Flyin' Miata : Stroker kit

There's no replacement for displacement. An extra 200cc can make a big difference to turbo spoolup or naturally aspirated power. Starting with a cut up block, we measured to determine the maximum stroke the 1.8 could handle without a modified block. That's 4 mm more than stock. The bore was set at 84.5 mm for a few reasons - it leaves a good margin of safety, allows use of stock head gaskets and puts the final displacement at 1995cc. Since the first car to get a stroker was the Track Dog running in an under-2000cc class, that was perfect.

The crank is made out of a solid 350 lb billet of steel by Moldex. We had Pauter make us custom rods that are 8 mm longer than stock. The pistons are made by Wiseco, and feature an extremely short compression height. The wristpin is actually inside the oil rings, requiring a support ring. Exotic stuff. Why go to this trouble? To retain the stock rod ratio so the engine will still want to rev.

We will be offering the pistons in a 9:1 compression ratio. If you are interested in an 11:1 version for naturally aspirated use, please let us know.

Progress:
March 19: Dyno run! 12 psi FM II with a stock 1994 head and a stroker motor. Now that's a fun car to drive. The little dip at 3700 rpm is a characteristic of our dyno.

March 12: The kit is good to go.
February 26, 2004: What happened to the 2.0? It was installed in a customer car here and fired up for the first time last night. The car is going for initial test drives today and if it all appears healthy then the stroker kit will be released to the world.
November 21st, 2003: It's been busy around here, building one engine after another. The 2.0 is finally being built.
October 23rd, 2003: We are going to build one more engine with the latest parts to ensure everything is good. Once it's been given the okay, the parts are ready to ship.

earlier: The stroker was raced in the 2002 Open Track Challenge. A few parts were redesigned after that engine was torn down. Unfortunately, the next few test engines suffered unrelated failures due to oil contamination from another source. This includes the engine that was to be used in the 2003 OTC as well as the engine for the Supertuner Challenge. It took us some time to track that down, but they had nothing to do with the stroker components themselves. Dyno testing shows that the larger engine benefits from oversize exhaust valves.

Photos (newest at top):

Assembling the final motor.
A close-up of the piston rings.
Pistons and rods, ready to be installed.
The first crank.
A cut-up 2001 block provided measurements.

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