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Registered
Join Date: Aug 2010
Location: NY & UK
Posts: 203
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Advice: Piston & Cylinder Best Option for 3.0 SC Race Car
What is best cost effective option for 3.0 SC Race Car Piston Cylinders... currently the car has 9.3 Comp Pistons (Group E, PCA Rules) and the Heads are Flycut to achieve Euro Spec Comp of 9.8... I would like to achieve max compression and Twin Plug the Heads, any advice welcome.
Here is my Club Rules Engine The engine cylinder head and block must be based on the normal production parts and materials as used when the car was manufactured. In the event that an exact original item is unavailable, an alternative block from the same manufacturer may be used, provided that the Eligibility Scrutineer and Competition Secretary are satisfied as to the necessity of the change. Engines may be rebored up to a maximum of + 0.060" without changing class even if the capacity exceeds the upper limit by the rebore. Where a competitor wishes to exceed the permitted overbore of +0.060" and this raises the engine's capacity above the class limit, the car will be included in the higher capacity class. Stroke must remain standard, and the crankshaft and associated connecting rods material is free. Multivalve cylinder heads are not permitted unless originally fitted as standard. Engine disposition and location must remain as standard and therefore no modifications to the base structure or chassis are allowed. |
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Try not, Do or Do not
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The best option I have found for this application is to use the euro 3.2 Carrera piston and cylinder set.
On the long stroke crank they are rated a 10.3 :1 compression so on the 3.0 crank you get right around 9.8:1. With your heads the compression is even higher. With this higher compression you can notch the pistons for more aggressive cam timing. The only issue you will find with the 3.2 95mm pistons is the pin diameter is larger and the location is higher to account for the longer stroke crank. You compensate for this anomaly by buying custom rods or relocating the bushing in the stock rod. This gives you the added length you need and as a bonus you improve rod length to stroke ratio making the engine spin much freer. With these pistons you may also be able to use Pankl GT3 titanium rods which have the added length you need. Edit In rereading your rules it appears that you don't need to use production pistons so my post has little or no value. Sorry. Call LN Engineering for a custom 96mm piston and cylinder combination with any compression you choose. 10:1 with street gas is max even with twin plug.
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Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net Last edited by Henry Schmidt; 01-06-2011 at 08:54 AM.. |
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Registered
Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
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Henry is right; call LN Engineering and get a 96mm P/C set. If you are not restricted to pump gas, get that CR up there above 11:1 for power unless you are using CIS.
If CIS is required, then stick with 10:1, otherwise you may be too lean.
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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Registered
Join Date: Aug 2010
Location: NY & UK
Posts: 203
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Thanks Henry/Steve... max fuel I can run under MSA Regs is RON 100 (MON 89)
Will be looking at bolting on a set of PMO 46's |
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