1 Bar spring Question
 

I just got done putting in a K-27 7200 on my 87 930 it is stock except for a B&B exhaust and BMC intake. Is it okay to run my 1 Bar boost spring or should I put the stock one back in. I dont want to mess up fuel mixtures.

If I understand your question, you're asking if a 1 bar spring affects mixtures. If you have the stock CIS, no, the fuel plate will compensate for the higher boost (more air in results in more fuel delivery). Whether it's safe to run 1 bar is up to you - lots and lots of guys do.

But did you just add the turbo and freeflow exhaust? You might want to get your mixture checked out if so. When I installed a Dynomax Turbo muffler last week, the mixture leaned out because it's a lot less restrictive than the stock 930 muffler. This was on a '77 930.

I would not run the 1 bar spring unless I did an intercooler upgrade, which you should do anyway if you have a k27 and full B&B. I think most guys in the know would say you are pushing it running it the way you are. And yes, get those fuel mixtures checked if you didn't after adding your mods.

CIS will provide fuel for 1 bar but it's on the limit. I don't like those pesky springs at all.

They are b***h to install and cannot be replecade easily. One T-orifice on wastegate hose will do the same and can be removed in 5 mins.

I had the 1 Bar spring and removed it back to stock (.8 bar).

On crappy California fuel (91 octane) I was getting predetonation - not good to hear. Back on stock boost, stock intercooler, and stock exhaust, my 930 with a K27 is plenty happy - and plenty fast (for now!).

I think you'll be OK.
But like Emission said predetonation
is a bad thing!!
A larger intercooler would be the next
step.
You can try a race fuel/pump mixture
just to be safe.
Have fun!!!

Larger intercooler (I chose Kokeln) and a fuel enrichment system (Andial) just to be sure that when you get boost you don't melt pistons.

If I were you I would get dynoed and see what your A/F is

We had a very similar situation. I think we had a 1.2 and a few months back I got a lot of very good info from Rarly8 about this topic.

We just had a top end rebuild completed and our tech also thought it was a good idea to go back to a stock spring bar. The old one is currently on our dining room table. I did not know they were that big.

Sarah, You had a 1.2 bar spring? That's pretty agressive.

That was what Tim was told by the PO who only had our 930 a year. We didn't even know what that meant at the time. We are the 4th owners. We think either the 1st or 2nd owner tracked it pretty hard. People have told us that some of the misc items in our PO parts box are used by people who race. So we don't know if it was a 1.2 for absolutely sure...but did not want to take any chances.

Sarah,

Did you upgrade the intercooler? Or was that the reason for the top end rebuild?

The top end rebuild was the result of a small oil leak that we wanted fixed when our 930 was having new gears and lots of other misc work done this past winter. After the leak down tests and once the engine was a part...there were a lot of parts (rings, gaskets, resurfacing metal parts, lots more) that needed to be taken care of. We luckily did not need a complete rebuild so we wanted every thing taken care that would prevent a larger engine problem in the future.

We really want to upgrade to a larger intercooler and a fuel enrichment kit...but that will have to be in the future (our wants became larger than our $$ means...;)...so a few things had to wait).

I emailed Stephen at Imagine Auto to see what he thought. When I spoke with him upon buying the turbo he said I would have no troubles running this turbo with the stock IC and with out changing the fuel. I realized after I forgot to tell him that I was planning on transfering the 1Bar spring in my old wastegate to my new one and if that would still be okay.
I will post his reply when I recieve it.

Dean I thought of that as well there is a dyno a mile from my house. Im going to call him on Friday. This way I can check the fuel and see what my horsepower is up too after my new items.

I agree with Dean, do some dyno pulls and go up to 4k rpms first to see where you are.

If you upgrade from stock like a K27 you better have more fuel or cooler intake air. The cheapest thing is modifying the WUR for more enrichment. Actually running lower boost with a K27 until you get some other goodies will be cheaper unless you know how to modify the WUR yourself, I can do this for you if you like. Let me know,

Brent