My 930 needs a top end rebuild. What mods to do while in there.

[jwakil]

I already have a K27 and larger intercooler and exhaust. Are bigger pistons the only next thing or is there something cheaper I can do to get some more horses?

[WPOZZZ]

Don't forget cams.

[Norm K]

When I pulled my engine the plan was to do just the top end. But seeing the case hanging there on the engine stand, only about a half-hour's worth of bolt-removal holding it together, it just seemed silly to not go for the Full Monty. Now I'm in the middle of a complete rebuild, including stock cams being reground to SC profile and a full EFI conversion. Whether you opt to stop at the top-end should depend in no small part on how many miles are on the engine and what sort of miles those are. Potential pocketbook issues notwithstanding, if the miles are, say, 80K or higher or if you have knowledge that a lower mileage car has been thrashed-on pretty hard over the years (e.g. tracked) then going all the way should perhaps be viewed as an imperative. Of course if, other than machine work, this is a DIY project things are much more affordable.

Good luck with whatever you decide!

[TurboKraft]

Cams
And items for reliability/longevity: ARP rod bolts & head studs, upgraded valve springs.

Beyond that, it depends on what you want the car to do, what you expect of it when finished.
More off-the-line performance?
Emphasis on midrange and passing power?
Maybe you love doing top speed runs?
Flexible all-around performer?

[Strygaldwir]

You can do so porting of the intake and exhausts.

If you're doing the cams, I certainly consider a compression increase to go along with it.

Then of course ceramic coating the heads.

Double valve springs and titanium retainers have already been mentioned.

You could pull the pistons, ceramic the tops, Teflon the skirts. Not sure that would do any thing to increase power, just longevity.

Good luck,

Keith

[Akila]

Carrera or SC heads will get you the larger ports. I have a set of Turbokraft injector blocks if you would go that route.

[Edelweiss]

+ 1 for cams !

They open up the engine they are the most effective way to get the next step done in making a good engine even better and way more dynamic.

SC cams are good but the 964 profile is even better - it is wrong to say that one is better in lower rpm and the other is better at the top end.

You have to see the package and the lift adjustment in TDC must correlate to the static comp ratio.

Most exhaust systems are way too big in diameter - and most of the turbos have a too small hot side.

As said before - the package must display a balanced and harmonic system.

Chris Caroll is the man to ask in the Americas....

If it comes to cams avoid pussy stuff - go for the real thing !

Best reg

Dirk

de-de.facebook.com/edelweissmotorsport

[speednme1]

Twin plugging the heads is always an option as well.

[JFairman]

You mentioned cheap ways to more horsepower.

You know those little 32mm intake ports in the 930 heads? You can make them bigger.
I opened mine up to 40mm to match some 40mm aluminum injector blocks. I opened up the holes in the intake manifold to 40mm too.

The heads already had new valve guides installed and a freshly ground valves and valve seats. I pushed the little pieces of rubber hose on to the valve guides to protect them from the carbide burs and sanding cones. They worked good at protecting the valve guides.





Here's how the intake ports looked afterwards.

[jwakil]

JFairman, it seems like it would be hard to get all six consistent and not affect the balance if you open up the intake ports with such odd shaped air paths. Have you tested performance enhancement yet after doing this?

[Darkhorse]

JFairman, it seems like it would be hard to get all six consistent and not affect the balance if you open up the intake ports with such odd shaped air paths. Have you tested performance enhancement yet after doing this?

I hope this works because I've just has it done to mine (38mm) . Plus 964 cams and a larger intercooler.
I'm hoping for some improvement !

[sundevil64]

custom cams and diy efi for bang for the buck.

[Hams930T]

Originally Posted by jwakil

JFairman, it seems like it would be hard to get all six consistent and not affect the balance if you open up the intake ports with such odd shaped air paths. Have you tested performance enhancement yet after doing this?

He did mention cheap. It's the DIY method. Think old school domestic here. Been doing this type of thing, home porting, for a long time. Perfect? No - but a lot cheaper too.

[JFairman]

Thanks.
Not much chance the 930 pancake plenum manifold flows evenly to each intake port anyway.
It gave me satisfaction to do this and hardly cost me anything to do it.
I'm sure it flows more air to the cylinders at full throttle now. If CIS can't keep up with enough fuel up top then I'll turn down the boost until it can.