I've got a 84 930, completly stock, except aftermarket exhaust. Should I have any concerns going with a 1.0 bar boost spring. If it sounds like a good idea, how do I go about installing it? Thanks, Matt.

 

I would NOT go up to 1 bar w/o using a larger intercooler... You're asking for big problems.

Once the intercooler is upgraded, changing the spring is just a matter of taking the top cover off the wastegate housing. Inside is the spring in question. It can be a PITA, but once you've done one they are pretty easy to change.

 

Then you have to ask yourself if your fuel system is 100% and then you will possibly need some extra enrichment if turning up the mixture doesn't cut it. You should get a base line on a dyno to see where you stand before upgrading. Something people fail to check out and pay dearly later.

 

Most would upgrade to a bigger intercooler, 1 bar spring and set the CO to 3%-4% for a start.

 

Take the 3-4% CO will a grain of salt, it doesn't mean **** if your fuel system isn't working right. Who cares if your fuel mixture is good at idle when your too lean up top. I know since I could have run a million % CO and would still be lean up top when I had a fuel problem a few years back. Yes, I'm in one of those moods right now.

To install the spring you just remove the WG and undo the screws that hold the top on but be carefull it will pop on you. Then just install the new one, you might need a clamp to help compress it.

 

You only need a larger IC if your charge temps approach 125. If they pass 125 then it is time to stop and let things cool down.

It is more important for those living in the southern states then those of us in more temperate (or cold) states.

 

In NC he WILL NEED a larger IC... PERIOD!

The fact is the stock unit is marginal in cool weather, once the summer hits it's not practical to run 1 bar w/o detonation. It sure isn't worth the risk in my mind... unless he just want's to use the car in the winter.

 

Hi Matt:

If I may add here,.....

Thes cars run too lean at 1 bar unless the FD and airflow meter is modified.

EGT's REALLY climb at 1 bar unless you get additional fuel into the engine, on-boost. The result is a far greater propensity for detonation that you likely not hear.

I cannot begin to tell you how many engines are disassembled and found with broken rings that ran at 1 bar, unmodified.

I would suggest that you retain the stock boost spring and look at other modifications for more power without compromising engine life.

 

Isn't an '84 a euro? I think he would be good with one bar. Should run it on the dyno to be sure of course.

 

Hi John:

Every stock 930 (US or Euro) I've had on our dyno shows very lean AFR's on boost and the more boost they have, the leaner they get.....

IMHO, they all need more fuel as boost gets higher than stock.

 

Exactly, if you want to run at 1 bar safely, without compimising engine life, you need a bigger intercooler and turn up the CO for extra fuel. Off course if you want to be sure, than put it on a dyno. Most of us who start modyfying take this route.

 

Here's mine on a '79 at 1 bar with no mods to the fuel system.

John

 

Hi John:

Nice power,....

If that is your A/F ratio, its not bad for something that is unmodified.

 

I agree, that is better than any other stock curve I have seen. Are you sure it's stock?

Brent

 

Absolutely. Never touched the fuel head. However it is a '79 so it moves a bit more fuel then later models of course.

It won't show the same dyno today, I put a stock wg spring back in and some castrating cones of silence in the muffler. Of course it would only take about an hour to get back to this