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Dynamohum Dynamohum is offline
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Join Date: Jan 2008
Location: Midland Ontario Canada
Posts: 173
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Quote:
Originally Posted by lucittm View Post
Paul,
How many miles on the engine? If there are close to 100K, you may want to think about new pistons and cylinders; considering the tolerances of course. This will also solve your problem of compression ratio being a bit high for a turbo. Reducing CR by changing deck height dimensions will lead to valvetrain geometry issues.
With all the head work, why not go to twin plug? Unless your pistons are flat, the flame propagation will be a problem for you.
How about some picture of the insides of your engine, that will get people motivated to chime in.

Welcome,
Mark
Hi Mark,
My engine has 140k on it but was well maintained the wear is minimal.
I plastigauged the rods and mains and was surprised to see them still within spec, regardless I'm installing new while I'm in there. The piston clearances are all good so I figure they will be OK for now and helps keep the cost down.

Originally I was debating increasing the bore to 98mm making it a 3.4 NA, but the costs are high and I would need cams and depending on the configuration twin pluging. The costs shoot up fast so in the end I figure you get more HP for the $ with going turbo. For now I'm trying to get the maximum HP within the confines of the Motronic sys. This way I can keep the initial cost down, keeping it a simpler build ,completed in less time.

Re:twin pluging; I haven't found anyone within 200 miles of me that's can do the machining for 10 or 12mm plugs. That and all the extra cost and complexity of the supporting systems, perhaps that will come with the next stage? Or perhaps I will learn the cutting angles and get set up to do them?

Re: possible valve train geometry issues. Personally I don't see that as an issue. From what I can make out the Promotive stage 2 kit goes this route. It only takes a .05mm shim on the bottom + the thickness of a C2turbo head gasket ring to drop the compression down to approx 8.8/1 Surely the cam chain adjuster can make up for this, the difference of deflection would be minimal less than .05mm. Perhaps I'm not seeing a potential pitfall and if so can someone please let me know.
I'm committed to doing a turbo conversion now, went ahead and ordered ARP head studs and Dansk header today. So let the fun begin!

Next purchase is the turbo, I'm thinking along the lines of a k7200 or GT30?

Re: photos, I suppose I should take a few photos along the way I'll work on that one.
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Thank You for your time, Paul. We do because we can.
87 911 3.2 (Turbo conversion, build in progress, Thermal Barrier Coatings, High Pressure Dry film coatings) Modified heads, boat-tailed case, ARP hardware, OBX Header, 930 clutch disk, G50 Trans
89 5.0 Mustang convertible (For Sale)
Old 01-20-2009, 07:50 PM
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