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spuggy spuggy is offline
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Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 2,830
Originally posted by Craig 930 RS
P.S. Think of flame ringing the heads and cylinders "while you are in there"
Steve Weiner recommends it highly.

P.P.S. SC heads are nice too

F.R. will cost about $600, the SC heads flow quite well and work great
but you probably really don't need them.....or do ya? ;-)
LOL. You swine...

The guy who would do the twin-plug work also recommended flame-ringing.

The machining prices are double the US going rate over here, it seems, but it's not frequently done so not that much choice if you want someone who's done it before.

However; there's no tell-tales of any blow-by on the heads/cylinders at all - in fact, the top-end was in great shape and had good leakdown figures very recently. So this didn't really seem necessary - will just use a Supertec stud kit this time around and call it good.

SC heads? No, they'd just make far too much power, I don't need 'em...


Originally posted by 930gt-40r
The whole question of twin-plugging was really prompted by "does it make sense to do the (relatively cheap) machining while the heads are sitting on the bench anyway".
Andy- do you plan on ever going somewhat nuts with the car? If you think that you will ever want to EFI the car I would go and have them machined, plug them and use them if and when the time comes. I had a whole bunch of stuff done to my heads last year (3.2 ports, ni-resist ringed, ported, new valves, etc..) and now wish I was flexible enough to kick my own a$$. I didn't want to spend the money after machine work such as coil packs or 964 distributer. But now Im pissed that I didn't do it because I need it to run the boost that I want.

But unless your going to do something nuts some day, its not worth it.
Sorry to hear that - that must really suck after all the other work! Maybe with water/alcohol injection you could get that boost level anyway without tearing it down?

I'm trying quite hard to just do things that "make sense" whilst it's apart; you'd have to spend far more than I intend to on this rebuild to be considered "somewhat nuts" in this company anyway.

The car is a hybrid - mid-year S chassis, 3.2 brakes (currently), 915 trans, 21 & 30 t/bars. It's lighter than a 930, which changes the equations somewhat. Way I figure it, there's a whole bunch of stuff (brakes, suspension, transmission, driver) that should be addressed if the power output were dramatically raised; not on the road map for this time around.

If twin-plugging wouldn't offset, say, 0.5:1 on the compression ratio, then it doesn't seem worth doing at all in my application. I was considering laying the groundwork for running up to (say) 1.0 bar, but if I can't make that with pump gas and my C/R, then well, hey, never mind.

It's very drivable off-boost with 8.0:1 and SC cams, so this does seem like a pretty good compromise for a mostly street-driven car which does duty as my daily driver. It's not like it's slow, exactly...

As the car makes road trips - and thus runs on pump gas - the boost will stay stock and the priority becomes "get my car assembled, I need my boost fix!"

Thanks everyone, your input really helped.

'77 S with '78 930 power and a few other things.
Old 03-14-2007, 09:34 AM
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