I'm trying to get some of the info that was missing in the article on stroking to explore the possibilities for another piston swap: I'm trying to evalute the possibility of using Mitsubishi 4G63 pistons in a slant six. They're 85 mm stock, so a set of 1.5 mm oversized ones would be perfect for a slant six. However, in addition to the specs for the Mitsu pistons (which I have asked about on another board), I don't have some key slant six dimensions. What is the compression height on a stock, flat top slant six piston? And what is the block's deck height?

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

matt-
what's the pin diameter on those pistons. any idea how much they weigh/what materieal they are made of?

-james

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Stock SL6 compression height 1.765
Block Deck is 10.680
225 con rod c to c is 6.700
Piston Pin is .901

Let us know if you find a good piston cross-over, we could use a nice "off the shelf" forged piston.
DD

Thanks. So far, I haven't turned up anything that can be stuffed into a 225 block without extra long custom rods. The long (by modern standards) compression height is trouble as most import pistons would not give enough compression even with 198 rods on a 225 crank. What's the deck height on a 170?

Here are some examples of off the shelf pistons that are about the right bore and designed for service in turbo engines First, I'll translate slant six piston specs into metric for comparison since it's easier to do that once than to convert all the metric specs in the catalog. The slant six has a 86.36 mm bore and can go up to 88.9 mm. The pistons have a 44.831 compression height and a 22.8854 mm piston pin. Specs are taken from Wiseco's catalog:

Nissan SR20DET. Availible in 86.5 and 87 mm bores. They have a 32 mm compression height, flat tops, and are bored for a 22 mm piston pin so they may need reaming.

Nissan VG30DETT. Like the SR20DET except with a 87.5 mm bore and a 9 cc dish top.

Nissan RB26DETT. This one has an 87 mm bore (stock) and a 30 mm compression height with 21 mm pins. They usually use a 14 cc dome. Ironic that it's easier to find Nissan Skyline pistons than slant six forgings!

Mitsubishi 4G63. They have an 85 mm bore in stock trim but 86.5 mm pistons are availible. These have a 35 mm compression height and a 17 cc dish, along with a 22 mm piston pin.

Toyota 2JZ-GTE (Supra Turbo). 86.5 mm bore, 34 mm compression height, 14.8 cc dish, 22 mm pins.

Toyota 3SGTE. 86.5 mm bore, 35.05 mm compression height, 13 cc dish, 22 mm pins.

It seems a lot of import turbo cars have the right bore for their pistons to be swapped into a slant six, but the wrong compression height. This may be something a bit of creative parts swapping could cure - possibly combined with grinding the journals on a slant six crank down to use other rods. The similarities between piston pins (the same pins will work in several different Honda, Nissan, and Toyota applications) may make it easier to adapt some sort of import connecting rods if it comes to that.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Good work Matt,
The issue is the Slant's long con rod, there is not much out there at 6.7 and 7 inch (198 con rods) or super long for modern engines.

Well, do the math. A little stroke on the crank with a 198 con rod and a bushed wrist pin may do the job.
Looks like the 2.2 / 198 combo is still the best low buck option at this point.
DD

Some block decking and head milling would also make some of those pistons useful with 198 rods.

Lou

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