The newest 930 is around 20 years old and it's tough to know whether or not yours has been messed with unless you have owned it from new and done all the work on it yourself. Case in point:

Under hard acceleration, my boost gauge (the one on the tach) was occasionally pegging at over 1 bar. I suspected a sticky wastegate and took the car in for service.

It turned out that the wastegate was NOT sticking. The crappy stock boost gauge was improperly reading over .8 bar. So maybe the boost gauge is more trouble than it's worth, right?

Well, the shop also found that the overboost cutout had been disabled by a previous owner. Apparently they had become annoyed by it activating prematurely and had disabled it.

So without a boost gauge, a sticky wastegate in combination with a disabled overboost control could easily become expensive. If you do all your own work this will never happen. In my case, I now have a nice big Andial 935-style boost gauge in place of the clock. I also have a new diverter valve so the engine doesn't mistakenly detect overboost.

JoeF · 05-24-2007, 02:39 AM

Wow! Thank you for all the answers. I will speak to the mechanic about the guage. I believe he did mention the 935 style guage. Thanks.
JoeF

Garen · Garen's Garage

Get a mechanical boost guage to replace the clock. It doesn't hurt to know. In stock form, it should not be above 0.8 bar or so. You shouldn't go much above that without properly adjusting the fuel mixture as well.

If your car is completely stock, with all safety systems (overboost cutoff, wastegate) in working order, then, theoretically, a boost guage is not really necessary for safe operation. Another benefit to having a good vaccuum/boost guage is that it can indicate a loss of vaccum in idle conditions, which can give you a hint of a loose vaccuum hose, intake leak, etc.

Plus, big boost guages are plain cool. Like 930's.

-Garen (87 930 CS)

rotorhead · 05-24-2007, 05:59 AM

Quote:

Originally posted by JoeF
I dont have alot of driving expierence with a 930. Is a working turbo boost guage a necessity for safe operation?
JoeF

Definately NOT.... if you are looking at the boost guage at full boost then you need to look up.....and live.

The car has overboost protection; there is a sensor on the inlet manifold that cuts fuel at 1.2 bar. So if your boost guage is not working then the system is still protected.

Also the boost guage is really there to show you what you can feel and hear happening anyhow.

Tom F2 · 05-24-2007, 06:11 AM

Quote:

Originally posted by JoeF
I dont have alot of driving expierence with a 930. Is a working turbo boost guage a necessity for safe operation?
JoeF

I would say that it's not a necessity, but it will definitely help with learning how to drive your 930 well. Like all Porsches, and maybe more than other models, a 930 requires that you re-think your driving techniques. Once you are familiar with it, a 930 is a truly great car, especially for long highway drives.

Miguel Antonett · 05-24-2007, 07:23 AM

I would say that it's not a necessity, but it will definitely help with learning how to drive your 930 well. Like all Porsches, and maybe more than other models, a 930 requires that you re-think your driving techniques. Once you are familiar with it, a 930 is a truly great car, especially for long highway drives.

And I would add: there in substitute!